Java中的使用及连接Redis数据库的方法

发布时间：2020-11-02 17:18:34 来源：亿速云阅读：235 作者：Leah 栏目：开发技术

Java中的使用及连接Redis数据库的方法？相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。

1. 在IDEA中搭建Redis

1.1 创建项目

1.2 添加依赖（不够手动添加）

<dependencies>
  <!--  1、 Jedis-->
  <dependency>
    <groupId>redis.clients</groupId>
    <artifactId>jedis</artifactId>
    <version>2.9.0</version>
  </dependency>
  <!--  2、 Junit测试-->
  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
  </dependency>

  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.2</version>
  </dependency>

  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
  </dependency>
  <dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
  </dependency>
</dependencies>

1.3 测试环境是否搭建成功

@Test
  public void test0() {
    //连接Redis
    Jedis jedis = new Jedis("127.0.0.1", 6379);
    //获取kak
    String kaka = jedis.get("kak");
    log.info(kaka);
    //创建datex
    String datex = jedis.set("datex", new Date().toString());
    //获取datex
    String datex1 = jedis.get("datex");
    log.info(datex1);
    //关闭资源
    jedis.close();
  }

Java中的使用及连接Redis数据库的方法

1.4 利用json存储数据

@Test
  public void test1() {
    JedisPool pool = new JedisPool("127.0.0.1", 6379);
    Jedis jedis = pool.getResource();
    Student student = new Student(1001, "kak", "man", "20");
    String key = "student";
    String field = "1001";
    String s = JsonUtils.objectToJson(student);
    String value = s;
    jedis.hset(key, field, value);
    String hget = jedis.hget(key, field);
    log.info(hget);
    jedis.close();
  }

Java中的使用及连接Redis数据库的方法

1.5 以byte的形式存储对象

@Test
  public void test02() {
    //连接redis
    Jedis jedis = new Jedis("127.0.0.1", 6379);
    String key = "Student";
    Student value = new Student(1002, "taotao", "woman", "20");
    //将key和value转换为byte[]
    byte[] byteKey = SerializationUtils.serialize(key);
    byte[] byteValue = SerializationUtils.serialize(value);
    //将key和value存储到redis中
    jedis.set(byteKey, byteValue);
    //获取value值
    byte[] bytes = jedis.get(byteKey);
    //bytes反序列化为Student对象
    Student stu = (Student) SerializationUtils.deserialize(bytes);
    System.out.println(stu);
    jedis.close();

  }

Java中的使用及连接Redis数据库的方法

1.6 加入连接池的操作

使用连接池操作，可以避免频繁的创建和销毁连接对象的消耗资源

@Test
  public void test3(){
    //创建连接池
    GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
    poolConfig.setMaxTotal(100);//连接池中的最大活跃数
    poolConfig.setMaxIdle(10);//最大空闲数
    poolConfig.setMinIdle(5);//最小空闲数
    poolConfig.setMaxWaitMillis(3000);//连接池空了，3000毫秒后没有获取Jedis对象，超时
    //创建连接池
    JedisPool pool = new JedisPool(poolConfig,"127.0.0.1",6379);
    //通过连接池获取Jedis对象
    Jedis resource = pool.getResource();
    //获取上面添加的datex
    String value = resource.get("datex");
    log.info(value);

    resource.close();
  }

Java中的使用及连接Redis数据库的方法

1.7 管道操作

Redis的管道操作，执行一个命令需要先发送请求到Redis，需要经历网络延迟，Redis还需给客户端一个响应；如果需要一次操作多个命令，可以通过管道，将命令放到客户端的一个Pipeline中，之后一次将命令发送到服务端，服务端一次性返回到客户端；

@Test
  public void test3(){
    //创建连接池
    GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
    poolConfig.setMaxTotal(100);//连接池中的最大活跃数
    poolConfig.setMaxIdle(10);//最大空闲数
    poolConfig.setMinIdle(5);//最小空闲数
    poolConfig.setMaxWaitMillis(3000);//连接池空了，3000毫秒后没有获取Jedis对象，超时
    //创建连接池
    JedisPool pool = new JedisPool(poolConfig,"127.0.0.1",6379);
    //通过连接池获取Jedis对象
    Jedis resource = pool.getResource();
    //获取上面添加的datex
    String value = resource.get("datex");
    log.info(value);

    resource.close();
  }

Java中的使用及连接Redis数据库的方法

2. 从数据中查询数据

场景：
将数据存入Redis中，避免访问量过大，造成数据库奔溃；

2.1 生成实体类

@Test
  public void test3(){
    //创建连接池
    GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
    poolConfig.setMaxTotal(100);//连接池中的最大活跃数
    poolConfig.setMaxIdle(10);//最大空闲数
    poolConfig.setMinIdle(5);//最小空闲数
    poolConfig.setMaxWaitMillis(3000);//连接池空了，3000毫秒后没有获取Jedis对象，超时
    //创建连接池
    JedisPool pool = new JedisPool(poolConfig,"127.0.0.1",6379);
    //通过连接池获取Jedis对象
    Jedis resource = pool.getResource();
    //获取上面添加的datex
    String value = resource.get("datex");
    log.info(value);

    resource.close();
  }

2.2 生成实体模板类

package com.sx.kak.po;

import java.util.ArrayList;
import java.util.List;

public class StudentExample {
  protected String orderByClause;

  protected boolean distinct;

  protected List<Criteria> oredCriteria;

  public StudentExample() {
    oredCriteria = new ArrayList<Criteria>();
  }

  public void setOrderByClause(String orderByClause) {
    this.orderByClause = orderByClause;
  }

  public String getOrderByClause() {
    return orderByClause;
  }

  public void setDistinct(boolean distinct) {
    this.distinct = distinct;
  }

  public boolean isDistinct() {
    return distinct;
  }

  public List<Criteria> getOredCriteria() {
    return oredCriteria;
  }

  public void or(Criteria criteria) {
    oredCriteria.add(criteria);
  }

  public Criteria or() {
    Criteria criteria = createCriteriaInternal();
    oredCriteria.add(criteria);
    return criteria;
  }

  public Criteria createCriteria() {
    Criteria criteria = createCriteriaInternal();
    if (oredCriteria.size() == 0) {
      oredCriteria.add(criteria);
    }
    return criteria;
  }

  protected Criteria createCriteriaInternal() {
    Criteria criteria = new Criteria();
    return criteria;
  }

  public void clear() {
    oredCriteria.clear();
    orderByClause = null;
    distinct = false;
  }

  protected abstract static class GeneratedCriteria {
    protected List<Criterion> criteria;

    protected GeneratedCriteria() {
      super();
      criteria = new ArrayList<Criterion>();
    }

    public boolean isValid() {
      return criteria.size() > 0;
    }

    public List<Criterion> getAllCriteria() {
      return criteria;
    }

    public List<Criterion> getCriteria() {
      return criteria;
    }

    protected void addCriterion(String condition) {
      if (condition == null) {
        throw new RuntimeException("Value for condition cannot be null");
      }
      criteria.add(new Criterion(condition));
    }

    protected void addCriterion(String condition, Object value, String property) {
      if (value == null) {
        throw new RuntimeException("Value for " + property + " cannot be null");
      }
      criteria.add(new Criterion(condition, value));
    }

    protected void addCriterion(String condition, Object value1, Object value2, String property) {
      if (value1 == null || value2 == null) {
        throw new RuntimeException("Between values for " + property + " cannot be null");
      }
      criteria.add(new Criterion(condition, value1, value2));
    }

    public Criteria andIdIsNull() {
      addCriterion("id is null");
      return (Criteria) this;
    }

    public Criteria andIdIsNotNull() {
      addCriterion("id is not null");
      return (Criteria) this;
    }

    public Criteria andIdEqualTo(Integer value) {
      addCriterion("id =", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdNotEqualTo(Integer value) {
      addCriterion("id <>", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdGreaterThan(Integer value) {
      addCriterion("id >", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdGreaterThanOrEqualTo(Integer value) {
      addCriterion("id >=", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdLessThan(Integer value) {
      addCriterion("id <", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdLessThanOrEqualTo(Integer value) {
      addCriterion("id <=", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdIn(List<Integer> values) {
      addCriterion("id in", values, "id");
      return (Criteria) this;
    }

    public Criteria andIdNotIn(List<Integer> values) {
      addCriterion("id not in", values, "id");
      return (Criteria) this;
    }

    public Criteria andIdBetween(Integer value1, Integer value2) {
      addCriterion("id between", value1, value2, "id");
      return (Criteria) this;
    }

    public Criteria andIdNotBetween(Integer value1, Integer value2) {
      addCriterion("id not between", value1, value2, "id");
      return (Criteria) this;
    }

    public Criteria andNameIsNull() {
      addCriterion("NAME is null");
      return (Criteria) this;
    }

    public Criteria andNameIsNotNull() {
      addCriterion("NAME is not null");
      return (Criteria) this;
    }

    public Criteria andNameEqualTo(String value) {
      addCriterion("NAME =", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameNotEqualTo(String value) {
      addCriterion("NAME <>", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameGreaterThan(String value) {
      addCriterion("NAME >", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameGreaterThanOrEqualTo(String value) {
      addCriterion("NAME >=", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameLessThan(String value) {
      addCriterion("NAME <", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameLessThanOrEqualTo(String value) {
      addCriterion("NAME <=", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameLike(String value) {
      addCriterion("NAME like", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameNotLike(String value) {
      addCriterion("NAME not like", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameIn(List<String> values) {
      addCriterion("NAME in", values, "name");
      return (Criteria) this;
    }

    public Criteria andNameNotIn(List<String> values) {
      addCriterion("NAME not in", values, "name");
      return (Criteria) this;
    }

    public Criteria andNameBetween(String value1, String value2) {
      addCriterion("NAME between", value1, value2, "name");
      return (Criteria) this;
    }

    public Criteria andNameNotBetween(String value1, String value2) {
      addCriterion("NAME not between", value1, value2, "name");
      return (Criteria) this;
    }

    public Criteria andSexIsNull() {
      addCriterion("sex is null");
      return (Criteria) this;
    }

    public Criteria andSexIsNotNull() {
      addCriterion("sex is not null");
      return (Criteria) this;
    }

    public Criteria andSexEqualTo(String value) {
      addCriterion("sex =", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexNotEqualTo(String value) {
      addCriterion("sex <>", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexGreaterThan(String value) {
      addCriterion("sex >", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexGreaterThanOrEqualTo(String value) {
      addCriterion("sex >=", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexLessThan(String value) {
      addCriterion("sex <", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexLessThanOrEqualTo(String value) {
      addCriterion("sex <=", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexLike(String value) {
      addCriterion("sex like", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexNotLike(String value) {
      addCriterion("sex not like", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexIn(List<String> values) {
      addCriterion("sex in", values, "sex");
      return (Criteria) this;
    }

    public Criteria andSexNotIn(List<String> values) {
      addCriterion("sex not in", values, "sex");
      return (Criteria) this;
    }

    public Criteria andSexBetween(String value1, String value2) {
      addCriterion("sex between", value1, value2, "sex");
      return (Criteria) this;
    }

    public Criteria andSexNotBetween(String value1, String value2) {
      addCriterion("sex not between", value1, value2, "sex");
      return (Criteria) this;
    }

    public Criteria andAgeIsNull() {
      addCriterion("age is null");
      return (Criteria) this;
    }

    public Criteria andAgeIsNotNull() {
      addCriterion("age is not null");
      return (Criteria) this;
    }

    public Criteria andAgeEqualTo(String value) {
      addCriterion("age =", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeNotEqualTo(String value) {
      addCriterion("age <>", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeGreaterThan(String value) {
      addCriterion("age >", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeGreaterThanOrEqualTo(String value) {
      addCriterion("age >=", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeLessThan(String value) {
      addCriterion("age <", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeLessThanOrEqualTo(String value) {
      addCriterion("age <=", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeLike(String value) {
      addCriterion("age like", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeNotLike(String value) {
      addCriterion("age not like", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeIn(List<String> values) {
      addCriterion("age in", values, "age");
      return (Criteria) this;
    }

    public Criteria andAgeNotIn(List<String> values) {
      addCriterion("age not in", values, "age");
      return (Criteria) this;
    }

    public Criteria andAgeBetween(String value1, String value2) {
      addCriterion("age between", value1, value2, "age");
      return (Criteria) this;
    }

    public Criteria andAgeNotBetween(String value1, String value2) {
      addCriterion("age not between", value1, value2, "age");
      return (Criteria) this;
    }
  }

  public static class Criteria extends GeneratedCriteria {

    protected Criteria() {
      super();
    }
  }

  public static class Criterion {
    private String condition;

    private Object value;

    private Object secondValue;

    private boolean noValue;

    private boolean singleValue;

    private boolean betweenValue;

    private boolean listValue;

    private String typeHandler;

    public String getCondition() {
      return condition;
    }

    public Object getValue() {
      return value;
    }

    public Object getSecondValue() {
      return secondValue;
    }

    public boolean isNoValue() {
      return noValue;
    }

    public boolean isSingleValue() {
      return singleValue;
    }

    public boolean isBetweenValue() {
      return betweenValue;
    }

    public boolean isListValue() {
      return listValue;
    }

    public String getTypeHandler() {
      return typeHandler;
    }

    protected Criterion(String condition) {
      super();
      this.condition = condition;
      this.typeHandler = null;
      this.noValue = true;
    }

    protected Criterion(String condition, Object value, String typeHandler) {
      super();
      this.condition = condition;
      this.value = value;
      this.typeHandler = typeHandler;
      if (value instanceof List<&#63;>) {
        this.listValue = true;
      } else {
        this.singleValue = true;
      }
    }

    protected Criterion(String condition, Object value) {
      this(condition, value, null);
    }

    protected Criterion(String condition, Object value, Object secondValue, String typeHandler) {
      super();
      this.condition = condition;
      this.value = value;
      this.secondValue = secondValue;
      this.typeHandler = typeHandler;
      this.betweenValue = true;
    }

    protected Criterion(String condition, Object value, Object secondValue) {
      this(condition, value, secondValue, null);
    }
  }
}

2.3 生成studentMapper.java

package com.sx.kak.po;

import java.util.ArrayList;
import java.util.List;

public class StudentExample {
  protected String orderByClause;

  protected boolean distinct;

  protected List<Criteria> oredCriteria;

  public StudentExample() {
    oredCriteria = new ArrayList<Criteria>();
  }

  public void setOrderByClause(String orderByClause) {
    this.orderByClause = orderByClause;
  }

  public String getOrderByClause() {
    return orderByClause;
  }

  public void setDistinct(boolean distinct) {
    this.distinct = distinct;
  }

  public boolean isDistinct() {
    return distinct;
  }

  public List<Criteria> getOredCriteria() {
    return oredCriteria;
  }

  public void or(Criteria criteria) {
    oredCriteria.add(criteria);
  }

  public Criteria or() {
    Criteria criteria = createCriteriaInternal();
    oredCriteria.add(criteria);
    return criteria;
  }

  public Criteria createCriteria() {
    Criteria criteria = createCriteriaInternal();
    if (oredCriteria.size() == 0) {
      oredCriteria.add(criteria);
    }
    return criteria;
  }

  protected Criteria createCriteriaInternal() {
    Criteria criteria = new Criteria();
    return criteria;
  }

  public void clear() {
    oredCriteria.clear();
    orderByClause = null;
    distinct = false;
  }

  protected abstract static class GeneratedCriteria {
    protected List<Criterion> criteria;

    protected GeneratedCriteria() {
      super();
      criteria = new ArrayList<Criterion>();
    }

    public boolean isValid() {
      return criteria.size() > 0;
    }

    public List<Criterion> getAllCriteria() {
      return criteria;
    }

    public List<Criterion> getCriteria() {
      return criteria;
    }

    protected void addCriterion(String condition) {
      if (condition == null) {
        throw new RuntimeException("Value for condition cannot be null");
      }
      criteria.add(new Criterion(condition));
    }

    protected void addCriterion(String condition, Object value, String property) {
      if (value == null) {
        throw new RuntimeException("Value for " + property + " cannot be null");
      }
      criteria.add(new Criterion(condition, value));
    }

    protected void addCriterion(String condition, Object value1, Object value2, String property) {
      if (value1 == null || value2 == null) {
        throw new RuntimeException("Between values for " + property + " cannot be null");
      }
      criteria.add(new Criterion(condition, value1, value2));
    }

    public Criteria andIdIsNull() {
      addCriterion("id is null");
      return (Criteria) this;
    }

    public Criteria andIdIsNotNull() {
      addCriterion("id is not null");
      return (Criteria) this;
    }

    public Criteria andIdEqualTo(Integer value) {
      addCriterion("id =", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdNotEqualTo(Integer value) {
      addCriterion("id <>", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdGreaterThan(Integer value) {
      addCriterion("id >", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdGreaterThanOrEqualTo(Integer value) {
      addCriterion("id >=", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdLessThan(Integer value) {
      addCriterion("id <", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdLessThanOrEqualTo(Integer value) {
      addCriterion("id <=", value, "id");
      return (Criteria) this;
    }

    public Criteria andIdIn(List<Integer> values) {
      addCriterion("id in", values, "id");
      return (Criteria) this;
    }

    public Criteria andIdNotIn(List<Integer> values) {
      addCriterion("id not in", values, "id");
      return (Criteria) this;
    }

    public Criteria andIdBetween(Integer value1, Integer value2) {
      addCriterion("id between", value1, value2, "id");
      return (Criteria) this;
    }

    public Criteria andIdNotBetween(Integer value1, Integer value2) {
      addCriterion("id not between", value1, value2, "id");
      return (Criteria) this;
    }

    public Criteria andNameIsNull() {
      addCriterion("NAME is null");
      return (Criteria) this;
    }

    public Criteria andNameIsNotNull() {
      addCriterion("NAME is not null");
      return (Criteria) this;
    }

    public Criteria andNameEqualTo(String value) {
      addCriterion("NAME =", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameNotEqualTo(String value) {
      addCriterion("NAME <>", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameGreaterThan(String value) {
      addCriterion("NAME >", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameGreaterThanOrEqualTo(String value) {
      addCriterion("NAME >=", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameLessThan(String value) {
      addCriterion("NAME <", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameLessThanOrEqualTo(String value) {
      addCriterion("NAME <=", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameLike(String value) {
      addCriterion("NAME like", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameNotLike(String value) {
      addCriterion("NAME not like", value, "name");
      return (Criteria) this;
    }

    public Criteria andNameIn(List<String> values) {
      addCriterion("NAME in", values, "name");
      return (Criteria) this;
    }

    public Criteria andNameNotIn(List<String> values) {
      addCriterion("NAME not in", values, "name");
      return (Criteria) this;
    }

    public Criteria andNameBetween(String value1, String value2) {
      addCriterion("NAME between", value1, value2, "name");
      return (Criteria) this;
    }

    public Criteria andNameNotBetween(String value1, String value2) {
      addCriterion("NAME not between", value1, value2, "name");
      return (Criteria) this;
    }

    public Criteria andSexIsNull() {
      addCriterion("sex is null");
      return (Criteria) this;
    }

    public Criteria andSexIsNotNull() {
      addCriterion("sex is not null");
      return (Criteria) this;
    }

    public Criteria andSexEqualTo(String value) {
      addCriterion("sex =", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexNotEqualTo(String value) {
      addCriterion("sex <>", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexGreaterThan(String value) {
      addCriterion("sex >", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexGreaterThanOrEqualTo(String value) {
      addCriterion("sex >=", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexLessThan(String value) {
      addCriterion("sex <", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexLessThanOrEqualTo(String value) {
      addCriterion("sex <=", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexLike(String value) {
      addCriterion("sex like", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexNotLike(String value) {
      addCriterion("sex not like", value, "sex");
      return (Criteria) this;
    }

    public Criteria andSexIn(List<String> values) {
      addCriterion("sex in", values, "sex");
      return (Criteria) this;
    }

    public Criteria andSexNotIn(List<String> values) {
      addCriterion("sex not in", values, "sex");
      return (Criteria) this;
    }

    public Criteria andSexBetween(String value1, String value2) {
      addCriterion("sex between", value1, value2, "sex");
      return (Criteria) this;
    }

    public Criteria andSexNotBetween(String value1, String value2) {
      addCriterion("sex not between", value1, value2, "sex");
      return (Criteria) this;
    }

    public Criteria andAgeIsNull() {
      addCriterion("age is null");
      return (Criteria) this;
    }

    public Criteria andAgeIsNotNull() {
      addCriterion("age is not null");
      return (Criteria) this;
    }

    public Criteria andAgeEqualTo(String value) {
      addCriterion("age =", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeNotEqualTo(String value) {
      addCriterion("age <>", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeGreaterThan(String value) {
      addCriterion("age >", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeGreaterThanOrEqualTo(String value) {
      addCriterion("age >=", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeLessThan(String value) {
      addCriterion("age <", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeLessThanOrEqualTo(String value) {
      addCriterion("age <=", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeLike(String value) {
      addCriterion("age like", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeNotLike(String value) {
      addCriterion("age not like", value, "age");
      return (Criteria) this;
    }

    public Criteria andAgeIn(List<String> values) {
      addCriterion("age in", values, "age");
      return (Criteria) this;
    }

    public Criteria andAgeNotIn(List<String> values) {
      addCriterion("age not in", values, "age");
      return (Criteria) this;
    }

    public Criteria andAgeBetween(String value1, String value2) {
      addCriterion("age between", value1, value2, "age");
      return (Criteria) this;
    }

    public Criteria andAgeNotBetween(String value1, String value2) {
      addCriterion("age not between", value1, value2, "age");
      return (Criteria) this;
    }
  }

  public static class Criteria extends GeneratedCriteria {

    protected Criteria() {
      super();
    }
  }

  public static class Criterion {
    private String condition;

    private Object value;

    private Object secondValue;

    private boolean noValue;

    private boolean singleValue;

    private boolean betweenValue;

    private boolean listValue;

    private String typeHandler;

    public String getCondition() {
      return condition;
    }

    public Object getValue() {
      return value;
    }

    public Object getSecondValue() {
      return secondValue;
    }

    public boolean isNoValue() {
      return noValue;
    }

    public boolean isSingleValue() {
      return singleValue;
    }

    public boolean isBetweenValue() {
      return betweenValue;
    }

    public boolean isListValue() {
      return listValue;
    }

    public String getTypeHandler() {
      return typeHandler;
    }

    protected Criterion(String condition) {
      super();
      this.condition = condition;
      this.typeHandler = null;
      this.noValue = true;
    }

    protected Criterion(String condition, Object value, String typeHandler) {
      super();
      this.condition = condition;
      this.value = value;
      this.typeHandler = typeHandler;
      if (value instanceof List<&#63;>) {
        this.listValue = true;
      } else {
        this.singleValue = true;
      }
    }

    protected Criterion(String condition, Object value) {
      this(condition, value, null);
    }

    protected Criterion(String condition, Object value, Object secondValue, String typeHandler) {
      super();
      this.condition = condition;
      this.value = value;
      this.secondValue = secondValue;
      this.typeHandler = typeHandler;
      this.betweenValue = true;
    }

    protected Criterion(String condition, Object value, Object secondValue) {
      this(condition, value, secondValue, null);
    }
  }
}

2.4 生成StudentMapper.xml

<&#63;xml version="1.0" encoding="UTF-8" &#63;>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.sx.kak.mapper.StudentMapper" >
 <resultMap id="BaseResultMap" type="com.sx.kak.po.Student" >
  <id column="id" property="id" jdbcType="INTEGER" />
  <result column="NAME" property="name" jdbcType="VARCHAR" />
  <result column="sex" property="sex" jdbcType="VARCHAR" />
  <result column="age" property="age" jdbcType="VARCHAR" />
 </resultMap>
 <sql id="Example_Where_Clause" >
  <where >
   <foreach collection="oredCriteria" item="criteria" separator="or" >
    <if test="criteria.valid" >
     <trim prefix="(" suffix=")" prefixOverrides="and" >
      <foreach collection="criteria.criteria" item="criterion" >
       <choose >
        <when test="criterion.noValue" >
         and ${criterion.condition}
        </when>
        <when test="criterion.singleValue" >
         and ${criterion.condition} #{criterion.value}
        </when>
        <when test="criterion.betweenValue" >
         and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
        </when>
        <when test="criterion.listValue" >
         and ${criterion.condition}
         <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
          #{listItem}
         </foreach>
        </when>
       </choose>
      </foreach>
     </trim>
    </if>
   </foreach>
  </where>
 </sql>
 <sql id="Update_By_Example_Where_Clause" >
  <where >
   <foreach collection="example.oredCriteria" item="criteria" separator="or" >
    <if test="criteria.valid" >
     <trim prefix="(" suffix=")" prefixOverrides="and" >
      <foreach collection="criteria.criteria" item="criterion" >
       <choose >
        <when test="criterion.noValue" >
         and ${criterion.condition}
        </when>
        <when test="criterion.singleValue" >
         and ${criterion.condition} #{criterion.value}
        </when>
        <when test="criterion.betweenValue" >
         and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
        </when>
        <when test="criterion.listValue" >
         and ${criterion.condition}
         <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
          #{listItem}
         </foreach>
        </when>
       </choose>
      </foreach>
     </trim>
    </if>
   </foreach>
  </where>
 </sql>
 <sql id="Base_Column_List" >
  id, NAME, sex, age
 </sql>
 <select id="selectByExample" resultMap="BaseResultMap" parameterType="com.sx.kak.po.StudentExample" >
  select
  <if test="distinct" >
   distinct
  </if>
  <include refid="Base_Column_List" />
  from student
  <if test="_parameter != null" >
   <include refid="Example_Where_Clause" />
  </if>
  <if test="orderByClause != null" >
   order by ${orderByClause}
  </if>
 </select>
 <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
  select 
  <include refid="Base_Column_List" />
  from student
  where id = #{id,jdbcType=INTEGER}
 </select>
 <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
  delete from student
  where id = #{id,jdbcType=INTEGER}
 </delete>
 <delete id="deleteByExample" parameterType="com.sx.kak.po.StudentExample" >
  delete from student
  <if test="_parameter != null" >
   <include refid="Example_Where_Clause" />
  </if>
 </delete>
 <insert id="insert" parameterType="com.sx.kak.po.Student" >
  insert into student (id, NAME, sex, 
   age)
  values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{sex,jdbcType=VARCHAR}, 
   #{age,jdbcType=VARCHAR})
 </insert>
 <insert id="insertSelective" parameterType="com.sx.kak.po.Student" >
  insert into student
  <trim prefix="(" suffix=")" suffixOverrides="," >
   <if test="id != null" >
    id,
   </if>
   <if test="name != null" >
    NAME,
   </if>
   <if test="sex != null" >
    sex,
   </if>
   <if test="age != null" >
    age,
   </if>
  </trim>
  <trim prefix="values (" suffix=")" suffixOverrides="," >
   <if test="id != null" >
    #{id,jdbcType=INTEGER},
   </if>
   <if test="name != null" >
    #{name,jdbcType=VARCHAR},
   </if>
   <if test="sex != null" >
    #{sex,jdbcType=VARCHAR},
   </if>
   <if test="age != null" >
    #{age,jdbcType=VARCHAR},
   </if>
  </trim>
 </insert>
 <select id="countByExample" parameterType="com.sx.kak.po.StudentExample" resultType="java.lang.Integer" >
  select count(*) from student
  <if test="_parameter != null" >
   <include refid="Example_Where_Clause" />
  </if>
 </select>
 <update id="updateByExampleSelective" parameterType="map" >
  update student
  <set >
   <if test="record.id != null" >
    id = #{record.id,jdbcType=INTEGER},
   </if>
   <if test="record.name != null" >
    NAME = #{record.name,jdbcType=VARCHAR},
   </if>
   <if test="record.sex != null" >
    sex = #{record.sex,jdbcType=VARCHAR},
   </if>
   <if test="record.age != null" >
    age = #{record.age,jdbcType=VARCHAR},
   </if>
  </set>
  <if test="_parameter != null" >
   <include refid="Update_By_Example_Where_Clause" />
  </if>
 </update>
 <update id="updateByExample" parameterType="map" >
  update student
  set id = #{record.id,jdbcType=INTEGER},
   NAME = #{record.name,jdbcType=VARCHAR},
   sex = #{record.sex,jdbcType=VARCHAR},
   age = #{record.age,jdbcType=VARCHAR}
  <if test="_parameter != null" >
   <include refid="Update_By_Example_Where_Clause" />
  </if>
 </update>
 <update id="updateByPrimaryKeySelective" parameterType="com.sx.kak.po.Student" >
  update student
  <set >
   <if test="name != null" >
    NAME = #{name,jdbcType=VARCHAR},
   </if>
   <if test="sex != null" >
    sex = #{sex,jdbcType=VARCHAR},
   </if>
   <if test="age != null" >
    age = #{age,jdbcType=VARCHAR},
   </if>
  </set>
  where id = #{id,jdbcType=INTEGER}
 </update>
 <update id="updateByPrimaryKey" parameterType="com.sx.kak.po.Student" >
  update student
  set NAME = #{name,jdbcType=VARCHAR},
   sex = #{sex,jdbcType=VARCHAR},
   age = #{age,jdbcType=VARCHAR}
  where id = #{id,jdbcType=INTEGER}
 </update>
</mapper>

2.5 编写application.yml

server:
 port: 8080
spring:
 datasource:
  driver-class-name: com.mysql.cj.jdbc.Driver
  url: jdbc:mysql://localhost:3306/db0711&#63;characterEncoding=utf8&serverTimezone=UTC
  username: root
  password: root
mybatis:
 type-aliases-package: po
 mapper-locations: classpath:mapping/*.xml

2.6 编写JsonUtils工具类

package com.sx.kak.utils;

import java.util.List;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;


public class JsonUtils {

  // 定义jackson对象
  private static final ObjectMapper MAPPER = new ObjectMapper();

  /**
   * 将对象转换成json字符串。
   * <p>Title: pojoToJson</p>
   * <p>Description: </p>
   * @param data
   * @return
   */
  public static String objectToJson(Object data) {
  	try {
			String string = MAPPER.writeValueAsString(data);
			return string;
		} catch (JsonProcessingException e) {
			e.printStackTrace();
		}
  	return null;
  }
  
  /**
   * 将json结果集转化为对象
   * 
   * @param jsonData json数据
   * @param clazz 对象中的object类型
   * @return
   */
  public static <T> T jsonToPojo(String jsonData, Class<T> beanType) {
    try {
      T t = MAPPER.readValue(jsonData, beanType);
      return t;
    } catch (Exception e) {
    	e.printStackTrace();
    }
    return null;
  }
  
  /**
   * 将json数据转换成pojo对象list
   * <p>Title: jsonToList</p>
   * <p>Description: </p>
   * @param jsonData
   * @param beanType
   * @return
   */
  public static <T>List<T> jsonToList(String jsonData, Class<T> beanType) {
  	JavaType javaType = MAPPER.getTypeFactory().constructParametricType(List.class, beanType);
  	try {
  		List<T> list = MAPPER.readValue(jsonData, javaType);
  		return list;
		} catch (Exception e) {
			e.printStackTrace();
		}
  	return null;
  }
}

2.7 编写RedisUtils工具类

package com.sx.kak.utils;

import java.util.List;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;


public class JsonUtils {

  // 定义jackson对象
  private static final ObjectMapper MAPPER = new ObjectMapper();

  /**
   * 将对象转换成json字符串。
   * <p>Title: pojoToJson</p>
   * <p>Description: </p>
   * @param data
   * @return
   */
  public static String objectToJson(Object data) {
  	try {
			String string = MAPPER.writeValueAsString(data);
			return string;
		} catch (JsonProcessingException e) {
			e.printStackTrace();
		}
  	return null;
  }
  
  /**
   * 将json结果集转化为对象
   * 
   * @param jsonData json数据
   * @param clazz 对象中的object类型
   * @return
   */
  public static <T> T jsonToPojo(String jsonData, Class<T> beanType) {
    try {
      T t = MAPPER.readValue(jsonData, beanType);
      return t;
    } catch (Exception e) {
    	e.printStackTrace();
    }
    return null;
  }
  
  /**
   * 将json数据转换成pojo对象list
   * <p>Title: jsonToList</p>
   * <p>Description: </p>
   * @param jsonData
   * @param beanType
   * @return
   */
  public static <T>List<T> jsonToList(String jsonData, Class<T> beanType) {
  	JavaType javaType = MAPPER.getTypeFactory().constructParametricType(List.class, beanType);
  	try {
  		List<T> list = MAPPER.readValue(jsonData, javaType);
  		return list;
		} catch (Exception e) {
			e.printStackTrace();
		}
  	return null;
  }
}

2.8 编写RedisUtils工具类的实现类

package com.sx.kak.utils;

import redis.clients.jedis.Jedis;

/**
 * Created by Kak on 2020/9/17.
 */
public class SingleTonRedisUtil implements RedisUtils{
  private Jedis jedis;
  public SingleTonRedisUtil(Jedis jedis){
    this.jedis = jedis;
  }
  @Override
  public void hset(String key, String filed, String value) {
    jedis.hset(key, filed, value);
  }

  @Override
  public String hget(String key, String field) {
    return jedis.hget(key, field);
  }
}

2.9 配置初始化文件

package com.sx.kak.config;

import com.sx.kak.utils.SingleTonRedisUtil;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import redis.clients.jedis.Jedis;

/**
 * Created by Kak on 2020/9/17.
 */
@Configuration
public class RedisConfig {
  @Bean
  public SingleTonRedisUtil singleTonRedisUtil(@Qualifier("jedis") Jedis jedis){
    SingleTonRedisUtil singleTonRedisUtil = new SingleTonRedisUtil(jedis);
    return singleTonRedisUtil;
  }

  @Bean(name = "jedis")
  public Jedis getJedis(){
    Jedis jedis = new Jedis("127.0.0.1",6379);
    return jedis;
  }
}

2.10 配置StudentService.java

package com.sx.kak.service;

import com.sx.kak.po.Student;

import java.util.List;

/**
 * Created by Kak on 2020/9/17.
 */
public interface StudentService {
  public List<Student> findAllStudent();
}

2.11 配置StudentServiceImpl.java

package com.sx.kak.service.serviceImpl;

import com.sx.kak.mapper.StudentMapper;
import com.sx.kak.po.Student;
import com.sx.kak.po.StudentExample;
import com.sx.kak.service.StudentService;
import com.sx.kak.utils.JsonUtils;
import com.sx.kak.utils.SingleTonRedisUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

/**
 * Created by Kak on 2020/9/17.
 */
@Service
@Slf4j
public class StudentServiceImpl implements StudentService {
  @Autowired(required = false)
  private StudentMapper studentMapper;
  //注入自定义的redis工具
  @Autowired
  private SingleTonRedisUtil redisUtil;

  @Override
  public List<Student> findAllStudent() {
    //获取redis中存出的json字符串
    String student = redisUtil.hget("student", "0");
    if(student!=null){
      log.info("get student from redis");
      //json对象，封装的对象类型
      List<Student> students = JsonUtils.jsonToList(student, Student.class);
      return students;
    }
    //创建查询模板对象
    StudentExample studentExample = new StudentExample();
    List<Student> students = studentMapper.selectByExample(studentExample);
    log.info("get student from db");
    try{
      //将查询的集合转化为json字符串
      String s = JsonUtils.objectToJson(students);
      //放入redis中
      redisUtil.hset("student","0",s);
      log.info("set data to redis");
    }catch (Exception ex){
      log.info(ex.getMessage());
    }
    return students;
  }
}

2.12 编写全查展示页面

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
  <meta charset="UTF-8"/>
  <title>学生全查页面</title>
</head>

<body>
<div id="findAll">
  <table>
    <tr>
      <th>ID</th>
      <th>NAME</th>
      <th>SEX</th>
      <th>AGE</th>
      <th>Action</th>
    </tr>
    <tr th:each="s:${students}">
      <td th:text="${s.id}"></td>
      <td th:text="${s.name}"></td>
      <td th:text="${s.sex}"></td>
      <td th:text="${s.age}"></td>
    </tr>
  </table>
</div>
</body>
</html>

2.13 编写StudentController

package com.sx.kak.Controller;

import com.sx.kak.po.Student;
import com.sx.kak.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * Created by Kak on 2020/9/17.
 */
@Controller
public class StudentController {
  @Autowired(required = false)
  private StudentService studentService;

  @RequestMapping("/findStudent")
  public String findAllStu(Model model){
    List<Student> allStudent = studentService.findAllStudent();
    model.addAttribute("students",allStudent);
    return "showAllStudent";
  }
}

Java中的使用及连接Redis数据库的方法

3. 结果

从打印出的日志可以看出，第一次访问是从数据库得到数据，然后存入redis中
第二次直接从redis中获取

Java中的使用及连接Redis数据库的方法

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