Redis在Java中的使用及连接数据库(附源码)

时间:2020-9-19 作者:admin

Redis在Java中的使用及连接数据库(附源码)

引言:

         本文主要分享了Redis如何在IDEA中部署,运行;模拟加入Redis的操作;

文章目录


Redis在Java中的使用及连接数据库(附源码)

1. 在IDEA中搭建Redis

1.1 创建项目

新建含有web的SpringBoot项目;

Redis在Java中的使用及连接数据库(附源码)

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();
    }

Redis在Java中的使用及连接数据库(附源码)

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();
    }

Redis在Java中的使用及连接数据库(附源码)

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();

    }

Redis在Java中的使用及连接数据库(附源码)

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();
    }

Redis在Java中的使用及连接数据库(附源码)

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 test04(){
        //创建连接池
        JedisPool pool = new JedisPool("127.0.0.1", 6379);
        long l = System.currentTimeMillis();
        //获取连接对象
        Jedis jedis = pool.getResource();
        //创建管道
        Pipeline pipelined = jedis.pipelined();
        //创建执行kk100000次放入管道中
        for(int i=0;i<100000;i++){
            pipelined.incr("kk");
        }
        //执行命令
        pipelined.syncAndReturnAll();
        jedis.close();

        System.out.print(System.currentTimeMillis() -1);
    }

Redis在Java中的使用及连接数据库(附源码)

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

package com.sx.kak.po;

import com.sun.xml.internal.ws.developer.Serialization;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.util.SerializationUtils;

import java.io.Serializable;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student implements Serializable {
    private Integer id;

    private String name;

    private String sex;

    private String age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex == null ? null : sex.trim();
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age == null ? null : age.trim();
    }
}

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<?>) {
                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.mapper;

import com.sx.kak.po.Student;
import com.sx.kak.po.StudentExample;
import java.util.List;
import org.apache.ibatis.annotations.Param;

public interface StudentMapper {
    int countByExample(StudentExample example);

    int deleteByExample(StudentExample example);

    int deleteByPrimaryKey(Integer id);

    int insert(Student record);

    int insertSelective(Student record);

    List<Student> selectByExample(StudentExample example);

    Student selectByPrimaryKey(Integer id);

    int updateByExampleSelective(@Param("record") Student record, @Param("example") StudentExample example);

    int updateByExample(@Param("record") Student record, @Param("example") StudentExample example);

    int updateByPrimaryKeySelective(Student record);

    int updateByPrimaryKey(Student record);
}

2.4 生成StudentMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!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?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;

/**
 * Created by Kak on 2020/9/17.
 */
public interface RedisUtils {
    public void hset(String key,String filed,String value);
    public String hget(String key,String field );
    public void set(String key ,String value);
    public String get (String key);
    public void expire(String key,int seconds);
    public long ttl(String key);
}

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";
    }
}

Redis在Java中的使用及连接数据库(附源码)

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

Redis在Java中的使用及连接数据库(附源码)

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