Redis之实战篇（与Mybatis整合）

摘要: 现在市面流行的java框架，一个是ssh（spring、struts2、hibernate），另一个是ssm（spring、springmvc、mybatis），由于之前已经有整合过ssm框架，所以在此基础上进行略微的改动，做一个Redis与Mybatis的整合

具体步骤如下：

1，准备好ssm工程，如果有不会的，可以参考

springmvc+mybatis整合

2，准备好Redis服务器

3，构建 pom.xml 文件，这个pom文件和之前ssm的基本一样，只是添加了redis的支持

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.demo</groupId>
	<artifactId>demo</artifactId>
	<packaging>war</packaging>
	<version>0.0.1-SNAPSHOT</version>
	<name>demo Maven Webapp</name>
	<properties>
		<!-- spring版本号 -->
		<spring.version>4.2.2.RELEASE</spring.version>
		<!-- mybatis版本号 -->
		<mybatis.version>3.3.0</mybatis.version>
		<!-- log4j日志文件管理包版本 -->
		<slf4j.version>1.7.7</slf4j.version>
		<log4j.version>1.2.17</log4j.version>
	</properties>

	<dependencies>
		<dependency>
		    <groupId>jdk.tools</groupId>
		    <artifactId>jdk.tools</artifactId>
		    <version>1.7</version>
		    <scope>system</scope>
		    <systemPath>${JAVA_HOME}/lib/tools.jar</systemPath>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.11</version>
			<!-- 表示开发的时候引入，发布的时候不会加载此包 -->
			<scope>test</scope>
		</dependency><!-- spring核心包 --><dependency><groupId>org.springframework</groupId><artifactId>spring-core</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-oxm</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-tx</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-aop</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context-support</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>${spring.version}</version></dependency><!-- mybatis核心包 --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>${mybatis.version}</version></dependency><!-- mybatis/spring包 --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>1.2.2</version></dependency><!-- 导入java ee jar 包 --><dependency><groupId>javax</groupId><artifactId>javaee-api</artifactId><version>7.0</version></dependency><!-- 导入Mysql数据库链接jar包 --><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.30</version></dependency><!-- 导入dbcp的jar包，用来在applicationContext.xml中配置数据库 --><dependency><groupId>commons-dbcp</groupId><artifactId>commons-dbcp</artifactId><version>1.2.2</version></dependency><!-- JSTL标签类 --><dependency><groupId>jstl</groupId><artifactId>jstl</artifactId><version>1.2</version></dependency><!-- 日志文件管理包 --><!-- log start --><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>${log4j.version}</version></dependency><!-- 格式化对象，方便输出日志 --><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.1.41</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>${slf4j.version}</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>${slf4j.version}</version></dependency><!-- log end --><!-- 映入JSON --><dependency><groupId>org.codehaus.jackson</groupId><artifactId>jackson-mapper-asl</artifactId><version>1.9.13</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-core</artifactId><version>2.1.0</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.1.0</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-annotations</artifactId><version>2.1.0</version></dependency><!-- 上传组件包 --><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3.1</version></dependency><dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.4</version></dependency><dependency><groupId>commons-codec</groupId><artifactId>commons-codec</artifactId><version>1.9</version></dependency><dependency>
		  <groupId>redis.clients</groupId>
		  <artifactId>jedis</artifactId>
		  <version>2.8.0</version></dependency><dependency>
		  <groupId>commons-pool</groupId>
		  <artifactId>commons-pool</artifactId>
		  <version>1.6</version></dependency></dependencies><build><finalName>${project.artifactId}</finalName><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>2.3.2</version><configuration><source>${java-version}</source><target>${java-version}</target><encoding>utf8</encoding></configuration></plugin></plugins></build></project>

4，编写Redis需要用的2个工具类   RedisUtil.java和SerializeUtil.java。这个在前一篇已经有过，这里不再重复贴代码了。

5，新增一个Cache类，需要实现 org.apache.ibatis.cache.Cache 接口

package demo.cache;

import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.ibatis.cache.Cache;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import demo.utils.RedisUtil;
import demo.utils.SerializeUtil;

public class MybatisRedisCache implements Cache {
	private static Logger logger = LoggerFactory.getLogger(MybatisRedisCache.class); 
	/** The ReadWriteLock. */ 
	private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
	
	private String id;
	
	public MybatisRedisCache(final String id) {  
		if (id == null) {
            throw new IllegalArgumentException("Cache instances require an ID");
        }
		logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>MybatisRedisCache:id="+id);
        this.id = id;
    }  
	
	public String getId() {
		return this.id;
	}

	public void putObject(Object key, Object value) {
		logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>putObject:"+key+"="+value);
		RedisUtil.getJedis().set(SerializeUtil.serialize(key.toString()), SerializeUtil.serialize(value));
	}

	public Object getObject(Object key) {
		Object value = SerializeUtil.unserialize(RedisUtil.getJedis().get(SerializeUtil.serialize(key.toString())));
		logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>getObject:"+key+"="+value);
		return value;
	}

	public Object removeObject(Object key) {
		return RedisUtil.getJedis().expire(SerializeUtil.serialize(key.toString()),0);
	}

	public void clear() {
		RedisUtil.getJedis().flushDB();
	}

	public int getSize() {
		return Integer.valueOf(RedisUtil.getJedis().dbSize().toString());
	}

	public ReadWriteLock getReadWriteLock() {
		return readWriteLock;
	}
	
}

6，开启mybatis对缓存的支持，在本项目中，是修改 spring-mybatis.xml 文件

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
		<property name="dataSource" ref="dataSource" />
		<!-- 自动扫描mapping.xml文件 -->
		<property name="mapperLocations" value="classpath:demo/mapping/*.xml"></property>
		<property name="configurationProperties">
			<props>
				<prop key="cacheEnabled">true</prop> 
				<prop key="lazyLoadingEnabled">false</prop> 
				<prop key="aggressiveLazyLoading">true</prop>
			</props>
		</property>
	</bean>

其中：

<prop key="cacheEnabled">true</prop>

是开启的关键。

7，在相关的 mapper.xml 添加所需要用的缓存类，我们这里是在 TUserMapper.xml 中添加

<?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="demo.dao.TUserMapper">

	<cache type="demo.cache.MybatisRedisCache" />
	
	<resultMap id="BaseResultMap" type="demo.domain.TUser">
		<id column="id" property="id" jdbcType="INTEGER" />
		<result column="username" property="username" jdbcType="VARCHAR" />
		<result column="password" property="password" jdbcType="VARCHAR" />
		<result column="createtime" property="createtime" jdbcType="TIMESTAMP" />
	</resultMap>
	<sql id="Base_Column_List">
		id, username, password, createtime
	</sql>
	<select id="selectByPrimaryKey" resultMap="BaseResultMap"
		parameterType="java.lang.Integer">
		select <include refid="Base_Column_List" /> from t_user where id = #{id,jdbcType=INTEGER}
	</select>
	<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
		delete from t_user
		where id = #{id,jdbcType=INTEGER}
	</delete>
	<insert id="insert" parameterType="demo.domain.TUser">
		insert into t_user (id, username, password,
		createtime)
		values (#{id,jdbcType=INTEGER}, #{username,jdbcType=VARCHAR},
		#{password,jdbcType=VARCHAR},
		#{createtime,jdbcType=TIMESTAMP})
	</insert><insert id="insertSelective" parameterType="demo.domain.TUser">
		insert into t_user
		<trim prefix="(" suffix=")" suffixOverrides=","><if test="id != null">
				id,
			</if><if test="username != null">
				username,
			</if><if test="password != null">
				password,
			</if><if test="createtime != null">
				createtime,
			</if></trim><trim prefix="values (" suffix=")" suffixOverrides=","><if test="id != null">
				#{id,jdbcType=INTEGER},
			</if><if test="username != null">
				#{username,jdbcType=VARCHAR},
			</if><if test="password != null">
				#{password,jdbcType=VARCHAR},
			</if><if test="createtime != null">
				#{createtime,jdbcType=TIMESTAMP},
			</if></trim></insert><update id="updateByPrimaryKeySelective" parameterType="demo.domain.TUser">
		update t_user
		<set><if test="username != null">
				username = #{username,jdbcType=VARCHAR},
			</if><if test="password != null">
				password = #{password,jdbcType=VARCHAR},
			</if><if test="createtime != null">
				createtime = #{createtime,jdbcType=TIMESTAMP},
			</if></set>
		where id = #{id,jdbcType=INTEGER}</update><update id="updateByPrimaryKey" parameterType="demo.domain.TUser">
		update t_user
		set username = #{username,jdbcType=VARCHAR},
		password = #{password,jdbcType=VARCHAR},
		createtime = #{createtime,jdbcType=TIMESTAMP}
		where id = #{id,jdbcType=INTEGER}</update><select id="selectAll" resultMap="BaseResultMap">
		select <include refid="Base_Column_List" /> from t_user
	</select></mapper>

其中：

<cache type="demo.cache.MybatisRedisCache" />

是关键。

然后就可以在自己写的测试类或者controller中做测试了，测试的时候可以把日志级别设置为debug级别，这样可以看到Mybatis的sql语句。当走缓存的时候，是不会打印sql语句的，反之会出现sql语句。

例如，我们在原有的数据里，新加了一条数据，这时缓存数据和数据库数据就对应不上，可以看到日志里有sql语句打印

[org.mybatis.spring.SqlSessionUtils] - Creating a new SqlSession
[org.mybatis.spring.SqlSessionUtils] - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@1005765] was not registered for synchronization because synchronization is not active
[demo.cache.MybatisRedisCache] - >>>>>>>>>>>>>>>>>>>>>>>>getObject:-1445659396:380449231:demo.dao.TUserMapper.selectAll:0:2147483647:select  
		id, username, password, createtime
	  from t_user:SqlSessionFactoryBean=null
[demo.dao.TUserMapper] - Cache Hit Ratio [demo.dao.TUserMapper]: 0.0
[org.springframework.jdbc.datasource.DataSourceUtils] - Fetching JDBC Connection from DataSource
[org.mybatis.spring.transaction.SpringManagedTransaction] - JDBC Connection [jdbc:mysql://127.0.0.1:3306/demo, UserName=root@localhost, MySQL Connector Java] will not be managed by Spring
[demo.dao.TUserMapper.selectAll] - ==>  Preparing: select id, username, password, createtime from t_user 
[demo.dao.TUserMapper.selectAll] - ==> Parameters: 
[demo.dao.TUserMapper.selectAll] - <==      Total: 9
[demo.cache.MybatisRedisCache] - >>>>>>>>>>>>>>>>>>>>>>>>putObject:-1445659396:380449231:demo.dao.TUserMapper.selectAll:0:2147483647:select  
		id, username, password, createtime
	  from t_user:SqlSessionFactoryBean=[demo.domain.TUser@4f6d47, demo.domain.TUser@8f7ea3, demo.domain.TUser@c309e0, demo.domain.TUser@bd7ea6, demo.domain.TUser@c5fc10, demo.domain.TUser@2784fd, demo.domain.TUser@8c0b75, demo.domain.TUser@443aea, demo.domain.TUser@177e204]

一旦这个执行过一次后，再执行（不再有数据变更），可以看到，也就不再有sql语句的打印了。

[org.mybatis.spring.SqlSessionUtils] - Creating a new SqlSession
[org.mybatis.spring.SqlSessionUtils] - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@b14a45] was not registered for synchronization because synchronization is not active
[demo.cache.MybatisRedisCache] - >>>>>>>>>>>>>>>>>>>>>>>>getObject:-1445659396:380449231:demo.dao.TUserMapper.selectAll:0:2147483647:select  
		id, username, password, createtime
	  from t_user:SqlSessionFactoryBean=[demo.domain.TUser@78471b, demo.domain.TUser@847332, demo.domain.TUser@1a6f080, demo.domain.TUser@f78840, demo.domain.TUser@11232a8, demo.domain.TUser@1bbe24e, demo.domain.TUser@672d9, demo.domain.TUser@15e2565, demo.domain.TUser@1e93ee7]
[demo.dao.TUserMapper] - Cache Hit Ratio [demo.dao.TUserMapper]: 0.6666666666666666
[org.mybatis.spring.SqlSessionUtils] - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@b14a45]
[demo.domain.TUser@78471b, demo.domain.TUser@847332, demo.domain.TUser@1a6f080, demo.domain.TUser@f78840, demo.domain.TUser@11232a8, demo.domain.TUser@1bbe24e, demo.domain.TUser@672d9, demo.domain.TUser@15e2565, demo.domain.TUser@1e93ee7]

备注：在网上看到有些人说mybatis和redis整合的时候，数据库使用mysql总是加载第一页的数据，不会显示以后的数据，经测试，可以正确加载指定页数的数据，分页也是采用常规的分页方法，这里就不再做描述了。

-------------------------------2016-5-12更新SerializeUtil.java------------------------

public class SerializeUtil {
    /**
     * 序列化
     * @param object
     */
    public static byte[] serialize(Object object) {
        ObjectOutputStream oos = null;
        ByteArrayOutputStream baos = null;
        try {
            // 序列化
            baos = new ByteArrayOutputStream();
            oos = new ObjectOutputStream(baos);
            oos.writeObject(object);
            byte[] bytes = baos.toByteArray();
            return bytes;
        } catch (Exception e) {
        	e.printStackTrace();
        }
        return null;
    }

    /**
     * 反序列化
     * @param bytes
     */
    public static Object unserialize(byte[] bytes) {
        ByteArrayInputStream bais = null;
        try {
            // 反序列化
            bais = new ByteArrayInputStream(bytes);
            ObjectInputStream ois = new ObjectInputStream(bais);
            return ois.readObject();
        } catch (Exception e) {
        	e.printStackTrace();
        }
        return null;
    }
}