MyBatis基础-05-缓存

MyBatis_cache

Teacher.java:

package com.atguigu.bean;

import java.io.Serializable;
import java.util.Date;

public class Teacher{

    private Integer id;
    private String name;
    private String course;
    private String address;
    private Date birth;
    /**
     * @return the id
     */
    public Integer getId() {
        return id;
    }
    /**
     * @param id the id to set
     */
    public void setId(Integer id) {
        this.id = id;
    }
    /**
     * @return the name
     */
    public String getName() {
        return name;
    }
    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }
    /**
     * @return the course
     */
    public String getCourse() {
        return course;
    }
    /**
     * @param course the course to set
     */
    public void setCourse(String course) {
        this.course = course;
    }
    /**
     * @return the address
     */
    public String getAddress() {
        return address;
    }
    /**
     * @param address the address to set
     */
    public void setAddress(String address) {
        this.address = address;
    }
    /**
     * @return the birth
     */
    public Date getBirth() {
        return birth;
    }
    /**
     * @param birth the birth to set
     */
    public void setBirth(Date birth) {
        this.birth = birth;
    }
    /* (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "Teacher [id=" + id + ", name=" + name + ", course=" + course
                + ", address=" + address + ", birth=" + birth + "]";
    }
    
}

MyCache.java:

package com.atguigu.dao;

import java.util.concurrent.locks.ReadWriteLock;

import org.apache.ibatis.cache.Cache;

public class MyCache implements Cache {
    //redis = new Redis();
    
    @Override
    public String getId() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void putObject(Object key, Object value) {
        // TODO Auto-generated method stub
        // mybatis-ehcache-1.0.3.jar ehcache-core-2.6.8.jar
        /**
         * 
         */
        //redis.put();
    }

    @Override
    public Object getObject(Object key) {
        // TODO Auto-generated method stub
        //redis.get
        return null;
    }

    @Override
    public Object removeObject(Object key) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void clear() {
        // TODO Auto-generated method stub
        
    }

    @Override
    public int getSize() {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public ReadWriteLock getReadWriteLock() {
        // TODO Auto-generated method stub
        return null;
    }

}

TeacherDao.java:

package com.atguigu.dao;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.atguigu.bean.Teacher;

public interface TeacherDao {
    
    public Teacher getTeacherById(Integer id);
    
    public List<Teacher> getTeacherByCondition(Teacher teacher);
    
    public List<Teacher> getTeacherByIdIn(@Param("ids")List<Integer> ids);
    
    public List<Teacher> getTeacherByConditionChoose(Teacher teacher);
    
    public int updateTeacher(Teacher teacher);

}

EmployeeDao.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.atguigu.dao.EmployeeDao">

    <!--和别的dao公用一块缓存-->
    <cache-ref namespace="com.atguigu.dao.TeacherDao"/>
</mapper>

TeacherDao.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.atguigu.dao.TeacherDao">
    <!-- 使用mybatis默认二级缓存<cache></cache> -->
    <cache type="org.mybatis.caches.ehcache.EhcacheCache"></cache>
    
    <resultMap type="com.atguigu.bean.Teacher" id="teacherMap">
        <id property="id" column="id" />
        <result property="address" column="address" />
        <result property="birth" column="birth_date" />
        <result property="course" column="class_name" />
        <result property="name" column="teacherName" />
    </resultMap>

    <!--抽取可重用的sql语句  -->
    <sql id="selectSql">select * from t_teacher</sql>
    <!--public Teacher getTeacherById(Integer id); -->
    <!-- 是否使用二级缓存的useCache="true"；默认是true -->
    <select id="getTeacherById" resultMap="teacherMap">
        <include refid="selectSql"></include>
        where id=#{id}
    </select>

    <!-- if：判断 -->
    <!--public List<Teacher> getTeacherByCondition(Teacher teacher); -->
    <select id="getTeacherByCondition" resultMap="teacherMap">
        select * from t_teacher
        <!-- test=""：编写判断条件 id!=null：取出传入的javaBean属性中的id的值，判断其是否为空 -->
        <!-- where可以帮我们去除掉前面的and; -->

        <!-- trim：截取字符串 
            prefix=""：前缀；为我们下面的sql整体添加一个前缀 
            prefixOverrides=""： 取出整体字符串前面多余的字符 
            suffix=""：为整体添加一个后缀 
            suffixOverrides=""：后面哪个多了可以去掉; -->
        <!-- 我们的查询条件就放在where标签中；每个and写在前面，
            where帮我们自动取出前面多余的and -->
        <trim prefix="where" prefixOverrides="and" suffixOverrides="and">
            <if test="id!=null">
                id > #{id} and
            </if>
            <!-- 空串 "" and； && or: ||； if()：传入非常强大的判断条件；
            OGNL表达式；对象导航图
                Person
                    ===lastName
                    ===email
                    ===Address
                        ===city
                        ===province
                        ===Street
                            ===adminName
                            ===info
                            ===perCount
            方法、静态方法、构造器。xxx
            在mybatis中，传入的参数可以用来做判断；
            额外还有两个东西；
            _parameter：代表传入来的参数；
                1）、传入了单个参数：_parameter就代表这个参数
                2）、传入了多个参数：_parameter就代表多个参数集合起来的map
            _databaseId：代表当前环境
                如果配置了databaseIdProvider：_databaseId就有值
                
             -->
            <!-- 绑定一个表达式的值到一个变量 -->
            <!-- <bind name="_name" value="'%'+name+'%'"/> -->
            <if test="name!=null &amp;&amp; !name.equals(&quot;&quot;)">
                teacherName like #{_name} and
            </if>
            <if test="birth!=null">
                birth_date &lt; #{birth} and
            </if>
        </trim>
    </select>
    
    <!-- public List<Teacher> getTeacherByIdIn(List<Integer> ids); -->
    <select id="getTeacherByIdIn" resultMap="teacherMap">
        
        SELECT * FROM t_teacher WHERE id IN
        <!-- 帮我们遍历集合的； collection=""：指定要遍历的集合的key 
        close=""：以什么结束 
        index="i"：索引； 
            如果遍历的是一个list； 
                index：指定的变量保存了当前索引 
                item：保存当前遍历的元素的值 
            如果遍历的是一个map： 
                index：指定的变量就是保存了当前遍历的元素的key 
                item：就是保存当前遍历的元素的值
        item="变量名"：每次遍历出的元素起一个变量名方便引用 
        open=""：以什么开始 
        separator=""：每次遍历的元素的分隔符 
            (#{id_item},#{id_item},#{id_item} -->
        <if test="ids.size >0">
            <foreach collection="ids" item="id_item" separator="," open="("
                close=")">
                #{id_item}
            </foreach>
        </if>
    </select>

    <!--public List<Teacher> getTeacherByConditionChoose(Teacher teacher); -->
    <select id="getTeacherByConditionChoose" resultMap="teacherMap">
        select * from t_teacher
        <where>
            <choose>
                <when test="id!=null">
                    id=#{id}
                </when>
                <when test="name!=null and !name.equals(&quot;&quot;)">
                    teacherName=#{name}
                </when>
                <when test="birth!=null">
                    birth_date = #{birth}
                </when>
                <otherwise>
                    1=1
                </otherwise>
            </choose>
        </where>
    </select>

    <!-- public int updateTeacher(Teacher teacher); -->
    <update id="updateTeacher" >
        UPDATE t_teacher
        <set>
            <if test="name!=null and !name.equals(&quot;&quot;)">
                teacherName=#{name},
            </if>
            <if test="course!=null and !course.equals(&quot;&quot;)">
                class_name=#{course},
            </if>
            <if test="address!=null and !address.equals(&quot;&quot;)">
                address=#{address},
            </if>
            <if test="birth!=null">
                birth_date=#{birth}
            </if>
        </set>
        <where>
            id=#{id}
        </where>
         
    </update>
</mapper>

ehcache.xml:

<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:noNamespaceSchemaLocation="../config/ehcache.xsd">
 <!-- 磁盘保存路径 -->
 <diskStore path="D:44ehcache" />
 <defaultCache 
   maxElementsInMemory="1" 
   maxElementsOnDisk="10000000"
   eternal="false" 
   overflowToDisk="true" 
   timeToIdleSeconds="120"
   timeToLiveSeconds="120" 
   diskExpiryThreadIntervalSeconds="120"
   memoryStoreEvictionPolicy="LRU">
 </defaultCache>
</ehcache>
 
<!-- 
属性说明：
l diskStore：指定数据在磁盘中的存储位置。
l defaultCache：当借助CacheManager.add("demoCache")创建Cache时，EhCache便会采用<defalutCache/>指定的的管理策略
 
以下属性是必须的：
l maxElementsInMemory - 在内存中缓存的element的最大数目 
l maxElementsOnDisk - 在磁盘上缓存的element的最大数目，若是0表示无穷大
l eternal - 设定缓存的elements是否永远不过期。如果为true，则缓存的数据始终有效，如果为false那么还要根据timeToIdleSeconds，timeToLiveSeconds判断
l overflowToDisk - 设定当内存缓存溢出的时候是否将过期的element缓存到磁盘上
 
以下属性是可选的：
l timeToIdleSeconds - 当缓存在EhCache中的数据前后两次访问的时间超过timeToIdleSeconds的属性取值时，这些数据便会删除，默认值是0,也就是可闲置时间无穷大
l timeToLiveSeconds - 缓存element的有效生命期，默认是0.,也就是element存活时间无穷大
 diskSpoolBufferSizeMB 这个参数设置DiskStore(磁盘缓存)的缓存区大小.默认是30MB.每个Cache都应该有自己的一个缓冲区.
l diskPersistent - 在VM重启的时候是否启用磁盘保存EhCache中的数据，默认是false。
l diskExpiryThreadIntervalSeconds - 磁盘缓存的清理线程运行间隔，默认是120秒。每个120s，相应的线程会进行一次EhCache中数据的清理工作
l memoryStoreEvictionPolicy - 当内存缓存达到最大，有新的element加入的时候， 移除缓存中element的策略。默认是LRU（最近最少使用），可选的有LFU（最不常使用）和FIFO（先进先出）
 -->

log4j.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
 
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
 
 <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
   <param name="Encoding" value="UTF-8" />
   <layout class="org.apache.log4j.PatternLayout">
    <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m  (%F:%L) 
" />
   </layout>
 </appender>
 <logger name="java.sql">
   <level value="debug" />
 </logger>
 <logger name="org.apache.ibatis">
   <level value="info" />
 </logger>
 <root>
   <level value="debug" />
   <appender-ref ref="STDOUT" />
 </root>
</log4j:configuration>

mybatis-config.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <settings>
        <!-- 开启延迟加载开关 -->
        <setting name="lazyLoadingEnabled" value="true"/>
        <!-- 开启属性按需加载 -->
        <setting name="aggressiveLazyLoading" value="false"/>
        <!-- 开启全局缓存开关；需要在dao.xml文件中指定 -->
        <setting name="cacheEnabled" value="true"/>
    </settings>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis_0325?characterEncoding=utf-8&amp;serverTimezone=GMT%2B8" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <package name="com.atguigu.dao"/>
    </mappers>
</configuration>

pom.xml:

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.8.2</version>
            <scope>compile</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/net.sf.ehcache/ehcache-core -->
        <dependency>
            <groupId>net.sf.ehcache</groupId>
            <artifactId>ehcache-core</artifactId>
            <version>2.6.11</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-log4j12 -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.30</version>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.30</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.mybatis.caches/mybatis-ehcache -->
        <dependency>
            <groupId>org.mybatis.caches</groupId>
            <artifactId>mybatis-ehcache</artifactId>
            <version>1.2.1</version>
        </dependency>

    </dependencies>