MyBatis入门（五）---延时加载、缓存
2024-06-01 19:05:33
一、创建数据库
1.1、建立数据库
/* SQLyog Enterprise v12.09 (64 bit) MySQL - 5.7.9-log : Database - mybatis ********************************************************************* *//*!40101 SET NAMES utf8 */;/*!40101 SET SQL_MODE=''*/;/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */; /*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */; /*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */; /*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */; CREATE DATABASE /*!32312 IF NOT EXISTS*/`mybatis` /*!40100 DEFAULT CHARACTER SET utf8 */;USE `mybatis`;/*Table structure for table `author` */DROP TABLE IF EXISTS `author`;CREATE TABLE `author` (`author_id` int(11) unsigned NOT NULL AUTO_INCREMENT COMMENT '作者ID主键',`author_username` varchar(30) NOT NULL COMMENT '作者用户名',`author_password` varchar(32) NOT NULL COMMENT '作者密码',`author_email` varchar(50) NOT NULL COMMENT '作者邮箱',`author_bio` varchar(1000) DEFAULT '这家伙很赖，什么也没留下' COMMENT '作者简介',`register_time` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '注册时间',PRIMARY KEY (`author_id`) ) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;/*Data for the table `author` */insert into `author`(`author_id`,`author_username`,`author_password`,`author_email`,`author_bio`,`register_time`) values (1,'张三','123456','123@qq.com','张三是个新手，刚开始注册','2015-10-29 10:23:59'),(2,'李四','123asf','lisi@163.com','魂牵梦萦 ','2015-10-29 10:24:29'),(3,'王五','dfsd342','ww@sina.com','康熙王朝','2015-10-29 10:25:23'),(4,'赵六','123098sdfa','zhaoliu@qq.com','花午骨','2015-10-29 10:26:09'),(5,'钱七','zxasqw','qianqi@qq.com','这家伙很赖，什么也没留下','2015-10-29 10:27:04'),(6,'张三丰','123456','zhangsf@qq.com','这家伙很赖，什么也没留下','2015-10-29 11:48:00'),(7,'张无忌','qwertyuiop','wuji@163.com','这家伙很赖，什么也没留下','2015-10-29 11:48:24'),(8,'fdsf','ffff','fdsfds',NULL,NULL),(9,'fdsf','ffff','fdsfds',NULL,NULL),(10,'aaaa','bbbb','ddd@qq.com','这家伙很赖，什么也没留下','2015-10-29 22:07:45');/*Table structure for table `blog` */DROP TABLE IF EXISTS `blog`;CREATE TABLE `blog` (`blog_id` int(11) unsigned NOT NULL AUTO_INCREMENT COMMENT 'BlogId主键',`blog_title` varchar(255) NOT NULL COMMENT 'blog标题',`author_id` int(11) unsigned NOT NULL COMMENT '作者ID外键',PRIMARY KEY (`blog_id`),KEY `fk_author_id` (`author_id`),CONSTRAINT `fk_author_id` FOREIGN KEY (`author_id`) REFERENCES `author` (`author_id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;/*Data for the table `blog` */insert into `blog`(`blog_id`,`blog_title`,`author_id`) values (1,'小张的Blog',1),(2,'小李',2),(3,'王五不是人',3),(4,'赵地人',4),(5,'钱钱钱',5);/*Table structure for table `posts` */DROP TABLE IF EXISTS `posts`;CREATE TABLE `posts` (`post_id` int(11) unsigned NOT NULL AUTO_INCREMENT COMMENT '文章主键ID',`post_subject` varchar(255) NOT NULL COMMENT '文章主题，标题',`post_body` text NOT NULL COMMENT '文章内容最大3000个字符',`blog_id` int(11) unsigned NOT NULL COMMENT 'Blog主键做外键',`createtime` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '文章创建时间',PRIMARY KEY (`post_id`),KEY `fk_blog_id` (`blog_id`),CONSTRAINT `fk_blog_id` FOREIGN KEY (`blog_id`) REFERENCES `blog` (`blog_id`) ) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8mb4;/*Data for the table `posts` */insert into `posts`(`post_id`,`post_subject`,`post_body`,`blog_id`,`createtime`) values (1,'Mybatis入门一','什么是 MyBatis ？\r\nMyBatis 是支持定制化 SQL、存储过程以及高级映射的优秀的持久层框架。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以对配置和原生Map使用简单的 XML 或注解，将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java对象)映射成数据库中的记录。',1,'2015-10-29 10:32:21'),(2,'Mybatis入门二','要使用 MyBatis， 只需将 mybatis-x.x.x.jar 文件置于 classpath 中即可。',1,'2015-10-29 10:32:52'),(3,'Oracle学习','Oracle Database，又名Oracle RDBMS，或简称Oracle。是甲骨文公司的一款关系数据库管理系统',2,'2015-10-29 10:33:26'),(4,'JAVA学习一','Java是由Sun Microsystems公司于1995年5月推出的Java面向对象程序设计语言和Java平台的总称',3,'2015-10-29 10:34:17'),(5,'PL/SQL','PL/SQL也是一种程序语言，叫做过程化SQL语言（Procedural Language/SQL）。PL/SQL是Oracle数据库对SQL语句的扩展',4,'2015-10-29 10:37:52'),(6,'CSS标签选择器','标签选择器\r\nID选择器\r\n类选择器\r\n特殊选择器',5,'2015-10-29 10:39:44'),(7,'javascript','js:是前端脚本语言',2,'2015-10-29 10:40:18');/*!40101 SET SQL_MODE=@OLD_SQL_MODE */; /*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */; /*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */; /*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
数据表和数据
二、创建项目
2.1、创建项目
三、建立实体类与Mapper接口
3.1、3个实体类
package com.pb.mybatis.po;import java.util.Date;/*** * @ClassName: Author* @Description: TODO(作者)* @author 刘楠* @date 2015-10-31 下午12:39:33**/
public class Author {//作者idprivate Integer authorId;//作者姓名private String authorUserName;//作者密码private String authorPassword;//作者邮箱private String authorEmail;//作者介绍private String authroBio;//注册时间private Date registerTime;public Integer getAuthorId() {return authorId;}public void setAuthorId(Integer authorId) {this.authorId = authorId;}public String getAuthorUserName() {return authorUserName;}public void setAuthorUserName(String authorUserName) {this.authorUserName = authorUserName;}public String getAuthorPassword() {return authorPassword;}public void setAuthorPassword(String authorPassword) {this.authorPassword = authorPassword;}public String getAuthorEmail() {return authorEmail;}public void setAuthorEmail(String authorEmail) {this.authorEmail = authorEmail;}public String getAuthroBio() {return authroBio;}public void setAuthroBio(String authroBio) {this.authroBio = authroBio;}public Date getRegisterTime() {return registerTime;}public void setRegisterTime(Date registerTime) {this.registerTime = registerTime;}@Overridepublic String toString() {return "Author [authorId=" + authorId + ", authorUserName="+ authorUserName + ", authorPassword=" + authorPassword+ ", authorEmail=" + authorEmail + ", authroBio=" + authroBio+ ", registerTime=" + registerTime + "]";}}package com.pb.mybatis.po;import java.util.List;public class Blog {//Blog,IDprivate Integer blogId;//Blog 名称标题private String blogTitle;//外键authorId//作者private Author author;//文章 列表private Integer authorId;//文章列表private List<Posts> postsList;public Integer getBlogId() {return blogId;}public void setBlogId(Integer blogId) {this.blogId = blogId;}public String getBlogTitle() {return blogTitle;}public void setBlogTitle(String blogTitle) {this.blogTitle = blogTitle;}public Author getAuthor() {return author;}public void setAuthor(Author author) {this.author = author;}public Integer getAuthorId() {return authorId;}public void setAuthorId(Integer authorId) {this.authorId = authorId;}public List<Posts> getPostsList() {return postsList;}public void setPostsList(List<Posts> postsList) {this.postsList = postsList;}@Overridepublic String toString() {return "Blog [blogId=" + blogId + ", blogTitle=" + blogTitle+ ", authorId=" + authorId + "]";}}package com.pb.mybatis.po;import java.util.Date;public class Posts {//文章IDprivate Integer postId;//文章标题private String postTitle;//文章主体内容private String postBody;//外键private Integer blogId;//建立时间private Date createTime;public Integer getPostId() {return postId;}public void setPostId(Integer postId) {this.postId = postId;}public String getPostTitle() {return postTitle;}public void setPostTitle(String postTitle) {this.postTitle = postTitle;}public String getPostBody() {return postBody;}public void setPostBody(String postBody) {this.postBody = postBody;}public Date getCreateTime() {return createTime;}public void setCreateTime(Date createTime) {this.createTime = createTime;}public Integer getBlogId() {return blogId;}public void setBlogId(Integer blogId) {this.blogId = blogId;}@Overridepublic String toString() {return "Posts [postId=" + postId + ", postTitle=" + postTitle+ ", postBody=" + postBody + ", createTime=" + createTime+ ", blogId=" + blogId + "]";}}3.2、3个接口
package com.pb.mybatis.mapper;import com.pb.mybatis.po.Author;public interface AuthorMapper {/*** * @Title: findAuthorById* @Description: TODO(根据id查找)* @param @param id* @param @return 设定文件* @return Author 返回类型* @throws*/public Author findAuthorById(int id);
}package com.pb.mybatis.mapper;import com.pb.mybatis.po.Blog;public interface BlogMapper {/*** * @Title: findBlogById* @Description: TODO(根据BLOGID查找BLOG，并关联author，与posts实现延时加载)* @param @param id* @param @return 设定文件* @return Blog 返回类型* @throws*/public Blog findBlogById(int blogId);}package com.pb.mybatis.mapper;import java.util.List;import com.pb.mybatis.po.Posts;public interface PostsMapper {/*** * @Title: findPostsByBlogId* @Description: TODO(根据BLOGID查找文章列表)* @param @param blogId* @param @return 设定文件* @return List<Posts> 返回类型* @throws*/public List<Posts> findPostsByBlogId(int blogId);
}四、建立mapper.xml与confinguration.xml
4.1、相对应的mapper.xml
AuthorMapper.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.pb.mybatis.mapper.AuthorMapper">
<!--映射作者Author -->
<resultMap type="Author" id="authorResultMap">
<id property="authorId" column="author_id"/>
<result property="authorUserName" column="author_username"/>
<result property="authorPassword" column="author_password"/>
<result property="authorEmail" column="author_email"/>
<result property="authroBio" column="author_bio"/>
<result property="registerTime" column="register_time"/>
</resultMap>
<!-- 根据ID查找 -->
<select id="findAuthorById" parameterType="int" resultMap="authorResultMap">
select * from author
where author_id=#{id}
</select>
</mapper>BlogMapper.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.pb.mybatis.mapper.BlogMapper">
<!--Blog映射 -->
<resultMap type="Blog" id="blogResultMap">
<!--Blog映射 -->
<id property="blogId" column="blog_id"/>
<result property="blogTitle" column="blog_title"/>
<result property="authorId" column="author_id"/><!--一对一 -->
<association property="author" javaType="Author" column="author_id" select="com.pb.mybatis.mapper.AuthorMapper.findAuthorById"/>
<!--关联作者
外键
column：外键
select:引用Authro的namespace.方法
--><!--一对多 ofType属性指定集合中元素的对象类型。-->
<collection property="postsList" ofType="Posts" javaType="ArrayList" column="blog_id" select="com.pb.mybatis.mapper.PostsMapper.findPostsByBlogId"/>
</resultMap><!-- 根据ID查找 -->
<select id="findBlogById" parameterType="int" resultMap="blogResultMap">
SELECT * FROM blog
WHERE blog_id=#{blogId}
</select>
</mapper>PostsMapper.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.pb.mybatis.mapper.PostsMapper">
<!--映射作者文章 -->
<resultMap type="Posts" id="postsResultMap">
<id property="postId" column="post_id"/>
<result property="postTitle" column="post_subject"/>
<result property="postBody" column="post_body"/>
<result property="blogId" column="blog_id"/>
<result property="createTime" column="createtime"/>
</resultMap>
<!-- 根据ID查找 -->
<select id="findPostsByBlogId" parameterType="int" resultMap="postsResultMap">
select * from posts
where blog_id=#{blogId}
</select>
</mapper>4.2、configuration.xml
db.properties
driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/mybatis?character=utf8 username=root password=root
开启延时加载，同时关闭立即加载
<settings> <!--开启延时加载 --> <setting name="lazyLoadingEnabled" value="true"/> <!--关闭立即加载 --> <setting name="aggressiveLazyLoading" value="false"/> </settings>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!--资源文件 -->
<properties resource="db.properties"/><settings>
<!--开启延时加载 -->
<setting name="lazyLoadingEnabled" value="true"/>
<!--关闭立即加载 -->
<setting name="aggressiveLazyLoading" value="false"/>
</settings>
<!-- 别名 -->
<typeAliases>
<!-- <typeAlias type="com.pb.mybatis.po.User" alias="User"/> -->
<package name="com.pb.mybatis.po"/>
</typeAliases>
<!--配置 --><environments default="development">
<environment id="development"><!--事务 --><transactionManager type="JDBC"/><!--数据源 --><dataSource type="POOLED"><property name="driver" value="${driver}"/><property name="url" value="${url}"/><property name="username" value="${username}"/><property name="password" value="${password}"/></dataSource>
</environment>
</environments>
<mappers><package name="com.pb.mybatis.mapper"/>
</mappers>
</configuration>五、测试
5.1、JUNIT
package com.pb.mybatis.mapper;import java.io.InputStream;
import java.util.List;import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;import com.pb.mybatis.po.Blog;
import com.pb.mybatis.po.Posts;public class BlogMapperTest {private SqlSessionFactory sqlSessionFactory;@Beforepublic void setUp() throws Exception {String config="configuration.xml";InputStream resource=Resources.getResourceAsStream(config);sqlSessionFactory=new SqlSessionFactoryBuilder().build(resource);}/*** * @Title: testFindBlogs* @Description: TODO(延时加载)* @param 设定文件* @return void 返回类型* @throws*/@Testpublic void testFindBlogById() {//建立会话SqlSession sqlSession=sqlSessionFactory.openSession();//获取Mapper接口对象BlogMapper blogMapper=sqlSession.getMapper(BlogMapper.class);//调用Mapper方法 Blog blog=blogMapper.findBlogById(1);System.out.println(blog.getBlogId()+"..."+blog.getBlogTitle());System.out.println("===========开始延时加载作者Author===========");System.out.println(blog.getAuthor());System.out.println("===========开始延时加载文章===========");List<Posts> list=blog.getPostsList();/*int count=0;for(Posts p:list){System.out.println("count+"+count++);System.out.println(p.getPostId());System.out.println(p.getPostTitle());System.out.println(p.getPostBody());System.out.println(p.getCreateTime());System.out.println(p.getBlogId());}*/}}结果：
DEBUG [main] - ==> Preparing: SELECT * FROM blog WHERE blog_id=? DEBUG [main] - ==> Parameters: 1(Integer) DEBUG [main] - <== Total: 1 1...小张的Blog ===========开始延时加载作者Author=========== DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 1(Integer) DEBUG [main] - <== Total: 1 Author [authorId=1, authorUserName=张三, authorPassword=123456, authorEmail=123@qq.com, authroBio=张三是个新手，刚开始注册, registerTime=Thu Oct 29 10:23:59 CST 2015] ===========开始延时加载文章=========== DEBUG [main] - ==> Preparing: select * from posts where blog_id=? DEBUG [main] - ==> Parameters: 1(Integer) DEBUG [main] - <== Total: 2
六、一级缓存
6.1、mybatis一级缓存
mybatis，默认开启了一级缓存，sqlSession中默认有一个hashMap
当查询时，先去hashMap中查找，
如果有就直接，取出，不再操作数据库
如果没有就去数据库查找，并放在haspMap中
当做事物时，如添加，删除，修改，后有commit时会清空一级缓存
sqlSession是互不影响的，一级缓存
6.2、还是上级的例子
测试:查询用户
package com.pb.mybatis.mapper;import static org.junit.Assert.*;import java.io.InputStream;import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;import com.pb.mybatis.po.Author;public class AuthorMapperTest {private SqlSessionFactory sqlSessionFactory;@Beforepublic void setUp() throws Exception {String config="configuration.xml";InputStream resource=Resources.getResourceAsStream(config);sqlSessionFactory=new SqlSessionFactoryBuilder().build(resource);}@Testpublic void testFindAuthorById() {//获取会话工厂SqlSession sqlSession=sqlSessionFactory.openSession();AuthorMapper authorMapper=sqlSession.getMapper(AuthorMapper.class);//第一次查询Author author1=authorMapper.findAuthorById(2);System.out.println(author1);//再次查询同样的Author author2=authorMapper.findAuthorById(2);System.out.println(author2);//再次查询不的同样的Author author3=authorMapper.findAuthorById(4);System.out.println(author3);}}结果：
DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer) DEBUG [main] - <== Total: 1 Author [authorId=2, authorUserName=李四, authorPassword=123asf, authorEmail=lisi@163.com, authroBio=魂牵梦萦 , registerTime=Thu Oct 29 10:24:29 CST 2015] Author [authorId=2, authorUserName=李四, authorPassword=123asf, authorEmail=lisi@163.com, authroBio=魂牵梦萦 , registerTime=Thu Oct 29 10:24:29 CST 2015] DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 4(Integer) DEBUG [main] - <== Total: 1 Author [authorId=4, authorUserName=赵六, authorPassword=123098sdfa, authorEmail=zhaoliu@qq.com, authroBio=花午骨, registerTime=Thu Oct 29 10:26:09 CST 2015]
6.3、当查询后，做事务，再查询第一次的
接口中做添加方法
/*** * @Title: addAuthor* @Description: TODO(添加)* @param @param author* @param @return 设定文件* @return int 返回类型* @throws*/public int addAuthor(Author author);
mapper.xml中做同样的select
<!--添加 -->
<insert id="addAuthor" parameterType="Author" useGeneratedKeys="true" keyProperty="authorId">
INSERT INTO author(author_username,author_password,author_email,author_bio)
VALUES(#{authorUserName},#{authorPassword},#{authorEmail},#{authroBio})
</insert>测试
package com.pb.mybatis.mapper;import static org.junit.Assert.*;import java.io.InputStream;import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;import com.pb.mybatis.po.Author;public class AuthorMapperTest {private SqlSessionFactory sqlSessionFactory;@Beforepublic void setUp() throws Exception {String config="configuration.xml";InputStream resource=Resources.getResourceAsStream(config);sqlSessionFactory=new SqlSessionFactoryBuilder().build(resource);}@Testpublic void testFindAuthorById() {//获取会话工厂SqlSession sqlSession=sqlSessionFactory.openSession();AuthorMapper authorMapper=sqlSession.getMapper(AuthorMapper.class);//第一次查询Author author1=authorMapper.findAuthorById(2);System.out.println(author1);System.out.println("=======下面有事务处理========");Author newAuthor=new Author();newAuthor.setAuthorEmail("qq.com@qq.com");newAuthor.setAuthorPassword("fdsfds");newAuthor.setAuthorUserName("郭靖");newAuthor.setAuthroBio("射雕英雄传");int num=authorMapper.addAuthor(newAuthor);sqlSession.commit();System.out.println(newAuthor.getAuthorId());System.out.println("num="+num);System.out.println("再次查询");//再次查询同样的Author author2=authorMapper.findAuthorById(2);System.out.println(author2);}}结果：
DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer) DEBUG [main] - <== Total: 1 Author [authorId=2, authorUserName=李四, authorPassword=123asf, authorEmail=lisi@163.com, authroBio=魂牵梦萦 , registerTime=Thu Oct 29 10:24:29 CST 2015] =======下面有事务处理======== DEBUG [main] - ==> Preparing: INSERT INTO author(author_username,author_password,author_email,author_bio) VALUES(?,?,?,?) DEBUG [main] - ==> Parameters: 郭靖(String), fdsfds(String), qq.com@qq.com(String), 射雕英雄传(String) DEBUG [main] - <== Updates: 1 DEBUG [main] - Committing JDBC Connection [com.mysql.jdbc.JDBC4Connection@42bb0406] 11 num=1 再次查询 DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer) DEBUG [main] - <== Total: 1 Author [authorId=2, authorUserName=李四, authorPassword=123asf, authorEmail=lisi@163.com, authroBio=魂牵梦萦 , registerTime=Thu Oct 29 10:24:29 CST 2015]
七、二级缓存
7.1、mybatis二级缓存与一级缓存
sqlSession是互不影响的，一级缓存
Mapper(namespace)是二级缓存
多个sqlSession可以共享一个Mapper的二级缓存区域
二级缓存按namespace分，其它的mapper也有自己的二级缓存区域namespace
第一个namespace的mapper都有一个二级缓存区域，2个mapper的namespace如果相同，这2个mapper执行sql查询数据将存在相同的二级缓存区域中.
7.2、开启二级缓存
1.二级缓存是mapper范围级别的，除了在configuration.xml设置二级缓存的总开关，还在在个体的mapper.xml中开启二级缓存
<settings> <!--开启延时加载 --> <setting name="lazyLoadingEnabled" value="true"/> <!--关闭立即加载 --> <setting name="aggressiveLazyLoading" value="false"/> <!--开启二级缓存 --> <setting name="cacheEnabled" value="true" /> </settings>
2.mapper对就的pojo类，实现序列化
3.在authorMapper中开启二级缓存
<!--开启本mapper下的二级缓冲 --> <cache />
7.3、测试
@Testpublic void testCache() {// 获取会话工厂SqlSession sqlSession1 = sqlSessionFactory.openSession();AuthorMapper authorMapper1 = sqlSession1.getMapper(AuthorMapper.class);// 第一次查询Author author1 = authorMapper1.findAuthorById(2);//必须关闭不数据无法写到缓存区域
sqlSession1.close();// 获取会话工厂/*SqlSession sqlSession2 = sqlSessionFactory.openSession();AuthorMapper authorMapper2 = sqlSession2.getMapper(AuthorMapper.class);sqlSession2.close();*/// 获取会话工厂SqlSession sqlSession3 = sqlSessionFactory.openSession();AuthorMapper authorMapper3 = sqlSession3.getMapper(AuthorMapper.class);// 第一次查询Author author3 = authorMapper3.findAuthorById(2);sqlSession3.close();}DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.0 DEBUG [main] - Opening JDBC Connection DEBUG [main] - Created connection 873769339. DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer) DEBUG [main] - <== Total: 1 DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Returned connection 873769339 to pool. DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.5
中间增加commit操作
@Testpublic void testCache() {// 获取会话工厂SqlSession sqlSession1 = sqlSessionFactory.openSession();AuthorMapper authorMapper1 = sqlSession1.getMapper(AuthorMapper.class);// 第一次查询Author author1 = authorMapper1.findAuthorById(2);//必须关闭不数据无法写到缓存区域
sqlSession1.close();// 获取会话工厂SqlSession sqlSession2 = sqlSessionFactory.openSession();AuthorMapper authorMapper2 = sqlSession2.getMapper(AuthorMapper.class);Author author2 = authorMapper2.findAuthorById(2);//更新author2.setAuthorUserName("董事长");author2.setAuthroBio("公司");authorMapper2.updateAuthor(author2);//commit会清空缓存区域
sqlSession2.commit();sqlSession2.close();// 获取会话工厂SqlSession sqlSession3 = sqlSessionFactory.openSession();AuthorMapper authorMapper3 = sqlSession3.getMapper(AuthorMapper.class);// 第一次查询Author author3 = authorMapper3.findAuthorById(2);sqlSession3.close();}结果：
DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.0 DEBUG [main] - Opening JDBC Connection DEBUG [main] - Created connection 873769339. DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer) DEBUG [main] - <== Total: 1 DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Returned connection 873769339 to pool. DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.5 DEBUG [main] - Opening JDBC Connection DEBUG [main] - Checked out connection 873769339 from pool. DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - ==> Preparing: update author SET author_username=?, author_password=?, author_email=?, author_bio=?, register_time=? where author_id=? DEBUG [main] - ==> Parameters: 董事长(String), 123asf(String), lisi@163.com(String), 公司(String), 2015-10-29 10:24:29.0(Timestamp), 2(Integer) DEBUG [main] - <== Updates: 1 DEBUG [main] - Committing JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Returned connection 873769339 to pool. DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.3333333333333333 DEBUG [main] - Opening JDBC Connection DEBUG [main] - Checked out connection 873769339 from pool. DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer) DEBUG [main] - <== Total: 1 DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@3414a97b] DEBUG [main] - Returned connection 873769339 to pool.
八、Mybatis与ehcache整合
8.1、把jar包导入项目
8.2、建立ehcache.xml
ehcache.xml
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:noNamespaceSchemaLocation="../config/ehcache.xsd"><diskStore path="F:\develop\ehcache" /><defaultCache maxElementsInMemory="1000" maxElementsOnDisk="10000000"eternal="false" overflowToDisk="false" timeToIdleSeconds="120"timeToLiveSeconds="120" diskExpiryThreadIntervalSeconds="120"memoryStoreEvictionPolicy="LRU"></defaultCache> </ehcache>
8.3、在mapper的cache中指定type
<!--开启本mapper下的二级缓冲 type指定为ehcachecache类开 在ehcache和mybatis的整合包中--> <cache type="org.mybatis.caches.ehcache.EhcacheCache"/>
8.4、测试
@Testpublic void testCache() {// 获取会话工厂SqlSession sqlSession1 = sqlSessionFactory.openSession();AuthorMapper authorMapper1 = sqlSession1.getMapper(AuthorMapper.class);// 第一次查询Author author1 = authorMapper1.findAuthorById(2);//必须关闭不数据无法写到缓存区域
sqlSession1.close();// 获取会话工厂SqlSession sqlSession2 = sqlSessionFactory.openSession();AuthorMapper authorMapper2 = sqlSession2.getMapper(AuthorMapper.class);Author author2 = authorMapper2.findAuthorById(2);//更新author2.setAuthorUserName("董事长");author2.setAuthroBio("公司");authorMapper2.updateAuthor(author2);//commit会清空缓存区域
sqlSession2.commit();sqlSession2.close();// 获取会话工厂SqlSession sqlSession3 = sqlSessionFactory.openSession();AuthorMapper authorMapper3 = sqlSession3.getMapper(AuthorMapper.class);// 第一次查询Author author3 = authorMapper3.findAuthorById(2);sqlSession3.close();}结果：
DEBUG [main] - Configuring ehcache from ehcache.xml found in the classpath: file:/E:/mywork/MybatisDemo2/bin/ehcache.xml DEBUG [main] - Configuring ehcache from URL: file:/E:/mywork/MybatisDemo2/bin/ehcache.xml DEBUG [main] - Configuring ehcache from InputStream DEBUG [main] - Ignoring ehcache attribute xmlns:xsi DEBUG [main] - Ignoring ehcache attribute xsi:noNamespaceSchemaLocation DEBUG [main] - Disk Store Path: F:\develop\ehcache DEBUG [main] - Creating new CacheManager with default config DEBUG [main] - propertiesString is null. DEBUG [main] - No CacheManagerEventListenerFactory class specified. Skipping... DEBUG [main] - No BootstrapCacheLoaderFactory class specified. Skipping... DEBUG [main] - CacheWriter factory not configured. Skipping... DEBUG [main] - No CacheExceptionHandlerFactory class specified. Skipping... DEBUG [main] - Initialized net.sf.ehcache.store.NotifyingMemoryStore for com.pb.mybatis.mapper.AuthorMapper DEBUG [main] - Initialised cache: com.pb.mybatis.mapper.AuthorMapper DEBUG [main] - CacheDecoratorFactory not configured for defaultCache. Skipping for 'com.pb.mybatis.mapper.AuthorMapper'. DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.0 DEBUG [main] - Opening JDBC Connection DEBUG [main] - Created connection 1286943672. DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer) DEBUG [main] - <== Total: 1 DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - Returned connection 1286943672 to pool. DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.5 DEBUG [main] - Opening JDBC Connection DEBUG [main] - Checked out connection 1286943672 from pool. DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - ==> Preparing: update author SET author_username=?, author_password=?, author_email=?, author_bio=?, register_time=? where author_id=? DEBUG [main] - ==> Parameters: 董事长(String), 123asf(String), lisi@163.com(String), 公司(String), 2015-10-29 10:24:29.0(Timestamp), 2(Integer) DEBUG [main] - <== Updates: 1 DEBUG [main] - Committing JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - Returned connection 1286943672 to pool. DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.3333333333333333 DEBUG [main] - Opening JDBC Connection DEBUG [main] - Checked out connection 1286943672 from pool. DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer) DEBUG [main] - <== Total: 1 DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@4cb533b8] DEBUG [main] - Returned connection 1286943672 to pool.
转载于:https://www.cnblogs.com/liunanjava/p/4925553.html
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