MyBatis入门（五）---延时加载、缓存
一、创建数据库
1.1、建立数据库
/*
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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','','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','','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id
private 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;
}
@Override
public 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,ID
private 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;
}
@Override
public String toString() {
return "Blog [blogId=" + blogId + ", blogTitle=" + blogTitle
+ ", authorId=" + authorId + "]";
}
}
package com.pb.mybatis.po;
import java.util.Date;
public class Posts {
//文章ID
private 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;
}
@Override
public 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 mapper
PUBLIC "-//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 mapper
PUBLIC "-//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 mapper
PUBLIC "-//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 configuration
PUBLIC "-//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; @Before
public 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
*/
@Test
public 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; @Before
public void setUp() throws Exception {
String config="configuration.xml";
InputStream resource=Resources.getResourceAsStream(config);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(resource);
} @Test
public 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; @Before
public void setUp() throws Exception {
String config="configuration.xml";
InputStream resource=Resources.getResourceAsStream(config);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(resource);
} @Test
public 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
@Test
public 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
@Test
public 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
@Test
public 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.
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