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[Java教程]MyBatis入门(五)


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 ',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.

4.1、相对应的mapper.

AuthorMapper.

 

<??><!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 authorwhere author_id=#{id}</select></mapper>

 

 

 

BlogMapper.

 

<??><!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 blogWHERE blog_id=#{blogId}</select></mapper>

 

 

 

PostsMapper.

 

<??><!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 postswhere blog_id=#{blogId}</select></mapper>

 

 

 

 

4.2、configuration.

db.properties

 

driver=com.mysql.jdbc.Driverurl=jdbc:mysql://localhost:3306/mybatis?character=utf8username=rootpassword=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>

 

<??><!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.;    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: 11...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: 1Author [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.;    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: 1Author [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: 1Author [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.

 

<!--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.;    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: 1Author [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: 1DEBUG [main] - Committing JDBC Connection [com.mysql.jdbc.JDBC4Connection@42bb0406]11num=1再次查询DEBUG [main] - ==> Preparing: select * from author where author_id=? DEBUG [main] - ==> Parameters: 2(Integer)DEBUG [main] - <==   Total: 1Author [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.

 

<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]: 0.0DEBUG [main] - Opening JDBC ConnectionDEBUG [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: 1DEBUG [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]: 0.0DEBUG [main] - Opening JDBC ConnectionDEBUG [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: 1DEBUG [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]: 0.5DEBUG [main] - Opening JDBC ConnectionDEBUG [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: 1DEBUG [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]: 0.3333333333333333DEBUG [main] - Opening JDBC ConnectionDEBUG [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: 1DEBUG [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.

ehcache.

 

<ehcache ="http://www.w3.org/2001/  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.ehcache.- Configuring ehcache from URL: file:/E:/mywork/MybatisDemo2/bin/ehcache.- Configuring ehcache from InputStreamDEBUG [main] - Ignoring ehcache attribute - Ignoring ehcache attribute xsi:noNamespaceSchemaLocationDEBUG [main] - Disk Store Path: F:\develop\ehcacheDEBUG [main] - Creating new CacheManager with default configDEBUG [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.AuthorMapperDEBUG [main] - Initialised cache: com.pb.mybatis.mapper.AuthorMapperDEBUG [main] - CacheDecoratorFactory not configured for defaultCache. Skipping for 'com.pb.mybatis.mapper.AuthorMapper'.DEBUG [main] - Cache Hit Ratio [com.pb.mybatis.mapper.AuthorMapper]: 0.0DEBUG [main] - Opening JDBC ConnectionDEBUG [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: 1DEBUG [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]: 0.5DEBUG [main] - Opening JDBC ConnectionDEBUG [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: 1DEBUG [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]: 0.3333333333333333DEBUG [main] - Opening JDBC ConnectionDEBUG [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: 1DEBUG [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.