MyBatis入门（二）---一对一，一对多

一、创建数据库表
1.1、创建数据表同时插入数据
/*sqlyog enterprise v12.09 (64 bit)mysql - 5.6.27-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=6 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');
/*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 */;
二、创建项目
2.1、创建项目并加入jar包
2.2、创建实体类以author为例
package com.pb.mybatis.po;import java.util.date;/**
*
* @title: author.java
* @package com.pb.mybatis.po
* @classname author
* @description: todo(blog作者类)
* @author 刘楠
* @date 2015-10-29 上午9:27:53
* @version v1.0 */public class author { //作者id
private int authorid;
//作者用户名
private string authorusername;
//作者密码
private string authorpassword;
//作者邮箱
private string authoremail;
//作者介绍
private int authorbio;
//注册时间
private date registertime; /**
* @return the authorid */
public int getauthorid() { return authorid;
} /**
* @param authorid the authorid to set */
public void setauthorid(int authorid) { this.authorid = authorid;
} /**
* @return the authorusername */
public string getauthorusername() { return authorusername;
} /**
* @param authorusername the authorusername to set */
public void setauthorusername(string authorusername) { this.authorusername = authorusername;
} /**
* @return the authorpassword */
public string getauthorpassword() { return authorpassword;
} /**
* @param authorpassword the authorpassword to set */
public void setauthorpassword(string authorpassword) { this.authorpassword = authorpassword;
} /**
* @return the authoremail */
public string getauthoremail() { return authoremail;
} /**
* @param authoremail the authoremail to set */
public void setauthoremail(string authoremail) { this.authoremail = authoremail;
} /**
* @return the authorbio */
public int getauthorbio() { return authorbio;
} /**
* @param authorbio the authorbio to set */
public void setauthorbio(int authorbio) { this.authorbio = authorbio;
} /**
* @return the registertime */
public date getregistertime() { return registertime;
} /**
* @param registertime the registertime to set */
public void setregistertime(date registertime) { this.registertime = registertime;
} /** (non javadoc)
* <p>title: tostring</p>
* <p>description:重写tostring方法 </p>
* @return
* @see java.lang.object#tostring() */
@override public string tostring() { return author [authorid= + authorid + , authorusername=
+ authorusername + , authorpassword= + authorpassword + , authoremail= + authoremail + , authorbio= + authorbio + , registertime= + registertime + ];
}
}
2.3、创建mybatis配置文件
<?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><properties resource="db.properties" /><typealiases><package name="com.pb.mybatis.po"/></typealiases><environments default="development"><environment id="development">
<transactionmanager type="jdbc"/>
<datasource type="pooled">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</datasource></environment></environments><mappers><package name="com.pb.mybatis.mapper"/></mappers></configuration>
2.4、创建实体类对象的接口以author为例
/***/package com.pb.mybatis.mapper;import java.util.list;import com.pb.mybatis.po.author;/**
* @title: authormapper.java
* @package com.pb.mybatis.mapper
* @classname authormapper
* @description: todo(作者接口)
* @author 刘楠
* @date 2015-10-29 上午11:13:10
* @version v1.0
*/public interface authormapper {
/**
*
* @title: findbyid
* @description: todo(根据查找一个用户)
* @param id
* @return author */
public author findauthorbyid(int authorid);
/**
*
* @title: findbyname
* @description: todo(根据用户名，模糊查询)
* @param name
* @return list<author> */
public list<author> findauthorbyname(string name);
/**
*
* @title: addauthor
* @description: todo(添加作者)
* @param author
* @return int */
public int addauthor(author author);
/**
*
* @title: updateauthor
* @description: todo(修改用户)
* @param authro
* @return int */
public int updateauthor(author authro);
/**
*
* @title: deleteaturho
* @description: todo(根据id删除作者)
* @param id
* @return int */
public int deleteauthor(int authorid);
}
2.5、创建接口对应的mapper.xm以author为例
<?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"><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="authorbio" column="author_bio"/><result property="registertime" column="register_time"/></resultmap><select id="findauthorbyid" parametertype="int" resultmap="authorresultmap">select * from author
where author_id=#{authorid}</select><select id="findauthorbyname" parametertype="string" resultmap="authorresultmap">select * from author
where author_username like %#{name}%</select><insert id="addauthor" parametertype="author" usegeneratedkeys="true" keyproperty="authorid">insert into author(author_username,author_password,author_email,author_bio,register_time)
values(#{authorusername},#{authorpassword},#{authoremail},#{authorbio},#{registertime})</insert><update id="updateauthor" parametertype="author">update author
set
author_username=#{authorusername},
author_password=#{authorpassword},
author_email=#{authoremail},
author_bio=#{authorbio},
register_time=#{registertime}
where author_id=#{authorid}</update><delete id="deleteauthor" parametertype="int">delete from author
where author_id=#{authorid}</delete></mapper>
三、简单实现增删改查
3.1、测试类以author为例
/***/package com.pb.mybatis.mapper;import java.io.inputstream;import java.util.date;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.author;/**
* @title: authormappertest.java
* @package com.pb.mybatis.mapper
* @classname authormappertest
* @description: todo(测试)
* @author 刘楠
* @date 2015-10-29 上午11:57:21
* @version v1.0
*/public class authormappertest {
private sqlsessionfactory sqlsessionfactory;
/**
*
* @title: setup
* @description: todo(在每个方法前执行的方法)
* @throws exception void */
@before public void setup() throws exception {
string resource=configuration.xml;
inputstream in=resources.getresourceasstream(resource); //获取会话工厂
sqlsessionfactory=new sqlsessionfactorybuilder().build(in);
} /**
*
* @title: testfindauthorbyid
* @description: todo(根据查找一个用户)
void */
@test public void testfindauthorbyid() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
authormapper authormapper=sqlsession.getmapper(authormapper.class); //调用方法
author author=authormapper.findauthorbyid(2);
system.out.println(author); //关闭会话 sqlsession.close();
} /**
*
* @title: testfindauthorbyname
* @description: todo(根据用户名，模糊查询)
void */
@test public void testfindauthorbyname() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
authormapper authormapper=sqlsession.getmapper(authormapper.class); //调用方法
list<author> authors=authormapper.findauthorbyname(张);
system.out.println(authors); //关闭会话 sqlsession.close(); for(author a:authors){
system.out.println(a.tostring());
}
} /**
*
* @title: testaddauthor
* @description: todo(添加作者)
void */
@test public void testaddauthor() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
authormapper authormapper=sqlsession.getmapper(authormapper.class); //调用方法
author author=new author();
author.setauthorusername(不知道);
author.setauthorpassword(1234567890);
author.setauthoremail(123456@qq.com);
author.setauthorbio(知道是个什么);
author.setregistertime(new date()); int num=authormapper.addauthor(author);
system.out.println(num=+num);
system.out.println(authorid=+author.getauthorid());
sqlsession.commit(); //关闭会话 sqlsession.close();
} /**
*
* @title: testupdateauthor
* @description: todo(修改用户)
void */
@test public void testupdateauthor() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
authormapper authormapper=sqlsession.getmapper(authormapper.class); //调用方法
author author=authormapper.findauthorbyid(8);
author.setauthorusername(知道了);
author.setauthorpassword(456789);
author.setauthoremail(456789@qq.com);
author.setauthorbio(哈哈哈哈哈雅虎);
author.setregistertime(new date()); int num=authormapper.updateauthor(author);
system.out.println(num=+num);
system.out.println(authorid=+author.getauthorid());
sqlsession.commit(); //关闭会话 sqlsession.close();
} /**
*
* @title: testdeleteauthor
* @description: todo(根据id删除作者)
void */
@test public void testdeleteauthor() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
authormapper authormapper=sqlsession.getmapper(authormapper.class); //调用方法
int num=authormapper.deleteauthor(10);
system.out.println(num=+num);
sqlsession.commit(); //关闭会话 sqlsession.close();
}
}
四、实现一对一
4.1、建立blog类
package com.pb.mybatis.po;/**
* @title: blog.java
* @package com.pb.mybatis.po
* @classname blog
* @description: todo(博客)
* @author 刘楠
* @date 2015-10-29 上午9:32:56
* @version v1.0
*/public class blog { //博客id
private int blogid;
//标题
private string blogtitle;
//博客作者
private author author; /**
* @return the blogid */
public int getblogid() { return blogid;
} /**
* @param blogid the blogid to set */
public void setblogid(int blogid) { this.blogid = blogid;
} /**
* @return the blogtitle */
public string getblogtitle() { return blogtitle;
} /**
* @param blogtitle the blogtitle to set */
public void setblogtitle(string blogtitle) { this.blogtitle = blogtitle;
} /**
* @return the author */
public author getauthor() { return author;
} /**
* @param author the author to set */
public void setauthor(author author) { this.author = author;
} /** (non javadoc)
* <p>title: tostring</p>
* <p>description: 重写tostring方法</p>
* @return
* @see java.lang.object#tostring() */
@override public string tostring() { return blog [blogid= + blogid + , blogtitle= + blogtitle + , author= + author + ];
}
}
4.2、建立blogmapper接口
/***/package com.pb.mybatis.mapper;import java.util.list;import com.pb.mybatis.po.author;import com.pb.mybatis.po.blog;/**
* @title: blogmapper.java
* @package com.pb.mybatis.mapper
* @classname blogmapper
* @description: todo(用一句话描述该文件做什么)
* @author 刘楠
* @date 2015-10-29 上午11:13:21
* @version v1.0
*/public interface blogmapper { /**
*
* @title: findblogbyid
* @description: todo(根据id查找blog)
* @param id
* @return blog */
public blog findblogbyid(int id);
/**
*
* @title: findbyname
* @description: todo(根据博客名查找)
* @param name
* @return list<blog> */
public list<blog> findblogbyname(string blogtitle);
/**
*
* @title: addblog
* @description: todo(添加博客)
* @param blog
* @return int */
public int addblog(blog blog);
/**
*
* @title: updateblog
* @description: todo(修改博客)
* @param blog
* @return int */
public int updateblog(blog blog);
/**
*
* @title: deleteblog
* @description: todo(删除博客)
* @param id
* @return int */
public int deleteblog(int id);
}
4.3、建立mapper.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"><resultmap type="blog" id="blogresultmap"><id property="blogid" column="blog_id"/><result property="blogtitle" column="blog_title"/><association property="author" resultmap="authorresultmap"/></resultmap><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="authorbio" column="author_bio"/><result property="registertime" column="register_time"/></resultmap><select id="findblogbyid" parametertype="int" resultmap="blogresultmap">select blog.blog_id,blog.blog_title,author.author_id,author.author_username,author.author_password,author.author_email,author.author_bio,author.register_time
from blog,author
where blog.author_id=author.author_id
and blog.blog_id=#{blogid}</select><select id="findblogbyname" parametertype="string" resultmap="blogresultmap">select blog.blog_id,blog.blog_title,author.author_id,author.author_username,author.author_password,author.author_email,author.author_bio,author.register_time
from blog,author
where blog.author_id=author.author_id
and blog_title like %#{blogtitle}%</select><insert id="addblog" parametertype="blog" usegeneratedkeys="true" keyproperty="blogid">insert into blog(blog_title,author_id)
values(#{blogtitle},#{author.authorid})</insert><update id="updateblog" parametertype="blog">update blog
set blog_title=#{blogtitle},
author_id=#{author.authorid}
where blog_id=#{blogid}</update><delete id="deleteblog" parametertype="int">delete from blog where blog_id=#{blogid}</delete></mapper>
4.1、测试类
package com.pb.mybatis.mapper;import static org.junit.assert.*;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.author;import com.pb.mybatis.po.blog;/**
* @title: blogmappertest.java
* @package com.pb.mybatis.mapper
* @classname blogmappertest
* @description: todo(用一句话描述该文件做什么)
* @author 刘楠
* @date 2015-10-29 下午3:12:52
* @version v1.0
*/public class blogmappertest { private sqlsessionfactory sqlsessionfactory;
@before public void setup() throws exception {
string resource=configuration.xml;
inputstream in=resources.getresourceasstream(resource); //获取会话工厂
sqlsessionfactory=new sqlsessionfactorybuilder().build(in);
} /**
* test method for {@link com.pb.mybatis.mapper.blogmapper#findblogbyid(int)}. */
@test public void testfindblogbyid() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
blogmapper blogmapper=sqlsession.getmapper(blogmapper.class); //调用方法
blog blog=blogmapper.findblogbyid(2);
system.out.println(blog); //关闭会话 sqlsession.close();
} /**
* test method for {@link com.pb.mybatis.mapper.blogmapper#findblogbyname(java.lang.string)}. */
@test public void testfindblogbyname() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
blogmapper blogmapper=sqlsession.getmapper(blogmapper.class); //调用方法
list<blog> blogs=blogmapper.findblogbyname(小);
system.out.println(blogs); //关闭会话 sqlsession.close();
} /**
* test method for {@link com.pb.mybatis.mapper.blogmapper#addblog(com.pb.mybatis.po.blog)}. */
@test public void testaddblog() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
blogmapper blogmapper=sqlsession.getmapper(blogmapper.class);
blog blog=new blog();
blog.setblogtitle(倚天屠龙记);
authormapper authormapper=sqlsession.getmapper(authormapper.class); //调用方法
author author=authormapper.findauthorbyid(2);
blog.setauthor(author); int num=blogmapper.addblog(blog);
system.out.println(num=+num);
system.out.println(blog.getblogid());
sqlsession.commit();
sqlsession.close();
} /**
* test method for {@link com.pb.mybatis.mapper.blogmapper#updateblog(com.pb.mybatis.po.blog)}. */
@test public void testupdateblog() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
blogmapper blogmapper=sqlsession.getmapper(blogmapper.class); //调用方法
blog blog=blogmapper.findblogbyid(8);
blog.setblogtitle(笑傲江湖);
author author=blog.getauthor();
author.setauthorusername(金庸);
authormapper authormapper=sqlsession.getmapper(authormapper.class); int authornum=authormapper.updateauthor(author); int num=blogmapper.updateblog(blog);
system.out.println(authornum=+authornum);
system.out.println(num=+num);
sqlsession.commit(); //关闭会话 sqlsession.close();
} /**
* test method for {@link com.pb.mybatis.mapper.blogmapper#deleteblog(int)}. */
@test public void testdeleteblog() { //获取会话
sqlsession sqlsession=sqlsessionfactory.opensession(); //mapper接口
blogmapper blogmapper=sqlsession.getmapper(blogmapper.class); int num=blogmapper.deleteblog(11);
system.out.println(num=+num);
sqlsession.commit();
sqlsession.close();
}
}
五、一对多
5.1、建立posts类
package com.pb.mybatis.po;import java.util.date;/**
* @title: posts.java
* @package com.pb.mybatis.po
* @classname posts
* @description: todo(blog文章)
* @author 刘楠
* @date 2015-10-29 上午9:31:22
* @version v1.0
*/public class posts { //文章id
private int postid;
//文件主题
private string postsubject;
//主体内容
private string postbody; //文章建立时间
private date createtime;
/**
* @return the postid */
public int getpostid() { return postid;
} /**
* @param postid the postid to set */
public void setpostid(int postid) { this.postid = postid;
} /**
* @return the postsubject */
public string getpostsubject() { return postsubject;
} /**
* @param postsubject the postsubject to set */
public void setpostsubject(string postsubject) { this.postsubject = postsubject;
} /**
* @return the postbody */
public string getpostbody() { return postbody;
} /**
* @param postbody the postbody to set */
public void setpostbody(string postbody) { this.postbody = postbody;
} /**
* @return the createtime */
public date getcreatetime() { return createtime;
} /**
* @param createtime the createtime to set */
public void setcreatetime(date createtime) { this.createtime = createtime;
} /** (non javadoc)
* <p>title: tostring</p>
* <p>description:重写tostring方法</p>
* @return
* @see java.lang.object#tostring() */
@override public string tostring() { return posts [postid= + postid + , postsubject= + postsubject + , postbody= + postbody +, createtime=
+ createtime + ];
}
}
5.2、在blog类中添加list
package com.pb.mybatis.po;import java.util.list;/**
* @title: blog.java
* @package com.pb.mybatis.po
* @classname blog
* @description: todo(博客)
* @author 刘楠
* @date 2015-10-29 上午9:32:56
* @version v1.0
*/public class blog { //博客id
private int blogid;
//标题
private string blogtitle;
//博客作者
private author author;
//文章list
private list<posts> posts; /**
* @return the blogid */
public int getblogid() { return blogid;
} /**
* @param blogid the blogid to set */
public void setblogid(int blogid) { this.blogid = blogid;
} /**
* @return the blogtitle */
public string getblogtitle() { return blogtitle;
} /**
* @param blogtitle the blogtitle to set */
public void setblogtitle(string blogtitle) { this.blogtitle = blogtitle;
} /**
* @return the author */
public author getauthor() { return author;
} /**
* @param author the author to set */
public void setauthor(author author) { this.author = author;
} /**
* @return the posts */
public list<posts> getposts() { return posts;
} /**
* @param posts the posts to set */
public void setposts(list<posts> posts) { this.posts = posts;
} /** (non javadoc)
* <p>title: tostring</p>
* <p>description: </p>
* @return
* @see java.lang.object#tostring() */
@override public string tostring() { return blog [blogid= + blogid + , blogtitle= + blogtitle + , author= + author + , posts= + posts + ];
}
}
5.3、修改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"><resultmap type="blog" id="blogresultmap"><id property="blogid" column="blog_id"/><result property="blogtitle" column="blog_title"/><association property="author" resultmap="authorresultmap"/><collection property="posts" resultmap="postsresultmap" oftype="posts"/></resultmap><resultmap type="posts" id="postsresultmap"><id property="postid" column="post_id"/><result property="postsubject" column="post_subject"/><result property="postbody" column="post_body"/><result property="createtime" column="createtime"/></resultmap><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="authorbio" column="author_bio"/><result property="registertime" column="register_time"/></resultmap><select id="findblogbyid" parametertype="int" resultmap="blogresultmap">select blog.blog_id,blog.blog_title,
author.author_id,author.author_username,author.author_password,author.author_email,author.author_bio,author.register_time,
posts.post_id,posts.post_subject,posts.post_body,posts.createtime,posts.blog_id
from blog,author,posts
where blog.author_id=author.author_id
and blog.blog_id=posts.blog_id
and blog.blog_id=#{blogid}</select><select id="findblogbyname" parametertype="string" resultmap="blogresultmap">select blog.blog_id,blog.blog_title,author.author_id,author.author_username,author.author_password,author.author_email,author.author_bio,author.register_time
from blog,author
where blog.author_id=author.author_id
and blog_title like %#{blogtitle}%</select><insert id="addblog" parametertype="blog" usegeneratedkeys="true" keyproperty="blogid">insert into blog(blog_title,author_id)
values(#{blogtitle},#{author.authorid})</insert><update id="updateblog" parametertype="blog">update blog
set blog_title=#{blogtitle},
author_id=#{author.authorid}
where blog_id=#{blogid}</update><delete id="deleteblog" parametertype="int">delete from blog where blog_id=#{blogid}</delete></mapper>
5.4、测试
测试类不变
以上就是mybatis入门（二）---一对一，一对多的内容。

MyBatis入门（二）---一对一，一对多

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