一、对象关系映射环境搭建
1、创建数据库表
CREATE DATABASE test;
CREATE TABLE `user` (
`id` int(11) NOT NULL auto_increment,
`username` varchar(32) NOT NULL COMMENT '用户名称',
`birthday` datetime default NULL COMMENT '生日',
`sex` char(1) default NULL COMMENT '性别',
`address` varchar(256) default NULL COMMENT '地址',
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into `user`(`id`,`username`,`birthday`,`sex`,`address`) values (41,'老王','2018-02-27 17:47:08','男','北京');
insert into `user`(`id`,`username`,`birthday`,`sex`,`address`) values (42,'小二王','2018-03-02 15:09:37','女','北京金燕龙');
insert into `user`(`id`,`username`,`birthday`,`sex`,`address`) values (43,'小二王','2018-03-04 11:34:34','女','北京金燕龙');
insert into `user`(`id`,`username`,`birthday`,`sex`,`address`) values (45,'传智播客','2018-03-04 12:04:06','男','北京金燕龙');
insert into `user`(`id`,`username`,`birthday`,`sex`,`address`) values (46,'老王','2018-03-07 17:37:26','男','北京');
insert into `user`(`id`,`username`,`birthday`,`sex`,`address`) values (48,'小马宝莉','2018-03-08 11:44:00','女','北京修正');
CREATE TABLE `account` (
`ID` int(11) NOT NULL COMMENT '编号',
`UID` int(11) default NULL COMMENT '用户编号',
`MONEY` double default NULL COMMENT '金额',
PRIMARY KEY (`ID`),
KEY `FK_Reference_8` (`UID`),
CONSTRAINT `FK_Reference_8` FOREIGN KEY (`UID`) REFERENCES `user` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into `account`(`ID`,`UID`,`MONEY`) values (1,46,1000),(2,45,1000),(3,46,2000);2、创建maven工程并导入坐标
3、创建实体类、持久层dao接口
在domain包中创建User类
package com.wedu.mybatis09.domain;
import java.io.Serializable;
import java.util.Date;
import java.util.List;
/**
* 用户实体
*/
public class User implements Serializable {
private Integer id;
private String username;
private String address;
private String sex;
private Date birthday;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", address='" + address + '\'' +
", sex='" + sex + '\'' +
", birthday=" + birthday +
'}';
}
}在domain包中创建Account类
package com.wedu.mybatis09.domain;
import java.io.Serializable;
/**
* 账户实体
*/
public class Account implements Serializable {
private Integer id;
private Integer uid;
private Double money;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getUid() {
return uid;
}
public void setUid(Integer uid) {
this.uid = uid;
}
public Double getMoney() {
return money;
}
public void setMoney(Double money) {
this.money = money;
}
@Override
public String toString() {
return "Account{" +
"id=" + id +
", uid=" + uid +
", money=" + money +
'}';
}
}在dao包中创建IUserDao接口
package com.wedu.mybatis09.dao;
/**
* 用户的持久层接口
*/
public interface IUserDao {
}在dao包中创建IAccountDao接口
package com.wedu.mybatis09.dao;
/**
* 账户持久层接口
*/
public interface IAccountDao {
}4、创建数据库配置文件：jdbc.properties
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test?useSSL=true&useUnicode=true&characterEncoding=utf8
jdbc.username=root
jdbc.password=1234565、创建日志文件：log4j.properties
# Set root category priority to INFO and its only appender to CONSOLE.
#log4j.rootCategory=INFO, CONSOLE debug info warn error fatal
log4j.rootCategory=debug, CONSOLE, LOGFILE
# Set the enterprise logger category to FATAL and its only appender to CONSOLE.
log4j.logger.org.apache.axis.enterprise=FATAL, CONSOLE
# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n
# LOGFILE is set to be a File appender using a PatternLayout.
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=E:\\project\\axis.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n6、创建配置文件：SqlMapConfig.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!--引用外部的配置文件信息-->
<properties resource="jdbc.properties"/>
<!--配置别名-->
<typeAliases>
<package name="com.wedu.mybatis09.domain"/>
</typeAliases>
<!--配置环境-->
<environments default="development">
<environment id="development">
<!--配置事务的类型-->
<transactionManager type="JDBC"></transactionManager>
<!--配置数据源-->
<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>
<!--配置映射文件的位置-->
<mappers>
<package name="com.wedu.mybatis09.dao" />
</mappers>
</configuration>7、创建测试类UserDaoTest和AccountDaoTest
UserDaoTest测试类
package com.wedu.mybatis09.dao;
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.After;
import org.junit.Before;
/**
* 对象关系映射测试
*/
public class UserDaoTest {
private SqlSession session;
private IUserDao userDao;
@Before
public void init() throws Exception{
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("SqlMapConfig.xml"));
session = factory.openSession();
userDao = session.getMapper(IUserDao.class);
}
@After
public void destroy() {
session.close();
}
}AccountDaoTest测试类
package com.wedu.mybatis09.dao;
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.After;
import org.junit.Before;
public class AccountDaoTest {
private SqlSession session;
private IAccountDao accountDao;
@Before
public void init() throws Exception{
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("SqlMapConfig.xml"));
session = factory.openSession();
accountDao = session.getMapper(IAccountDao.class);
}
@After
public void destroy() {
session.close();
}
} /**
* 查询所有账户
*/
@Test
public void testFindAll() {
List<Account> accounts = accountDao.findAll();
for (Account account : accounts) {
System.out.println(account);
System.out.println(account.getUser());
}
}二、mybatis基于XML的对象关系映射的实现
1、创建映射文件：IUserDao.xml和IAccountDao.xml
IUserDao.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.wedu.mybatis09.dao.IUserDao">
</mapper>IAccountDao.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.wedu.mybatis09.dao.IAccountDao">
</mapper>2、一对一的关系映射
2.1、在Account实体类添加User属性
//一对一的关系映射:从表实体应该包含一个主表实体的对象引用
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}2.2、在IAccountDao中添加查询方法
/**
* 查询所有账户,，同时还要获取到当前账户的所属用户信息
* @return
*/
List<Account> findAll();2.3、在IAccountDao.xml添加sql语句
<!--定义封装account和user的resultMap-->
<resultMap id="accountUserMap" type="account">
<id property="id" column="aid"></id>
<result property="uid" column="uid"></result>
<result property="money" column="money"></result>
<!-- 一对一的关系映射：配置封装user的内容-->
<association property="user" column="uid" javaType="user">
<id property="id" column="id"></id>
<result property="username" column="username"></result>
<result property="birthday" column="birthday"></result>
<result property="sex" column="sex"></result>
<result property="address" column="address"></result>
</association>
</resultMap>
<!-- 查询所有 -->
<select id="findAll" resultMap="accountUserMap">
select u.*,a.id as aid,a.uid,a.money from account a , user u where u.id = a.uid;
</select>2.4、在AccountDaoTest的测试类中测试
/**
* 查询所有账户
*/
@Test
public void testFindAll() {
List<Account> accounts = accountDao.findAll();
for (Account account : accounts) {
System.out.println(account);
System.out.println(account.getUser());
}
}3、一对多（多对一）映射
3.1、在User实体类添加Account属性
//一对多关系映射：主表实体应该包含从表实体的集合引用
private List<Account> accounts;
public List<Account> getAccounts() {
return accounts;
}
public void setAccounts(List<Account> accounts) {
this.accounts = accounts;
}3.2、在IUserDao中添加查询方法
/**
* 查询所有用户,，同时获取到用户下所有账户的信息
* @return
*/
List<User> findAll();3.3、在IUserDao.xml添加sql语句
<!--定义User的resultMap-->
<resultMap id="userAccountMap" type="user">
<id property="id" column="id"></id>
<result property="username" column="username"></result>
<result property="birthday" column="birthday"></result>
<result property="sex" column="sex"></result>
<result property="address" column="address"></result>
<!--一对多的关系映射：配置user对象中accounts集合的映射-->
<collection property="accounts" ofType="account">
<id property="id" column="aid"></id>
<result property="uid" column="uid"></result>
<result property="money" column="money"></result>
</collection>
</resultMap>
<!-- 查询所有 -->
<select id="findAll" resultMap="userAccountMap">
select u.*,a.id as aid,a.uid,a.money from user u left outer join account a on u.id = a.uid
</select>3.4、在UserDaoTest的测试类中测试
/**
* 查询所有用户
*/
@Test
public void testFindAll() {
List<User> users = userDao.findAll();
for (User user : users) {
System.out.println(user);
System.out.println(user.getAccounts());
}
}三、mybatis基于注解的对象关系映射的实现
1、一对一的关系映射
1.1、在Account实体类添加User属性
//一对一的关系映射:从表实体应该包含一个主表实体的对象引用
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}1.2、在IAccountDao接口中添加查询方法并添加一对一的关系映射的注解
/**
* 查询所有账户
* @return
*/
@Select("select * from account")
@Results(id = "accountMap",value = {
@Result(id = true,column = "id",property = "id"),
@Result(column = "uid",property = "uid"),
@Result(column = "money",property = "money"),
@Result(property = "user",column = "uid",one=@One(select="com.wedu.mybatis15.dao.IUserDao.findById",fetchType= FetchType.EAGER))
})
List<Account> findAll();1.3、 在IUserDao接口中添加根据id查询方法
/**
* 根据id查询用户
* @param id
* @return
*/
@Select("select * from user where id=#{id}")
User findById(Integer id);1.4、在AccountDaoTest的测试类中测试
/**
* 查询所有账户
*/
@Test
public void testFindAll() {
List<Account> accounts = accountDao.findAll();
for (Account account : accounts) {
System.out.println(account);
System.out.println(account.getUser());
}
}2、一对多（多对一）映射
1.1、在User实体类添加Account属性
//一对多关系映射：主表实体应该包含从表实体的集合引用
private List<Account> accounts;
public List<Account> getAccounts() {
return accounts;
}
public void setAccounts(List<Account> accounts) {
this.accounts = accounts;
}1.2、在IUserDao接口中添加关联查询方法并添加多对一的关系映射注解
/**
* 查询所有用户
* @return
*/
@Select("select * from user")
@Results(id = "userMap",value = {
@Result(id = true,column = "id",property = "id"),
@Result(column = "username",property = "username"),
@Result(column = "birthday",property = "birthday"),
@Result(column = "sex",property = "sex"),
@Result(column = "address",property = "address"),
@Result(property = "accounts",column = "id",
many = @Many(select = "com.wedu.mybatis15.dao.IAccountDao.findAccountByUid",
fetchType = FetchType.LAZY))
})
List<User> findAll();1.3、在IAccountDao接口中添加根据id查询方法
/**
* 根据用户id查询账户信息
* @param id
* @return
*/
@Select("select * from account where uid=#{id}")
Account findAccountByUid(Integer id);1.3、在UserDaoTest的测试类中测试
/**
* 查询所有用户
*/
@Test
public void testFindAll() {
List<User> users = userDao.findAll();
for (User user : users) {
System.out.println(user);
System.out.println(user.getAccounts());
}
}