1、數據庫準備

CREATE TABLE `role` (

? `ID` INT(11) NOT NULL COMMENT '編號',
? `ROLE_NAME` VARCHAR(30) DEFAULT NULL COMMENT '角色名稱',
? `ROLE_DESC` VARCHAR(60) DEFAULT NULL COMMENT '角色描述',
? PRIMARY KEY? (`ID`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;
INSERT? INTO `role`(`ID`,`ROLE_NAME`,`ROLE_DESC`) VALUES (1,'院長','管理整個學院'),(2,'總裁','管理整個公司'),(3,'校長','管理整個學校');
CREATE TABLE `user` (
? `id` INT(11) NOT NULL AUTO_INCREMENT,
? `username` VARCHAR(32) NOT NULL COMMENT '用戶名稱',
? `birthday` DATETIME DEFAULT NULL COMMENT '生日',
? `sex` CHAR(1) DEFAULT NULL COMMENT '性別',
? `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'),(42,'小二王','2018-03-02 15:09:37','女','北京金燕龍'),(43,'小二王','2018-03-04 11:34:34','女','北京金燕龍'),(45,'傳智播客','2018-03-04 12:04:06','男','北京金燕龍'),(46,'老王','2018-03-07 17:37:26','男','北京'),(48,'小馬寶莉','2018-03-08 11:44:00','女','北京修正');

2、創建一個Maven項目

在pom.xml引入約束:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
? <modelVersion>4.0.0</modelVersion>
? <groupId>cn.wzq</groupId>
? <artifactId>MyBatis_day04_01_note_user_role_onetomany</artifactId>
? <version>0.0.1-SNAPSHOT</version>
??? <dependencies>
?? ??? ?<!-- log4j日志 -->
?? ??? ?<dependency>
?? ??? ??? ?<groupId>log4j</groupId>
?? ??? ??? ?<artifactId>log4j</artifactId>
?? ??? ??? ?<version>1.2.12</version>
?? ??? ?</dependency>
?? ??? ?<!-- mysql驅動 -->
?? ??? ?<dependency>
?? ??? ??? ?<groupId>mysql</groupId>
?? ??? ??? ?<artifactId>mysql-connector-java</artifactId>
?? ??? ??? ?<version>5.1.6</version>
?? ??? ?</dependency>
?? ??? ?<!-- mybatis的坐標 -->
?? ??? ?<dependency>
?? ??? ??? ?<groupId>org.mybatis</groupId>
?? ??? ??? ?<artifactId>mybatis</artifactId>
?? ??? ??? ?<version>3.4.5</version>
?? ??? ?</dependency>
?? ??? ?<dependency>
?? ??? ??? ?<groupId>junit</groupId>
?? ??? ??? ?<artifactId>junit</artifactId>
?? ??? ??? ?<version>4.12</version>
?? ??? ?</dependency>
?? ?</dependencies>
</project>

2、創建數據庫信息配置文件：jdbc.properties

jdbc.username=root
jdbc.password=root
jdbc.url=jdbc:mysql://localhost:3306/mybatisdb?characterEncoding=utf8

jdbc.driver=com.mysql.jdbc.Driver

3、配置核心配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!-- 核心配置文件的約束 -->
<!DOCTYPE configuration
? PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
? "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>? ?
?? ?<!-- 引入數據庫配置信息 -->
?? ?<properties resource="jdbc.properties"></properties>
?? ?<!-- 別名配置 -->
?? <typeAliases>
? ?? ???? <package name="cn.wzq.mybatis.domin"/>
?? </typeAliases>
?? <environments default="development">? ?
????? <environment id="development">? ?
??????? <transactionManager type="JDBC" />? ?
??????? <dataSource type="POOLED">? ?
????????? <property name="driver" value="${jdbc.driver}" ></property>? ?
????????? <property name="url" value="${jdbc.url}" ></property>? ?
????????? <property name="username" value="${jdbc.username}"></property>
????????? <property name="password" value="${jdbc.password}"></property>
??????? </dataSource>? ?
???? </environment>? ?
? </environments>
? <!-- sql映射配置 -->
? <mappers>
? ?? ?<package name="cn.wzq.mybatis.dao"/>
? </mappers>
</configuration>??

4、創建user和role對象

public class User {

?? ?private Integer id;
?? ?private String username;
?? ?private String sex;
?? ?private String address;
?? ?private Date birthday;

??? private List<Role> list;

?? //get/set/toString省略；

｝

public class Role {
?? ?private Integer id;
?? ?private String ROLE_NAME;
?? ?private String ROLE_DESC;
??? //get/set/toString省略；

｝

5、創建IRoleDao接口

public interface IRoleDao {

?? ?//根據用戶查詢角色
?? ?@Select(value="select * from role where id = #{id}")
?? ?public Role findRole(int uid);
?? ??? ?
}

6、創建IUserDao接口

public interface IUserDao {
?? ?
?? ?//查詢用戶下的所有角色
?? ?@Select(value="select * from user")
?? ?@Results(value= {
?? ??? ??? ?@Result(property="id",column="id",id=true),
?? ??? ??? ?@Result(property="username",column="username"),
?? ??? ??? ?@Result(property="sex",column="sex"),
?? ??? ??? ?@Result(property="address",column="address"),
?? ??? ??? ?@Result(property="birthday",column="birthday"),
?? ??? ??? ?@Result(property="list",javaType=List.class,column="id",
?? ??? ??? ??? ?many=@Many(select="cn.wzq.mybatis.dao.IRoleDao.findRole",fetchType=FetchType.LAZY)
?? ??? ??? ?)
?? ?})
?? ?public List<User> findAll();

}

7、測試

??? //查詢用戶下所有角色
?? ?@Test
?? ?public void findAllTest() {
?? ??? ?SqlSession openSession = sqlSessionFactory.openSession();
?? ??? ?IUserDao userDao = openSession.getMapper(IUserDao.class);
?? ??? ?List<User> list = userDao.findAll();
?? ??? ?for (User user : list) {
?? ??? ??? ?System.out.println(user.getId());
?? ??? ??? ?//System.out.println(user.getList()); //需要使用時釋放注解
?? ??? ?}

?? ?}

整體目錄結構