mybatis一对多配置问题

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1.数据库

user:

role:

2.实体类

User：

public class User {private int userId;private String userName;private String password;private String email;private Role role;public Role getRole() {return role;}public void setRole(Role role) {this.role = role;}//private int type;public int getUserId() {return userId;}public void setUserId(int userId) {this.userId = userId;}public String getUserName() {return userName;}public void setUserName(String userName) {this.userName = userName;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getEmail() {return email;}public void setEmail(String email) {this.email = email;}/*public int getType() {return type;}public void setType(int type) {this.type = type;}*/}

Role:

public class Role {private int roleId;private String roleName;public int getRoleId() {return roleId;}public void setRoleId(int roleId) {this.roleId = roleId;}public String getRoleName() {return roleName;}public void setRoleName(String roleName) {this.roleName = roleName;}}

3.映射文件mapper

最为重要的一部分

UserMap.xml

其中：resultMap对应的为在xml文件定义的resultMap id="xxx"

resultType则是写实体类

association负责进行自动查询相关联的表

property:与实体类中定义的属性相对应

colump:则与数据库中表的外键名相对应

javaType:相关联的实体类

select:查询语句的id

<pre name="code" class="plain"><?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.ssm.mapper.UserMapper" ><resultMap id="user" type="com.ssm.model.User"><id property="userId" column="UserID"/><result property="userName" column="UserName"/><result property="password" column="PassWord"/><association property="role" column="Type" javaType="com.ssm.model.Role" select="getRoleForID"><result property="email" column="Email"/></association></resultMap><select id="selectUserByModel"  parameterType="com.ssm.model.User" resultMap="user">select * from user where UserName=#{user.userName} and PassWord=#{user.password}</select>

RoleMap.xml

<pre name="code" class="plain"><?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.ssm.mapper.UserMapper" ><resultMap id="role" type="com.ssm.model.Role"><id property="roleId" column="RoleID"/><result property="roleName" column="RoleName"/></resultMap><select id="getRoleForID" parameterType="int" resultType="com.ssm.model.Role">select *from rolewhere RoleID=#{roleid}</select></mapper>

4.接口该接口不用实现即可完成dao层功能使用注解注入

@Repository(value = "userMapper") public interface UserMapper{

  User selectUserByModel(@Param(value = "user") User user);   Role getRoleForID(@Param(value = "roleid")int roleid);}

5.配置aapplicationContext.xml中的配置直接对目录进行扫描省去了将每一个mapper配置文件一一配置的麻烦

<pre name="code" class="plain"><!-- 创建SqlSessionFactory，同时指定数据源 --><bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"><property name="dataSource" ref="dataSource" /><property name="mapperLocations" value="classpath:com/ssm/mapping/*.xml"></property></bean>

讲的不专业，自己看着玩

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