MyBatis学习笔记（六）一对多的关联查询和传递多个参数
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本文讲解一对多的关联查询，传递多个参数。
源码获取github
1.传递多个参数
-
当你的形参传递>1个的时候，parameterType不写，让其自动处理 - #{值}，默认为arg0，arg1…..或param1，param2，，，
- 若在接口中注解了@Param(相当于指明了key值)，即也可以写xxx，默认的也可以写，相当于3个值
2.结构
3.数据库属性文件
同之前
4.核心配置文件
mybatis-config.xml
<configuration>
<properties resource="jdbc.properties"/>
<typeAliases>
<package name="com.hs.model"/>
typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${jdbc.mysql.driver}" />
<property name="url" value="${jdbc.mysql.url}" />
<property name="username" value="${jdbc.mysql.username}" />
<property name="password" value="${jdbc.mysql.password}" />
dataSource>
environment>
environments>
<mappers>
<mapper resource="com/hs/model/UserMapper.xml"/>
<mapper resource="com/hs/model/RoleMapper.xml"/>
mappers>
configuration>5.持久化类
Role.java
package com.hs.model;
import java.util.List;
public class Role {
private Integer role_id;
private String role_name;
private String role_key;
private Integer status;
//关联对象,一对多，一个角色可以有多个用户
private List userList;
public List getUserList() {
return userList;
}
public void setUserList(List userList) {
this.userList = userList;
}
public Integer getRole_id() {
return role_id;
}
public void setRole_id(Integer role_id) {
this.role_id = role_id;
}
public String getRole_name() {
return role_name;
}
public void setRole_name(String role_name) {
this.role_name = role_name;
}
public String getRole_key() {
return role_key;
}
public void setRole_key(String role_key) {
this.role_key = role_key;
}
public Integer getStatus() {
return status;
}
public void setStatus(Integer status) {
this.status = status;
}
@Override
public String toString() {
return "Role{" +
"role_id=" + role_id +
", role_name='" + role_name + '\'' +
", role_key='" + role_key + '\'' +
", status=" + status +
", userList=" + userList +
'}';
}
}
User.java
package com.hs.model;
import java.util.Date;
public class User {
private Integer user_id;
private String account;
private String password;
private String user_name;
private Integer status;
private Date login_time;
private String ip;
private Integer fk_role_id;
//关联对象 一对一或多对一
private Role role;
public Integer getUser_id() {
return user_id;
}
public void setUser_id(Integer user_id) {
this.user_id = user_id;
}
public String getAccount() {
return account;
}
public void setAccount(String account) {
this.account = account;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getUser_name() {
return user_name;
}
public void setUser_name(String user_name) {
this.user_name = user_name;
}
public Integer getStatus() {
return status;
}
public void setStatus(Integer status) {
this.status = status;
}
public Date getLogin_time() {
return login_time;
}
public void setLogin_time(Date login_time) {
this.login_time = login_time;
}
public String getIp() {
return ip;
}
public void setIp(String ip) {
this.ip = ip;
}
public Integer getFk_role_id() {
return fk_role_id;
}
public void setFk_role_id(Integer fk_role_id) {
this.fk_role_id = fk_role_id;
}
public Role getRole() {
return role;
}
public void setRole(Role role) {
this.role = role;
}
@Override
public String toString() {
return "User{" +
"user_id=" + user_id +
", account='" + account + '\'' +
", password='" + password + '\'' +
", user_name='" + user_name + '\'' +
", status=" + status +
", login_time=" + login_time +
", ip='" + ip + '\'' +
", fk_role_id=" + fk_role_id +
", role=" + role +
'}';
}
}
6.XML映射文件
RoleMapper.xml
<mapper namespace="com.hs.dao.RoleDao">
<resultMap type="Role" id="BaseResultMapper">
<id column="role_id" property="role_id"/>
<result column="role_name" property="role_name"/>
<result column="role_key" property="role_key"/>
<result column="status" property="status"/>
resultMap>
<sql id="sys_role_columns">
role_id,role_name,role_key,status
sql>
<sql id="sys_role_columns_alias">
${alias}.role_id,${alias}.role_name,${alias}.role_key,${alias}.status
sql>
<resultMap id="SimpleResultMapper" type="Role" extends="BaseResultMapper">
<collection property="userList"
javaType="java.util.List"
ofType="User"
column="role_id"
select="com.hs.dao.UserDao.getUserByFk"/>
resultMap>
<select id="getRoleByPk" parameterType="_int" resultMap="SimpleResultMapper">
select
<include refid="sys_role_columns"/>
from sys_role
where role_id = #{role_id}
select>
<resultMap id="JoinResultMapper" type="Role" extends="BaseResultMapper">
<collection property="userList" javaType="list" ofType="com.hs.model.User"
resultMap="com.hs.dao.UserDao.BaseResultMapper"/>
resultMap>
<select id="getRoleByLeftJoin" parameterType="_int" resultMap="JoinResultMapper">
SELECT
<include refid="com.hs.dao.UserDao.sys_user_colums_alias">
<property name="alias" value="su"/>
include>
,
<include refid="sys_role_columns_alias">
<property name="alias" value="sr"/>
include>
FROM
sys_role sr
LEFT JOIN sys_user su ON sr.role_id = su.fk_role_id
WHERE
sr.role_id =#{role_id}
select>
mapper>UserMapper.xml
<mapper namespace="com.hs.dao.UserDao">
<resultMap id="BaseResultMapper" type="User">
<id column="user_id" property="user_id" />
<result column="account" property="account" />
<result column="passwrod" property="pasword" />
<result column="user_name" property="user_name" />
<result column="status" property="status" />
<result column="login_time" property="login_time" />
<result column="ip" property="ip" />
<result column="fk_role_id" property="fk_role_id" />
resultMap>
<resultMap id="SimpleResultMapper" type="User" extends="BaseResultMapper">
<association property="role" javaType="Role" column="fk_role_id" select="com.hs.dao.RoleDao.getRoleByPk"/>
resultMap>
<sql id="sys_user_colums">
user_id,account,password,user_name,status,login_time,ip,fk_role_id
sql>
<sql id="sys_user_colums_alias">
${alias}.user_id,${alias}.account,${alias}.password,${alias}.user_name,${alias}.status,${alias}.login_time,${alias}.ip,${alias}.fk_role_id
sql>
<select id="getUserByFk" parameterType="_int" resultMap="BaseResultMapper">
select <include refid="sys_user_colums"/>
from sys_user
where fk_role_id = #{role_id}
select>
<select id="getUser" resultMap="BaseResultMapper">
select <include refid="sys_user_colums"/>
from sys_user
where account=#{account} and password=#{password}
select>
mapper>7.接口
RoleDao.java
package com.hs.dao;
import com.hs.model.Role;
public interface RoleDao {
/**
* select方式，先在role表查出主键，然后传给user表当做条件，查询出user的信息
*
* @param role_id
* @return
*/
Role getRoleByPk(int role_id);
/**
* 利用连接查询方式，查询结果集
*
* @param role_id
* @return
*/
Role getRoleByLeftJoin(int role_id);
}UserDao.java
package com.hs.dao;
import com.hs.model.User;
import org.apache.ibatis.annotations.Param;
public interface UserDao {
/**
* 传递多个参数
* 1.当你的形参传递>1个的时候，parameterType不写，让其自动处理
* 2.#{值}，默认为arg0，arg1.....或param1，param2，，，
* 若在dao注解了@xxx(相当于指明了key值)，即也可以写xxx，默认的也可以写，相当于3个值
*/
User getUser(@Param("account") String account, @Param("password") String password);
}
8.日志配置文件
mybatis-config.xml
# 日志配置文件Global logging configuration
log4j.rootLogger=ERROR, stdout
# MyBatis logging configuration...
# 如果要显示SQL语句，那么这个位置需要配置为命名空间log4j.logger.命名空间
log4j.logger.com.hs.dao.UserDao=TRACE
log4j.logger.com.hs.dao.RoleDao=TRACE
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n9.测试类
MyBatisTest.java
package com.hs.test;
import com.hs.dao.RoleDao;
import com.hs.dao.UserDao;
import com.hs.util.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
/**
* 接口代理模式实现操作，在xxDao接口中，定义方法： sql语句返回的结果类型 sql语句的id(要传的值);
* 不用写实现类，直接写测试类,具体实现见测试类
* sql的映射文件的命名空间跟接口的全路径一致
* 可以根据接口的返回类型自动判断使用selectOne还是selectList eg:返回的是一个对象的为one，返回的是list的就是list，如果是List，也是list
*/
public class MyBatisTest {
/**
* 利用select方式，
*/
@Test
public void getUserByPk(){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlsession();
RoleDao roleDao = sqlSession.getMapper(RoleDao.class);
System.out.println(roleDao.getRoleByPk(-100));
} finally {
MyBatisUtils.closeSqlSession(sqlSession);
}
}
/**
* 利用连接方式查询
*/
@Test
public void getUserByFk(){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlsession();
RoleDao roleDao = sqlSession.getMapper(RoleDao.class);
System.out.println(roleDao.getRoleByLeftJoin(-100));
} finally {
MyBatisUtils.closeSqlSession(sqlSession);
}
}
/**
* 传递多个参数
*/
@Test
public void getUser(){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlsession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
String account = "admin";
String password = "admin";
System.out.println(userDao.getUser(account,password));
} finally {
MyBatisUtils.closeSqlSession(sqlSession);
}
}
}