mybatis入门篇：Mapper接口/关联查询/新增数据
1、数据准备
2、编写实体类
package com.forest.owl.entity;
import java.util.Date;
public class User {
private Long id;
private String userName;
private String userPassword;
private String userPhone;
private String userEmail;
private byte[] headImg;
private Date createTime;
private Date updateTime;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserPassword() {
return userPassword;
}
public void setUserPassword(String userPassword) {
this.userPassword = userPassword;
}
public String getUserPhone() {
return userPhone;
}
public void setUserPhone(String userPhone) {
this.userPhone = userPhone;
}
public String getUserEmail() {
return userEmail;
}
public void setUserEmail(String userEmail) {
this.userEmail = userEmail;
}
public byte[] getHeadImg() {
return headImg;
}
public void setHeadImg(byte[] headImg) {
this.headImg = headImg;
}
public Date getCreateTime() {
return createTime;
}
public void setCreateTime(Date createTime) {
this.createTime = createTime;
}
public Date getUpdateTime() {
return updateTime;
}
public void setUpdateTime(Date updateTime) {
this.updateTime = updateTime;
}
}
3、编写相对应的Mapper接口
package com.forest.owl.mapper;
import com.forest.owl.entity.User;
import java.util.List;
public interface UserMapper {
User selectUserById(Long id);
List<User> selectAllUser();
}
4、编写UserMapper.xml
在resources中加入文件夹com/forest/owl/mapper，在此文件夹中添加UserMapper文件
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.forest.owl.mapper.UserMapper">
<resultMap id="userMap" type="com.forest.owl.entity.User">
<id property="id" column="id" />
<result property="userName" column="user_name" />
<result property="userPassword" column="user_password" />
<result property="userPhone" column="user_phone" />
<result property="userEmail" column="user_email" />
<result property="headImg" column="head_img" jdbcType="BLOB" />
<result property="createTime" column="create_time" jdbcType="TIMESTAMP" />
<result property="updateTime" column="update_time" jdbcType="TIMESTAMP" />
</resultMap>
<select id="selectUserById" resultMap="userMap">
SELECT * FROM user WHERE id=#{id}
</select>
<select id="selectAllUser" resultType="com.forest.owl.entity.User">
SELECT id, user_name, user_password, user_phone, user_email, head_img, create_time, update_time
FROM user
</select>
</mapper>
5、修改mybatis-config.xml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>
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
<typeAliases>
<package name="com.forest.owl.entity"/>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC">
<property name="" value=""/>
</transactionManager>
<dataSource type="UNPOOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/forest?useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<mappers>
<package name="com.forest.owl.mapper"/>
</mappers>
</configuration>
6、编写测试代码
package com.forest.owl;
import com.forest.owl.entity.User;
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.BeforeClass;
import java.io.IOException;
import java.io.Reader;
public class BaseMapperTest {
private static SqlSessionFactory sqlSessionFactory;
@BeforeClass
public static void init(){
try {
Reader reader = Resources.getResourceAsReader("mybatis.config.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public SqlSession getSqlSession(){
SqlSession sqlSession = sqlSessionFactory.openSession();
return sqlSession;
}
}
package com.forest.owl;
import com.forest.owl.entity.User;
import com.forest.owl.mapper.UserMapper;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class MapperTest extends BaseMapperTest{
@Test
public void UserMapperTest(){
SqlSession sqlSession = getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.selectUserById((long) 3);
System.out.println(user.getUserName());
List<User> userList = userMapper.selectAllUser();
userList.stream().forEach(i -> System.out.println(i.getUserName()));
}
}
7、关联查询
假设在用户信息查询的基础上，我还想查询用户的角色与权限，该如何？
首先定义角色与权限的实体类
package com.forest.owl.entity;
import java.util.Date;
public class Role {
private Long id;
private String roleName;
private int enabled;
private Long createBy;
private Date createTime;
private Long updateBy;
private Date updateTime;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getRoleName() {
return roleName;
}
public void setRoleName(String roleName) {
this.roleName = roleName;
}
public int getEnabled() {
return enabled;
}
public void setEnabled(int enabled) {
this.enabled = enabled;
}
public Long getCreateBy() {
return createBy;
}
public void setCreateBy(Long createBy) {
this.createBy = createBy;
}
public Date getCreateTime() {
return createTime;
}
public void setCreateTime(Date createTime) {
this.createTime = createTime;
}
public Long getUpdateBy() {
return updateBy;
}
public void setUpdateBy(Long updateBy) {
this.updateBy = updateBy;
}
public Date getUpdateTime() {
return updateTime;
}
public void setUpdateTime(Date updateTime) {
this.updateTime = updateTime;
}
}
package com.forest.owl.entity;
import java.util.Date;
public class Privilege {
private Long id;
private String privilegeName;
private String privilegeUrl;
private Long createBy;
private Date createTime;
private Long updateBy;
private Date updateTime;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getPrivilegeName() {
return privilegeName;
}
public void setPrivilegeName(String privilegeName) {
this.privilegeName = privilegeName;
}
public String getPrivilegeUrl() {
return privilegeUrl;
}
public void setPrivilegeUrl(String privilegeUrl) {
this.privilegeUrl = privilegeUrl;
}
public Long getCreateBy() {
return createBy;
}
public void setCreateBy(Long createBy) {
this.createBy = createBy;
}
public Date getCreateTime() {
return createTime;
}
public void setCreateTime(Date createTime) {
this.createTime = createTime;
}
public Long getUpdateBy() {
return updateBy;
}
public void setUpdateBy(Long updateBy) {
this.updateBy = updateBy;
}
public Date getUpdateTime() {
return updateTime;
}
public void setUpdateTime(Date updateTime) {
this.updateTime = updateTime;
}
}
在User实体类中添加Role与Privilege属性
private Role role;
private Privilege privilege;
public Role getRole() { return role; }
public void setRole(Role role) { this.role = role; }
public Privilege getPrivilege() { return privilege; }
public void setPrivilege(Privilege privilege) { this.privilege = privilege; }
修改UserMapper.xml文件
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.forest.owl.mapper.UserMapper">
<resultMap id="userMap" type="com.forest.owl.entity.User">
<id property="id" column="id" />
<result property="userName" column="user_name" />
<result property="userPassword" column="user_password" />
<result property="userPhone" column="user_phone" />
<result property="userEmail" column="user_email" />
<result property="headImg" column="head_img" jdbcType="BLOB" />
<result property="createTime" column="create_time" jdbcType="TIMESTAMP" />
<result property="updateTime" column="update_time" jdbcType="TIMESTAMP" />
<association property="role">
<result property="roleName" column="role_name" />
</association>
<association property="privilege">
<result property="privilegeName" column="privilege_name" />
<result property="privilegeUrl" column="privilege_url" />
</association>
</resultMap>
<select id="selectUserById" resultMap="userMap">
SELECT u.*,
r.role_name,
p.privilege_name,
p.privilege_url
FROM user u
INNER JOIN user_role ur on ur.user_id=u.id
INNER JOIN role r on r.id=ur.role_id
INNER JOIN role_privilege rp on rp.role_id=r.id
INNER JOIN privilege p on p.id=rp.privilege_id
WHERE u.id=#{id}
</select>
<select id="selectAllUser" resultType="com.forest.owl.entity.User">
SELECT u.id,
u.user_name,
u.user_password,
u.user_phone,
u.user_email,
u.head_img,
u.create_time,
u.update_time,
r.role_name as "role.roleName",
p.privilege_name as "privilege.privilegeName",
p.privilege_url as "privilege.privilegeUrl"
FROM user u
INNER JOIN user_role ur on ur.user_id=u.id
INNER JOIN role r on r.id=ur.role_id
INNER JOIN role_privilege rp on rp.role_id=r.id
INNER JOIN privilege p on p.id=rp.privilege_id
</select>
</mapper>
编写测试类
@Test
public void UserMapperTest(){
SqlSession sqlSession = getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.selectUserById((long) 3);
System.out.println(user.getUserName());
System.out.println(user.getRole().getRoleName());
System.out.println(user.getPrivilege().getPrivilegeName());
System.out.println(user.getPrivilege().getPrivilegeUrl());
List<User> userList = userMapper.selectAllUser();
userList.stream().forEach(i -> {
System.out.println(i.getUserName());
System.out.println(i.getRole().getRoleName());
System.out.println(i.getPrivilege().getPrivilegeName());
System.out.println(i.getPrivilege().getPrivilegeUrl());
});
}
8、新增数据
在UserMapper接口中新增方法
int insertUser(User user);
UserMapper.xml
<insert id="insertUser">
INSERT INTO user (user_name, user_password, user_phone, user_email, head_img, create_time, update_time)
VALUES( #{userName}, #{userPassword}, #{userPhone}, #{userEmail}, #{headImg}, #{createTime}, #{updateTime} )
</insert>
测试代码
@Test
public void UserMapperTest(){
SqlSession sqlSession = getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = new User();
user.setUserName("新用户名");
user.setUserPassword("密码");
user.setUserPhone("手机号");
user.setUserEmail("邮箱号");
int result = userMapper.insertUser(user);
System.out.println(result);
sqlSession.commit();
}
因为SqlSessionFactory.openSession()是不自动提交的，故此处需要手动提交，否则无效。
对于想要得到插入数据的主键，可以设置mybatis-config.xml的配置项useGeneratedKeys为true
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
<setting name="useGeneratedKeys" value="true"/>
</settings>
然后在<insert />配置中添加keyProperty="id"，在数据插入成功后，mybatis会将主键回写至id里，届时使用user.getId()获取即可。
<insert id="insertUser" keyProperty="id">
INSERT INTO user (user_name, user_password, user_phone, user_email, head_img, create_time, update_time)
VALUES( #{userName}, #{userPassword}, #{userPhone}, #{userEmail}, #{headImg}, #{createTime}, #{updateTime} )
</insert>
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