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@Beeder 2018-02-23T13:17:38.000000Z 字数 15707 阅读 650

Mybatis框架

javaWeb Mybatis

导入jar包

  1. asm-3.3.1.jar
  2. cglib-2.2.2.jar
  3. commons-logging-1.1.1.jar
  4. javassist-3.17.1-GA.jar
  5. log4j-1.2.17.jar
  6. log4j-api-2.0-rc1.jar
  7. log4j-core-2.0-rc1.jar
  8. slf4j-api-1.7.5.jar
  9. slf4j-log4j12-1.7.5.jar

操作流程

基本操作

log4j.properties

  1. # Global logging configuration
  2. log4j.rootLogger=DEBUG, stdout
  3. # Console output...
  4. log4j.appender.stdout=org.apache.log4j.ConsoleAppender
  5. log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
  6. log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

db.properties

  1. jdbc.driver=com.mysql.jdbc.Driver
  2. jdbc.url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8
  3. jdbc.username=root
  4. jdbc.password=admin

SqlMapConfig.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3. PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-config.dtd">
  5. <configuration>
  6.     <properties resource="db.properties"></properties>
  9.     <environments default="development">
  10.         <environment id="development">
  11.         <!-- 使用jdbc事务管理-->
  12.         <transactionManager type="JDBC" />
  13.         <!-- 数据库连接池-->
  14.         <dataSource type="POOLED">
  15.             <property name="driver" value="${jdbc.driver}" />
  16. 			<property name="url" value="${jdbc.url}" />
  17.             <property name="username" value="${jdbc.username}" />
  18. 			<property name="password" value="${jdbc.password}" />
  19.         </dataSource>
  20.         </environment>
  21.     </environments>
  23.     <mappers>
  24.         <mapper resource="User.xml"/>
  25.     </mappers>
  26. </configuration>

pojo类

  1. package cn.itheima.pojo;
  3. public class User {
  4.     private int id;
  5.     private String username;// 用户姓名
  6.     //省略……
  8.     public int getId() {
  9.         return id;
  10.     }
  11.     public void setId(int id) {
  12.         this.id = id;
  13.     }
  14.     //省略……

基本查询

User.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3. PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <!-- namespace:命名空间,做sql隔离 -->
  6. <mapper namespace="test">
  8.     <!-- 
  9.     id:sql语句唯一标识
  10.     parameterType:指定传入参数类型
  11.     resultType:返回结果集类型
  12.     #{}占位符:起到占位作用,如果传入的是基本类型(string,long,double,int,boolean,float等),那么#{}中的变量名称可以随意写.
  13.      -->
  14.     <select id="findUserById" parameterType="java.lang.Integer" resultType="cn.itheima.pojo.User">
  15.         select * from user where id=#{id}
  16.     </select>
  17. </mapper>

java测试类

  1. public class UserTest {
  3.     @Test
  4.     public void testFindUserById() throws Exception{
  5.         String resource = "SqlMapConfig.xml";
  6.         //通过流将核心配置文件读取进来
  7.         InputStream inputStream = Resources.getResourceAsStream(resource);
  8.         //通过核心配置文件输入流来创建会话工厂
  9.         SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
  10.         //通过工厂创建会话
  11.         SqlSession openSession = factory.openSession();
  12.         //第一个参数:所调用的sql语句= namespace+.+sql的ID
  13.         User user = openSession.selectOne("test.findUserById", 1);
  14.         System.out.println(user);
  15.         openSession.close();
  16.     }
  17. }
模糊查询

User.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3. PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <!-- namespace:命名空间,做sql隔离 -->
  6. <mapper namespace="test">
  8. <!-- 
  9.     返回结果为集合,可以调用selectList方法,这个方法返回的结果就是一个集合,以映射文件中应该配置成集合泛型的类型
  10.     ${}拼接符:字符串原样拼接,如果传入的参数是基本类型(string,long,double,int,boolean,float等),那么${}中的变量名称必须是value
  11.     注意:拼接符有sql注入的风险,所以慎重使用
  12.      -->
  13.     <select id="findUserByUserName" parameterType="java.lang.String" resultType="cn.itheima.pojo.User">
  14.         select * from user where username like '%${value}%'
  15.     </select>
  16. </mapper>

java测试类

  1. import cn.itheima.pojo.User;
  3. public class UserTest {
  5.     @Test
  6.     public void testFindUserbyUserName() throws Exception{
  7.         String resource = "SqlMapConfig.xml";
  8.         InputStream inputStream = Resources.getResourceAsStream(resource);
  9.         SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
  10.         SqlSession openSession = factory.openSession();
  12.         List<User> list = openSession.selectList("test.findUserByUserName", "王");
  13.         System.out.println(list);
  14.     }
  15. }

插入数据

User.xml

  1. <!-- 
  2.     #{}:如果传入的是pojo类型,那么#{}中的变量名称必须是pojo中对应的属性.属性.属性.....
  3.     如果要返回数据库自增主键:可以使用select LAST_INSERT_ID()
  4.      -->
  5.     <insert id="insertUser" parameterType="cn.itheima.pojo.User" >
  6.         <!-- 执行 select LAST_INSERT_ID()数据库函数,返回自增的主键
  7.         keyProperty:将返回的主键放入传入参数的Id中保存.
  8.         order:当前函数相对于insert语句的执行顺序,在insert前执行是before,在insert后执行是AFTER
  9.         resultType:id的类型,也就是keyproperties中属性的类型
  10.         -->
  11.         <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
  12.             select LAST_INSERT_ID()
  13.         </selectKey>
  14.         insert into user (username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})
  15.     </insert>

java测试类

  1. @Test
  2.     public void testInsertUser() throws Exception{
  3.         String resource = "SqlMapConfig.xml";
  4.         //通过流将核心配置文件读取进来
  5.         InputStream inputStream = Resources.getResourceAsStream(resource);
  6.         //通过核心配置文件输入流来创建会话工厂
  7.         SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
  8.         //通过工厂创建会话
  9.         SqlSession openSession = factory.openSession();
  11.         User user = new User();
  12.         user.setUsername("赵四");
  13.         user.setBirthday(new Date());
  14.         user.setSex("1");
  15.         user.setAddress("北京昌平");
  16.         System.out.println("====" + user.getId());
  18.         openSession.insert("test.insertUser", user);
  19.         //提交事务(mybatis会自动开启事务,但是它不知道何时提交,所以需要手动提交事务)
  20.         openSession.commit();
  22.         System.out.println("====" + user.getId());
  23.     }

删除数据

User.xml

  1.     <delete id="delUserById" parameterType="int">
  2.         delete from user where id=#{id}
  3.     </delete>

java测试类

  1.     @Test
  2.     public void testDelUserById()throws Exception{
  3.         String resource = "SqlMapConfig.xml";
  4.         //通过流将核心配置文件读取进来
  5.         InputStream inputStream = Resources.getResourceAsStream(resource);
  6.         //通过核心配置文件输入流来创建会话工厂
  7.         SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
  8.         //通过工厂创建会话
  9.         SqlSession openSession = factory.openSession();
  11.         openSession.delete("test.delUserById", 29);
  12.         //提交
  13.         openSession.commit();
  14.     }

更新数据

User.xml

  1.     <update id="updateUserById" parameterType="cn.itheima.pojo.User">
  2.         update user set username=#{username} where id=#{id}
  3.     </update>

java测试类

  1.     @Test
  2.     public void testUpdateUserById() throws Exception{
  3.         String resource = "SqlMapConfig.xml";
  4.         //通过流将核心配置文件读取进来
  5.         InputStream inputStream = Resources.getResourceAsStream(resource);
  6.         //通过核心配置文件输入流来创建会话工厂
  7.         SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
  8.         //通过工厂创建会话
  9.         SqlSession openSession = factory.openSession();
  11.         User user = new User();
  12.         user.setId(28);
  13.         user.setUsername("王麻子");
  14.         openSession.update("test.updateUserById", user);
  16.         //提交
  17.         openSession.commit();
  18.     }

动态代理Dao实现

SqlMapConfig.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3. PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-config.dtd">
  5. <configuration>
  6.     <properties resource="db.properties"></properties>
  8.     <!-- 和spring整合后 environments配置将废除-->
  9.     <environments default="development">
  10.         <environment id="development">
  11.         <!-- 使用jdbc事务管理-->
  12.         <transactionManager type="JDBC" />
  13.         <!-- 数据库连接池-->
  14.         <dataSource type="POOLED">
  15.             <property name="driver" value="${jdbc.driver}" />
  16. 			<property name="url" value="${jdbc.url}" />
  17.             <property name="username" value="${jdbc.username}" />
  18. 			<property name="password" value="${jdbc.password}" />
  19.         </dataSource>
  20.         </environment>
  21.     </environments>
  23.     <mappers>
  24.         <!-- 
  25.         使用class属性引入接口的全路径名称:
  26.         使用规则:
  27.             1. 接口的名称和映射文件名称除扩展名外要完全相同
  28.             2. 接口和映射文件要放在同一个目录下
  29.          -->
  30.             <mapper class="cn.itheima.mapper.UserMapper"/> 
  32.         <!-- 使用包扫描的方式批量引入Mapper接口 
  33.                 使用规则:
  34.                 1. 接口的名称和映射文件名称除扩展名外要完全相同
  35.                 2. 接口和映射文件要放在同一个目录下
  36.         -->
  37. <!--        <package name="cn.itheima.mapper"/> -->
  38.     </mappers>
  39. </configuration>

Mapper接口类UserMapper.java

  1. public interface UserMapper {
  3.     public User findUserById(Integer id);
  5.     //动态代理形势中,如果返回结果集问List,那么mybatis会在生成实现类的使用会自动调用selectList方法
  6.     public List<User> findUserByUserName(String userName);
  8.     public void insertUser(User user);
  9. }

Mapper接口映射文件UserMapper.xml
路径：与Mapper接口类同目录

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3. PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <!-- 
  6. mapper接口代理实现编写规则:
  7.     1. 映射文件中namespace要等于接口的全路径名称
  8.     2. 映射文件中sql语句id要等于接口的方法名称
  9.     3. 映射文件中传入参数类型要等于接口方法的传入参数类型
  10.     4. 映射文件中返回结果集类型要等于接口方法的返回值类型
  11.  -->
  12. <mapper namespace="cn.itheima.mapper.UserMapper">
  14.     <!-- 
  15.     id:sql语句唯一标识
  16.     parameterType:指定传入参数类型
  17.     resultType:返回结果集类型
  18.     #{}占位符:起到占位作用,如果传入的是基本类型(string,long,double,int,boolean,float等),那么#{}中的变量名称可以随意写.
  19.      -->
  20.     <select id="findUserById" parameterType="int" resultType="cn.itheima.pojo.User">
  21.         select * from user where id=#{id}
  22.     </select>
  24.     <!-- 
  25.     如果返回结果为集合,可以调用selectList方法,这个方法返回的结果就是一个集合,所以映射文件中应该配置成集合泛型的类型
  26.     ${}拼接符:字符串原样拼接,如果传入的参数是基本类型(string,long,double,int,boolean,float等),那么${}中的变量名称必须是value
  27.     注意:拼接符有sql注入的风险,所以慎重使用
  28.      -->
  29.     <select id="findUserByUserName" parameterType="string" resultType="user">
  30.         select * from user where username like '%${value}%'
  31.     </select>
  33.     <!-- 
  34.     #{}:如果传入的是pojo类型,那么#{}中的变量名称必须是pojo中对应的属性.属性.属性.....
  35.     如果要返回数据库自增主键:可以使用select LAST_INSERT_ID()
  36.      -->
  37.     <insert id="insertUser" parameterType="cn.itheima.pojo.User" >
  38.         <!-- 执行 select LAST_INSERT_ID()数据库函数,返回自增的主键
  39.         keyProperty:将返回的主键放入传入参数的Id中保存.
  40.         order:当前函数相对于insert语句的执行顺序,在insert前执行是before,在insert后执行是AFTER
  41.         resultType:id的类型,也就是keyproperties中属性的类型
  42.         -->
  43.         <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
  44.             select LAST_INSERT_ID()
  45.         </selectKey>
  46.         insert into user (username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})
  47.     </insert>
  48. </mapper>

java测试类

  1. public class UserMapperTest {
  2.     private SqlSessionFactory factory;
  4.     //作用:在测试方法前执行这个方法
  5.     @Before
  6.     public void setUp() throws Exception{
  7.         String resource = "SqlMapConfig.xml";
  8.         //通过流将核心配置文件读取进来
  9.         InputStream inputStream = Resources.getResourceAsStream(resource);
  10.         //通过核心配置文件输入流来创建会话工厂
  11.         factory = new SqlSessionFactoryBuilder().build(inputStream);
  12.     }
  14.     @Test
  15.     public void testFindUserById() throws Exception{
  16.         SqlSession openSession = factory.openSession();
  17.         //通过getMapper方法来实例化接口
  18.         UserMapper mapper = openSession.getMapper(UserMapper.class);
  20.         User user = mapper.findUserById(1);
  21.         System.out.println(user);
  22.     }
  24.     @Test
  25.     public void testFindUserByUserName() throws Exception{
  26.         SqlSession openSession = factory.openSession();
  27.         //通过getMapper方法来实例化接口
  28.         UserMapper mapper = openSession.getMapper(UserMapper.class);
  29.         List<User> list = mapper.findUserByUserName("王");
  30.     }
  32.     @Test
  33.     public void testInsertUser() throws Exception{
  34.         SqlSession openSession = factory.openSession();
  35.         //通过getMapper方法来实例化接口
  36.         UserMapper mapper = openSession.getMapper(UserMapper.class);
  38.         User user = new User();
  39.         user.setUsername("老王");
  40.         user.setSex("1");
  41.         user.setBirthday(new Date());
  42.         user.setAddress("北京昌平");
  43.         mapper.insertUser(user);
  44.         openSession.commit();
  45.     }
  46. }

SqlMapConfig核心配置文件

SqlMapConfig.xml
目录:项目\config\

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3. PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-config.dtd">
  5. <configuration>
  6.     <properties resource="db.properties"></properties>
  8.     <typeAliases> 
  9.         <!-- 定义单个pojo类别名
  10.         type:类的全路劲名称
  11.         alias:别名
  12.          -->
  13. <!--        <typeAlias type="cn.itheima.pojo.User" alias="user"/> -->
  15.         <!-- 使用包扫描的方式批量定义别名 
  16.         定以后别名等于类名,不区分大小写,但是建议按照java命名规则来,首字母小写,以后每个单词的首字母大写
  17.         -->
  18.         <package name="cn.itheima.pojo"/>
  19.     </typeAliases>
  21.     <!-- 和spring整合后 environments配置将废除-->
  22.     <environments default="development">
  23.         <environment id="development">
  24.         <!-- 使用jdbc事务管理-->
  25.         <transactionManager type="JDBC" />
  26.         <!-- 数据库连接池-->
  27.         <dataSource type="POOLED">
  28.             <property name="driver" value="${jdbc.driver}" />
  29. 			<property name="url" value="${jdbc.url}" />
  30.             <property name="username" value="${jdbc.username}" />
  31. 			<property name="password" value="${jdbc.password}" />
  32.         </dataSource>
  33.         </environment>
  34.     </environments>
  36.     <mappers>
  37.         <mapper resource="User.xml"/>
  39.         <!-- 
  40.         使用class属性引入接口的全路径名称:
  41.         使用规则:
  42.             1. 接口的名称和映射文件名称除扩展名外要完全相同
  43.             2. 接口和映射文件要放在同一个目录下
  44.          -->
  45. <!--        <mapper class="cn.itheima.mapper.UserMapper"/> -->
  47.         <!-- 使用包扫描的方式批量引入Mapper接口 
  48.                 使用规则:
  49.                 1. 接口的名称和映射文件名称除扩展名外要完全相同
  50.                 2. 接口和映射文件要放在同一个目录下
  51.         -->
  52.         <package name="cn.itheima.mapper"/>
  53.     </mappers>
  54. </configuration>

动态sql语句

if where

UserMapper.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3. PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  6. <mapper namespace="cn.itheima.mapper.UserMapper">
  7.     <!-- 封装sql条件,封装后可以重用. 
  8.     id:是这个sql条件的唯一标识 -->
  9.     <sql id="user_Where">
  10.         <!-- where标签作用:
  11.                 会自动向sql语句中添加where关键字
  12.                 会去掉第一个条件的and关键字
  13.         -->
  14.         <where>
  15.             <if test="username != null and username != ''">
  16.                 and username like '%${username}%'
  17.             </if>
  18.             <if test="sex != null and sex != ''">
  19.                 and sex=#{sex}
  20.             </if>
  21.         </where>
  22.     </sql>
  24.     <select id="findUserByUserNameAndSex" parameterType="cn.itheima.pojo.User" resultType="cn.itheima.pojo.User">
  25.         select * from user 
  27.         <!-- 调用sql条件 -->
  28.         <include refid="user_Where"></include>
  29.     </select>
  31. </mapper>

UserMapper.java

  1. public interface UserMapper {
  3.     public List<User> findUserByUserNameAndSex(User user);
  4. }

java测试类

  1. public class UserMapperTest {
  2.     private SqlSessionFactory factory;
  4.     //作用:在测试方法前执行这个方法
  5.     @Before
  6.     public void setUp() throws Exception{
  7.         String resource = "SqlMapConfig.xml";
  8.         //通过流将核心配置文件读取进来
  9.         InputStream inputStream = Resources.getResourceAsStream(resource);
  10.         //通过核心配置文件输入流来创建会话工厂
  11.         factory = new SqlSessionFactoryBuilder().build(inputStream);
  12.     }
  14.     @Test
  15.     public void testFindUserbyUserNameAndSex() throws Exception{
  16.         SqlSession openSession = factory.openSession();
  17.         //通过getMapper方法来实例化接口
  18.         UserMapper mapper = openSession.getMapper(UserMapper.class);
  20.         User user = new User();
  21.         user.setUsername("王");
  22.         user.setSex("1");
  24.         List<User> list = mapper.findUserByUserNameAndSex(user);
  26.         System.out.println(list);
  27.     }
  28. }

foreach

UserMapper.xml

  1.     <select id="findUserByIds" parameterType="cn.itheima.pojo.QueryVo" resultType="cn.itheima.pojo.User">
  2.         <!--select * from user where id in (1,16,28,22)-->
  3.         select * from user
  4.         <where>
  5.             <if test="ids != null">
  6.                 <!-- 
  7.                 foreach:循环传入的集合参数
  8.                 collection:传入的集合的变量名称
  9.                 item:每次循环将循环出的数据放入这个变量中
  10.                 open:循环开始拼接的字符串
  11.                 close:循环结束拼接的字符串
  12.                 separator:循环中拼接的分隔符
  13.                  -->
  14.                 <foreach collection="ids" item="id" open="id in (" close=")" separator=",">
  15.                     #{id}
  16.                 </foreach>
  17.             </if>
  18.         </where>
  19.     </select>

UserMapper.java

  1. public interface UserMapper {
  3.     public List<User> findUserByIds(QueryVo vo);
  4. }

VO(View Object)类

  1. public class QueryVo {
  3.     private User user;
  5.     private List<Integer> ids;
  7.     //省略……
  8.     public List<Integer> getIds() {
  9.         return ids;
  10.     }
  12.     public void setIds(List<Integer> ids) {
  13.         this.ids = ids;
  14.     }

java测试类

  1. public class UserMapperTest {
  2.     @Test
  3.     public void testFindUserbyIds() throws Exception{
  4.         SqlSession openSession = factory.openSession();
  5.         //通过getMapper方法来实例化接口
  6.         UserMapper mapper = openSession.getMapper(UserMapper.class);
  7.         QueryVo vo = new QueryVo();
  8.         List<Integer> ids = new ArrayList<Integer>();
  9.         ids.add(1);
  10.         ids.add(16);
  11.         ids.add(28);
  12.         ids.add(22);
  13.         vo.setIds(ids);
  14.         List<User> list = mapper.findUserByIds(vo);
  15.         System.out.println(list);
  16.     }
  17. }

关联查询

一对一关系

自定义POJO对象类:用于自动映射

  2. //继承Orders类加入User类属性
  3. public class CustomOrders extends Orders{
  5.     private int uid;
  6.     private String username;// 用户姓名
  7.     //省略……
  9.     public int getUid() {
  10.         return uid;
  11.     }
  12.     public void setUid(int uid) {
  13.         this.uid = uid;
  14.     }
  15.     public String getUsername() {
  16.         return username;
  17.     }
  18.     //省略……
  19. }

POJO对象类

  1. public class Orders {
  2.     private Integer id;
  4.     private Integer userId;
  5.     //省略……
  6.     private User user;
  8.     public Integer getId() {
  9.         return id;
  10.     }
  11.     public void setId(Integer id) {
  12.         this.id = id;
  13.     }
  14.     public Integer getUserId() {
  15.         return userId;
  16.     }
  17.     public void setUserId(Integer userId) {
  18.         this.userId = userId;
  19.     }
  20.     //省略……
  21.     public User getUser() {
  22.         return user;
  23.     }
  25.     public void setUser(User user) {
  26.         this.user = user;
  27.     }
  28. }
  1. public class User {
  2.     private int id;
  3.     //省略……
  5.     public int getId() {
  6.         return id;
  7.     }
  8.     public void setId(int id) {
  9.         this.id = id;
  10.     }

UserMapper.xml

  1. <!-- 一对一:自动映射 -->
  2.     <select id="findOrdersAndUser1" resultType="cn.itheima.pojo.CustomOrders">
  3.         select a.*, b.id uid, username, birthday, sex, address 
  4.         from orders a, user b 
  5.         where a.user_id = b.id
  6.     </select>
  9. <!-- 一对一:手动映射 -->
  10.     <!-- 
  11.     id:resultMap的唯一标识
  12.     type:将查询出的数据放入这个指定的对象中
  13.     注意:手动映射需要指定数据库中表的字段名与java中pojo类的属性名称的对应关系
  14.      -->
  15.     <resultMap type="cn.itheima.pojo.Orders" id="orderAndUserResultMap">
  16.         <!-- id标签指定主键字段对应关系
  17.         column:列,数据库中的字段名称
  18.         property:属性,java中pojo中的属性名称
  19.          -->
  20.         <id column="id" property="id"/>
  22.         <!-- result:标签指定非主键字段的对应关系 -->
  23.         <result column="user_id" property="userId"/>
  24.         <result column="number" property="number"/>
  25.         <result column="createtime" property="createtime"/>
  26.         <result column="note" property="note"/>
  28.         <!-- 这个标签指定单个对象的对应关系 
  29.         property:指定将数据放入Orders中的user属性中
  30.         javaType:user属性的类型
  31.         -->
  32.         <association property="user" javaType="cn.itheima.pojo.User">
  33.             <id column="uid" property="id"/>
  34.             <result column="username" property="username"/>
  35.             <result column="birthday" property="birthday"/>
  36.             <result column="sex" property="sex"/>
  37.             <result column="address" property="address"/>
  38.         </association>
  39.     </resultMap>
  41.     <select id="findOrdersAndUser2" resultMap="orderAndUserResultMap">
  42.         select a.*, b.id uid, username, birthday, sex, address 
  43.         from orders a, user b 
  44.         where a.user_id = b.id
  45.     </select>

UserMapper.java接口类

  1. public interface UserMapper {
  3.     public List<CustomOrders> findOrdersAndUser1() ;
  5.     public List<Orders> findOrdersAndUser2();
  7. }

java测试类

  1. public class UserMapperTest {
  2.     private SqlSessionFactory factory;
  4.     //作用:在测试方法前执行这个方法
  5.     @Before
  6.     public void setUp() throws Exception{
  7.         String resource = "SqlMapConfig.xml";
  8.         //通过流将核心配置文件读取进来
  9.         InputStream inputStream = Resources.getResourceAsStream(resource);
  10.         //通过核心配置文件输入流来创建会话工厂
  11.         factory = new SqlSessionFactoryBuilder().build(inputStream);
  12.     }
  14.     @Test
  15.     public void testFindOrdersAndUser() throws Exception{
  16.         SqlSession openSession = factory.openSession();
  17.         //通过getMapper方法来实例化接口
  18.         UserMapper mapper = openSession.getMapper(UserMapper.class);
  20.         List<CustomOrders> list = mapper.findOrdersAndUser1();
  21.         System.out.println(list);
  22.     }
  24.     @Test
  25.     public void testFindOrdersAnduUser2() throws Exception{
  26.         SqlSession openSession = factory.openSession();
  27.         //通过getMapper方法来实例化接口
  28.         UserMapper mapper = openSession.getMapper(UserMapper.class);
  30.         List<Orders> list = mapper.findOrdersAndUser2();
  31.         System.out.println(list);
  32.     }
  33. }
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