第五章：MyBatis注解开发

OVERVIEW

• 第五章：MyBatis注解开发
• • • 一、基于注解的CURD
    • • 1.xml文件映射
      • 2.注解实现映射
    • 二、基于注解的关联查询
    • • 1.1v1查询
      • • （1）配置方式：
        • （2）程序演示：
      • 2.1vN查询
      • • （1）配置方式：
        • （2）程序演示：
      • 3.NvN查询
      • • （1）配置方式：
        • （2）程序演示：

一、基于注解的CURD

1.xml文件映射

package com.itcast.domain;import java.util.Date;public class User {private int id;private String username;private String password;private Date birthday;public int getId() {return id;}public void setId(int id) {this.id = id;}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 Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +", birthday=" + birthday +'}';}
}

package com.itcast.mapper;import com.itcast.domain.User;import java.util.List;public interface UserMapper {public void save(User user);public void update(User user);public void delete(int id);public User findById(int id);public List<User> findAll();
}

DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.itcast.mapper.UserMapper"><insert id="save" parameterType="user">insert into user values(#{id}, #{username}, #{password}, #{birthday})insert><update id="update" parameterType="user">update user set username = #{username}, password = #{password} where id = #{id}update><delete id="delete" parameterType="int">delete from user where id = #{id}delete><select id="findById" parameterType="int" resultType="user">select * from user where id = #{id}select><select id="findAll" resultType="user">select * from userselect>
mapper>

DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><typeAliases><typeAlias type="com.itcast.domain.User" alias="user">typeAlias>typeAliases><typeHandlers><typeHandler handler="com.itcast.handler.DateTypeHandler">typeHandler>typeHandlers><environments default="development"><environment id="development"><transactionManager type="JDBC">transactionManager><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/test"/><property name="username" value="root"/><property name="password" value="20001201"/>dataSource>environment>environments><mappers><mapper resource="com.itcast.mapper/UserMapper.xml">mapper>mappers>
configuration>

package com.itcast.test;import com.itcast.domain.User;
import com.itcast.mapper.UserMapper;
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.Before;
import org.junit.Test;import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.List;public class MybatisTest {private UserMapper mapper;@Beforepublic void before() throws IOException {InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);SqlSession sqlSession = sqlSessionFactory.openSession(true);//自动提交事务mapper = sqlSession.getMapper(UserMapper.class);}@Testpublic void testSave() {User user = new User();user.setUsername("Tom");user.setPassword("1234456");user.setBirthday(new Date());mapper.save(user);}@Testpublic void testUpdate() {User user = new User();user.setId(7);user.setUsername("Lucy");user.setPassword("abcdefg");user.setBirthday(new Date());mapper.update(user);}@Testpublic void testDelete() {mapper.delete(8);}@Testpublic void testFindById() {User user = mapper.findById(3);System.out.println(user);}@Testpublic void testFindAll() {List<User> userList = mapper.findAll();for (User user : userList) {System.out.println(user);}}
}

2.注解实现映射

通过注解同样能够实现映射POJO对象和数据表之间的关联映射，对xml文件实现的映射进行修改：

• step1：修改UserMapper文件，将xml文件中的映射以注解的形式写入UserMapper接口中（resources下的xml文件已无用）

package com.itcast.mapper;import com.itcast.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;import java.util.List;public interface UserMapper {@Insert("insert into user values(#{id}, #{username}, #{password}, #{birthday})")public void save(User user);@Update("update user set username = #{username}, password = #{password} where id = #{id}")public void update(User user);@Delete("delete from user where id = #{id}")public void delete(int id);@Select("select * from user where id = #{id}")public User findById(int id);@Select("select * from user")public List<User> findAll();
}

• step2：对sqlMapConfig.xml文件中的映射加载语句进行修改

DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><typeAliases><typeAlias type="com.itcast.domain.User" alias="user">typeAlias>typeAliases><typeHandlers><typeHandler handler="com.itcast.handler.DateTypeHandler">typeHandler>typeHandlers><environments default="development"><environment id="development"><transactionManager type="JDBC">transactionManager><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/test"/><property name="username" value="root"/><property name="password" value="20001201"/>dataSource>environment>environments><mappers><package name="com.itcast.mapper"/>mappers>
configuration>

全部修改完成，进行test测试如下：

二、基于注解的关联查询

1.1v1查询

用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户。

一对一查询的需求：查询一个订单，与此同时查询出该订单所属的用户。

SELECT *, o.id oid
FROM orders o, user u
WHERE o.uid = u.id

（1）配置方式：

配置方式1：

package com.itcast.mapper;import com.itcast.domain.Order;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;import java.util.List;public interface OrderMapper {@Select("SELECT *, o.id oid FROM orders o, user u WHERE o.uid = u.id")@Results({@Result(column = "oid", property = "id"),@Result(column = "ordertime", property = "ordertime"),@Result(column = "total", property = "total"),@Result(column = "uid", property = "user.id"),@Result(column = "username", property = "user.username"),@Result(column = "password", property = "user.password"),@Result(column = "birthday", property = "user.birthday"),})public List<Order> findAll();
}

配置方式2：

package com.itcast.mapper;import com.itcast.domain.Order;
import com.itcast.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;import java.util.List;public interface OrderMapper {@Select("SELECT * FROM orders")@Results({@Result(column = "oid", property = "id"),@Result(column = "ordertime", property = "ordertime"),@Result(column = "total", property = "total"),@Result(property = "user", //要封装的属性column = "uid", //根据哪个字段去查询user表的数据javaType = User.class, //要封装的实体类型//select属性 代表查询哪个接口的方法获得数据one = @One(select = "com.itcast.mapper.UserMapper.findById"))})public List<Order> findAll();
}

（2）程序演示：

package com.itcast.domain;import java.sql.Timestamp;
import java.util.Date;public class Order {private int id;private Timestamp ordertime;private double total;private User user;//该定单属于的用户public int getId() {return id;}public void setId(int id) {this.id = id;}public Date getOrdertime() {return ordertime;}public void setOrdertime(Timestamp ordertime) {this.ordertime = ordertime;}public double getTotal() {return total;}public void setTotal(double total) {this.total = total;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}@Overridepublic String toString() {return "Order{" +"id=" + id +", ordertime=" + ordertime +", total=" + total +", user=" + user +'}';}
}

package com.itcast.domain;import java.util.Date;public class User {private int id;private String username;private String password;private Date birthday;public int getId() {return id;}public void setId(int id) {this.id = id;}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 Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +", birthday=" + birthday +'}';}
}

package com.itcast.mapper;import com.itcast.domain.Order;
import com.itcast.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;import java.util.List;public interface OrderMapper {@Select("SELECT * FROM orders")@Results({@Result(column = "oid", property = "id"),@Result(column = "ordertime", property = "ordertime"),@Result(column = "total", property = "total"),@Result(property = "user", //要封装的属性column = "uid", //根据哪个字段去查询user表的数据javaType = User.class, //要封装的实体类型//select属性 代表查询哪个接口的方法获得数据one = @One(select = "com.itcast.mapper.UserMapper.findById"))})public List<Order> findAll();
}

DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><typeAliases><typeAlias type="com.itcast.domain.User" alias="user">typeAlias>typeAliases><typeHandlers><typeHandler handler="com.itcast.handler.DateTypeHandler">typeHandler>typeHandlers><environments default="development"><environment id="development"><transactionManager type="JDBC">transactionManager><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/test"/><property name="username" value="root"/><property name="password" value="20001201"/>dataSource>environment>environments><mappers><package name="com.itcast.mapper"/>mappers>
configuration>

package com.itcast.test;import com.itcast.domain.Order;
import com.itcast.mapper.OrderMapper;
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.Before;
import org.junit.Test;import java.io.IOException;
import java.io.InputStream;
import java.util.List;public class MybatisTest2 {private OrderMapper mapper;@Beforepublic void before() throws IOException {InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);SqlSession sqlSession = sqlSessionFactory.openSession(true);//自动提交事务mapper = sqlSession.getMapper(OrderMapper.class);}@Testpublic void testFindAll() {List<Order> orderList = mapper.findAll();for (Order order : orderList) {System.out.println(order);}}
}

2.1vN查询

用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户。

一对多查询的需求：查询一个用户，与此同时查询出该用户具有的订单。

select * from user;
select * from orders where uid = 查询出用户的id;

（1）配置方式：

package com.itcast.mapper;import com.itcast.domain.User;
import org.apache.ibatis.annotations.*;import java.util.List;public interface UserMapper {@Select("select * from user")@Results({@Result(column = "id", property = "id"),@Result(column = "username", property = "username"),@Result(column = "password", property = "password"),@Result(property = "orderList",column = "id",javaType = List.class,many = @Many(select = "com.itcast.mapper.OrderMapper.findByUid"))})public List<User> findUserAndOrderAll();
}

package com.itcast.mapper;import com.itcast.domain.Order;
import com.itcast.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.omg.CORBA.PUBLIC_MEMBER;import java.util.List;public interface OrderMapper {@Select("select * from orders where uid = #{uid}")public List<Order> findByUid(int uid);
}

（2）程序演示：

package com.itcast.domain;import java.sql.Timestamp;
import java.util.Date;public class Order {private int id;private Timestamp ordertime;private double total;public int getId() {return id;}public void setId(int id) {this.id = id;}public Date getOrdertime() {return ordertime;}public void setOrdertime(Timestamp ordertime) {this.ordertime = ordertime;}public double getTotal() {return total;}public void setTotal(double total) {this.total = total;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}@Overridepublic String toString() {return "Order{" +"id=" + id +", ordertime=" + ordertime +", total=" + total +", user=" + user +'}';}
}

package com.itcast.domain;import java.util.Date;
import java.util.List;public class User {private int id;private String username;private String password;private Date birthday;private List<Order> orderList;//该用户的所有订单public List<Order> getOrderList() {return orderList;}public void setOrderList(List<Order> orderList) {this.orderList = orderList;}public int getId() {return id;}public void setId(int id) {this.id = id;}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 Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +", birthday=" + birthday +", orderList=" + orderList +'}';}
}

package com.itcast.mapper;import com.itcast.domain.User;
import org.apache.ibatis.annotations.*;import java.util.List;public interface UserMapper {@Select("select * from user")@Results({@Result(column = "id", property = "id"),@Result(column = "username", property = "username"),@Result(column = "password", property = "password"),@Result(property = "orderList",column = "id",javaType = List.class,many = @Many(select = "com.itcast.mapper.OrderMapper.findByUid"))})public List<User> findUserAndOrderAll();
}

package com.itcast.mapper;import com.itcast.domain.Order;
import com.itcast.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.omg.CORBA.PUBLIC_MEMBER;import java.util.List;public interface OrderMapper {@Select("select * from orders where uid = #{uid}")public List<Order> findByUid(int uid);
}

DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><typeAliases><typeAlias type="com.itcast.domain.User" alias="user">typeAlias>typeAliases><typeHandlers><typeHandler handler="com.itcast.handler.DateTypeHandler">typeHandler>typeHandlers><environments default="development"><environment id="development"><transactionManager type="JDBC">transactionManager><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/test"/><property name="username" value="root"/><property name="password" value="20001201"/>dataSource>environment>environments><mappers><package name="com.itcast.mapper"/>mappers>
configuration>

package com.itcast.test;import com.itcast.domain.User;
import com.itcast.mapper.UserMapper;
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.Before;
import org.junit.Test;import java.io.IOException;
import java.io.InputStream;
import java.util.List;public class MybatisTest3 {private UserMapper mapper;@Beforepublic void before() throws IOException {InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);SqlSession sqlSession = sqlSessionFactory.openSession(true);//自动提交事务mapper = sqlSession.getMapper(UserMapper.class);}@Testpublic void testFindAll() {List<User> orderList = mapper.findUserAndOrderAll();for (User user : orderList) {System.out.println(user);}}
}

3.NvN查询

用户表和角色表的关系为，一个用户有多个角色，一个角色被多个用户使用。

多对多查询的需求：查询用户同时查询出该用户的所有角色。

select * from user;
select * from role r, user_role ur where r.id = ur.role_id and ur.user_id = 用户的id

（1）配置方式：

package com.itcast.mapper;import com.itcast.domain.User;
import org.apache.ibatis.annotations.*;import java.util.List;public interface UserMapper {@Select("select * from user")@Results({@Result(column = "id", property = "id"),@Result(column = "username", property = "username"),@Result(column = "password", property = "password"),@Result(property = "roleList",column = "id",javaType = List.class,many = @Many(select = "com.itcast.mapper.RoleMapper.findByUid"))})public List<User> findUserAndRoleAll();
}

package com.itcast.mapper;import com.itcast.domain.Role;
import org.apache.ibatis.annotations.Select;import java.util.List;public interface RoleMapper {@Select("select * from role r, user_role ur where r.id = ur.role_id and ur.user_id = #{uid}")public List<Role> findByUid(int uid);
}

（2）程序演示：

package com.itcast.domain;import java.util.Date;
import java.util.List;public class User {private int id;private String username;private String password;private Date birthday;private List<Role> roleList;//当前用户具有的角色public List<Role> getRoleList() {return roleList;}public void setRoleList(List<Role> roleList) {this.roleList = roleList;}public int getId() {return id;}public void setId(int id) {this.id = id;}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 Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +", birthday=" + birthday +", roleList=" + roleList +'}';}
}

package com.itcast.domain;public class Role {private int id;private String roleName;private String roleDesc;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getRoleName() {return roleName;}public void setRoleName(String roleName) {this.roleName = roleName;}public String getRoleDesc() {return roleDesc;}public void setRoleDesc(String roleDesc) {this.roleDesc = roleDesc;}@Overridepublic String toString() {return "Role{" +"id=" + id +", roleName='" + roleName + '\'' +", roleDesc='" + roleDesc + '\'' +'}';}
}

package com.itcast.mapper;import com.itcast.domain.User;
import org.apache.ibatis.annotations.*;import java.util.List;public interface UserMapper {@Select("select * from user")@Results({@Result(column = "id", property = "id"),@Result(column = "username", property = "username"),@Result(column = "password", property = "password"),@Result(property = "roleList",column = "id",javaType = List.class,many = @Many(select = "com.itcast.mapper.RoleMapper.findByUid"))})public List<User> findUserAndRoleAll();
}

package com.itcast.mapper;import com.itcast.domain.Role;
import org.apache.ibatis.annotations.Select;import java.util.List;public interface RoleMapper {@Select("select * from role r, user_role ur where r.id = ur.role_id and ur.user_id = #{uid}")public List<Role> findByUid(int uid);
}

DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><typeAliases><typeAlias type="com.itcast.domain.User" alias="user">typeAlias>typeAliases><typeHandlers><typeHandler handler="com.itcast.handler.DateTypeHandler">typeHandler>typeHandlers><environments default="development"><environment id="development"><transactionManager type="JDBC">transactionManager><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/test"/><property name="username" value="root"/><property name="password" value="20001201"/>dataSource>environment>environments><mappers><package name="com.itcast.mapper"/>mappers>
configuration>

package com.itcast.test;import com.itcast.domain.User;
import com.itcast.mapper.UserMapper;
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.Before;
import org.junit.Test;import java.io.IOException;
import java.io.InputStream;
import java.util.List;public class MybatisTest4 {private UserMapper mapper;@Beforepublic void before() throws IOException {InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);SqlSession sqlSession = sqlSessionFactory.openSession(true);//自动提交事务mapper = sqlSession.getMapper(UserMapper.class);}@Testpublic void testfindAll() {List<User> userAndRoleAll = mapper.findUserAndRoleAll();for (User user : userAndRoleAll) {System.out.println(user);}}
}

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