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Singerw
2021-09-25

XML实现CRUD

# MyBatis实现 XML形式的CURD⛵️

# 1、增加操作

# 🅰️方案一、通过对象插入

【示例：UserMapper.java】

public interface UserMapper {

    boolean addUser(User user);
}
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【示例：UserMapper.xml】

<mapper namespace="com.singerw.mapper.UserMapper">

    <!--增加用户-->
    <insert id="addUser">
        insert into g_users
        value (null,
        #{username},
        #{userphone},
        #{userpassword},
        0,
        now(),
        now(),
        1)
    </insert>

</mapper>
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【示例：UserMapperTest.java】

public class UserMapperTest {

    private SqlSession sqlSession = MyBatisUtils.getSqlSession();
    private UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

    @Test
    public void addUser() {
        User user = new User("张欣", "19999999999", "assam1314520");
        boolean flag = userMapper.addUser(user);
        sqlSession.commit();
        System.out.println(flag ? "增加成功" : "增加失败");
    }

}
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# 🅱️方案二、通过Map插入

💛（万能方法）工作必备野路子方法，也可以使用到查询，修改，删除等等中💛

假设我们的实体类中，或者数据库的表中，字段或者参数很多，我们应当考虑使用Map插入

【示例：UserMapper.java】

public interface UserMapper {

    boolean addUser2(Map<String,Object> map);
}
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【示例：UserMapper.xml】

<?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.singerw.mapper.UserMapper">

    <!--增加用户-->
    <insert id="addUser2" parameterType="map">
        insert into g_users (userid, username, userphone, userpassword, jurisdiction, createtime, logintime, userstatus)
        values (null,#{username},#{userphone},#{userpassword},#{jurisdiction},now(),now(),#{userstatus});
    </insert>

</mapper>
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【示例：UserMapperTest.java】

public class UserMapperTest {

    private SqlSession sqlSession = MyBatisUtils.getSqlSession();
    private UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

    @Test
    public void addUser() {
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        HashMap hashMap = new HashMap<String,Object>();
        hashMap.put("username","singerw");
        hashMap.put("userphone","18888888888");
        hashMap.put("userpassword","123456");
        hashMap.put("jurisdiction",1);
        hashMap.put("userstatus",1);
        mapper.addUser2(hashMap);
    }
}
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# 2、删除操作

【示例：UserMapper.java】

public interface UserMapper {

    boolean delUser(int userid);
}
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【示例：UserMapper.xml】

<mapper namespace="com.singerw.mapper.UserMapper">

    <!--根据ID删除用户-->
    <delete id="delUser">
        delete
        from goku.g_users
        where userid = #{userid}
    </delete>
    
</mapper>
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【示例：UserMapperTest.java】

public class UserMapperTest {

    private SqlSession sqlSession = MyBatisUtils.getSqlSession();
    private UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

    @Test
    public void delUser() {
        boolean flag = userMapper.delUser(10);
        //必须要提交
        sqlSession.commit();
        System.out.println(flag ? "删除成功" : "删除失败");
        sqlSession.close();
    }
}
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# 3、修改操作

# 🅰️方案一、参数为一个对象

【示例：UserMapper.java】

public interface UserMapper {

    boolean updateUser2(User user);
}
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【示例：UserMapper.xml】

<mapper namespace="com.singerw.mapper.UserMapper">

    <!--根据ID修改用户-->
    <update id="updateUser">
        update g_users
        set username     = #{username},
        userphone    = #{userphone},
        userpassword = #{userpassword},
        jurisdiction = #{jurisdiction},
        userstatus   = #{userstatus}
        where userid = #{userid}
    </update>

</mapper>
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【示例：UserMapperTest.java】

public class UserMapperTest {

    private SqlSession sqlSession = MyBatisUtils.getSqlSession();
    private UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

    @Test
    public void updateUser2() {
        User user = new User("测试测试测试", "156515561561", "123456", 1, 1, 8);
        boolean flag = userMapper.updateUser2(user);
        //必须要提交
        sqlSession.commit();
        System.out.println(flag ? "修改成功" : "修改失败");
    }
}
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# 🅱️方案二、参数为多个不同参数

注意:此时我们的修改的方法的参数不再是单一的参数,而是多个参数

【示例：UserMapper.java】

public interface UserMapper {

    boolean updateUser(String username, String userphone, String userpassword, int jurisdiction, int userstatus, int userid);
}
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【示例：UserMapper.xml】

<mapper namespace="com.singerw.mapper.UserMapper">

    <!--根据ID修改用户-->
    <update id="updateUser">
        update g_users
        set username     = #{username},
        userphone    = #{userphone},
        userpassword = #{userpassword},
        jurisdiction = #{jurisdiction},
        userstatus   = #{userstatus}
        where userid = #{userid}
    </update>

</mapper>
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【示例：UserMapperTest.java】

public class UserMapperTest {

    private SqlSession sqlSession = MyBatisUtils.getSqlSession();
    private UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

    @Test
    public void updateUser() {
        boolean flag = userMapper.updateUser("测试测试测试", "1444444444", "123456", 1, 1, 5);
        //必须要提交
        sqlSession.commit();
        System.out.println(flag ? "修改成功" : "修改失败");
    }
}
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报错处理

这时我们发现测试结果报错：

Parameter 'username' not found. Available parameters are [arg3, arg2, param5, arg5, arg4, param6, arg1, arg0, param3, param4, param1, param2]

多个参数的绑定默认按照顺序；

🅰️解决方法一（推荐）：修改UserMapper.xml中的update参数信息为如下，MyBatis才能识别到。

【解决方法示例：UserMapper.xml】

<mapper namespace="com.singerw.mapper.UserMapper">

    <!--根据ID修改用户-->
    <update id="updateUser">
        update g_users
        set username     = #{arg0},
        userphone    = #{arg1},
        userpassword = #{arg2},
        jurisdiction = #{arg3},
        userstatus   = #{arg4}
        where userid = #{arg5}
    </update>

</mapper>
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或者修改UserMapper.java中的updateUser方法的参数信息，这样MyBatis也能识别到。

public interface UserMapper {

    boolean updateUser(@Param("username") String username, @Param("userphone") String userphone, @Param("userpassword") String userpassword, @Param("jurisdiction") int jurisdiction, @Param("userstatus") int userstatus, @Param("userid") int userid);

}
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🅱️解决方法二：将参数构造成一个map对象，将我们的属性传递进来

【解决方法示例：UserMapper.java】

public interface UserMapper {

    boolean updateUser(Map map);
}
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【解决方法示例：UserMapper.xml】

<mapper namespace="com.singerw.mapper.UserMapper">
    <!--根据ID修改用户-->
    <!--根据ID修改用户-->
    <!--根据ID修改用户-->
    <update id="updateUser">
        update g_users
        set username     = #{username},
        userphone    = #{userphone},
        userpassword = #{userpassword},
        jurisdiction = #{jurisdiction},
        userstatus   = #{userstatus}
        where userid = #{userid}
    </update>
    
</mapper>
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【解决方法示例：UserMapperTest.java】

public class UserMapperTest {

    private SqlSession sqlSession = MyBatisUtils.getSqlSession();
    private UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

    @Test
    public void updateUser() {
        HashMap map = new HashMap();
        map.put("username","测试测试测试");
        map.put("userphone","1444444444");
        map.put("userpassword","123456");
        map.put("jurisdiction",1);
        map.put("userstatus",0);
        map.put("userid",10);

        boolean flag = userMapper.updateUser(map);  
        //必须要提交
        sqlSession.commit();
        System.out.println(flag ? "修改成功" : "修改失败");
    }
}
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# 4 、查询操作

【示例：UserMapper.java】

public interface UserMapper { 

    List<User> getUsers();

    User getUser(int userid);
}
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【示例：UserMapper.xml】

<mapper namespace="com.singerw.mapper.UserMapper">
    <!--查询所有用户-->
    <!-- 此时没有指定包的情况，其实用的是别名Blog -->
    <select id="getUsers" resultType="User">
        select *
        from goku.g_users
    </select>

    <!-- 此时没有指定包的情况，其实用的是别名Blog -->
    <select id="getUser" resultType="User">
        select *
        from goku.g_users
        where userid = #{userid}
    </select>

</mapper>
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【示例：UserMapperTest.java】

public class UserMapperTest {

    private SqlSession sqlSession = MyBatisUtils.getSqlSession();
    private UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

    @Test
    public void getUsers() {
        List<User> users = userMapper.getUsers();
        for (User user : users) {
            System.out.println(user);
        }
        sqlSession.close();
    }

    @Test
    public void getUser() {
        User user = userMapper.getUser(2);
        System.out.println(user);
        sqlSession.close();
    }
}
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