2017 06 14

本次笔记主要记录 mapper 映射文件

讨论mybatis中where条件查询的一些应用

mapper映射文件代码示例：

    <?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">
    <!-- 类似于包名,但是不允许其重复 命名控件:package 规则: 1.使用类的全路径 com.shxt.servlet.UserServlet -->
    <mapper namespace="com.shxt.model.User">
        <!-- 结果集处理标签,只能是针对于查询 -->
    <resultMap type="User" id="BaseResultMapper">
        <id column="user_id" jdbcType="INTEGER" property="userId" javaType="java.lang.Integer" />
        <result column="account" jdbcType="VARCHAR" property="account" javaType="java.lang.String" />
        <result column="password" jdbcType="VARCHAR" property="pwd" javaType="java.lang.String" />
        <result column="user_name" jdbcType="VARCHAR" property="userName" javaType="java.lang.String" />
    </resultMap>
    <sql id="sys_user_columns">
        user_id,account,password,user_name
    </sql>
    
    <!-- 01.Like -->
    <select id="like01" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
        WHERE
        user_name like '%管%'
    </select>
    
    <!-- 02.Like Java代码解决方案 -->
    <select id="like02" parameterType="string" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
        WHERE
        user_name like #{name}
    </select>
    <!-- 03.Like 数据库SQL语句解决方案 -->
    <select id="like03" parameterType="string" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
        WHERE
        user_name like CONCAT('%',#{name},'%')
    </select>
    
    <!-- 04.使用${}完成查询,但是面试题问MyBatis${}和#{}之区别 -->
    <!-- ${} 必须有KEY或属性 -->
    <!-- ${} 原封不动,不进行转义 #{}根据你的数据会自动进行转义 -->
    <!-- ORDER BY user_name|account|id -->
    <!-- 别忽略${} 如果以后匿名涉及特别赋值的业务逻辑的SQL语句的时候,会使用${} -->
    <select id="like04" parameterType="string" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
        WHERE
        user_name like CONCAT('%','${shxt}','%')
    </select>
    
    <!-- 05.请查询数据USER_ID小于 10 的所有数据 -->
    <!--  < 小于号在xml文件里是不被允许的符号  需要方法来对它进行转化 -->
    <!-- <![CDATA[ 这里的内容教会转化为纯文本内容 ]]> -->
    <!-- 方法一 : 利用提供的特殊字符来进行小于号的表示 -->
    <select id="less01" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
        WHERE
        <!-- XML不允许使用5个特殊字符 -->
            user_id <= 10
        </select>
    <!-- 方法二 ： 利用<![CDATA[?]]> 特殊标志来进行转化 -->
    <select id="less02" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
        WHERE
        <!-- XML不允许使用5个特殊字符 -->
    <![CDATA[
        user_id <= 10
    ]]>
               
        </select>
    
    <!-- &表示 & 特殊字符转化 -->
    <select id="if01" parameterType="map" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
        WHERE 1=1
        <!-- test中写的类中的属性或者Map中的KEY -->
        <if test="user_name !=null && user_name != ''">
            AND user_name like CONCAT('%',#{user_name},'%')
        </if>
        <if test="account != null and account != ''">
            AND account like CONCAT('%',#{account},'%')
        </if>
    
    </select>
    
    <select id="if02" parameterType="map" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
        WHERE 1=1
        <!-- test中写的类中的属性或者Map中的KEY -->
        <if test="user_name !=null && user_name != ''">
            AND user_name like CONCAT('%',#{user_name},'%')
        </if>
        <if test="account != null and account != ''">
            AND account like CONCAT('%',#{account},'%')
        </if>
    
    </select>
    
    <select id="if03" parameterType="map" resultMap="BaseResultMapper">
        SELECT
        <include refid="sys_user_columns" />
        FROM
        sys_user
    
        <!-- test中写的类中的属性或者Map中的KEY -->
            <trim prefix="WHERE" prefixOverrides="AND |OR ">
                <if test="user_name !=null && user_name != ''">
                    AND user_name like CONCAT('%',#{user_name},'%')
                </if>
                <if test="account != null and account != ''">
                    AND account like CONCAT('%',#{account},'%')
                </if>
            </trim>
    
        </select>
    
        <update id="update01" parameterType="User">
            UPDATE
            user
            <set>
                <if test="account !=null and account !='' ">
                    account = #{account},
                </if>
                <if test="userName !=null and userName !='' ">
                    user_name = #{userName},
                </if>
                <if test="pwd !=null and pwd !='' ">
                    password = #{pwd},
                </if>
            </set>
            WHERE
            user_Id = #{userId}
        </update>
        <update id="update02" parameterType="User">
            UPDATE
            user
            <set>
                <if test="account !=null and account !='' ">
                    account = #{account},
                </if>
                <if test="userName !=null and userName !='' ">
                    user_name = #{userName},
                </if>
                <if test="pwd !=null and pwd !='' ">
                    password = #{pwd},
                </if>
            </set>
            WHERE
            user_Id = #{userId}
        </update>
    
        <delete id="delete01">
            DELETE FROM user WHERE user_Id in
            <foreach collection="array" item="v" open="(" close=")" separator=",">
                #{v}
            </foreach>
        </delete>
    </mapper>

新建UserDao文件 作为接口定义实现方法
新建UserDaoImpl文件 作为UserDao文件的接口实现类

在test文件中接口回调创建对象 调用接口实现类(UserDaoImpl)实现的方法

对应的test文件内容 ：

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.junit.Test;
import com.shxt.dao.UserDao;
import com.shxt.dao.impl.UserDaoImpl;
import com.shxt.model.User;

public class UserDaoTest {


    @Test
    public void testLike01Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();
        List<User> userList = userDao.like01();

        System.out.println(userList);

    }
    @Test
    public void testLike02Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();
        List<User> userList = userDao.like02("管");

        System.out.println(userList);

    }
    @Test
    public void testLike03Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();
        List<User> userList = userDao.like03("管");

        System.out.println(userList);

    }
    @Test
    public void testLike04Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();

        Map<String, String> tempMap = new HashMap<String, String>();
        tempMap.put("shxt", "管");

        List<User> userList = userDao.like04(tempMap);

        System.out.println(userList);

    }

    @Test
    public void testLess01Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();
        List<User> userList = userDao.less01();

        System.out.println(userList);

    }
    @Test
    public void testLess02Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();
        List<User> userList = userDao.less02();

        System.out.println(userList);

    }
    @Test
    public void testIf01Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();

        Map<String, String> tempMap = new HashMap<String, String>();
        tempMap.put("user_name", "管");
        //tempMap.put("account", "s");

        List<User> userList = userDao.if01(tempMap);

        System.out.println(userList);

    }
    @Test
    public void testIf03Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();

        Map<String, String> tempMap = new HashMap<String, String>();
        tempMap.put("user_name", "管");
        //tempMap.put("account", "s");

        List<User> userList = userDao.if03(tempMap);

        System.out.println(userList);

    }
    @Test
    public void testUpdate01Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();
        User  user = new User();
        user.setAccount("test");
        user.setPwd("12312313");
        user.setUserName("test");
        user.setUserId(1);
        userDao.Update01(user);
    }
    @Test
    public void testUpdate02Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();
        User  user = new User();
        user.setAccount("test");
        user.setPwd("12312313");
        user.setUserName("test");
        user.setUserId(1);
        userDao.Update01(user);
    }

    @Test
    public void testDelete01Method(){
        //接口回调
        UserDao userDao = new UserDaoImpl();
        int[]arr = {1,3};
        userDao.batchDel(arr);;
    }
}