关于Mybatis的一些随笔

时间：2021-05-17 22:03:54

Mapper.xml头文件

<!DOCTYPE mapper
 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

Mybatis配置头文件

<!DOCTYPE configuration
 PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 "http://mybatis.org/dtd/mybatis-3-config.dtd">

Mybatis配置文件

<?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>
        <!-- 设置resultMap的自动映射级别 -->
        <setting name="autoMappingBehavior" value="FULL"/>
        <!-- 设置全局性延迟加载 -->
        <setting name="lazyLoadingEnabled" value="false"/>
    </settings>

    <!-- 设置实体类别名 -->
    <typeAliases>
        <package name="cn.xin.pojo" />
    </typeAliases>

</configuration>

Sql映射文件

<?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="cn.xin.dao.user.UserMapper">
     <select id="queryLogin" resultType="User">
         select * from smbms_user where userCode=#{userCode}
     </select>

     <select id="userCount" resultType="int">
         select count(*) from smbms_user,smbms_role
         where smbms_user.userRole=smbms_role.id
         <if test="userName!=null and userName!=''">
             and smbms_user.userName=#{userName}
         </if>
         <if test="roleName!=null and roleName!=''">
             and smbms_role.roleName=#{roleName}
         </if>
     </select>

     <select id="getUserList" resultMap="userlist">
         select * from smbms_user,smbms_role where smbms_user.userRole=smbms_role.id
         <trim suffixOverrides="and">
             <if test="userName!=null and userName!=''">
                 and smbms_user.userName=#{userName}
             </if>
             <if test="roleName!=null and roleName!=''">
                 and smbms_role.roleName=#{roleName}
             </if>
         </trim>
         order by smbms_user.id limit #{from},#{pageSize}
     </select>
     <resultMap type="UserList" id="userlist">
         <id property="id" column="id"/>
         <result property="userCode" column="userCode"/>
         <association property="role" javaType="Role">
             <id property="id" column="r_id"/>
             <result property="roleName" column="roleName"/>
         </association>
     </resultMap>

     <insert id="addUser" parameterType="User">
         insert into smbms_user(userCode,userName,userPassword,gender,birthday,phone,address,userRole,idPicPath,workPicPath)
         value(#{userCode},#{userName},#{userPassword},#{gender},#{birthday},#{phone},#{address},#{userRole},#{idPicPath},#{workPicPath})
     </insert>

     <select id="getUserById" resultType="User">
         select * from smbms_user where id=#{id};
     </select>

     <update id="modifyUserById" parameterType="User">
         update smbms_user
         set userName=#{userName},gender=#{gender},birthday=#{birthday},phone=#{phone},address=#{address},userRole=#{userRole}
         where id=#{id}
     </update>

     <select id="queryUserById" parameterType="int" resultType="User">
         select * from smbms_user where id=#{id}
     </select>

     <delete id="delUserById" parameterType="int">
         delete from smbms_user where id=#{id}
     </delete>

     <select id="getUserByuserCode" >
         select * from smbms_user where userCode=#{userCode}
     </select>

 </mapper>

逆向工程配置头文件

<!DOCTYPE generatorConfiguration
  PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
  "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

逆向工程generatorConfig.xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
  PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
  "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

  <generatorConfiguration>
      <context id="testTables" targetRuntime="Mybatis3">
          <commentGenerator>
              <!-- 是否去除自动生成的注释true、flase -->
              <property name="suppressAllComments" value="true"/>
          </commentGenerator>

          <!-- 数据库连接的信息：驱动类、连接地址、用户名、密码 -->
          <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://localhost:3306/smbms"
                          userId="root" password="174173315">
          </jdbcConnection>

          <!-- 默认false，把JDBC DECIMAL 和 NUMERIC类型解析为Integer，为true时解析为java.math.BigDecimal -->
          <javaTypeResolver>
              <property name="forceBigDecimals" value="false"/>
          </javaTypeResolver>

          <!-- targetProject:生成PO类的位置 -->
          <javaModelGenerator targetPackage="cn.xin.pojo" targetProject=".\src">
              <!-- enableSubPackages:是否让schema作为包的后缀 -->
              <property name="trimSubPackges" value="false"/>
              <!-- 从数据库返回的值被清理前后的空格 -->
              <property name="trimString" value="true"/>
          </javaModelGenerator>

          <!-- targetProject:mapper映射文件生成的位置 -->
          <sqlMapGenerator targetPackage="cn.xin.dao" targetProject=".\src">
              <!-- enableSubPackages:是否让schema作为包的后缀 -->
              <property name="enableSubPackages" value="false"/>
          </sqlMapGenerator>

          <!-- targetPackage:mapper接口生成的位置 -->
          <javaClientGenerator targetPackage="cn.xin.dao" type="XMLMAPPER" targetProject=".\src">
              <!-- 是否让schema作为包的后缀 -->
              <property name="enableSubPackages" value="false"/>
          </javaClientGenerator>

          <!-- 指定数据库表 -->
          <table tableName="smbms_user"></table>

      </context>

  </generatorConfiguration>

逆向工程生成类

package cn.com.generator.main;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.api.ShellCallback;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.internal.DefaultShellCallback;

public class GeneratorSqlMap {
    public void generator() throws Exception{
        //warnings为用于放置生成过程中警告信息的集合对象
        List<String> warnings = new ArrayList<String>();
        //指定DefaultShellCallback是否覆盖重名文件
        boolean overwrite = true;
        //加载配置文件
        File configFile = new File("generatorConfig.xml");
        //配置解析类
        ConfigurationParser cp = new ConfigurationParser(warnings);
        //配置解析类解析配置文件并生成Configuration配置对象
        Configuration config = cp.parseConfiguration(configFile);
        //DefaultShellCallback负责如何处理重复文件
        ShellCallback callback = new DefaultShellCallback(overwrite);
        //逆向工程对象
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config,
                callback, warnings);
        //执行逆向文件生成操作
        myBatisGenerator.generate(null);
    }
    public static void main(String[] args) throws Exception {
        GeneratorSqlMap generatorSqlmap = new GeneratorSqlMap();
        generatorSqlmap.generator();
    }
}

Mybatis随笔

1.多参数入参：
　　Mapper接口参数：(@Param("id")Integer id,@Param("password")String pwd)；Mapper.xml无需填写parameterType2.@Param注解：　　Mybatis的参数类型为Map，使用@Param注解的参数，会记录指定的参数名为key；否则默认为"param"+序号作为Map的key，这种情况可能会引起sql语句中获取不到#{参数名}，从而报错3.resultMap的作用：　　描述数据库结果集合对象的对应关系，属性名与字段名不同的匹配、association处理一对一关联关系、collection处理一对多关联关系、自动映射级别：NONE：禁止自动匹配，PARTIAL（默认）：自动匹配所有属性，有内部嵌套的除外，FULL：自动匹配所有属性，包括内部嵌套4.动态SQL：　　if+where、if+trim、if+set、foreach、choose(when/otherwise)、where 1=1、分页：oreder by id limit #{start}},#{count}（查询结果根据id排序，从start开始，每次显示5个查询结果）　foreach:迭代对象为数组，collection=array、迭代对象为List，collection=list、迭代对象为Map，collection=key
select * from tb_member where id in <foreach collection="array" item="id" open="(" separator="," close=")">#{id}</foreach>

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