一、Mybatis动态语句分为4种元素

①if元素

②where 元素

?③choose(?? when???? otherwise)

④set用在update上

⑤foreache遍历

?二、方法传递多个参数时如何为参数起名

三、mybatis处理特殊字符

（1）使用转义字符替换

   <select id="selectFw" resultType="com.ykq.entity.Emp">
        select * from tbl_emp where empId>#{min} and empId &lt;#{max}
    </select>

（2）CDATA内容会原翻不动的解析＜！［ＣＤＡＴＡ［］］＞

<select id="selectFw" resultType="com.ykq.entity.Emp">
    <![CDATA[ select * from tbl_emp where empId>#{min} and empId <=#{max}]]>
</select>

四、ｐａｇｅｈｅｌｐｅｒ分页插件－－－完成分页查询

使用步骤：

①引入相关依赖

        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
            <version>5.1.11</version>
        </dependency>

②在ｍｙｂａｔｉｓ配置文件中引入插件

③使用分页的功能

public static void main(String[] args) throws Exception{
        Reader resourceAsReader = Resources.getResourceAsReader("mybatis-conf.xml");
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(resourceAsReader);
        SqlSession sqlSession = sessionFactory.openSession();
        FoodMapper foodMapper = sqlSession.getMapper(FoodMapper.class);
        PageHelper.startPage(2, 3);

        List<Food> all = foodMapper.findAll();
        PageInfo<Food> pageInfo=new PageInfo<Food>(all);
        System.out.println("当前总条数:"+pageInfo.getTotal());
      System.out.println("当前页码:"+pageInfo.getPageNum());
      System.out.println("当前记录:"+pageInfo.getList());
      System.out.println("总页数:"+pageInfo.getPages());

    }

五、代码生成器－－－－单表查询ｃｒｕｄ－－－ｇｅｎｅｒａｔｏｒ

①引入依赖

<dependency>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-core</artifactId>
    <version>1.4.0</version>
</dependency>

②ｇｅｎｅｒａｔｏｒ的配置文件－－－必须放在工程下

<?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>
  <!--数据库驱动包所在的路径 我建议写成绝对路径-->
  <classPathEntry location="D:\repMaven\mysql\mysql-connector-java\8.0.20\mysql-connector-java-8.0.20.jar" />


  <context id="DB2Tables" targetRuntime="MyBatis3">
    <!--注释的生成-->
    <commentGenerator>
      <property name="suppressAllComments" value="true" />
    </commentGenerator>
    <!--数据库连接信息-->
    <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
        connectionURL="jdbc:mysql://localhost:3306/mybatis02?serverTimezone=Asia/Shanghai"
        userId="root"
        password="root">
    </jdbcConnection>

    <javaTypeResolver >
      <property name="forceBigDecimals" value="false" />
    </javaTypeResolver>

    <!--生成的实体类所在的包-->
    <javaModelGenerator targetPackage="com.ykq.entity" targetProject="./src/main/java">
      <property name="enableSubPackages" value="true" />
      <property name="trimStrings" value="true" />
    </javaModelGenerator>

    <!--映射文件存在目录-->
    <sqlMapGenerator targetPackage="mapper"  targetProject="./src/main/resources">
      <property name="enableSubPackages" value="true" />
    </sqlMapGenerator>

    <!--dao接口所在的包-->
    <javaClientGenerator type="XMLMAPPER" targetPackage="com.ykq.dao"  targetProject="./src/main/java">
      <property name="enableSubPackages" value="true" />
    </javaClientGenerator>
    <!--表
          schema：表所在的数据库
          tableName:表名
          domainObjectName:实体类得名称
    -->
    <table schema="mybatis02" tableName="tbl_emp" domainObjectName="Emp"
           enableDeleteByExample="false"
           enableSelectByExample="false"
           enableUpdateByExample="false"
           enableCountByExample="false"/>

    <table schema="mybatis02" tableName="tbl_dept" domainObjectName="Dept"
           enableDeleteByExample="false"
           enableSelectByExample="false"
           enableUpdateByExample="false"
           enableCountByExample="false"/>



  </context>
</generatorConfiguration>

?③测试

public static void main(String[] args) throws Exception {
    List<String> warnings = new ArrayList<String>();
    boolean overwrite = true;
    File configFile = new File("generator-mybatis.xml");
    ConfigurationParser cp = new ConfigurationParser(warnings);
    Configuration config = cp.parseConfiguration(configFile);
    DefaultShellCallback callback = new DefaultShellCallback(overwrite);
    MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
    myBatisGenerator.generate(null);
}