Mybatis核心配置文件深入

typeHandlers标签

这个感觉不是很重要，知道是干啥的就行了，以后有需要再深入了解。

plugins标签

先查询一下全部看一下：

package com.itheima.dao;

        import com.itheima.domain.User;

        import java.io.IOException;
        import java.util.List;

public interface UserMapper {

    public List<User> findByCondition(User user) throws IOException;

    public List<User> findByIds(List<Integer> ids);
    
    //查询全部
    public List<User> findAll();
}

    <select id="findAll" resultType="user">
        select * from user
    select>

测试：

 @Test
    public void test6() throws IOException {
        //获得核心配置文件
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        //获得session工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //获得session会话对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        List<User> userList = mapper.findAll();
        for (User user : userList) {
            System.out.println(user);
        }
        sqlSession.close();
    }

效果：

现在我们来使用PageHelper
第一步：导入坐标

 
        <dependency>
            <groupId>com.github.pagehelpergroupId>
            <artifactId>pagehelperartifactId>
            <version>3.7.5version>
        dependency>
        
        <dependency>
            <groupId>com.github.jsqlparsergroupId>
            <artifactId>jsqlparserartifactId>
            <version>0.9.1version>
        dependency>

第二步去到mybatis的核心配置文件当中配置这个分页助手

    <plugins>
        <plugin interceptor="com.github.pagehelper.PageHelper">
            
            <property name="dialect" value="mysql">property>
        plugin>
    plugins>

测试代码：

@Test
    public void test6() throws IOException {
        //获得核心配置文件
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        //获得session工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //获得session会话对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        //设置分页相关参数：当前页 和 每页显示条数
        PageHelper.startPage(2,1);

        List<User> userList = mapper.findAll();
        for (User user : userList) {
            System.out.println(user);
        }

        //获得与分页相关的参数
        PageInfo<User> pageInfo = new PageInfo<User>(userList);
        System.out.println("当前页"+pageInfo.getPageNum());
        System.out.println("每页显示条数"+pageInfo.getPageSize());
        System.out.println("总条数"+pageInfo.getTotal());
        System.out.println("总页数"+pageInfo.getPages());
        System.out.println("上一页是谁"+pageInfo.getPrePage());
        System.out.println("下一页是谁"+pageInfo.getNextPage());
        System.out.println("是否是第一页"+pageInfo.isIsFirstPage());
        System.out.println("是否是第一页"+pageInfo.isIsLastPage());
        //关闭资源
        sqlSession.close();
    }

小结