mybatis中使用PageHelper分页助手

MyBatis可以使用第三方的插件来对功能进行扩展，分页助手PageHelper是将分页的复杂操作进行封装，使用简单的方式即可获得分页的相关数据

开发步骤：

1、导入通用PageHelper的依赖坐标

		 <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
            <version>3.7.5</version>
        </dependency>
        <dependency>
            <groupId>com.github.jsqlparser</groupId>
            <artifactId>jsqlparser</artifactId>
            <version>0.9.1</version>
        </dependency>

2、在mybatis核心配置文件中配置PageHelper插件

<!--配置分页助手插件-->
    <plugins>
        <plugin interceptor="com.github.pagehelper.PageHelper">
            <property name="dialect" value="mysql"></property>
        </plugin>
    </plugins>

3、测试分页数据获取

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.itheima.domain.User;
import com.itheima.mapper.UserMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

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

public class MybatisTest {

    @Test
    public void test() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        //设置分页相关参数   当前页+每页显示的条数
        PageHelper.startPage(3, 3);
        List<User> userList = mapper.findAll();
        for (User user : userList) {
            System.out.println(user);
        }
        //获得与分页相关参数
        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：" + pageInfo.getPrePage());
        System.out.println("下一页：" + pageInfo.getNextPage());
        System.out.println("是否是第一个：" + pageInfo.isIsFirstPage());
        System.out.println("是否是最后一个：" + pageInfo.isIsLastPage());

        sqlSession.close();
    }

}