020.PageHelper分页插件

1.分页查询要面临的问题

 

 2.使用流程

 

 2.1 pom.xml

       <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
            <version>5.1.10</version>
        </dependency>
        
        <dependency>
            <groupId>com.github.jsqlparser</groupId>
            <artifactId>jsqlparser</artifactId>
            <version>2.0</version>
        </dependency>

        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.4</version>
        </dependency>

2.2  mybatis-config.xml

 <!--启用Pagehelper分页插件-->
    <plugins>
        <plugin interceptor="com.github.pagehelper.PageInterceptor">
            <!--设置数据库类型-->
            <property name="helperDialect" value="mysql"/>
            <!--分页合理化-->
            <property name="reasonable" value="true"/>
        </plugin>
    </plugins>

2.3  分页的处理

2.3.1  goods.xml

    <select id="selectPage" resultType="com.imooc.mybatis.entity.Goods">
        select * from t_goods where current_price &lt; 1000
    </select>

2.3.2  测试类

@Test
    /**
     * PageHelper分页查询
     */
    public void testSelectPage() throws Exception {
        SqlSession session = null;
        try {
            session = MyBatisUtils.openSession();
            /*startPage方法会自动将下一次查询进行分页*/
            PageHelper.startPage(2,10);
            Page<Goods> page = (Page) session.selectList("goods.selectPage");
            System.out.println("总页数:" + page.getPages());
            System.out.println("总记录数:" + page.getTotal());
            System.out.println("开始行号:" + page.getStartRow());
            System.out.println("结束行号:" + page.getEndRow());
            System.out.println("当前页码:" + page.getPageNum());
            List<Goods> data = page.getResult();//当前页数据
            for (Goods g : data) {
                System.out.println(g.getTitle());
            }
            System.out.println("");
        } catch (Exception e) {
            throw e;
        } finally {
            MyBatisUtils.closeSession(session);
        }
    }