mybatis分页查询的实现

Posted 2021-02-22 青青子衿啊

一、总结了mybatis中五种不同实现分页查询的方法

　　UserMapper.java接口文件

public interface UserMapper {
	//分页查询
	public List<User> selectForPage1(int startIndex,int pageSize);
	
	public List<User> selectForPage2(Map<String, Object> map);
	
	public Integer selectCount();
	
	public List<User> selectForPage3(PageBean pageBean);
	
	//分页加模糊查询
	public Integer selectCount2(String keywords);
	public List<User> selectForPage4(Map<String, Object> map);
}

　　工具类PageBean.java

public class PageBean {
	private Integer currentPage;
	private Integer startIndex;
	private Integer pageSize=5;
	private Integer totalCount;
	private Integer totalPage;
	public Integer getCurrentPage() {
		return currentPage;
	}
	public void setCurrentPage(Integer currentPage) {
		this.currentPage = currentPage;
		this.startIndex=(this.currentPage-1)*this.pageSize;
	}
	public Integer getPageSize() {
		return pageSize;
	}
	public void setPageSize(Integer pageSize) {
		this.pageSize = pageSize;
	}
	public Integer getTotalCount() {
		return totalCount;
	}
	public void setTotalCount(Integer totalCount) {
		this.totalCount = totalCount;
		//计算总页数
		this.totalPage=(int)Math.ceil((this.totalCount*1.0/this.pageSize));
	}
	public Integer getTotalPage() {
		return totalPage;
	}
	public void setTotalPage(Integer totalPage) {
		this.totalPage = totalPage;
	}
	public Integer getStartIndex() {
		return startIndex;
	}
	public void setStartIndex(Integer startIndex) {
		this.startIndex = startIndex;
	}
	
}

　　UserMapper.xml文件 

　　其中查询5是模糊加分页查询语句

<?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">
<!-- namespace和Mapper接口类名字一样 -->
<mapper namespace="com.gx.mapper.UserMapper">
	<!-- 查询1 -->
	<select id="selectForPage1" resultType="User">
		select * from user limit #{param1},#{param2}
	</select>
	<!-- 查询2-->
	<select id="selectForPage2" resultType="User">
		select * from user limit #{startIndex},#{pageSize}
	</select>
		<!-- 查询3-->
	<select id="selectAll" resultType="User">
		select * from user 
	</select>
	
		<!-- 查询总条数-->
	<select id="selectCount" resultType="java.lang.Integer">
		select count(*) from user 
	</select>
	<!-- 查询4-->
	<select id="selectForPage3" resultType="User">
		select * from user limit  #{startIndex},#{pageSize}
	</select>
	
	<!-- 查询5-->
	<select id="selectForPage4" resultType="User">
		select * from user 
		where name like "%"#{keywords}"%" or address like "%"#{keywords}"%"
		 limit  #{startIndex},#{pageSize}
	</select>
	<!-- 模糊查询查询总条数-->
	<select id="selectCount2" resultType="java.lang.Integer" parameterType="java.lang.String">
		select count(*) from user where name like "%"#{value}"%" or address like "%"#{value}"%"
	</select>
</mapper>

　　测试test

　　其中方法6是模糊加分页查询测试

public class myTest {

	SqlSession session = MyBatisUtils.openSession();
	UserMapper userMapper = session.getMapper(UserMapper.class);
	
	@Test
	public void selectForPage1() {
		int currentPage=1;
		int pageSize=5;
		List<User> selectForPage = userMapper.selectForPage1((currentPage-1)*pageSize, pageSize);
		for (User user : selectForPage) {
			System.out.println(user);
		}
		MyBatisUtils.closeSession(session);
	}
	
	@Test
	public void selectForPage2() {
		int currentPage=1;
		int pageSize=5;
		Map<String , Object> map=new HashMap<>();
		map.put("startIndex", (currentPage-1)*pageSize);
		map.put("pageSize", pageSize);
		List<User> selectForPage = userMapper.selectForPage2(map);
		for (User user : selectForPage) {
			System.out.println(user);
		}
		MyBatisUtils.closeSession(session);
	}

	@Test
	public void selectForPage3() {
		int currentPage=1;
		int pageSize=5;
		/**
		 * 参数1：开始条 偏移量,下标
		 * 参数2：参数总条数
		 */
		RowBounds rowBounds = new RowBounds((currentPage-1)*pageSize, pageSize);
		//使用mybatis里面提供的api去写的
		List<User> list = session.selectList("com.gx.mapper.UserMapper.selectAll", null, rowBounds);
		for (User user : list) {
			System.out.println(user);
		}
		MyBatisUtils.closeSession(session);
	}
	
	@Test
	public void selectForPage4() {
		Integer count = userMapper.selectCount();
		System.out.println(count);
		int currentPage=1;
		int pageSize=5;
		Map<String , Object> map=new HashMap<>();
		map.put("startIndex", (currentPage-1)*pageSize);
		map.put("pageSize", pageSize);
		List<User> list = userMapper.selectForPage2(map);
		for (User user : list) {
			System.out.println(user);
		}
		System.out.println("当前第"+currentPage+"页，共"+count+"条");
		MyBatisUtils.closeSession(session);
	}
	
	@Test
	public void selectForPage5() {
		PageBean bean = new PageBean();
		bean.setCurrentPage(1);
		bean.setPageSize(5);
		//查询总条数
		Integer count = userMapper.selectCount();
		//放到pageBean
		bean.setTotalCount(count);
		List<User> list = userMapper.selectForPage3(bean);
		for (User user : list) {
			System.out.println(user);
		}
		System.out.println("当前第"+bean.getCurrentPage()+"页，共"+count+"条");
		MyBatisUtils.closeSession(session);
	}
	
	@Test
	public void selectForPage6() {
		String keywords="云6";
		PageBean bean = new PageBean();
		bean.setCurrentPage(1);
		bean.setPageSize(5);
		//查询总条数
		Integer count = userMapper.selectCount2(keywords);
		//放到pageBean
		bean.setTotalCount(count);
		Map<String , Object> map = new HashMap<>();
		map.put("startIndex", bean.getStartIndex());
		map.put("pageSize", bean.getPageSize());
		map.put("keywords", keywords);
		List<User> list = userMapper.selectForPage4(map);
		for (User user : list) {
			System.out.println(user);
		}
		System.out.println("当前第"+bean.getCurrentPage()+"页，共"+count+"条");
		MyBatisUtils.closeSession(session);
	}
	
}