mybatis-分页显示数据
转载原文 http://www.cnblogs.com/yangw/p/3315398.html
分页用到的两个实体类
package com.yangwei.shop.entity;
/**
* 注意 get，set，remove 方法与一般的实体类的不同
*/
public classSystemContext {
private static ThreadLocal<Integer> pageSize = new ThreadLocal<Integer>();
private static ThreadLocal<Integer> pageIndex = new ThreadLocal<Integer>();
private static ThreadLocal<Integer> pageOffset = new ThreadLocal<Integer>();
/**
* 升序还是降序
*/
private static ThreadLocal<String> order = new ThreadLocal<String>();
/**
* 根据那个字段排序
*/
private static ThreadLocal<String> sort = new ThreadLocal<String>();
public static String getOrder() {
return order.get();
}
public static void setOrder(String _order) {
order.set(_order);
}
public static void removeOrder() {
order.remove();
}
public static String getSort() {
return sort.get();
}
public static void setSort(String _sort) {
sort.set(_sort);
}
public static void removeSort() {
sort.remove();
}
public static int getPageOffset() {
return pageOffset.get();
}
public static void setPageOffset(int _pageOffset) {
pageOffset.set(_pageOffset);
}
public static void removePageOffset() {
pageOffset.remove();
}
public static void setPageSize(int _pageSize) {
pageSize.set(_pageSize);
}
public static int getPageSize() {
return pageSize.get();
}
public static void removePageSize() {
pageSize.remove();
}
public static void setPageIndex(int _pageIndex) {
pageIndex.set(_pageIndex);
}
public static int getPageIndex() {
return pageIndex.get();
}
public static void removePageIndex() {
pageIndex.remove();
}
}
package com.yangwei.shop.entity;
import java.util.List;
public class Pager<E> {
/**
* 第几页
*/
private int pageIndex;
/**
* 每页显示多少条
*/
private int pageSize;
/**
* 分页的开始值
*/
private int pageOffset;
/**
* 总共多少条记录
*/
private int totalRecord;
/**
* 总共多少页
*/
private int totalPage;
/**
* 放置具体数据的列表
*/
private List<E> datas;
public int getPageIndex() {
return pageIndex;
}
public void setPageIndex(int pageIndex) {
this.pageIndex = pageIndex;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getTotalRecord() {
return totalRecord;
}
public void setTotalRecord(int totalRecord) {
this.totalRecord = totalRecord;
}
public int getTotalPage() {
return totalPage;
}
public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}
public List<E> getDatas() {
return datas;
}
public void setDatas(List<E> datas) {
this.datas = datas;
}
public int getPageOffset() {
return pageOffset;
}
public void setPageOffset(int pageOffset) {
this.pageOffset = pageOffset;
}
}
接下来就是真正的分页了， mybatis中mapper.xml配置文件中的两条查询语句如下
<!--多个参数的形式，需要使用map来存储-->
<select id="find" parameterType="map" resultType="User">
<!--只要是#{}这种形式的，都会以？形式替代，对应字符串形式，都会加上引号-->
<!--只要是${}这种形式的，不会用？形式替代，传过来什么，就什么替代-->
select * from t_user where
( username like #{name} or nickname like #{name} )
order by ${sort} ${order}
limit #{pageOffset},#{pageSize}
<!--
对应的sql便是
select * from t_user where (username like ? or nickname like ?)
order by id desc limit ? ?
-->
</select>
<select id="count" parameterType="map" resultType="int">
select count(*) from t_user where
( username like #{name} or nickname like #{name} )
</select>
java代码实现分页
/**
* 分页显示
*/
public static Pager<User> testFind(String name){
int pageOffset=SystemContext.getPageOffset();
int pageSize=SystemContext.getPageSize();
String order=SystemContext.getOrder();
String sort=SystemContext.getSort();
Pager<User> pages=new Pager<User>();
SqlSession session=null;
try {
session = MyBatisUtil.createSession();
Map<String,Object> map=new HashMap<String,Object>();
//使用like模糊查询的时候，注意百分号加在这里
map.put("name", "%"+name+"%");
map.put("pageOffset", pageOffset);
map.put("pageSize", pageSize);
map.put("order", order);
map.put("sort", sort);
List<User> users=session.selectList(User.class.getName()+".find", map);
pages.setDatas(users);
pages.setPageOffset(pageOffset);
pages.setPageSize(pageSize);
int count=session.selectOne(User.class.getName()+".count", map);
pages.setTotalRecord(count);
//所有的数据都存到了Pager对象中
} finally{
MyBatisUtil.closeSession(session);
}
return pages;
}
测试上面分页代码
SystemContext.setPageOffset(0);
SystemContext.setPageSize(15);
SystemContext.setOrder("desc");
SystemContext.setSort("id");
Pager<User> ps = testFind("zhang");
System.out.println(ps.getTotalRecord());
for(User u: ps.getDatas()){
System.out.println(u.getNickname());
}