How to use the paging plugin
-
Modify pom file, add paging jar package dependency
-
Modify the mybatis.xml file
-
UserDao interface, UserMapper.xml adds corresponding methods and implements sql
-
Add a paging query method corresponding to the UserService interface
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Test paging effect
Case practice
1. Modify pom file, add paging jar package dependency
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>4.1.0</version>
</dependency>
2. Modify the mybatis.xml file
<plugins>
<!-- com.github.pagehelper 为 PageHelper 类所在包名 -->
<plugin interceptor="com.github.pagehelper.PageHelper">
<property name="dialect" value="mysql" />
<!-- 该参数默认为 false -->
<!-- 设置为 true 时，会将 RowBounds 第一个参数 offset 当成 pageNum 页码使用
-->
<!-- 和 startPage 中的 pageNum 效果一样 -->
<property name="offsetAsPageNum" value="true" />
<!-- 该参数默认为 false -->
<!-- 设置为 true 时，使用 RowBounds 分页会进行 count 查询 -->
<property name="rowBoundsWithCount" value="true" />
<!-- 设置为 true 时，如果 pageSize=0 或者 RowBounds.limit = 0 就会查询出全
部的结果 -->
<!-- （相当于没有执行分页查询，但是返回结果仍然是 Page 类型） -->
<property name="pageSizeZero" value="true" />
<!-- 3.3.0 版本可用 - 分页参数合理化，默认 false 禁用 -->
<!-- 启用合理化时，如果 pageNum<1 会查询第一页，如果 pageNum>pages 会查询
最后一页 -->
<!-- 禁用合理化时，如果 pageNum<1 或 pageNum>pages 会返回空数据 -->
<property name="reasonable" value="true" />
<!-- 3.5.0 版本可用 - 为了支持 startPage(Object params)方法 -->
<!-- 增加了一个`params`参数来配置参数映射，用于从 Map 或 ServletRequest
中取值 -->
<!-- 可以配置 pageNum,pageSize,count,pageSizeZero,reasonable,不配置映射
的用默认值 -->
<property name="params"
value="pageNum=start;pageSize=limit;pageSizeZero=zero;reasonable=heli;count=cou
ntsql" />
</plugin>
</plugins>
3. UserDao interface, UserMapper.xml adds corresponding methods and implements sql
UserDao interface:
public interface UserDao {
public User queryUserById(int id);
public List<User> queryUsers();
}
UserMapper.xml
<?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">
<mapper namespace="com.mage.dao.UserDao">
<select id="queryUserById" parameterType="int" resultType="user">
select id,userName,userPwd from user where id=#{id}
</select>
<select id="queryUsers" resultType="user">
select id,userName,userPwd from user
</select>
</mapper>
4. Add a paging query method corresponding to the UserService interface
public interface UserService {
public User queryUserById();
/**
* 分页方法定义
* @param pageNum 当前页号
* @param pageSize 设置每页显示数量
* @return
*/
public PageInfo<User> queryUsers(int pageNum,int pageSize);
}
UserServiceImpl implementation method:
@Service
public class UserServiceImpl implements UserService{
@Resource
private UserDao userDao;
public User queryUserById(){
return userDao.queryUserById(7);
}
@Override
public PageInfo<User> queryUsers(int pageNum, int pageSize) {
/**
* PageHelper 类设置分页页号与每页大小
*/
PageHelper.startPage(pageNum, pageSize);
List<User> list=userDao.queryUsers();
PageInfo<User> pageInfo=new PageInfo<User>(list);
return pageInfo;
}
}
5. Test the paging effect
Database raw records
test
The first time PageNum =1 pageSize=1
@Test
public void testQueryUsers() {
PageInfo<User> pageInfo= userService.queryUsers(1, 1);
for(User user:pageInfo.getList()){
System.out.println("user:"+user);
}
}
result:
Second time pageNum=2 pageSize=1
@Test
public void testQueryUsers() {
PageInfo<User> pageInfo= userService.queryUsers(2, 1);
for(User user:pageInfo.getList()){
System.out.println("user:"+user);
}
}
result
Remarks: If the paging plug-in is the total number of pages of the incoming page number operation record, what we get is the record of the last page.
The third test PageNum=3 pageSize=1
@Test
public void testQueryUsers() {
PageInfo<User> pageInfo= userService.queryUsers(3, 1);
for(User user:pageInfo.getList()){
System.out.println("user:"+user);
}
}
result:
Expand
Paging plugin compressed version
Unzip it and use it, configure config.xml as before, and then run run.bat
