Mybatis分页插件PageHelper配置及使用方法详解

环境

框架：spring+springmvc+mybatis

pom.xml

<!-- 引入mybatis的 pagehelper 分页插件 -->
    <dependency>
      <groupId>com.github.pagehelper</groupId>
      <artifactId>pagehelper</artifactId>
      <version>5.1.2</version>
    </dependency>

配置全局配置文件

在mybatis的全局配置文件中配置PageHelper分页插件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
  <!-- 引入 pageHelper插件 -->
  <!--注意这里要写成PageInterceptor, 5.0之前的版本都是写PageHelper, 5.0之后要换成PageInterceptor-->
  <plugins>
    <plugin interceptor="com.github.pagehelper.PageInterceptor">
      <!--reasonable：分页合理化参数，默认值为false,直接根据参数进行查询。
       当该参数设置为 true 时，pageNum<=0 时会查询第一页， pageNum>pages（超过总数时），会查询最后一页。-->
      <!--<property name="reasonable" value="true"/>-->
    </plugin>
  </plugins>
</configuration>

使用

例如：实现对用户的多条件查询

package com.szfore.model;
import java.util.Date;
import java.util.List;
public class User {
	private Integer id;
	private String uname;
	private String pwd;
	private String name;
	private Integer sex;
	private String phone;
	private String company;
	private String jobtitle;
	private String birth;
	private Date createdate;
	private Date lastlogintime;
	private List<Role> roleList;
	public List<Role> getRoleList() {
		return roleList;
	}
	public void setRoleList(List<Role> roleList) {
		this.roleList = roleList;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getUname() {
		return uname;
	}
	public void setUname(String uname) {
		this.uname = uname == null ? null : uname.trim();
	}
	public String getPwd() {
		return pwd;
	}
	public void setPwd(String pwd) {
		this.pwd = pwd == null ? null : pwd.trim();
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name == null ? null : name.trim();
	}
	public Integer getSex() {
		return sex;
	}
	public void setSex(Integer sex) {
		this.sex = sex;
	}
	public String getPhone() {
		return phone;
	}
	public void setPhone(String phone) {
		this.phone = phone == null ? null : phone.trim();
	}
	public String getCompany() {
		return company;
	}
	public void setCompany(String company) {
		this.company = company == null ? null : company.trim();
	}
	public String getJobtitle() {
		return jobtitle;
	}
	public void setJobtitle(String jobtitle) {
		this.jobtitle = jobtitle == null ? null : jobtitle.trim();
	}
	public String getBirth() {
		return birth;
	}
	public void setBirth(String birth) {
		this.birth = birth == null ? null : birth.trim();
	}
	public Date getCreatedate() {
		return createdate;
	}
	public void setCreatedate(Date createdate) {
		this.createdate = createdate;
	}
	public Date getLastlogintime() {
		return lastlogintime;
	}
	public void setLastlogintime(Date lastlogintime) {
		this.lastlogintime = lastlogintime;
	}
}

UserMapper

注意：mapper中就按不分页的那种写法就好

package com.szfore.dao;

import com.szfore.model.User;
import com.szfore.model.UserExample;
import java.util.List;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper {
  /**
   * 多条件分页查询
   * @param userParam
   * @return
   */
  public List<User> queryByPage(User userParam);
}

UserMapper.xml

注意：sql中就不要写limit了，pageHelp会自己处理，sql就按不分页的那种写法就好

<!--多条件分页查询用户-->
 <select id="queryByPage" resultType="com.szfore.model.User">
  SELECT
     *
  FROM
    `user`
  <WHERE>
     <if test="id != null and id != ''">
     AND id = #{id}
    </if>
    <if test="uname != null and uname != ''">
     AND uname = #{uname}
    </if>
    <if test="name != null and name != ''">
     AND name like '%${name}%'
    </if>
    <if test="phone != null and phone != ''">
     AND phone like '%${phone}%'
    </if>
    <if test="company != null and company != ''">
     AND company like '%${company}%'
    </if>
    <if test="jobtitle != null and jobtitle != ''">
     AND jobTitle like '%${jobtitle}%'
    </if>
    <if test="birth != null and birth != ''">
     AND birth like '%${birth}%'
    </if>　　</WHERE>
 </select>

UserServiceImpl

package com.szfore.service.impl;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.szfore.dao.MenuMapper;
import com.szfore.dao.UserMapper;
import com.szfore.dao.UserRoleMapper;
import com.szfore.model.*;
import com.szfore.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.servlet.http.HttpSession;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Service
public class UserServiceImpl implements IUserService{

  @Autowired
  private UserMapper userMapper;
  @Autowired
  private MenuMapper menuMapper;
  @Autowired
  private UserRoleMapper userRoleMapper;

  /**
   * 多条件分页查询用户
   * @param userParam
   * @param pageNum
   * @param pageSize
   * @return
   */
  public Json queryByPage(User userParam,Integer pageNum,Integer pageSize) {
    //利用PageHelper分页查询 注意：这个一定要放查询语句的前一行,否则无法进行分页,因为它对紧随其后第一个sql语句有效
    PageHelper.startPage(pageNum, pageSize);
    List<User> userList = userMapper.queryByPage(userParam);
    PageInfo<User> pageInfo = new PageInfo<User>(userList);
    Json json = new Json();
    json.setMsg("成功！");
    json.setObj(pageInfo);
    json.setSuccess(true);
    return json;
  }
}

说明：PageInfo是PageHelper自带的分页对象类，详情如下：

当前页
private int pageNum;
每页的数量
private int pageSize;
当前页的数量
private int size;
//由于startRow和endRow不常用，这里说个具体的用法
//可以在页面中"显示startRow到endRow 共size条数据"

当前页面第一个元素在数据库中的行号
private int startRow;
当前页面最后一个元素在数据库中的行号
private int endRow;
总记录数
private long total;
总页数
private int pages;
结果集
private List<T> list;

第一页
private int firstPage;
前一页
private int prePage;

是否为第一页
private boolean isFirstPage = false;
是否为最后一页
private boolean isLastPage = false;
是否有前一页
private boolean hasPreviousPage = false;
是否有下一页
private boolean hasNextPage = false;
导航页码数
private int navigatePages;
所有导航页号
private int[] navigatepageNums;

通过PageInfo获取其他信息

PageHelper.startPage(req.getCurrentPage(), req.getPageSize(), true);
List<SecurityRiskLibary> list=securityRiskLibaryDAO.queryList(srl);
PageInfo page=new PageInfo(list);
page.getTotal();
page.xxxx

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