前言

之前一篇文章介绍了《SpringBoot+Mybatis+MySql学习》的整合，这一片扩展一下Mybatis的分页插件-Mybatis-PageHelper。

新建项目

首先，pom文件中加入pagehelper依赖，完整pom代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.dalaoyang</groupId><artifactId>springboot_mybatis_pagehelper</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>springboot_mybatis_pagehelper</name><description>springboot_mybatis_pagehelper</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.9.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>1.3.2</version></dependency><!--pagehelper --><dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper-spring-boot-starter</artifactId><version>1.2.5</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

配置文件增加PageHelper的配置，由于demo很简单，只用到了分页，所以没有增加其他配置，只设置了分页方言，完整代码如下：

##端口号
server.port=8888##日志级别
logging.level.com.dalaoyang.dao.UserMapper=debug##数据库url
spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false
##数据库用户名
spring.datasource.username=root
##数据库密码
spring.datasource.password=root
##数据库驱动
spring.datasource.driver-class-name=com.mysql.jdbc.Driver#pagehelper分页插件配置
pagehelper.helperDialect=mysql

实体类User代码如下：

package com.dalaoyang.entity;import org.apache.ibatis.type.Alias;/*** @author dalaoyang* @Description* @project springboot_learn* @package com.dalaoyang.entity* @email 397600342@qq.com* @date 2018/6/22*/
@Alias("user")
public class User {private int id;private String user_name;private String user_password;public User(String user_name, String user_password) {this.user_name = user_name;this.user_password = user_password;}public User(int id, String user_name, String user_password) {this.id = id;this.user_name = user_name;this.user_password = user_password;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getUser_name() {return user_name;}public void setUser_name(String user_name) {this.user_name = user_name;}public String getUser_password() {return user_password;}public void setUser_password(String user_password) {this.user_password = user_password;}
}

启动类代码如下：

package com.dalaoyang;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class SpringbootMybatisPagehelperApplication {public static void main(String[] args) {SpringApplication.run(SpringbootMybatisPagehelperApplication.class, args);}
}

新建一个UserMapper，之前介绍的整合mybatis是使用的mapper方式，本文选择使用注解方式，代码如下：

package com.dalaoyang.dao;import com.dalaoyang.entity.User;
import com.github.pagehelper.Page;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;/*** @author dalaoyang* @Description* @project springboot_learn* @package com.dalaoyang.dao* @email 397600342@qq.com* @date 2018/6/22*/
@Mapper
public interface UserMapper {@Select("SELECT * FROM USER")Page<User> getUserList();
}

还是一如既往的使用controller作为测试，代码如下：

package com.dalaoyang.controller;import com.dalaoyang.dao.UserMapper;
import com.dalaoyang.entity.User;
import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/*** @author dalaoyang* @Description* @project springboot_learn* @package com.dalaoyang.controller* @email 397600342@qq.com* @date 2018/6/22*/
@RestController
public class UserController {@AutowiredUserMapper userMapper;//http://localhost:8888/getUserList?pageNum=1&pageSize=2@RequestMapping("/getUserList")public Page<User> getUserList(Integer pageNum, Integer pageSize){PageHelper.startPage(pageNum, pageSize);Page<User>  userList= userMapper.getUserList();return userList;}
}

到这里项目就完全创建完成了。

测试

浏览器访问http://localhost:8888/getUserList?pageNum=1&pageSize=2，结果如下：

然后查看控制台如下：

可以看到sql已经进行分页了。

然后回头看controller的方法，返回的Page对象中包含了很多关于分页的参数等数据，下面是Page的代码，具体使用可以查看一下：

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//package com.github.pagehelper;import java.io.Closeable;
import java.util.ArrayList;
import java.util.List;public class Page<E> extends ArrayList<E> implements Closeable {private static final long serialVersionUID = 1L;private int pageNum;private int pageSize;private int startRow;private int endRow;private long total;private int pages;private boolean count;private Boolean reasonable;private Boolean pageSizeZero;private String countColumn;private String orderBy;private boolean orderByOnly;public Page() {this.count = true;}public Page(int pageNum, int pageSize) {this(pageNum, pageSize, true, (Boolean)null);}public Page(int pageNum, int pageSize, boolean count) {this(pageNum, pageSize, count, (Boolean)null);}private Page(int pageNum, int pageSize, boolean count, Boolean reasonable) {super(0);this.count = true;if (pageNum == 1 && pageSize == 2147483647) {this.pageSizeZero = true;pageSize = 0;}this.pageNum = pageNum;this.pageSize = pageSize;this.count = count;this.calculateStartAndEndRow();this.setReasonable(reasonable);}public Page(int[] rowBounds, boolean count) {super(0);this.count = true;if (rowBounds[0] == 0 && rowBounds[1] == 2147483647) {this.pageSizeZero = true;this.pageSize = 0;} else {this.pageSize = rowBounds[1];this.pageNum = rowBounds[1] != 0 ? (int)Math.ceil(((double)rowBounds[0] + (double)rowBounds[1]) / (double)rowBounds[1]) : 0;}this.startRow = rowBounds[0];this.count = count;this.endRow = this.startRow + rowBounds[1];}public List<E> getResult() {return this;}public int getPages() {return this.pages;}public Page<E> setPages(int pages) {this.pages = pages;return this;}public int getEndRow() {return this.endRow;}public Page<E> setEndRow(int endRow) {this.endRow = endRow;return this;}public int getPageNum() {return this.pageNum;}public Page<E> setPageNum(int pageNum) {this.pageNum = this.reasonable != null && this.reasonable && pageNum <= 0 ? 1 : pageNum;return this;}public int getPageSize() {return this.pageSize;}public Page<E> setPageSize(int pageSize) {this.pageSize = pageSize;return this;}public int getStartRow() {return this.startRow;}public Page<E> setStartRow(int startRow) {this.startRow = startRow;return this;}public long getTotal() {return this.total;}public void setTotal(long total) {this.total = total;if (total == -1L) {this.pages = 1;} else {if (this.pageSize > 0) {this.pages = (int)(total / (long)this.pageSize + (long)(total % (long)this.pageSize == 0L ? 0 : 1));} else {this.pages = 0;}if (this.reasonable != null && this.reasonable && this.pageNum > this.pages) {this.pageNum = this.pages;this.calculateStartAndEndRow();}}}public Boolean getReasonable() {return this.reasonable;}public Page<E> setReasonable(Boolean reasonable) {if (reasonable == null) {return this;} else {this.reasonable = reasonable;if (this.reasonable && this.pageNum <= 0) {this.pageNum = 1;this.calculateStartAndEndRow();}return this;}}public Boolean getPageSizeZero() {return this.pageSizeZero;}public Page<E> setPageSizeZero(Boolean pageSizeZero) {if (pageSizeZero != null) {this.pageSizeZero = pageSizeZero;}return this;}public String getOrderBy() {return this.orderBy;}public <E> Page<E> setOrderBy(String orderBy) {this.orderBy = orderBy;return this;}public boolean isOrderByOnly() {return this.orderByOnly;}public void setOrderByOnly(boolean orderByOnly) {this.orderByOnly = orderByOnly;}private void calculateStartAndEndRow() {this.startRow = this.pageNum > 0 ? (this.pageNum - 1) * this.pageSize : 0;this.endRow = this.startRow + this.pageSize * (this.pageNum > 0 ? 1 : 0);}public boolean isCount() {return this.count;}public Page<E> setCount(boolean count) {this.count = count;return this;}public Page<E> pageNum(int pageNum) {this.pageNum = this.reasonable != null && this.reasonable && pageNum <= 0 ? 1 : pageNum;return this;}public Page<E> pageSize(int pageSize) {this.pageSize = pageSize;this.calculateStartAndEndRow();return this;}public Page<E> count(Boolean count) {this.count = count;return this;}public Page<E> reasonable(Boolean reasonable) {this.setReasonable(reasonable);return this;}public Page<E> pageSizeZero(Boolean pageSizeZero) {this.setPageSizeZero(pageSizeZero);return this;}public Page<E> countColumn(String columnName) {this.countColumn = columnName;return this;}public PageInfo<E> toPageInfo() {PageInfo<E> pageInfo = new PageInfo(this);return pageInfo;}public PageSerializable<E> toPageSerializable() {PageSerializable<E> serializable = new PageSerializable(this);return serializable;}public <E> Page<E> doSelectPage(ISelect select) {select.doSelect();return this;}public <E> PageInfo<E> doSelectPageInfo(ISelect select) {select.doSelect();return this.toPageInfo();}public <E> PageSerializable<E> doSelectPageSerializable(ISelect select) {select.doSelect();return this.toPageSerializable();}public long doCount(ISelect select) {this.pageSizeZero = true;this.pageSize = 0;select.doSelect();return this.total;}public String getCountColumn() {return this.countColumn;}public void setCountColumn(String countColumn) {this.countColumn = countColumn;}public String toString() {return "Page{count=" + this.count + ", pageNum=" + this.pageNum + ", pageSize=" + this.pageSize + ", startRow=" + this.startRow + ", endRow=" + this.endRow + ", total=" + this.total + ", pages=" + this.pages + ", reasonable=" + this.reasonable + ", pageSizeZero=" + this.pageSizeZero + '}' + super.toString();}public void close() {PageHelper.clearPage();}
}

其他

关于更多Mybatis-PageHelper配置及介绍可以查看下面网站：
https://gitee.com/free/Mybatis_PageHelper
https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/HowToUse.md

源码下载 ：大老杨码云

个人网站：https://www.dalaoyang.cn

关注作者公众号