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urlspring.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;@SpringBootApplicationpublic 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
*/@Mapperpublic 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
*/@RestControllerpublic class UserController { @Autowired
UserMapper 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：
image
然后查看控制台如下：
image
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
作者：dalaoyang
链接：https://www.jianshu.com/p/48b190bf08fe
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