SpringBoot使用Mybatis-PageHelper

电玩女神 2022-05-22 11:06 204阅读 0赞

## 前言 ##

> 之前一篇文章介绍了[《SpringBoot+Mybatis+MySql学习》][SpringBoot_Mybatis_MySql]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/> 
        </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>
            
            <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 {
    
        @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][http_localhost_8888_getUserList_pageNum_1_pageSize_2]，结果如下：

![1][]

然后查看控制台如下：

![2][]

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_gitee.com_free_Mybatis_PageHelper]  
[https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/HowToUse.md][https_github.com_pagehelper_Mybatis-PageHelper_blob_master_wikis_zh_HowToUse.md]

源码下载 ：[大老杨码云][Link 1]

个人网站：[https://www.dalaoyang.cn][https_www.dalaoyang.cn]

[SpringBoot_Mybatis_MySql]: https://www.jianshu.com/p/8b545a537fd0
[http_localhost_8888_getUserList_pageNum_1_pageSize_2]: http://localhost:8888/getUserList?pageNum=1&pageSize=2
[1]: /images/20220522/5334c71fc048412a821d5deda6f68331.png
[2]: /images/20220522/f2b018ec716247d391001ff171c859ce.png
[https_gitee.com_free_Mybatis_PageHelper]: https://gitee.com/free/Mybatis_PageHelper
[https_github.com_pagehelper_Mybatis-PageHelper_blob_master_wikis_zh_HowToUse.md]: https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/HowToUse.md
[Link 1]: https://gitee.com/dalaoyang/springboot_learn
[https_www.dalaoyang.cn]: https://www.dalaoyang.cn