SpringBoot使用Mybatis-PageHelper

之前一篇文章介绍了介绍了 《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 {

    @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：

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();
    }
}