SpringBoot学习－（七）SpringBoot分页插件PageHelper

访问数据库采用mybatis框架

1.添加pom文件依赖

<!-- spring mvc支持 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- springboot整合mybatis -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.1</version>
</dependency>

<!-- springboot分页插件 -->
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <!-- 特别注意版本问题, 看到评论以后得以纠正 -->
    <version>1.2.3</version>
</dependency>

<!-- 阿里巴巴druid数据库连接池 -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.3</version>
</dependency>

<!-- mysql驱动 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

2.配置application.yml

# 与mybatis整合
mybatis:
  config-location: classpath:mybatis.xml
  mapper-locations:
  - classpath:mapper/*.xml

# 分页配置
pagehelper:
  helper-dialect: mysql
  reasonable: true
  support-methods-arguments: true
  params:

3.service层中使用插件

package com.ahut.serviceImpl;

import java.util.List;

import javax.servlet.ServletContext;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.context.ContextLoader;

import com.ahut.entity.GoodsType;
import com.ahut.mapper.GoodsTypeMapper;
import com.ahut.service.GoodsTypeService;
import com.github.pagehelper.PageHelper;

/**
 * 
 * @ClassName: GoodsTypeServiceImpl
 * @Description: 商品类型业务逻辑处理
 * @author cheng
 * @date
@Service
@Transactional(rollbackFor = { RuntimeException.class, Exception.class })
public class GoodsTypeServiceImpl implements GoodsTypeService
    // 数据访问
    @Autowired
    private GoodsTypeMapper typeDao;

    /**
     * 
     * @Title: getList
     * @Description: 从数据库中获取所有商品类型列表
     * @param pageNum 当前页
     * @param pageSize 当前页面展示数目
     * @return
     * @throws
    public List<GoodsType> getList(int pageNum, int pageSize) throws Exception {
        //使用分页插件,核心代码就这一行
        PageHelper.startPage(pageNum, pageSize);
        // 获取
        List<GoodsType> typeList = typeDao.getList();
        return

4.controller层代码

package com.ahut.action;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.ahut.entity.GoodsType;
import com.ahut.service.GoodsTypeService;

/**
 * 
 * @ClassName: GoodsTypeAction
 * @Description: 商品类型控制层
 * @author cheng
 * @date
@RestController // 等价于@Controller+@ResponseBody
public class GoodsTypeAction
    // 业务逻辑
    @Autowired
    private GoodsTypeService typeService;

    /**
     * 
     * @Title: getGoodsTypeList
     * @Description: 获取商品类型列表
     * @return
     * @throws
    @RequestMapping(value = "/getGoodsTypeList")
    public List<GoodsType> getGoodsTypeList(int pageNum, int pageSize) throws Exception {
        // 调用业务逻辑,返回数据
        return

5.测试

已知我数据库中有九条数据：

正常情况：

1.显示第一页或者第二页数据
请求url：

http://localhost:8080/getGoodsTypeList?pageNum=1&pageSize=4

返回数据：

[
    {
        "typeId": "708cc61c6a9811e796dee09467355fab",
        "typeName": "全部",
        "createTime": 1500258859000,
        "updateTime": 1500621762000},
    {
        "typeId": "98f8a04e6a9811e796dee09467355fab",
        "typeName": "考研资料",
        "createTime": 1500258927000,
        "updateTime": null},
    {
        "typeId": "b720c87f6a9811e796dee09467355fab",
        "typeName": "交通工具",
        "createTime": 1500258978000,
        "updateTime": null},
    {
        "typeId": "cbe3c2326a9811e796dee09467355fab",
        "typeName": "生活用品",
        "createTime": 1500259013000,
        "updateTime": 1500626046000}
]

2.显示最后一页
请求url：

http://localhost:8080/getGoodsTypeList?pageNum=3&pageSize=4

返回数据：

[
    {
        "typeId": "d992195f6df111e7bab4e09467355fab",
        "typeName": "测试2改变了",
        "createTime": 1501145516000,
        "updateTime": 1500716178000}
]

不正常情况：
1.显示的页数小于第一页（显示第一页数据）

pageNumber <= 0

请求url：

http://localhost:8080/getGoodsTypeList?pageNum=0&pageSize=4

返回数据：

[
    {
        "typeId": "708cc61c6a9811e796dee09467355fab",
        "typeName": "全部",
        "createTime": 1500258859000,
        "updateTime": 1500621762000},
    {
        "typeId": "98f8a04e6a9811e796dee09467355fab",
        "typeName": "考研资料",
        "createTime": 1500258927000,
        "updateTime": null},
    {
        "typeId": "b720c87f6a9811e796dee09467355fab",
        "typeName": "交通工具",
        "createTime": 1500258978000,
        "updateTime": null},
    {
        "typeId": "cbe3c2326a9811e796dee09467355fab",
        "typeName": "生活用品",
        "createTime": 1500259013000,
        "updateTime": 1500626046000}
]

结论：当请求页数小于第一页时，显示第一页数据

2.显示的页数大于最后一页（显示最后一页数据）
pageNum > 最后一页

请求url：

http://localhost:8080/getGoodsTypeList?pageNum=4&pageSize=4

返回数据：

[
    {
        "typeId": "d992195f6df111e7bab4e09467355fab",
        "typeName": "测试2改变了",
        "createTime": 1501145516000,
        "updateTime": 1500716178000}
]

结论：当请求页面大于最后一页时，显示最后一页数据