52: Chapter 5: developing admin management services: 5: developing [paging query admin account list, interface]; (swagger's @apiparam(), annotate the method parameters; PageHelper paging plug-in; Inte

explain ：

（1） The content of this blog ： Development 【 Paging query admin Account list , Interface 】;

Catalog

One ： Rationality of this blog ; 

Two ： Formal development ;

1. stay 【api】 Interface Engineering AdminMngControllerApi Interface , Definition 【 Paging query admin Account list , Interface 】;

2. stay 【admin】 Managed services AdminMngController Class , To achieve 【 Paging query admin Account list , Interface 】;

3. stay 【admin】 Managed services AdminUserService Interface , Define an implementation 【 Paging query admin Account list , Interface 】;

4. stay 【admin】 Managed services AdminUserServiceImpl In the implementation class , To achieve 【 Paging query admin Account list , Interface 】;

3、 ... and ： effect ;

Four ：【 newly added admin account number , Interface 】、【 Paging query admin Account list , Interface 】, It also requires users to log in , Can be operated ;

---

One ： Rationality of this blog ; 

then , This blog , Is to develop 【 Inquire about admin Account list , Interface 】

---

Two ： Formal development ;

1. stay 【api】 Interface Engineering AdminMngControllerApi Interface , Definition 【 Paging query admin Account list , Interface 】;

    /**
     * 【 Paging query admin Account list , Interface 】;
     *
     * @param page： Which page do you want to query ;
     * @param pageSize： Number of entries per page ;
     * @return
     */
    @ApiOperation(value = " Inquire about admin list ", notes = " Inquire about admin list ", httpMethod = "POST")
    @PostMapping("/getAdminList") // Set the routing , This needs to be agreed between the front and back ;
    public GraceJSONResult getAdminList(@RequestParam @ApiParam(name = "page", value = " Which page do you want to query ", required = false)
                                                Integer page,
                                        @RequestParam @ApiParam(name = "pageSize", value = " Number of entries per page ", required = false)
                                                Integer pageSize);

explain ：

（1） This interface's url、 Request mode 、 Parameters , It's not nonsense , The front and rear ends should be consistent ;

（2） here , Using the Swagger Of @ApiParam(), To set the parameters in the method , Annotate ;

2. stay 【admin】 Managed services AdminMngController Class , To achieve 【 Paging query admin Account list , Interface 】;

    /**
     * 【 Paging query admin Account list , Interface 】;
     *
     * @param page： Which page do you want to query ;
     * @param pageSize： Number of entries per page ;
     * @return
     */
    @Override
    public GraceJSONResult getAdminList(Integer page, Integer pageSize) {

        // If the front end requests this interface , No transmission page Parameters ; Then we will give it a default value 1;
        if (page == null) {
            page = COMMON_START_PAGE;
        }
        // If the front end requests this interface , No transmission pageSize Parameters ; Then we will give it a default value 10;
        if (pageSize == null) {
            pageSize = COMMON_PAGE_SIZE;
        }

        // call service Layer logic , To query paging data ;
        PagedGridResult result = adminUserService.queryAdminList(page, pageSize);
        return GraceJSONResult.ok(result);
    }

explain ：

（1） Here we judge page and pageSize Two parameters ; If the front end does not transmit , Take the default value ;

（2）PageHelper Paging plug-ins have been heavily used by themselves before ; of PageHelper Contents of paging plug-in , If necessary , You can refer to 【 additional ：PageHelper Paging plug-in's ：Page and PageInfo The difference between ;】、【Spring Boot E-commerce projects 40： Commodity module 6 ： Backstage 【 List of goods 】 Interface ;（ Thought of a question ：【PageHelper When paging query , In any case, you must first find out all the data 】： Isn't that a waste ？PS： Wrong understanding ）】 And so on ;

（3） then , call Service Logic written by layer , Paging query data , And assemble it into paging objects that meet the requirements of the front end ;

          ●  here , We are 【common】 In general engineering , Created PagedGridResult class ; We are based on this class , To assemble paging objects ;

package com.imooc.utils;

import java.util.List;

/**
 * 
 * @Title: PagedGridResult.java
 * @Package com.imooc.utils
 * @Description:  Used to return paging Grid Data format 
 * Copyright: Copyright (c) 2019
 */
public class PagedGridResult {
	
	private int page;			//  What page is it now 
	private long total;			//  Total number of pages 
	private long records;		//  Total number of records 
	private List<?> rows;		//  What is displayed on each line , That is, the data in the current page ;

	public int getPage() {
		return page;
	}
	public void setPage(int page) {
		this.page = page;
	}

	public long getTotal() {
		return total;
	}

	public void setTotal(long total) {
		this.total = total;
	}

	public void setTotal(int total) {
		this.total = total;
	}
	public long getRecords() {
		return records;
	}
	public void setRecords(long records) {
		this.records = records;
	}
	public List<?> getRows() {
		return rows;
	}
	public void setRows(List<?> rows) {
		this.rows = rows;
	}
}

          ●  The reason why we , No direct use PageHelper Provided Page Object or PageInfo object , As a " The back end returns to the paging object of the front end ", It's about creating PagedGridResult, As a " The back end returns to the paging object of the front end "; The main reason is , The back end returns to the paging object of the front end , It needs to meet the requirements of the front end ;

          ●  Be reasonable , I didn't take a close look at the content of the front end here ; The agreement between the front end and the back end , I didn't make it myself ; There is no clear interface document ; therefore , There is no need to spend energy here for the time being , Thoroughly understand everything ;

          ●  Just need to know 【 We created PagedGridResult object ; then , When we page , according to PagedGridResult Assemble paging objects in the specified format , And then it goes back to the front end , It is in line with the agreement between the front and back , Namely OK Of ;】,（ For now ） That's enough ;

3. stay 【admin】 Managed services AdminUserService Interface , Define an implementation 【 Paging query admin Account list , Interface 】;

    /**
     *  Paging query ,admin_user Admin list 
     * @param page： Which page do you want to query ;
     * @param pageSize
     * @return
     */
    public PagedGridResult queryAdminList(Integer page, Integer pageSize);

explain ：

（1）service This method of layer , The return value type is PagedGridResult Paging object ;

4. stay 【admin】 Managed services AdminUserServiceImpl In the implementation class , To achieve 【 Paging query admin Account list , Interface 】;

    /**
     *  Paging query ,admin_user Admin list 
     * @param page： Which page do you want to query ;
     * @param pageSize
     * @return
     */
    @Override
    public PagedGridResult queryAdminList(Integer page, Integer pageSize) {

        // 1. Open paging 
        PageHelper.startPage(page, pageSize);

        // 2. utilize tkmybatis Of Example, User defined query criteria ; Use the paging information set above , Go to query admin_user surface ;
        // 2.1 First create a query instance , The instance , Is aimed at AdminUser Inquiring ;
        Example adminExample = new Example(AdminUser.class);
        //Example You can set no query conditions ; meanwhile , You can also add some parameters ; such as , Here we arrange them in reverse order of creation time ;
        adminExample.orderBy("createdTime").desc();
        //  Here we are ： Without any conditions , Go to query admin_user surface ; let me put it another way ,( If we're not here 1 If paging information is set in )
        //  We just want to inquire admin_user All the contents of the table ;
        List<AdminUser> adminUserList = adminUserMapper.selectByExample(adminExample);

        // 3. then , According to the requirements of the front end , Assemble a paging object that meets the requirements ; We , Here, according to the requirements of the front end , Created a 
        //  individual PagedGridResult object ; We will use this object , To assemble the paging object returned to the front end ;
        return setterPagedGrid(adminUserList, page);

    }

    /**
     *  Tool method ： According to the results of paging query database , Assemble into （ Meet the requirements of the front end ） Paging object ;
     *  For our project , We created one PagedGridResult object ; This object , It can meet the requirements of the front end for paging data format ;
     *
     * @param adminUserList:  According to the paging conditions , Query the database , Get the data of the current page ;
     * @param page： Which page do you want to query ;
     * @return
     */
    private PagedGridResult setterPagedGrid(List<?> adminUserList, Integer page) {

        /**
         *  utilize PageHelper Official PageInfo： According to the results of the paging query above , obtain PageInfo Paging object ;
         *  This PageInfo Paging object , It will help us calculate a lot of information about paging ;
         */
        PageInfo<?> pageInfo = new PageInfo<>(adminUserList);

        // establish PagedGridResult object , And assemble ;
        PagedGridResult pagedGridResult = new PagedGridResult();
        pagedGridResult.setRows(adminUserList);//  hold 【 Query the database according to paging conditions , Get the data of the current page ;】 Set it in ;
        pagedGridResult.setPage(page);// Set the current page 
        pagedGridResult.setRecords(pageInfo.getTotal());// Todo  adopt pageInfo, Get the total number of records ;( Through the measured , My writing here is reliable )
        pagedGridResult.setTotal(pageInfo.getPages());// Todo  adopt pageInfo, Get the total number of pages ;

        // return , Assembled PagedGridResult object ;
        return pagedGridResult;
    }

explain ： 

（1） of PageHelper Paged content , You can refer to  【 additional ：PageHelper Paging plug-in's ：Page and PageInfo The difference between ;】 And so on ;

（2） We are 【model】 In model engineering , Has introduced PageHelper Rely on ;

、

（3） Code logic description ;

（4） That means , When the front and back end interact here , Processing of paging data , No selection PageHelper Provided off the shelf PageInfo or Page; It doesn't seem very elegant ？

（5） Code logic description ： In the assembly PagedGridResult When paging objects , I still use PageHelper Provided PageInfo;

（6） Code logic description ： according to PagedGridResult Definition of paging object , Assign values to its attributes ;（ What we do here , Different from the course ; however , Through the measured , The practice in the course is wrong ）

（7） The revision of the previous two blogs ：

          ●  stay 【Spring Boot E-commerce projects 40： Commodity module 6 ： Backstage 【 List of goods 】 Interface ;（ Thought of a question ：【PageHelper When paging query , In any case, you must first find out all the data 】： Isn't that a waste ？PS： Unresolved ）_ Xiao kulin's blog -CSDN Blog _springboot List of goods 】 Medium , This question , I think more ;

          ●  stay  【 additional ：PageHelper Paging plug-in's ：Page and PageInfo The difference between ;】 in , There are many places where the description is not rigorous , A little adjustment ;

---

3、 ... and ： effect ;

First, the whole situation install Look at the whole project ; then , Start the front-end project ; Remember to use SwitchHost Open virtual domain name mapping ; start-up 【admin】 The main startup class of the management service ;

---

Four ：【 newly added admin account number , Interface 】、【 Paging query admin Account list , Interface 】, It also requires users to log in , Can be operated ;

Use us in 【50： The fifth chapter ： Development admin management service ：3： Development 【 Inquire about admin Does the user name already exist , Interface 】;（ This interface can only be called when logging in ; So we wrote interceptors , Let it intercept the request , Determine whether the user is logged in ;）】 Created in the AdminTokenInterceptor Interceptor ; stay InterceptorConfig Class AdminTokenInterceptor Where the interceptor is , Add to 【 newly added admin account number , Interface 】、【 Paging query admin Account list , Interface 】 Interception of ;