50: Chapter 5: develop admin management service: 3: develop [query whether the admin user name already exists, interface]; (this interface can only be called when logging in; so we have written an int

explain ：

（1） The content of this blog ： Development 【 Inquire about admin Does the user name already exist , Interface 】;

Catalog

One ： Development 【 Inquire about admin Does the user name already exist , Interface 】;

0. Rationality description ; 

1. stay 【api】 Interface Engineering AdminMngControllerApi Interface , Definition 【 Inquire about admin Does the user name already exist , Interface 】;

2. stay 【admin】 Managed services AdminMngController Class , To achieve 【 Inquire about admin Does the user name already exist , Interface 】;

3. test ;

4.【 Inquire about admin Does the user name already exist , Interface 】, It also requires users to log in , Can be operated ;

（1） First , stay 【api】 Interface engineering , establish AdminTokenInterceptor Interceptor , To intercept requests , Judge whether the user is in login status according to the request ;

（2） then , stay 【api】 Interface engineering , stay InterceptorConfig class , De configuration AdminTokenInterceptor Interceptor ;

（3） effect ;

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One ： Development 【 Inquire about admin Does the user name already exist , Interface 】;

0. Rationality description ; 

stay 【49： The fifth chapter ： Development admin management service ：2： Development 【 Administrator login 】 Interface ;】 in , After the administrator user logs in , Will jump to the following page ;

then , We can set the administrator user ;

          ●  As mentioned earlier , Duplicate login names of administrators are not allowed ; therefore , We type " Login name " When , The front-end code will capture this input action ; then , It will automatically call the corresponding interface of the back end , Check whether the login name entered has duplicate names ;

          ●  therefore , Let's develop 【 Inquire about admin Does the user name already exist , Interface 】;

1. stay 【api】 Interface Engineering AdminMngControllerApi Interface , Definition 【 Inquire about admin Does the user name already exist , Interface 】;

    /**
     *  Inquire about admin user name , Does it already exist ;
     * @param username
     * @return
     */
    @ApiOperation(value = " Inquire about admin user name , Does it already exist ", notes = " Inquire about admin user name , Does it already exist ", httpMethod = "POST")
    @PostMapping("/adminIsExist") // Set the routing , This needs to be agreed between the front and back ;
    public GraceJSONResult adminIsExist(@RequestParam String username);

explain ：

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

2. stay 【admin】 Managed services AdminMngController Class , To achieve 【 Inquire about admin Does the user name already exist , Interface 】;

    /**
     *  Inquire about admin user name , Does it already exist ;
     * @param username
     * @return
     */
    @Override
    public GraceJSONResult adminIsExist(String username) {
        checkAdminExist(username);//【 Judge admin user name , Does it already exist 】 The logic of , We have drawn a single method ;
        return GraceJSONResult.ok();
    }
    
    /**
     *  Tool method ： Judge admin user name , Does it already exist ;
     * @param username
     */
    private void checkAdminExist(String username) {
        // 1. call Service Layer method , According to the user name , Try to check in the database , See if there is this user ;
        AdminUser adminUser = adminUserService.queryAdminByUsername(username);
        if (adminUser != null) {
            // If the administrator name Already exists , Directly throw a containing " The administrator login already exists ！" The information of MyCustomException Custom exception ;
            GraceException.display(ResponseStatusEnum.ADMIN_USERNAME_EXIST_ERROR);
        }
    }

explain ：

（1）service Layer of 【 according to " Administrator user name ", How to query administrator users queryAdminByUsername(username);】 In the last blog , It's already developed ;

（2）【 according to " Administrator user name ", Query administrator user ;】 This logic , We have drawn a single method ;

3. test ;

（1） First, the whole situation install Look at the whole project ;

（2） then , Start the front-end project ; Remember to use SwitchHost Open virtual domain name mapping ;

（3） start-up 【admin】 The main startup class of the management service ;

……………………………………………………

（4） then , Enter a different admin user name ;

4.【 Inquire about admin Does the user name already exist , Interface 】, It also requires users to log in , Can be operated ;

PS： This is in 【36： The third chapter ： Developing a pass service ：19： Intercept those “ Want to visit 【 Get user account information , Interface 】 and 【 change / Improve user information , Interface 】 Request “, Check login information , Release after passing the verification ;（ Use 【Spring MVC Interceptors in 】 To achieve ）】、【44： Chapter four ： Developing file services ：5： stay 【files】 File service , Integrate FastDFS, Realization 【 Upload your avatar 】 The logic of ;】 There are settings in ;

（1） First , stay 【api】 Interface engineering , establish AdminTokenInterceptor Interceptor , To intercept requests , Judge whether the user is in login status according to the request ;

package com.imooc.api.interceptors;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *  So far, ： Intercept access 【 change / Improve user information , Interface 】、【 Get user account information , Interface 】, Check whether the user login status OK;
 */
public class AdminTokenInterceptor extends BaseInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        // First , Try from the requested header in , obtain "adminUserId" and "adminUserToken";
        //  That is to get , Before calling 【 Inquire about admin Does the user name already exist , Interface 】 When setting into the front-end browser cookie Medium "uid" and "utoken";
        // PS： When the front end initiates a request , The front-end program will put cookie in "uid" and "utoken" Set the incoming request header ; then , When setting , Their names are set to "adminUserId" and "adminUserToken";
        //  therefore , Don't write nonsense here , Be sure to keep consistent with the front end ;
        // PS： If this request is header There is no "adminUserId" and "adminUserToken", What it gets is empty ;
        String userId = request.getHeader("adminUserId");
        String token = request.getHeader("adminUserToken");

        // call BaseInterceptor Methods written in , Judge the requested header Medium "adminUserId" and "adminUserToken" whether OK;
        //  in other words , Determine whether a front-end user is logged in ;
        boolean run = verifyUserIdToken(userId, token,REDIS_ADMIN_TOKEN);

        System.out.println(run);
        // If the top verifyUserIdToken() There's no problem with execution , Then the current user is logged in ,
        //  Can go to this step , direct return true, Release this request , Let it visit 【 change / Improve user information , Interface 】、【 Get user account information , Interface 】;
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

explain ：

（1） How to write here , You can refer to  【36： The third chapter ： Developing a pass service ：19： Intercept those “ Want to visit 【 Get user account information , Interface 】 and 【 change / Improve user information , Interface 】 Request “, Check login information , Release after passing the verification ;（ Use 【Spring MVC Interceptors in 】 To achieve ）】;

（2） From the request header , Try to get "adminUserId" and "adminUserToken"; These two , Don't write , The front and rear ends need to be consistent ;

（3） We need to be in BaseInterceptor in , Definition REDIS_ADMIN_TOKEN;（ When the user gets the administrator user login , Deposit in redis Medium token）

（2） then , stay 【api】 Interface engineering , stay InterceptorConfig class , De configuration AdminTokenInterceptor Interceptor ;

    @Bean
    public AdminTokenInterceptor adminTokenInterceptor() {
        return new AdminTokenInterceptor();
    }


        // 【 Inquire about admin Does the user name already exist , Interface 】 You need to log in to operate ;
        registry.addInterceptor(adminTokenInterceptor())
                .addPathPatterns("/adminMng/adminIsExist");

（3） 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 ;

If , Let's get rid of cookie Information , Make it no longer login ;