[Java Spring MVC] Controller for development confirmation

Web application development in Java is difficult if you are accustomed to PHP

• Assigned to a Web system development project in Java Spring MVC.
• Systems created by other companies in the past must be inherited and improved or modified.
• I'm not on the mechanism called Spring Boot.
• In PHP, you can easily check the contents of variables using var_dump (); or the debugging functions provided by each framework, but it is difficult to do in Java.
• If you can start the application via software (Eclipse etc.) in the integrated development environment, you can output the character string to the console with System.out.println (""); , but is it because the existing system settings are bad? , I couldn't run the app from the integrated development environment even after working for several hours.
• When the code ends with an exception, the already created error page is displayed, and since there is no debug information such as stack trace on this page, I do not know what kind of error it is. Even if you look at the log file, an error may or may not be written. If possible, please display the information on the screen when an error occurs.

Make a dummy controller to help development

• Therefore, I made a dummy controller that serves as a place to write the code I want to try and check the operation and variables.
• It doesn't support the mechanism like var_dump (); that passes objects roughly and displays all the contents. Since only character strings can be output, some ingenuity is required for confirmation output.
• If it ends with an exception, the stack trace is displayed on the screen.

Dummy controller

package package name;

import java.io.*;
import java.util.ArrayList;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


// @By specifying RestController, you can control the output only with this controller without using the View file.
@RestController
public class DummyController {

    private static final Logger logger = LoggerFactory.getLogger(DummyController.class);

    /**
     *Write the content you want to check in the test code, add the output to the list of strings, and display them on the screen.
     * URL :Site domain/dummy
     * produces = "text/plain;charset=UTF-8"By specifying, the output will be treated as text instead of HTML, and Japanese character strings can also be used.
     */
    @RequestMapping(value = {"/dummy"}, produces = "text/plain;charset=UTF-8")
    public String dummy() {
      return this.printToScreen(this.buildListToConfirm());
    }


    /**
     *Test code you want to check the output
     */
    private List<String> codeTrial(List<String> list) {
      /*-----------------------------------*/
      //Test code from here
      /*-----------------------------------*/

      //Write the code you want to check here
      //Add the character string you want to output to the screen to list
      list.add("hoge");

      /*-----------------------------------*/
      //Test code up to here
      /*-----------------------------------*/
      return list;
    }

    private List<String> buildListToConfirm(){
      List<String> list = new ArrayList<String>();
      try {
        list.add("----------start----------");
        list = this.codeTrial(list);
        list.add("----------End----------");
      } catch (Exception e) {
        list.add(this.getStackTraceStr(e));
      }
      return list;
    }

    /**
     *Show stack trace of errors
     */
    private String getStackTraceStr(Exception e) {
      StringWriter sw = new StringWriter();
      PrintWriter pw = new PrintWriter(sw);
      e.printStackTrace(pw);
      pw.flush();
      String stackTraceStr = sw.toString();
      return stackTraceStr;
    }

    /**
     *Display on screen for confirmation
     */
    private String printToScreen(List<String> list){
      String output = "";
      for(String s : list){
          output = output + s + "\n";
      }

      return output;
    }
}

After writing the code, build it and access the URL of "/ dummy". The URL can be changed.

Screen output sample

A stack trace is output when exiting with an error