Spring Boot - 测试：当返回非 200 响应状态码时，前端能否接收到 JSON 数据

• 实践
• • 环境
  • 新建项目
  • 测试
• 参考

集成开发环境：

Spring Tool Suite 4 
Version: 4.12.1.RELEASE
Build Id: 202110260750
OS: Windows 10, v.10.0, x86_64 / win32

新建 Spring Starter Project，其结构如下：

编辑 pom.xml 依赖配置文件，主要引入：

• spring-boot-starter-web
• fastjson

	4.0.0
	
	
		org.springframework.boot
		spring-boot-starter-parent
		2.6.2
		 
	
	
	com.mk
	demo
	0.0.1-SNAPSHOT
	demo
	Demo project for Spring Boot
	
	
		1.2.8
		1.8
	
	
	
		
			org.springframework.boot
			spring-boot-starter-web
		

		
			org.springframework.boot
			spring-boot-devtools
			runtime
			true
		
		
			org.springframework.boot
			spring-boot-configuration-processor
			true
		
		
			org.projectlombok
			lombok
			true
		
		
			org.springframework.boot
			spring-boot-starter-test
			test
		
		
        
            com.alibaba
            fastjson
            ${fastjson.version}
        
	

	
		
			
				org.springframework.boot
				spring-boot-maven-plugin
				
					
						
							org.projectlombok
							lombok
						
					
				
			
		
	

新建一个 HelloController 控制器，这里面的方法的主要作用是设置不同的响应状态码，并返回 JSON 数据：

package com.mk.controller;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;

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

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.fasterxml.jackson.databind.ObjectMapper;

@RestController
public class HelloController {

	private static final ObjectMapper objectMapper = new ObjectMapper();
	
	
	@RequestMapping(method = RequestMethod.GET, path = "ok")
	public void ok(HttpServletRequest request, HttpServletResponse response) throws IOException {
		response.setStatus(HttpStatus.OK.value());
		response.setCharacterEncoding("UTF-8");
		response.setContentType("application/json");
		
		Map result = new HashMap<>();
		result.put("message", HttpStatus.OK.name());
		result.put("ip", request.getRemoteAddr());
		
		PrintWriter writer = response.getWriter();
		writer.write(objectMapper.writevalueAsString(result));
		writer.flush();
		writer.close();
	}
	
	@GetMapping(path = "bad request")
	public void badRequest(HttpServletRequest request, HttpServletResponse response) throws IOException {
		response.setStatus(HttpStatus.BAD_REQUEST.value());
		response.setCharacterEncoding("UTF-8");
		response.setContentType("application/json");
		
		Map result = new HashMap<>();
		result.put("message", HttpStatus.BAD_REQUEST.name());
		result.put("ip", request.getRemoteAddr());
		
		PrintWriter writer = response.getWriter();
		writer.write(objectMapper.writevalueAsString(result));
		writer.flush();
		writer.close();
	}
	
	@GetMapping(path = "unauthorized")
	public void unauthorized(HttpServletRequest request, HttpServletResponse response) throws IOException {
		response.setStatus(HttpStatus.UNAUTHORIZED.value());
		response.setCharacterEncoding("UTF-8");
		response.setContentType("application/json");
		
		Map result = new HashMap<>();
		result.put("message", HttpStatus.UNAUTHORIZED.name());
		result.put("ip", request.getRemoteAddr());
		
		PrintWriter writer = response.getWriter();
		writer.write(objectMapper.writevalueAsString(result));
		writer.flush();
		writer.close();
	}
	
	@GetMapping(path = "forbidden")
	public void forbidden(HttpServletRequest request, HttpServletResponse response) throws IOException {
		response.setStatus(HttpStatus.FORBIDDEN.value());
		response.setCharacterEncoding("UTF-8");
		response.setContentType("application/json");
		
		Map result = new HashMap<>();
		result.put("message", HttpStatus.FORBIDDEN.name());
		result.put("ip", request.getRemoteAddr());
		
		PrintWriter writer = response.getWriter();
		writer.write(objectMapper.writevalueAsString(result));
		writer.flush();
		writer.close();
	}
}

在静态资源目录下，新建一个 index.html 文件，使用 XMLHttpRequest 请求 HelloController 控制器中提供的服务：

运行该项目，接着使用浏览器访问 http://localhost:8080/index.html，分别测试：

从以上测试结果可知，即使在返回非 200 响应状态码时，前端也能接收到 JSON 数据。

Web technology for developers > HTTP > HTTP response status codes