There was an unexpected error (type=Not Found, status=404).

使用spring項目訪問後臺接口時返回了這個錯誤。

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.

Fri Oct 25 17:31:57 CST 2019
There was an unexpected error (type=Not Found, status=404).
No message available

後臺是這樣

@Controller
@EnableAutoConfiguration
@RequestMapping("/test")
public class TestController {
	
	@RequestMapping("/testMethod")
	public JSON testMethod() {
		System.out.println("12345");
		Map res = new HashMap();
		res.put("data", 321);
		return JSONObject.fromObject(res);
	}
	
}

通過後臺查看發現，請求確實收到了，但是依然報404 。最後發現是沒有設置@ResponseBody。

解決方法，方法上面加上註解@ResponseBody，或者將類的註解@Controller改爲@RestController。

@RestController = @Controller + @ResponseBody

修改後的代碼

@Controller
@EnableAutoConfiguration
@RequestMapping("/test")
public class TestController {
	
	@RequestMapping("/testMethod")
	@ResponseBody
	public JSON testMethod() {
		System.out.println("12345");
		Map res = new HashMap();
		res.put("data", 321);
		return JSONObject.fromObject(res);
	}
	
}

或者

@RestController
@EnableAutoConfiguration
@RequestMapping("/test")
public class TestController {
	
	@RequestMapping("/testMethod")
	public JSON testMethod() {
		System.out.println("12345");
		Map res = new HashMap();
		res.put("data", 321);
		return JSONObject.fromObject(res);
	}
	
}