Spring Boot + REST 应用程序出现“无可用消息”错误

Question

I have created demo Spring Boot project and implemented Restful services as shown here

@RestController
public class GreetingsController {
    @RequestMapping(value="/api/greetings", method=RequestMethod.GET, produces=MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<String> getGreetings(){
        return new ResponseEntity<String>("Hello World", HttpStatus.OK);
    }
}

When I tried to invoke the service with Postman tool with url " http://localhost:8080/api/greetings " as request method GET, I am getting below error message

{
  "timestamp": 1449495844177,
  "status": 404,
  "error": "Not Found",
  "message": "No message available",
  "path": "/api/greetings"
}

Per Spring Boot application, I don't have to configure the Spring Dispatcher servlet in web.xml.

Can someone help me to find out the missing point here?

Answer 1

You're probably missing @SpringBootApplication :

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(Application.class, args);
    }
}

@SpringBootApplication includes @ComponentScan which scans the package it's in and all children packages. Your controller may not be in any of them.

Answer 2

Three Possible Solutions:

1) Make sure the YourController.java file that has the @Controller and the YourSpringBootFile.java file that has the @SpringBootApplication are in the same package.

For example, this is wrong:

This is the right way:

So you know what I'm talking about, here is my WebController.java file:

@RestController
public class WebController {
private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @RequestMapping(value= "/hi", method = RequestMethod.GET)
    public @ResponseBody Greeting sayHello(
            @RequestParam(value = "name", required = false, defaultValue = "Stranger") String name) {
        System.out.println("Inside sayHello() of WebController.java");
        return new Greeting(counter.incrementAndGet(), String.format(template, name));
    }
}

Here is my JsonPostExampleProj1Application.java:

@SpringBootApplication
public class JsonPostExampleProj1Application {

    public static void main(String[] args) {
        SpringApplication.run(JsonPostExampleProj1Application.class, args);
    }
}

2) If you want your controller to be in a different package outside of YourSpringBootFile.java's package, then follow these instructions = Spring: Run multiple "SpringApplication.Run()" in application main method

3) Try using @RestController instead of @Controller on top of your Controller class.

Answer 3

This can help someone as it was in my case.

Make sure the package name of the controller is the derived (or child) package of your Spring main method package.

For example:

If the main method package is com.company.demo.example then the controller package should be like com.company.demo.example.controller (if you specify something like com.company.demo.controller it won't work!).

Answer 4

I just came across this error and none of the solutions above worked for me, so im adding another posible thing that perhaps you can be missing too, make sure that you have annotation @ResponseBody on your method.

@RequestMapping(value="/yourPath", method=RequestMethod.GET)
@ResponseBody
public String exampleMethod() {
return "test";
}

Answer 5

Apart from the anotatting the SpringBoot entry point with @SpringBootApplication((scanBasePackages = "com.duwamish.xy") so that it includes all the spring components/beans when initialized,

The contextPath also has to be right. If the application is deployed to tomcat with the application name as myapplication see below,

$ ll /usr/local/apache-tomcat-8.0.42/webapps/
total 179216
12495017 drwxrwxrwx  17 urayagppd  NORD\Domain Users       578 Mar  8 11:59 ROOT
12495019 drwxrwxrwx  55 urayagppd  NORD\Domain Users      1870 Mar  8 11:59 docs
12495042 drwxrwxrwx   7 urayagppd  NORD\Domain Users       238 Mar  8 11:59 examples
12495109 drwxrwxrwx   7 urayagppd  NORD\Domain Users       238 Mar  8 11:59 host-manager
12495114 drwxrwxrwx   8 urayagppd  NORD\Domain Users       272 Mar  8 11:59 manager
16169612 drwxr-xr-x   4 urayagppd  NORD\Domain Users       136 May  7 18:47 myapplication
16169594 -rw-r--r--   1 urayagppd  NORD\Domain Users  45340041 May  7 18:47 myapplication.war

Then REST endpoint would be /myapplication/api/greetings

But if the application war is deployed as ROOT , the endpoint resource will be /api/greetings only.

Answer 6

If you are using @SpringBootApplication alone, then make sure your rest service controller is in the same package like below -

 com.testSpring->SpringBootApplication class com.testSpring.controller->RestfulController classes com.testSpring.model->Model classes ..etc

If you are using @ComponentScan(basePackageClasses = UserController.class) , then mention specific controller class names.

Answer 7

In my case I called the wrong path via ribbon.

@FeignClient(name = "currency-exchange")
@RibbonClient(name = "currency-exchange")
public interface CurrencyExchangeProxy {

    @GetMapping("/exchange/{from}/to/{to}")
    PairRateDto callForExchangeValue(@PathVariable("from") String fromValue, @PathVariable("to") String toValue);

}

Remote currency-exchange service didn't have handlers for /exchange/{from}/to/{to} path.

So for nonexistent URL I've got 404 which is fair with "No message available" which is strange.

Answer 8

Actually you need to put the Controller package under same path as your SpringBootApplication java file (spring boot main java class) contains.

com.abc | |---- @SpringBootApplication main java class

com.abc.controller | |---- @RestController class

Answer 9

For me I have the same error, but I realise that the path I put to call the api is the problem. If my application name is demo , I have to call http://localhost:9090/AdminProducts to access AdminProducts, not http://localhost:9090/demo/AdminProducts . This name may be use after deploying the war in tomcat.

Answer 10

If “No message available” is accompanied by 404, just check your http request, any syntax issue might be the case.

at least mine was a syntax error in a request while posting with postman.

Answer 11

我得到了同样的错误，但我意识到我正在返回 String 我将它更改为 ResponseEntity 现在它工作得很好。

Answer 12

all your packages should be after the main package,

like this com.example.demo.* (all your packages)