[FIXED] Read HttpServletRequest object from Spring Boot controller method

Issue

Below is my controller method definition

@Autowired
private HttpServletRequest request;

@PostMapping(path = "/abc")
public String createAbc(@RequestBody HttpServletRequest request)
        throws IOException {

    logger.info("Request body: "+request.getInputStream());

    return "abc";

}

All i want to do is print contents to request body. But when i make a POST request i see below error:

Type definition error: [simple type, class javax.servlet.http.HttpServletRequest]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of javax.servlet.http.HttpServletRequest (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information\n at [Source: (PushbackInputStream); line: 1, column: 2]",

I'm using Spring boot 2.x version.Any idea what's wrong in my code?

Solution

First, remove the @Autowired field. It's wrong and you're not using it anyway.

Now you have two choices:

1. Let Spring process the request body for you, by using the @RequestBody annotation:

   @PostMapping(path = "/abc")
   public String createAbc(@RequestBody String requestBody) throws IOException {
       logger.info("Request body: " + requestBody);
       return "abc";
   }
   

2. Process it yourself, i.e. don't use the @RequestBody annotation:

   @PostMapping(path = "/abc")
   public String createAbc(HttpServletRequest request) throws IOException {
       StringBuilder builder = new StringBuilder();
       try (BufferedReader in = request.getReader()) {
           char[] buf = new char[4096];
           for (int len; (len = in.read(buf)) > 0; )
               builder.append(buf, 0, len);
       }
       String requestBody = builder.toString();
       logger.info("Request body: " + requestBody);
       return "abc";
   }
   

Don't know why you'd use option 2, but you can if you want.

Answered By - Andreas
Answer Checked By - David Marino (JavaFixing Volunteer)