I am new to web programming in general, especially in Java, so I just learned what a header and body is.
I'm writing RESTful services using Spring MVC. I am able to create simple services with the @RequestMapping in my controllers. I need help understanding how to get HTTP header information from a request that comes to my method in my REST service controller. I would like to parse out the header and get some attributes from it.
Could you explain how I go about getting that information?
When you annotate a parameter with @RequestHeader, the parameter retrieves the header information. So you can just do something like this:
@RequestHeader("Accept")
to get the Accept header.
So from the documentation:
@RequestMapping("/displayHeaderInfo.do")
public void displayHeaderInfo(@RequestHeader("Accept-Encoding") String encoding,
@RequestHeader("Keep-Alive") long keepAlive) {
}
The Accept-Encoding and Keep-Alive header values are provided in the encoding and keepAlive parameters respectively.
And no worries. We are all noobs with something.
Servlet API. I can use the annotations to pull what I need out of the request.
required flag like @RequestHeader(name = "Keep-Alive", required = false) long keepAlive that will set the keepAlive to null if not provided. There is also defaultValue field for the annotation docs.spring.io/spring-framework/docs/5.0.7.RELEASE/javadoc-api/…You can use the @RequestHeader annotation with HttpHeaders method parameter to gain access to all request headers:
@RequestMapping(value = "/restURL")
public String serveRest(@RequestBody String body, @RequestHeader HttpHeaders headers) {
// Use headers to get the information about all the request headers
long contentLength = headers.getContentLength();
// ...
StreamSource source = new StreamSource(new StringReader(body));
YourObject obj = (YourObject) jaxb2Mashaller.unmarshal(source);
// ...
}
StringReader is used to read the incoming character stream. StreamSource works as a holder for a transformation source in the form of a stream of XML markup.My solution in Header parameters with example is user="test" is:
@RequestMapping(value = "/restURL")
public String serveRest(@RequestBody String body, @RequestHeader HttpHeaders headers){
System.out.println(headers.get("user"));
}
You can use HttpEntity to read both Body and Headers.
@RequestMapping(value = "/restURL")
public String serveRest(HttpEntity<String> httpEntity){
MultiValueMap<String, String> headers =
httpEntity.getHeaders();
Iterator<Map.Entry<String, List<String>>> s =
headers.entrySet().iterator();
while(s.hasNext()) {
Map.Entry<String, List<String>> obj = s.next();
String key = obj.getKey();
List<String> value = obj.getValue();
}
String body = httpEntity.getBody();
}
