@Produces，@ GET，@ Path和@QueryParam在函数定义之前的重要性

Question

I am new to java. I was looking the below code.

@Produces("text/xml")
@GET
@Path("/xml/search")
public Object searchXML(@QueryParam("query") String query,
        @QueryParam("granularity") String granularity) {
    return search(query, granularity);
}

I couldn't understand the uses of @Produces, @GET, @Path and @QueryParam before function definition in above code. Can anybody put some light on this. Thanks

Answer 1

Those anotations are defined by JAX-RS , a Standard for RESTful Web Services.

In the example above, it mean the method will handle a:

• GET request

• on path "/xml/search"

• and map the query argument "query" to String query argument,

• as well as the "granularity" to granularity

• the resulting content-type will be "text/xml"

(and it will probably call a custom marshaller for this)

(see this page for a reference)

Answer 2

A producer method is a method that generates an object that can then be injected. Link When you want to inject an object that is not itself a bean When the concrete type of the object to be injected may vary at runtime When the object requires some custom initialization that the bean constructor does not perform

@GET: Transmits a representation of the resource identified by the URI to the client. The format might be HTML, plain text, JPEG, and so on. See How to Transmit a Representation of the Resource (@GET). Link

@Path(param) : @PathParam is a parameter annotation which allows you to map variable URI path fragments into your method call. Link

can use @QueryParam annotation to inject URI query parameter into Java method Link

Answer 3

@Produces annotation is to specify the MIME media types of representations a resource can produce and send back to the client.here mediatype is an text rather xml can be recieved,

@GET is an HTTP Methods like @PUT, @POST, @DELETE

@Path annotation's value is a relative URI path .In this the function call will be from service is through the path as /xml/search/ to the function with the params.

@QueryParam is to extract query parameters from the Query component of the request URL, in this receives the param as strings from the URL .

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