JAX-RS之@QueryParam和@DefaultValue

先来看@queryparam
   先看例子:
 

Path("/users")
public class UserService {

    @GET
    @Path("/query")
    public Response getUsers(
        @QueryParam("from") int from,
        @QueryParam("to") int to,
        @QueryParam("orderBy") List<String> orderBy) {

        return Response
           .status(200)
           .entity("getUsers is called, from : " + from + ", to : " + to
            + ", orderBy" + orderBy.toString()).build();

    }

}

Path("/users")
public class UserService {
 
	@GET
	@Path("/query")
	public Response getUsers(
		@QueryParam("from") int from,
		@QueryParam("to") int to,
		@QueryParam("orderBy") List<String> orderBy) {
 
		return Response
		   .status(200)
		   .entity("getUsers is called, from : " + from + ", to : " + to
			+ ", orderBy" + orderBy.toString()).build();
 
	}
 
}

   URL输入为:users/query?from=100&to=200&orderBy=age&orderBy=name
  此时,输出为:
getUsers is called, from : 100, to : 200, orderBy[age, name]
   要注意的是,跟@pathparam不同,@queryparam
中,指定的是URL中的参数是以键值对的形式出现的,而在程序中
@QueryParam("from") int from则读出URL中from的值,
而@pathparem中,URL中只出现参数的值,不出现键值对,比如:
“/users/2011/06/30”

则:
 

@GET
    @Path("{year}/{month}/{day}")
    public Response getUserHistory(
            @PathParam("year") int year,
            @PathParam("month") int month,
            @PathParam("day") int day) {

       String date = year + "/" + month + "/" + day;

       return Response.status(200)
        .entity("getUserHistory is called, year/month/day : " + date)
        .build();

    }

@GET
	@Path("{year}/{month}/{day}")
	public Response getUserHistory(
			@PathParam("year") int year,
			@PathParam("month") int month, 
			@PathParam("day") int day) {
 
	   String date = year + "/" + month + "/" + day;
 
	   return Response.status(200)
		.entity("getUserHistory is called, year/month/day : " + date)
		.build();
 
	}

输出为:
getUserHistory is called, year/month/day : 2011/6/30

2 以动态的方式获得:
  

@Path("/users")
public class UserService {

    @GET
    @Path("/query")
    public Response getUsers(@Context UriInfo info) {

        String from = info.getQueryParameters().getFirst("from");
        String to = info.getQueryParameters().getFirst("to");
        List<String> orderBy = info.getQueryParameters().get("orderBy");

        return Response
           .status(200)
           .entity("getUsers is called, from : " + from + ", to : " + to
            + ", orderBy" + orderBy.toString()).build();

    }

@Path("/users")
public class UserService {
 
	@GET
	@Path("/query")
	public Response getUsers(@Context UriInfo info) {
 
		String from = info.getQueryParameters().getFirst("from");
		String to = info.getQueryParameters().getFirst("to");
		List<String> orderBy = info.getQueryParameters().get("orderBy");
 
		return Response
		   .status(200)
		   .entity("getUsers is called, from : " + from + ", to : " + to
			+ ", orderBy" + orderBy.toString()).build();
 
	}
 

URL;users/query?from=100&to=200&orderBy=age&orderBy=name
输出为:
getUsers is called, from : 100, to : 200, orderBy[age, name]
注意这里把orderby后的两个参数读入为LIST处理了.


3 @DefaultValue,默认值

  例子:
 

@Path("/users")
public class UserService {

    @GET
    @Path("/query")
    public Response getUsers(
        @DefaultValue("1000") @QueryParam("from") int from,
        @DefaultValue("999")@QueryParam("to") int to,
        @DefaultValue("name") @QueryParam("orderBy") List<String> orderBy) {

        return Response
           .status(200)
           .entity("getUsers is called, from : " + from + ", to : " + to
            + ", orderBy" + orderBy.toString()).build();

    }

@Path("/users")
public class UserService {
 
	@GET
	@Path("/query")
	public Response getUsers(
		@DefaultValue("1000") @QueryParam("from") int from,
		@DefaultValue("999")@QueryParam("to") int to,
		@DefaultValue("name") @QueryParam("orderBy") List<String> orderBy) {
 
		return Response
		   .status(200)
		   .entity("getUsers is called, from : " + from + ", to : " + to
			+ ", orderBy" + orderBy.toString()).build();
 
	}

URL:users/query
输出:getUsers is called, from : 1000, to : 999, orderBy[name]

很好理解吧