java - 为什么我的 Jersey ClientResponse 不为空，但可用返回 0？

Question

我有这个 Jersey 网络资源代码:

   @Override
    public int Foo(long uId, String secretKey, long tileId) {
        int answer = 0;
        String ans;
        try {
            ClientResponse response = webResource
                    // .path("multi-get")
                    .queryParam("reqtype", "tileBatch")
                    .queryParam("protocol", "1")
                    .queryParam("sessionid", String.valueOf(uId))
                    .queryParam("cookie", String.valueOf(secretKey))
                    .queryParam("num", "1")
                    .queryParam("t0", String.valueOf(tileId))
                    .queryParam("v0", "0")
                    .get(ClientResponse.class);

            if (response.getStatus() != 200) {
                throw new RuntimeException("Failed : HTTP error code : "
                        + response.getStatus());
            }
            String output = response.getEntity(String.class);
            answer = response.getEntityInputStream().available();

            byte[] byteArray = output.getBytes("UTF-8");
            ans = new String(byteArray, "UTF-8");


        } catch (Exception e) {
            e.printStackTrace();
        }
        return answer;
    }
}

我看到 String output = response.getEntity(String.class); 不为空，但在 answer = response.getEntityInputStream().available(); 中答案==0怎么来的？

如果我想将二进制数据的前 2 个字节解析为整数我怎样才能做到这一点？ (int) byteArray[0] ?

例如00000000-00010000

编辑

我尝试了这段代码:

InputStream entityInputStream = response.getEntityInputStream();
            answer = entityInputStream.available();
            String output = response.getEntity(String.class);

            byte[] byteArray = new byte[2];
          //  entityInputStream.reset();

            entityInputStream.read(byteArray);

            String s = new String(byteArray);

但是即使output不为空，byteArray == {0,0}。

output == ....
�*WZDF04x��:w|������6[�!�M���@HH �� �����TQ�W�""$@�Z $(���ұ=��[��� ��d�s�n6K�������{�99��{����$qE48"

我的方法正确吗？

Answer 1

I see String output = response.getEntity(String.class); is not empty and yet in answer = response.getEntityInputStream().available(); then answer == 0 how come?

当您执行response.readEntity(String.class)时，将读取输入流并清除输入流。因此，您下次尝试检索输入流将返回一个空流。

If I want to parse the 2 first bytes from binary data into an integer how can I do this?

您可以简单地将InputStream 包装在DataInputStream 中，并使用DataInputStream.readInt()。然后，您可以使用 response.readEntity(String.class); 读取输入流的其余部分。您似乎正在尝试读取字符串，然后读取 int，这与您的上述语句不符。

测试

@Path("/string")
public class StringResource {  
    @GET
    public StreamingOutput getString() {
        return new StreamingOutput(){
            @Override
            public void write(OutputStream out) 
                    throws IOException, WebApplicationException {
                DataOutputStream outStream = new DataOutputStream(out);
                outStream.writeInt(1234567);
                outStream.writeUTF("Hello World");
            }
        };
    }
}

@Test
public void testMyResource() throws Exception {
    ClientConfig config = new DefaultClientConfig();
    Client client = Client.create(config);
    WebResource wr = client
            .resource("http://localhost:8080/api/string");
    ClientResponse response = wr.get(ClientResponse.class);

    InputStream is = response.getEntityInputStream();
    DataInputStream dis = new DataInputStream(is);
    int num = dis.readInt();
    System.out.println(num);    
    System.out.println(response.getEntity(String.class));
    response.close();
}

打印出1234567，然后打印出Hello World