对象值在传递给 JAX-RS 中的 servlet 时变为 NULL

Question

使用 Jersey 的 JAX-RS

我正在尝试将对象 "Broadcast" 从客户端发送到 servlet 并在 servlet 端打印值。但是我的输出变为空。帮我解决这个问题提前谢谢:-)

Servlet

@POST
@Path("/receiverMessage")
public Response sendMessage(Broadcast broadcast) {
    System.out.println(broadcast.getSenderName());
    System.out.println(broadcast.getReceiverName());
    System.out.println(broadcast.getTime());
    return Response.ok().status(200).entity("SUCCESS").build();
}

客户端

public class Client {
public static void main(String[] args) {
    Client client = ClientBuilder.newClient();
    Broadcast broadcast = new Broadcast("SENDER", "RECEIVER", new Timestamp(System.currentTimeMillis()));
    Response messagePost = client.target("http://localhost:8081/xyz/abc")
            .path("receiverMessage")
            .request()
            .post(Entity.entity(broadcast, MediaType.APPLICATION_JSON), Response.class);
    System.out.println(messagePost.getStatus());
}}

广播模型

public class Broadcast {
private String senderName;
private String receiverName;
private Timestamp time;
}

MessageBodyWriter

@Override
public void writeTo(Broadcast broadcast, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) throws IOException, WebApplicationException {
    System.setProperty("javax.xml.bind.context.factory","org.eclipse.persistence.jaxb.JAXBContextFactory");
    try {
        JAXBContext context = JAXBContext.newInstance(type);
        Marshaller marshaller = context.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.setProperty(MarshallerProperties.MEDIA_TYPE, "application/json");
        marshaller.marshal(broadcast, entityStream);
    } catch (JAXBException e) {
        e.printStackTrace();
    }
}

输出

null 
null
null

Answer 1

如果您使用的是 Jersey，则无需执行任何额外操作。 Jersey 有能力（反）序列化你的 JSON。但是，您需要做一些更改。

您在服务器端缺少 @Consumes 和 @Produces 注释

@POST
@Path("/receiverMessage")
@Consumes ( { MediaType.APPLICATION_JSON })
@Produces ( { MediaType.TEXT_PLAIN })
public Response sendMessage(Broadcast broadcast) {
   System.out.println(broadcast.getSenderName());
   System.out.println(broadcast.getReceiverName());
   System.out.println(broadcast.getTime());
   return Response.ok().status(200).entity("SUCCESS").build();
}

此外，您的 POJO class 没有注释表明它是 JAXB class。你可以找到很好的例子 Using JAX-RS with JAXB

对象值在传递给 JAX-RS 中的 servlet 时变为 NULL

Object values becomes NULL while passing to the servlet in JAX-RS

java

servlets

jax-rs

jersey-client

使用 Jersey 的 JAX-RS