将 JSON 响应解析为对象

本文介绍了将 JSON 响应解析为对象的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

Good evening, I am a newbie in web services and i just want to write a simple client that simply gets responses from REST calls. I downloaded and added jersey-bundle-1.17.1.jar to my build path and i found a working piece of code that makes a REST call to a url and returns a response as a String.

import javax.ws.rs.core.MediaType; import com.sun.jersey.api.client.Client; import com.sun.jersey.api.client.ClientResponse; import com.sun.jersey.api.client.WebResource; public class TestJerseyClient { public static void main(String[] args) { try { Client client = Client.create(); WebResource webResource = client .resource("path/to/service"); ClientResponse response = webResource .accept(MediaType.APPLICATION_JSON) .get(ClientResponse.class); if (response.getStatus() != 200) throw new RuntimeException("Failed : HTTP error code : " + response.getStatus()); String output = response.getEntity(String.class); System.out.println("Output from Server .... "); System.out.println(output); } catch (Exception e) { e.printStackTrace(); } } }

But i don't want to do string manipulations to get the parts of the response that im interested in.

I would prefer a more structured approach, like getting an Object instead of a string (a JSON Object, a Map<K,V> Object, etc...)

TRY#1 - Map<K,V>

Sep 15, 2013 2:46:13 AM com.sun.jersey.api.client.ClientResponse getEntity SEVERE: A message body reader for Java class java.util.Map, and Java type java.util.Map<java.lang.String, java.lang.Object>, and MIME media type application/json; charset=UTF-8 was not found Sep 15, 2013 2:46:13 AM com.sun.jersey.api.client.ClientResponse getEntity SEVERE: The registered message body readers compatible with the MIME media type are: application/json; charset=UTF-8 -> com.sun.jersey.json.impl.provider.entity.JSONJAXBElementProvider$App com.sun.jersey.json.impl.provider.entity.JSONRootElementProvider$App com.sun.jersey.json.impl.provider.entity.JSONListElementProvider$App */* -> com.sun.jersey.core.impl.provider.entity.FormProvider com.sun.jersey.core.impl.provider.entity.StringProvider com.sun.jersey.core.impl.provider.entity.ByteArrayProvider com.sun.jersey.core.impl.provider.entity.FileProvider com.sun.jersey.core.impl.provider.entity.InputStreamProvider com.sun.jersey.core.impl.provider.entity.DataSourceProvider com.sun.jersey.core.impl.provider.entity.XMLJAXBElementProvider$General com.sun.jersey.core.impl.provider.entity.ReaderProvider com.sun.jersey.core.impl.provider.entity.DocumentProvider com.sun.jersey.core.impl.provider.entity.SourceProvider$StreamSourceReader com.sun.jersey.core.impl.provider.entity.SourceProvider$SAXSourceReader com.sun.jersey.core.impl.provider.entity.SourceProvider$DOMSourceReader com.sun.jersey.json.impl.provider.entity.JSONJAXBElementProvider$General com.sun.jersey.core.impl.provider.entity.XMLRootElementProvider$General com.sun.jersey.core.impl.provider.entity.XMLListElementProvider$General com.sun.jersey.core.impl.provider.entity.XMLRootObjectProvider$General com.sun.jersey.core.impl.provider.entity.EntityHolderReader com.sun.jersey.json.impl.provider.entity.JSONRootElementProvider$General com.sun.jersey.json.impl.provider.entity.JSONListElementProvider$General com.sun.jersey.api.client.ClientHandlerException: A message body reader for Java class java.util.Map, and Java type java.util.Map<java.lang.String, java.lang.Object>, and MIME media type application/json; charset=UTF-8 was not found at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:561) at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:535) at com.sun.jersey.api.client.WebResource.handle(WebResource.java:696) at com.sun.jersey.api.client.WebResource.access$300(WebResource.java:74) at com.sun.jersey.api.client.WebResource$Builder.get(WebResource.java:512) at rest.TestJerseyClientAdvanced.main(TestJerseyClientAdvanced.java:36)

解决方案

I recommend you use Jackson for (un)marshalling JSON responses. This can be done is two steps as below.

Step1. create a java bean with member/object names that match the expected response. e.g, MyResponse.class

Step2. use the java bean when reading the entity from the client response.

private static ClientConfig clientConfig = new DefaultClientConfig(); clientConfig.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE); ClientResponse response = Client.create(clientConfig). resource(uri).accept(MediaType.APPLICATION_JSON). header("content-type", MediaType.APPLICATION_JSON). get(MY_RESPONSE.class); MyResponse output = response.getEntity(MyResponse.class);