如何使用Google API Java客户端向Google Shortener API发送请求并解析JSON响应？

我想使用Google Shortener API 。 我想使用google api java客户端库发布请求并解析JSON响应。

接下来，我发布了我尝试过的代码：

import java.io.IOException; import net.sf.json.JSONObject; import com.google.api.client.googleapis.GoogleHeaders; import com.google.api.client.googleapis.GoogleTransport; import com.google.api.client.googleapis.json.JsonCParser; import com.google.api.client.http.HttpRequest; import com.google.api.client.http.HttpResponse; import com.google.api.client.http.HttpTransport; import com.google.api.client.json.JsonHttpContent; import com.google.api.client.util.GenericData; public class GoogleShortener { public static final String GOOGL_URL = "https://www.googleapis.com/urlshortener/v1/url"; public static void main(String[] args) { // setup up the HTTP transport HttpTransport transport = GoogleTransport.create(); // add default headers GoogleHeaders defaultHeaders = new GoogleHeaders(); transport.defaultHeaders = defaultHeaders; transport.defaultHeaders.put("Content-Type", "application/json"); transport.addParser(new JsonCParser()); // build the HTTP GET request and URL GenericData data = new GenericData(); data.put("longUrl", "http://www.google.com/"); JsonHttpContent content = new JsonHttpContent(); content.data = data; HttpRequest request = transport.buildPostRequest(); request.content = content; request.setUrl(GOOGL_URL); HttpResponse response; try { JSONObject json = request.execute().parseAs(JSONObject.class); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } 

当我执行上面的代码时，我得到下一个输出：

 Exception in thread "main" java.lang.IllegalArgumentException: data key not found at com.google.api.client.googleapis.json.JsonCParser.parserForResponse(JsonCParser.java:77) at com.google.api.client.googleapis.json.JsonCParser.parse(JsonCParser.java:47) at com.google.api.client.http.HttpResponse.parseAs(HttpResponse.java:261) at GoogleShortener.main(GoogleShortener.java:43) 

知道如何正确设置JsonCParser吗？

错误路径

一开始我没有正确设置请求内容。 正如@dwb所指出的，应该设置请求内容：

 GenericData data = new GenericData(); data.put("longUrl", "http://www.google.com/"); JsonHttpContent content = new JsonHttpContent(); content.data = data; request.content = content; 

如果未正确设置内容，则会出现下一个错误

com.google.api.client.http.HttpResponseException：411 GoogleShortener.main上的com.google.api.client.http.HttpRequest.execute（HttpRequest.java:209）所需的长度（GoogleShortener.java:32）

Answer 1

您需要将JSON内容添加到请求正文中，如下所示：

 GenericData data = new GenericData(); data.put("longUrl", "http://www.google.com/"); JsonHttpContent content = new JsonHttpContent(); content.data = data; request.content = content; 

对于响应，请尝试使用JsonHttpParser而不是JsonCParser。 您需要创建GenericJson的子类，其中包含对要检索的每个JSON属性都带有@Key批注的字段。 您可以使用response.parseAsString（）来查看所有可用的属性。

这是一个完整的工作示例：

 import com.google.api.client.googleapis.GoogleHeaders; import com.google.api.client.googleapis.GoogleTransport; import com.google.api.client.http.HttpRequest; import com.google.api.client.http.HttpResponse; import com.google.api.client.http.HttpTransport; import com.google.api.client.json.GenericJson; import com.google.api.client.json.JsonHttpContent; import com.google.api.client.json.JsonHttpParser; import com.google.api.client.util.GenericData; import com.google.api.client.util.Key; public class Shortener { public static final String GOOGL_URL = "https://www.googleapis.com/urlshortener/v1/url"; /** * @param args */ public static void main(String[] args) throws Exception { // setup up the HTTP transport HttpTransport transport = GoogleTransport.create(); // add default headers GoogleHeaders defaultHeaders = new GoogleHeaders(); transport.defaultHeaders = defaultHeaders; transport.defaultHeaders.put("Content-Type", "application/json"); transport.addParser(new JsonHttpParser()); // build the HTTP GET request and URL HttpRequest request = transport.buildPostRequest(); request.setUrl(GOOGL_URL); GenericData data = new GenericData(); data.put("longUrl", "http://www.google.com/"); JsonHttpContent content = new JsonHttpContent(); content.data = data; request.content = content; HttpResponse response = request.execute(); Result result = response.parseAs(Result.class); System.out.println(result.shortUrl); } public static class Result extends GenericJson { @Key("id") public String shortUrl; } } 

Answer 2

dwb给出的代码是正确的，但它使用的是谷歌客户端api的弃用方法。

当前库支持的实现如下：

 import java.util.HashMap; import java.util.Map; import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport; import com.google.api.client.http.GenericUrl; import com.google.api.client.http.HttpContent; import com.google.api.client.http.HttpHeaders; import com.google.api.client.http.HttpRequest; import com.google.api.client.http.HttpResponse; import com.google.api.client.http.HttpTransport; import com.google.api.client.http.json.JsonHttpContent; import com.google.api.client.json.GenericJson; import com.google.api.client.json.JsonObjectParser; import com.google.api.client.json.jackson.JacksonFactory; import com.google.api.client.util.Key; public class ShortenUrl { /** * @param args */ public static void main(String[] args) throws Exception { HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport(); HttpHeaders headers = new HttpHeaders(); JsonObjectParser parser = new JsonObjectParser(new JacksonFactory()); GenericUrl url = new GenericUrl("https://www.googleapis.com/urlshortener/v1/url"); Map json = new HashMap(); json.put("longUrl", "http://www.google.com/"); final HttpContent content = new JsonHttpContent(new JacksonFactory(), json); HttpRequest request = httpTransport.createRequestFactory().buildPostRequest(url, content); try { HttpResponse response = request.execute(); Result result = response.parseAs(Result.class); System.out.println(result.shortUrl); } catch (Exception e) { e.printStackTrace(); } } public static class Result extends GenericJson { @Key("id") public String shortUrl; } } 

注意：您应该使用您的Oauth 2.0凭据来使用google api服务。