Restlet无法使用Android获取数据

Question

我将使用 official OData 页面的 Restlet 获取数据： http://services.odata.org/OData/OData.svc/

我已经开始了这个教程： http://weblogs.asp.net/uruit/archive/2011/09/13/accessing-odata-from-android-using-restlet.aspx

我的问题是，最后，他无法获取元数据。但首先：

当我尝试生成 Restleg-Files（第 5 点）时，控制台显示了这一点，其中 date 行是 红色：

---------------------------
OData client code generator
---------------------------
step 1 - check parameters
step 2 - check the ouput directory
step 3 - get the metadata descriptor
Nov 28, 2011 3:12:46 PM org.restlet.engine.http.connector.HttpClientHelper start
Information: Starting the default HTTP client
Nov 28, 2011 3:12:48 PM org.restlet.ext.odata.Service getMetadata
Information: Get the metadata for http://services.odata.org/OData/OData.svc/ at http://services.odata.org/OData/OData.svc/$metadata
Nov 28, 2011 3:12:48 PM org.restlet.engine.http.connector.HttpClientHelper start
Information: Starting the default HTTP client
step 4 - generate source code
Nov 28, 2011 3:12:48 PM org.restlet.engine.http.connector.HttpClientHelper start
Information: Starting the default HTTP client
Nov 28, 2011 3:12:49 PM org.restlet.ext.odata.Service getMetadata
Information: Get the metadata for http://services.odata.org/OData/OData.svc/ at http://services.odata.org/OData/OData.svc/$metadata
Nov 28, 2011 3:12:49 PM org.restlet.engine.http.connector.HttpClientHelper start
Information: Starting the default HTTP client
Nov 28, 2011 3:12:49 PM org.restlet.engine.http.connector.HttpClientHelper stop
Information: Stopping the default HTTP client
Nov 28, 2011 3:12:50 PM org.restlet.engine.http.connector.HttpClientHelper stop
Information: Stopping the default HTTP client
The source code has been generated in directory: C:\Projects\MyProjects\Android App\main\app\Java\Workspace\TestOData2\src

所以文件生成了，但是当我在教程中继续前进时，将类复制到我的Android项目中，导入库并编写以下代码，然后我得到了错误如下。

public ArrayList<Product> getOdataSampleProduct(String zip) {           

    ODataDemoService proxy = new OdataDemoService();  

    try {       
        Query<Product> query = proxy.createProductQuery("Products(1)");
        Product product = query.iterator().next(); //breaks here
        Log.d("Test","id: "+product.getId()); //isn't logged

    }
    catch(Exception e) {
            //is catched before query.iterator().next()
    };

所以，LogCat 显示此错误（第 3 行是红色）：

...
11-29 09:01:01.039: INFO/org.restlet(700): Starting the default HTTP client
11-29 09:01:01.329: INFO/org.restlet(700): A recoverable error was detected (1001), attempting again in 2000 ms.
11-29 09:01:05.589: ERROR/org.restlet(700): Can't get the metadata for http://services.odata.org/OData/OData.svc/ (response's status: Communication Error (1001) - services.odata.org)
11-29 09:01:05.629: INFO/org.restlet(700): Get the metadata for http://services.odata.org/OData/OData.svc/ at http://services.odata.org/OData/OData.svc/$metadata
11-29 09:01:06.200: INFO/org.restlet(700): Starting the default HTTP client
11-29 09:01:06.329: INFO/org.restlet(700): A recoverable error was detected (1001), attempting again in 2000 ms.
11-29 09:01:06.359: DEBUG/dalvikvm(408): GC_EXPLICIT freed 3K, 5% free 6308K/6595K, paused 3ms+2ms
11-29 09:01:08.409: INFO/org.restlet(700): A recoverable error was detected (1001), attempting again in 2000 ms.
11-29 09:01:10.499: ERROR/org.restlet(700): Can't get the metadata for http://services.odata.org/OData/OData.svc/ (response's status: Communication Error (1001) - services.odata.org)
11-29 09:01:10.579: WARN/org.restlet(700): Can't parse the content of http://services.odata.org/OData/OData.svc/Products(1)
11-29 09:01:10.579: WARN/org.restlet(700): java.lang.Exception: Can't execute the query without the service's metadata.
11-29 09:01:10.579: WARN/org.restlet(700):     at org.restlet.ext.odata.Query.execute(Query.java:347)
11-29 09:01:10.579: WARN/org.restlet(700):     at org.restlet.ext.odata.Query.iterator(Query.java:642)
11-29 09:01:10.579: WARN/org.restlet(700):     at my.folder.testApp.MapView.getData(MapView.java:77)
11-29 09:01:10.579: WARN/org.restlet(700):     at my.folder.testApp.MapView.onCreate(MapView.java:141)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.app.Activity.performCreate(Activity.java:4397)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.app.ActivityThread.access$500(ActivityThread.java:122)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.os.Looper.loop(Looper.java:132)
11-29 09:01:10.579: WARN/org.restlet(700):     at android.app.ActivityThread.main(ActivityThread.java:4123)
11-29 09:01:10.579: WARN/org.restlet(700):     at java.lang.reflect.Method.invokeNative(Native Method)
11-29 09:01:10.579: WARN/org.restlet(700):     at java.lang.reflect.Method.invoke(Method.java:491)
11-29 09:01:10.579: WARN/org.restlet(700):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
11-29 09:01:10.579: WARN/org.restlet(700):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
11-29 09:01:10.579: WARN/org.restlet(700):     at dalvik.system.NativeStart.main(Native Method)

似乎元数据存在问题，但我不知道是什么问题。 有什么想法吗？

Answer 1

您能否尝试为 Apache HTTP 客户端注册 Restlet 扩展而不是默认的内部连接器？

查看此页面了解详情： http://wiki.restlet.org/docs_2.1/13-restlet/275-restlet/266-restlet.html

Answer 2

至少，我找到了一个解决方案： 我不得不将查询放入AsyncTask。 之前，在 UI 线程中，查询没有时间得到答案。

所以我把它放到了doInBackground。