[翻译]实例：在Android调用WCF服务

原文:http://fszlin.dymetis.com/post/2010/05/10/Comsuming-WCF-Services-With-Android.aspx

在移动设备中，使用XML传输可能会消耗更多的资源，Android没有提供任何组件来直接调用WCF，但是我们可以通过第三方的包（例如：org.apache.http，org.json）来相对简单的调用REST形式的WCF服务。

本文将演示如何创建REST形式的WCF服务和在Android上如何调用服务。

第一步，创建一个包含两个GET操作和一个POST操作的Service Contract。由于是通过JSON对象传输数据，这里需要指定Request和Response的数据格式为JSON。为了支持多个参数，还需要设置BodyStyle为WrappedRequest。

 1 namespace HttpWcfWeb
 2 {
 3     [ServiceContract(Namespace = "http://services.example.com")]
 4     public interface IVehicleService
 5     {
 6         [OperationContract]
 7         [WebGet(
 8             UriTemplate = "GetPlates",
 9             BodyStyle = WebMessageBodyStyle.WrappedRequest,
10             ResponseFormat = WebMessageFormat.Json,
11             RequestFormat = WebMessageFormat.Json)]
12         IList<string> GetPlates();
13  
14         [OperationContract]
15         [WebGet(UriTemplate = "GetVehicle/{plate}",
16             BodyStyle = WebMessageBodyStyle.WrappedRequest,
17             ResponseFormat = WebMessageFormat.Json,
18             RequestFormat = WebMessageFormat.Json)]
19         Vehicle GetVehicle(string plate);
20  
21         [OperationContract]
22         [WebInvoke(
23             Method = "POST",
24             UriTemplate = "SaveVehicle",
25             BodyStyle = WebMessageBodyStyle.WrappedRequest,
26             ResponseFormat = WebMessageFormat.Json,
27             RequestFormat = WebMessageFormat.Json)]
28         void SaveVehicle(Vehicle vehicle);
29     }
30 }

下一步，定义一个用于数据传输的对象，这个对象很简单。

 1 namespace HttpWcfWeb
 2 {
 3     [DataContract]
 4     public class Vehicle
 5     {
 6         [DataMember(Name = "year")]
 7         public int Year
 8         {
 9             get;
10             set;
11         }
12 
13         [DataMember(Name = "plate")]
14         public string Plate
15         {
16             get;
17             set;
18         }
19 
20         [DataMember(Name = "make")]
21         public string Make
22         {
23             get;
24             set;
25         }
26 
27         [DataMember(Name = "model")]
28         public string Model
29         {
30             get;
31             set;
32         }
33     }
34 }

现在，我们修改web.config文件，发布WCF服务。

<system.serviceModel>
  <behaviors>
    <endpointBehaviors>
      <behavior name="httpBehavior">
        <webHttp />
      </behavior>
    </endpointBehaviors>
    <serviceBehaviors>
      <behavior name="">
        <serviceMetadata httpGetEnabled="true" />
        <serviceDebug includeExceptionDetailInFaults="false" />
      </behavior>
    </serviceBehaviors>
  </behaviors>
  <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
    <services>
      <service name="HttpWcfWeb.VehicleService">
        <endpoint address=""
                     behaviorConfiguration="httpBehavior"
                     binding="webHttpBinding"
                     contract="HttpWcfWeb.IVehicleService" />
    </service>
  </services>
</system.serviceModel>

由于VS内置的开发服务器只能处理来自本机的请求，所以需要把服务部署到IIS。

另外，如果你在URL中使用主机名（比如：机器名）的话，你也许还需要在设备或模拟器中设置DNS，这样才可以解析主机名。方法是，进入“系统设置(Setting)”->无线网络设置（Wireless Control)->网络接入点，选择正在使用的那一个，填写代理和端口。

现在，我需要创建Android客户端来调用WCF服务。

在启动过程中，活动(Activity)调用IVehicleService.GetPlates方法填充Spinner。

当Load Vehicle按钮点击时，通过调用IVehicleService.GetVehicle方法得到Vehicle对象并填充到EditText中。

点击Save按钮时，将数据包装并提交到IVehicleService.SaveVehicle方法。

public class MainActivity extends Activity {

    private final static String SERVICE_URI = "http://lt0.studio.entail.ca:8080/VehicleService.svc";

    private Spinner plateSpinner;
    private EditText makeEdit;
    private EditText plateEdit;
    private EditText yearEdit;
    private EditText modelEdit;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        plateSpinner = (Spinner)findViewById(R.id.plate_spinner);
        makeEdit = (EditText)findViewById(R.id.make_edit);
        plateEdit = (EditText)findViewById(R.id.plate_edit);
        yearEdit = (EditText)findViewById(R.id.year_edit);
        modelEdit = (EditText)findViewById(R.id.model_edit);
    }
     
    @Override
    public void onResume() {
        super.onResume();

        // Invoke IVehicleService.GetPlates and populate plateSpinner
        refreshVehicles();
    }
}

在数据保存或者Activity被恢复(resumed)的时候会调用refreshVehicles方法，它向WCF服务发送一个Get请求，得到一个由JSON字符串表达的数据对象。

private void refreshVehicles() {
    try {

        // Send GET request to <service>/GetPlates
        HttpGet request = new HttpGet(SERVICE_URI + "/GetPlates");
        request.setHeader("Accept", "application/json");
        request.setHeader("Content-type", "application/json");

        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpResponse response = httpClient.execute(request);

        HttpEntity responseEntity = response.getEntity();
         
        // Read response data into buffer
        char[] buffer = new char[(int)responseEntity.getContentLength()];
        InputStream stream = responseEntity.getContent();
        InputStreamReader reader = new InputStreamReader(stream);
        reader.read(buffer);
        stream.close();

        JSONArray plates = new JSONArray(new String(buffer));

        // Reset plate spinner
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        for (int i = 0; i < plates.length(); ++i) {
            adapter.add(plates.getString(i));
        }
        plateSpinner.setAdapter(adapter);
         
    } catch (Exception e) {
        e.printStackTrace();
    }
}

onLoadVehicleClick 方法处理Load Vehicle 点击事件，和refreshVehicles 方法相似，它发送一个GET请求到WCF服务，通过plate number得到一个vehicle对象，但区别在于，它在结果处理中使用了JSONObject 转换，就像直接从WCF服务中拿到的vehicle对象一样。

public void onLoadVehicleClick(View button) {
    try {
        // Send GET request to <service>/GetVehicle/<plate>
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpGet request = new HttpGet(SERVICE_URI + "/GetVehicle/" + plateSpinner.getSelectedItem());

        request.setHeader("Accept", "application/json");
        request.setHeader("Content-type", "application/json");

        HttpResponse response = httpClient.execute(request);

        HttpEntity responseEntity = response.getEntity();

        // Read response data into buffer
        char[] buffer = new char[(int)responseEntity.getContentLength()];
        InputStream stream = responseEntity.getContent();
        InputStreamReader reader = new InputStreamReader(stream);
        reader.read(buffer);
        stream.close();

        JSONObject vehicle = new JSONObject(new String(buffer));

        // Populate text fields
        makeEdit.setText(vehicle.getString("make"));
        plateEdit.setText(vehicle.getString("plate"));
        modelEdit.setText(vehicle.getString("model"));
        yearEdit.setText(vehicle.getString("year"));

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

当Save按钮点击时，调用onSaveVehicleClick 方法。这个方法中简单的将所有的文本字段的值放入一个JSONObject对象，然后提交(POST)给WCF服务。注意所有的数据包装进了一个叫vehicle的对象，WCF收到后，会将其作为名称为vehicle的参数。

public void onSaveVehicleClick(View button) {

    try {

        Editable make = makeEdit.getText();
        Editable plate = plateEdit.getText();
        Editable model = modelEdit.getText();
        Editable year = yearEdit.getText();

        boolean isValid = true;

        // Data validation goes here

        if (isValid) {

            // POST request to <service>/SaveVehicle
            HttpPost request = new HttpPost(SERVICE_URI + "/SaveVehicle");
            request.setHeader("Accept", "application/json");
            request.setHeader("Content-type", "application/json");

            // Build JSON string
            JSONStringer vehicle = new JSONStringer()
                .object()
                    .key("vehicle")
                        .object()
                            .key("plate").value(plate)
                            .key("make").value(make)
                            .key("model").value(model)
                            .key("year").value(Integer.parseInt(year.toString()))
                        .endObject()
                    .endObject();
            StringEntity entity = new StringEntity(vehicle.toString());

            request.setEntity(entity);

            // Send request to WCF service
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpResponse response = httpClient.execute(request);

            Log.d("WebInvoke", "Saving : " + response.getStatusLine().getStatusCode());
             
            // Reload plate numbers
            refreshVehicles();
        }

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

最后，在AndroidManifest.xml中添加Internet的访问权限。

<uses-permission android:name="android.permission.INTERNET" />

DEMO可以运行。

posted @ 2011-12-16 17:16 一味阅读(14718) 评论(9) 编辑收藏举报

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[翻译]实例：在Android调用WCF服务

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