[英]null pointer exception while accesing .net wcf services
我是Android的新手,我正嘗試從android訪問wcf服務,它給出了空指針異常,這是我的.net wcf服務IUserService
[ServiceContract]
public interface IUserService
{ [OperationContract]
[WebInvoke(Method="GET",ResponseFormat = WebMessageFormat.Json,UriTemplate = "GetName")]
string GetName();
}
這是我的UserService
public class UserService : IUserService
{
public string GetName()
{
return "Hello ! ";
}
}
這是我的xml
<service name="Lera.Template.Services.WCF.UserService">
<endpoint address="" binding="webHttpBinding" contract="Lera.Template.Services.WCF.IUserService"
behaviorConfiguration="httpBehavior">
<identity>
<dns value="localhost" />
</identity>
</endpoint>
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
<host>
<baseAddresses>
<add baseAddress="http://localhost:8888/Lera.Template.Services.WCF/UserService/" />
</baseAddresses>
</host>
</service>
我正在使用eclipse這是我的主要活動
public class MainActivity extends Activity {
private String values ="";
Button btn;
TextView tv;
private static String url = "http://192.168.12.146:8888/Lera.Template.Services.WCF/UserService/GetName";
private static final String StringVal = "StringValue";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);
try {
String temp = json.getString(StringVal);
Toast toast = Toast.makeText(this ,temp , Toast.LENGTH_SHORT);
toast.show();
}
catch (JSONException e) {
e.printStackTrace();
}
catch (Exception ex) {
Log.e("final:", ex.toString());
}
}
}
我正在使用json解析器類公共類JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet httpget = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpget);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
Log.e("connection" , e.toString());
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();//here json type is string
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
WCF服務在瀏覽器上工作正常,但是當我嘗試從我的Android應用程序訪問時,它給出了空指針異常
提供空指針異常的行是
HttpResponse httpResponse = httpClient.execute(httpget);
請幫助我解決這個問題,我已經嘗試了網上所有可用的方法,但仍然無法克服。
正如我提到的那樣,我更新了我的主要活動類,這是通過異步調用進行的主要活動,但例外是與網址的連接被拒絕
public class MainActivity extends Activity implements OnClickListener {
private String values ="";
Button btn;
TextView tv;
String uri = "http://192.168.0.144:8888/Lera.Template.Services.WCF/UserService/GetName";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn = (Button)this.findViewById(R.id.btnAccess);
tv = (TextView)this.findViewById(R.id.tvAccess);
btn.setOnClickListener(this);
}
@Override
public void onClick(View arg0) {
try
{
AsyncTaskExample task = new AsyncTaskExample(this);
task.execute("");
String test = values;
tv.setText(values);
} catch(Exception e)
{
Log.e("Click Exception: ", e.getMessage());
}
}
public class AsyncTaskExample extends AsyncTask<String, Void,String>
{
private String Result="";
//private final static String SERVICE_URI = "http://10.0.2.2:8889";
private final static String SERVICE_URI = "http://192.168.12.146:8888/Lera.Template.Services.WCF/UserService";
private MainActivity host;
public AsyncTaskExample(MainActivity host)
{
this.host = host;
}
public String GetSEssion(String URL)
{
boolean isValid = true;
if(isValid)
{
HttpClient client = new DefaultHttpClient();
//http://192.168.0.144:8888/Lera.Template.Services.WCF/UserService/
// HttpPost post = new HttpPost(uri);
HttpGet httpget = new HttpGet(uri);
httpget.setHeader("Accept", "application/json");
httpget.setHeader("Content-type", "application/json; charset=utf-8");
try
{
HttpResponse response = client.execute(httpget) ;
BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
String line ="";
while((line = rd.readLine()) != null)
{
System.out.println(line);
}
}catch(Exception e)
{
Log.e("Error:", e.getMessage());
}
}
return Result;
}
@Override
protected String doInBackground(String... arg0) {
android.os.Debug.waitForDebugger();
String t = GetSEssion(SERVICE_URI);
return t;
}
@Override
protected void onPostExecute(String result) {
// host.values = Result;
super.onPostExecute(result);
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
}
@Override
protected void onCancelled() {
// TODO Auto-generated method stub
super.onCancelled();
}
}
}
任何幫助將被申請。 謝謝。
否則,我可以給您以下建議:只需一個方法就不需要整個類(JSONParser)。 只需將方法和變量添加到MainActivity。
編輯:實際上您正在使用android設備或模擬器嗎? 如果您使用的是模擬器,則可以使用10.0.2.2訪問主機。 您可以將網址更改為http://10.0.2.2.146:8888 / Lera.Template.Services.WCF / UserService / GetName
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