我想检查localhost中是否存在位置，如果该位置存在与否，它将响应系统并获取消息（toast），但我的应用程序在我运行时强行停止，我不知道为什么，并且我的代码在哪里？
这是我的主要代码
public class SetLocationActivity extends Activity implements OnClickListener{
private JSONParser jsonParser;
private static String ServerURL="http://myurl/asset";
private static String location_tag ="location";
private String stats = null;
Button go;
EditText location;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_set_location);
location = (EditText)findViewById(R.id.edit_location);
go = (Button)findViewById(R.id.btn_go);
go.setOnClickListener(this);
}
@Override
public void onClick(View view) {
//Call class JSONParser
jsonParser = new JSONParser();
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("tag",location_tag));
params.add(new BasicNameValuePair("loc",location.getText().toString()));
JSONObject json = jsonParser.getJSONFromUrl(ServerURL, params);
try {
Context context = getApplicationContext();
int duration = Toast.LENGTH_SHORT;
stats = json.getString("lo");
if(stats != null) {
CharSequence text = "List Location in"+stats;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
} else {
CharSequence text = "Location not found";
Toast toast = Toast.makeText(context, text, duration);
toast.show();
}
}catch(JSONException e) {
//TODO Auto-Generated catch block
e.printStackTrace();
}
}
这是我的JSONParser代码
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json ="";
//Constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url, List<NameValuePair> params) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
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();
Log.e("JSON", json);
} 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;
}
}
这是我的logcat
01-05 16:37:23.382: E/AndroidRuntime(1096): FATAL EXCEPTION: main
01-05 16:37:23.382: E/AndroidRuntime(1096): android.os.NetworkOnMainThreadException
01-05 16:37:23.382: E/AndroidRuntime(1096): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
01-05 16:37:23.382: E/AndroidRuntime(1096): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
01-05 16:37:23.382: E/AndroidRuntime(1096): at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
01-05 16:37:23.382: E/AndroidRuntime(1096): at libcore.io.IoBridge.connect(IoBridge.java:112)
01-05 16:37:23.382: E/AndroidRuntime(1096): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
01-05 16:37:23.382: E/AndroidRuntime(1096): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
01-05 16:37:23.382: E/AndroidRuntime(1096): at java.net.Socket.connect(Socket.java:842)
01-05 16:37:23.382: E/AndroidRuntime(1096): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
01-05 16:37:23.382: E/AndroidRuntime(1096): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
01-05 16:37:23.382: E/AndroidRuntime(1096): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
01-05 16:37:23.382: E/AndroidRuntime(1096): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
01-05 16:37:23.382: E/AndroidRuntime(1096): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
01-05 16:37:23.382: E/AndroidRuntime(1096): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
01-05 16:37:23.382: E/AndroidRuntime(1096): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
01-05 16:37:23.382: E/AndroidRuntime(1096): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
01-05 16:37:23.382: E/AndroidRuntime(1096): at com.example.assetscanner.JSONParser.getJSONFromUrl(JSONParser.java:84)
01-05 16:37:23.382: E/AndroidRuntime(1096): at com.example.assetscanner.SetLocationActivity.onClick(SetLocationActivity.java:54)
01-05 16:37:23.382: E/AndroidRuntime(1096): at android.view.View.performClick(View.java:4162)
01-05 16:37:23.382: E/AndroidRuntime(1096): at android.view.View$PerformClick.run(View.java:17082)
01-05 16:37:23.382: E/AndroidRuntime(1096): at android.os.Handler.handleCallback(Handler.java:615)
01-05 16:37:23.382: E/AndroidRuntime(1096): at android.os.Handler.dispatchMessage(Handler.java:92)
01-05 16:37:23.382: E/AndroidRuntime(1096): at android.os.Looper.loop(Looper.java:137)
01-05 16:37:23.382: E/AndroidRuntime(1096): at android.app.ActivityThread.main(ActivityThread.java:4867)
01-05 16:37:23.382: E/AndroidRuntime(1096): at java.lang.reflect.Method.invokeNative(Native Method)
01-05 16:37:23.382: E/AndroidRuntime(1096): at java.lang.reflect.Method.invoke(Method.java:511)
01-05 16:37:23.382: E/AndroidRuntime(1096): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1007)
01-05 16:37:23.382: E/AndroidRuntime(1096): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:774)
01-05 16:37:23.382: E/AndroidRuntime(1096): at dalvik.system.NativeStart.main(Native Method)
在这个logcat上面的主要错误我认为是“android.os.NetworkOnMainThreadException”，我搜索了这个错误，有人说使用AsyncTask或StrictMode来解决这个问题。但我不知道我在哪里放置AsyncTask代码以及如何使用？
我想知道我的代码在哪里出错，它是在主代码或JSONParser代码上。
请帮我解决这个问题，谢谢你的关注
答案 0 :(得分：1)
对于长时间的操作，我们必须使用ui线程中的另一个线程。使用Async Task fornetwork relation opeartion。它不会阻止你的ui更新。
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