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每當我跑在我的MainActivity點擊列表項目啓動DetailsActivity即是假設diaply關於選擇列表中的一點信息項目（名稱，描述）的logcat引發以下我：NetworkOnMainThereadException約一個列表項顯示細節
E/AndroidRuntime（678）：在 com.example.myfirstapp.JSONParser.makeHttpRequest（JSONParser.java:61） E/AndroidRuntime（678 ）：在 com.example.myfirstapp.DetailsActivity $ GetProductDetails $ 1.run（Detail sActivity.java:93）
線61（JSONParser）：HttpResponse httpResponse = httpClient.execute(httpGet); 線93（DetailsActivity）：JSONObject json = jsonParser.makeHttpRequest( url_car_details, "GET", params);
DetailsActivity：
package com.example.myfirstapp;
/*
* ...imports...
*/
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET method
public JSONObject makeHttpRequest(String url, String method, List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if(method == "POST"){
// request method is POST
// 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();
}else if(method == "GET"){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
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();
}
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();
} 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;
}
}
JSONParser：
package com.example.myfirstapp;
/*
* ...imports...
*/
public class DetailsActivity extends Activity {
TextView lblTitle;
TextView lblDesc;
String id;
// Progress Dialog
private ProgressDialog pDialog;
// JSON parser class
JSONParser jsonParser = new JSONParser();
// single product url
private static final String url_car_details = "http://10.0.2.2/webservice/get_car_details.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_CAR = "car";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_DESC = "description";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
// getting product details from intent
Intent i = getIntent();
// getting product id (pid) from intent
id = i.getStringExtra(TAG_ID);
// Getting complete product details in background thread
new GetProductDetails().execute();
}
/**
* Background Async Task to Get complete product details
* */
class GetProductDetails extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(DetailsActivity.this);
pDialog.setMessage("Loading car details. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
/**
* Getting product details in background thread
* */
protected String doInBackground(String... params) {
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
// Check for success tag
int success;
try {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("id", id));
// getting product details by making HTTP request
// Note that product details url will use GET request
JSONObject json = jsonParser.makeHttpRequest(
url_car_details, "GET", params);
// check your log for json response
Log.d("Single Car Details", json.toString());
// json success tag
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// successfully received product details
JSONArray productObj = json
.getJSONArray(TAG_CAR); // JSON Array
// get first product object from JSON Array
JSONObject product = productObj.getJSONObject(0);
// product with this pid found
// Edit Text
lblTitle = (TextView) findViewById(R.id.lblTitle);
lblDesc = (TextView) findViewById(R.id.lblDesc);
// display product data in EditText
lblTitle.setText(product.getString(TAG_NAME));
lblDesc.setText(product.getString(TAG_DESCRIPTION));
}else{
// product with pid not found
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once got all details
pDialog.dismiss();
}
}
}
那麼'runOnUiThread'的名字就是這麼做的，它在主UI線程上運行了一些代碼。所以你基本上在主UI線程上運行'doInBackground'方法中的所有代碼（這可能會阻塞UI線程）。 – Luksprog