我的Android應用程序httpGet錯誤

Question

基本上，我的Android應用程序遇到了一個奇怪的問題，它應該獲取一個JSON數組並打印一些值，該類如下所示：

ShowComedianActivity.class

package com.example.connecttest;

public class ShowComedianActivity extends Activity{

    TextView name;
    TextView add;
    TextView email;
    TextView tel;

    String id;

    // Progress Dialog
    private ProgressDialog pDialog;

    //JSON Parser class
    JSONParser jsonParser = new JSONParser();

    // Single Comedian url
    private static final String url_comedian_details = "http://86.9.71.17/connect/get_comedian_details.php";


    // JSON Node names
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_COMEDIAN = "comedian";
    private static final String TAG_ID = "id";
    private static final String TAG_NAME = "name";
    private static final String TAG_ADDRESS = "address";
    private static final String TAG_EMAIL = "email";
    private static final String TAG_TEL = "tel";

    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.show_comedian);

        // Getting Comedian Details from intent
        Intent i = getIntent();

        // Getting id from intent
        id = i.getStringExtra(TAG_ID);

        new GetComedianDetails().execute();

    }

    class GetComedianDetails extends AsyncTask<String, String, String>{

        protected void onPreExecute(){
            super.onPreExecute();
            pDialog = new ProgressDialog(ShowComedianActivity.this);
            pDialog.setMessage("Fetching Comedian details. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        @Override
        protected String doInBackground(String... params) {

            runOnUiThread(new Runnable(){
                public void run(){
                    int success;
                    try{
                        //Building parameters
                        List<NameValuePair> params = new ArrayList<NameValuePair>();
                        params.add(new BasicNameValuePair("id",id));

                        // Getting comedian details via HTTP request
                        // Uses a GET request

                        JSONObject json = jsonParser.makeHttpRequest(url_comedian_details, "GET", params);
                        // Check Log for json response
                        Log.d("Single Comedian details", json.toString());

                        //JSON Success tag
                        success = json.getInt(TAG_SUCCESS);
                        if(success == 1){
                            // Succesfully received product details
                            JSONArray comedianObj = json.getJSONArray(TAG_COMEDIAN); //JSON Array

                            // get first comedian object from JSON Array
                            JSONObject comedian = comedianObj.getJSONObject(0);

                            // comedian with id found
                            name = (TextView) findViewById(R.id.name);
                            add = (TextView) findViewById(R.id.add);
                            email = (TextView) findViewById(R.id.email);
                            tel = (TextView) findViewById(R.id.tel);

                            // Set text to details
                            name.setText(comedian.getString(TAG_NAME));
                            add.setText(comedian.getString(TAG_ADDRESS));
                            email.setText(comedian.getString(TAG_EMAIL));
                            tel.setText(comedian.getString(TAG_TEL));

                        }

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

            return null;
        }

    }


}

我的JSON Parser類如下所示：

package com.example.connecttest;

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;

    }
}

現在，當我運行調試時，它正在查詢URL末尾帶有？id = 1的正確地址，並且當我導航到該URL時，將得到以下JSON數組：

{"success":1,"comedian":[{"id":"1","name":"Michael Coombes","address":"5 Trevethenick Road","email":"mc6415@gmail.com","tel":"xxxxxxxxxxxx"}]}

但是我的應用程序崩潰了，日志記錄報告看起來像這樣：

03-22 02:05:02.140: E/Trace(3776): error opening trace file: No such file or directory (2)
03-22 02:05:04.590: E/AndroidRuntime(3776): FATAL EXCEPTION: main
03-22 02:05:04.590: E/AndroidRuntime(3776): android.os.NetworkOnMainThreadException
03-22 02:05:04.590: E/AndroidRuntime(3776):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at libcore.io.IoBridge.connect(IoBridge.java:112)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at java.net.Socket.connect(Socket.java:842)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at com.example.connecttest.JSONParser.makeHttpRequest(JSONParser.java:62)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at com.example.connecttest.ShowComedianActivity$GetComedianDetails$1.run(ShowComedianActivity.java:89)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at android.os.Handler.handleCallback(Handler.java:615)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at android.os.Handler.dispatchMessage(Handler.java:92)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at android.os.Looper.loop(Looper.java:137)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at android.app.ActivityThread.main(ActivityThread.java:4745)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at java.lang.reflect.Method.invokeNative(Native Method)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at java.lang.reflect.Method.invoke(Method.java:511)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-22 02:05:04.590: E/AndroidRuntime(3776):     at dalvik.system.NativeStart.main(Native Method)

從這個我猜錯誤是在jsonParser.makeHttpRequest中，但是我無法終生弄清楚出了什么問題，並希望有人比我能照亮我。

Answer 1

您正在獲取android.os.NetworkOnMainThreadException，因為您“試圖在其主線程上執行聯網操作”。 AsyncTask是一個線程，因此刪除：

 runOnUiThread(new Runnable(){
                public void run(){

和右括號。

Answer 2

首先，記住要實際讀取堆棧跟蹤，答案在第一行。 當在嚴格模式下運行你的App（我認為Android的新版本默認情況下這樣做），Android將拋出NetworkOnMainThreadException ，如果你嘗試做UI線程上的任何網絡電話，因為你不希望阻止UI線程。

E/AndroidRuntime(3776): android.os.NetworkOnMainThreadException
E/AndroidRuntime(3776):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)

在跟蹤中查找導致問題的代碼：

E/AndroidRuntime(3776):     at com.example.connecttest.JSONParser.makeHttpRequest(JSONParser.java:62)
E/AndroidRuntime(3776):     at com.example.connecttest.ShowComedianActivity$GetComedianDetails$1.run(ShowComedianActivity.java:89)

這是實際的行：

JSONObject json = jsonParser.makeHttpRequest(url_comedian_details, "GET", params);

經過檢查，您實際上是在doInBackground運行網絡調用， doInBackground在主線程（您要進行網絡調用的地方）上運行（因為您可以阻塞所有想要的線程）。 但是，您是在runOnUiThread內運行網絡調用，因此您需要轉回原位並在UI線程上運行網絡調用，然后Android引發NetworkOnMainThreadException 。

我建議您刪除runOnUiThread塊，因為這是一種不好的做法，並將您的請求參數傳遞給AsyncTask 。

有關錯誤的更多信息- 如何修復android.os.NetworkOnMainThreadException？ 。