在 Android 中使用 JSON 时出错

Question

我在我的 Android 应用程序中使用 JSON 进行帐户注册时遇到问题。这是我调试后发现的问题部分：

// check for login response
                try {
                    if (json.getString(KEY_SUCCESS) != null) {
                        registerErrorMsg.setText("");
                        String res = json.getString(KEY_SUCCESS); 
                        if(Integer.parseInt(res) == 1){
                            // user successfully registered
                            // Store user details in SQLite Database
                            DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                            JSONObject json_user = json.getJSONObject("user");

                            // Clear all previous data in database
                            userFunction.logoutUser(getApplicationContext());
                            db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));                        
                            // Launch Dashboard Screen
                            Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
                            // Close all views before launching Dashboard
                            dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                            startActivity(dashboard);
                            // Close Registration Screen
                            finish();
                        }else{
                            // Error in registration
                            registerErrorMsg.setText("Error occured in registration");
                        }
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }

完整的 LogCat：

12-09 14:31:02.360: D/dalvikvm(5339): GC_EXTERNAL_ALLOC 释放 118K，52% 释放 2666K/5447K，外部 943K/1034K，暂停 30ms 12-09 14:31:08.735: W/System.err(5339): java.net.SocketException: 权限被拒绝 12-09 14:31:08.735: W/System.err(5339): at org.apache.harmony.luni.platform.OSNetworkSystem.socket(本机方法) 12-09 14:31:08.735: W/System.err(5339): 在 dalvik.system.BlockGuard$WrappedNetworkSystem.socket(BlockGuard.java:335) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.harmony.luni.net.PlainSocketImpl.create(PlainSocketImpl.java:216) 12-09 14:31:08.740: W/System.err(5339): 在 java.net.Socket.checkOpenAndCreate(Socket.java:821) 12-09 14:31:08.740: W/System.err(5339): 在 java.net.Socket.connect(Socket.java:967) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:156) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:359) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 12-09 14:31:08.740: W/System.err(5339): 在 org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 12-09 14:31:08.740: W/System.err(5339): 在 com.example.musicshare.library.JSONParser.getJSONFromUrl(JSONParser.java:42) 12-09 14:31:08.740: W/System.err(5339): 在 com.example.musicshare.library.UserFunctions.registerUser(UserFunctions.java:59) 12-09 14:31:08.740: W/System.err(5339): 在 com.example.musicshare.RegisterActivity$1.onClick(RegisterActivity.java:55) 12-09 14:31:08.740: W/System.err(5339): 在 android.view.View.performClick(View.java:2538) 12-09 14:31:08.740: W/System.err(5339): 在 android.view.View$PerformClick.run(View.java:9152) 12-09 14:31:08.740: W/System.err(5339): 在 android.os.Handler.handleCallback(Handler.java:587) 12-09 14:31:08.740: W/System.err(5339): 在 android.os.Handler.dispatchMessage(Handler.java:92) 12-09 14:31:08.740: W/System.err(5339): 在 android.os.Looper.loop(Looper.java:123) 12-09 14:31:08.760: W/System.err(5339): 在 android.app.ActivityThread.main(ActivityThread.java:3691) 12-09 14:31:08.760: W/System.err(5339): 在 java.lang.reflect.Method.invokeNative(Native Method) 12-09 14:31:08.760: W/System.err(5339): 在 java.lang.reflect.Method.invoke(Method.java:507) 12-09 14:31:08.760: W/System.err(5339): 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847) 12-09 14:31:08.760: W/System.err(5339): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605) 12-09 14:31:08.760: W/System.err(5339): 在 dalvik.system.NativeStart.main(Native Method) 12-09 14:31:08.760：E/Buffer 错误（5339）：错误转换结果 java.lang.NullPointerException 12-09 14:31:08.760: E/JSON Parser(5339): 解析数据时出错 org.json.JSONException: 在字符 0 处输入结束 12-09 14:31:08.760: D/AndroidRuntime(5339): 关闭虚拟机 12-09 14:31:08.760: W/dalvikvm(5339): threadid=1: 线程以未捕获的异常退出 (group=0x4001e578) 12-09 14:31:08.765：E/AndroidRuntime（5339）：致命异常：主要 12-09 14:31:08.765: E/AndroidRuntime(5339): java.lang.NullPointerException 12-09 14:31:08.765: E/AndroidRuntime(5339): at com.example.musicshare.RegisterActivity$1.onClick(RegisterActivity.java:59) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 android.view.View.performClick(View.java:2538) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 android.view.View$PerformClick.run(View.java:9152) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 android.os.Handler.handleCallback(Handler.java:587) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 android.os.Handler.dispatchMessage(Handler.java:92) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 android.os.Looper.loop(Looper.java:123) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 android.app.ActivityThread.main(ActivityThread.java:3691) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 java.lang.reflect.Method.invokeNative(Native Method) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 java.lang.reflect.Method.invoke(Method.java:507) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847) 12-09 14:31:08.765: E/AndroidRuntime(5339): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605) 12-09 14:31:08.765：E/AndroidRuntime（5339）：在 dalvik.system.NativeStart.main（本机方法） 12-09 14:31:08.800: D/dalvikvm(5339): GC_CONCURRENT freed 208K, 51% free 2789K/5639K, external 1350K/1690K, paused 3ms+4ms

这是我的 JSON 解析代码：

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;

    }
}

Answer 1

如日志所说：

java.net.SocketException: Permission denied

确保您已在AndroidMainfest.xml 中添加了所有必需的权限，包括 Internet 访问权限：

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