使用Android PHP和JSON處理logcat時出錯，

Question

我有一個PHP文件返回JSON數組，這裏是我的代碼連接到該PHP並在jsonArray中獲取響應。 這是正確的嗎？

JSON響應從PHP

[{ 「ID」： 「1」， 「名」： 「Swapnil」， 「年齡」： 「21」， 「地址」： 「Nerul」， 「移動」 ： 「4475478983」}]

activity_main.xml中

RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" 
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"> 


    <Button 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Display All" 
     android:id="@+id/send" 
     android:layout_marginTop="139dp" 
     android:layout_alignParentTop="true" 
     android:layout_centerHorizontal="true" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/display" 
     android:layout_centerVertical="true" 
     android:layout_centerHorizontal="true" /> 
</RelativeLayout> 

---

MainActivity.java

package com.lnt.swapnil; 

import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.Button; 
import android.widget.TextView; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

public class MainActivity extends AppCompatActivity { 

    private Button sendButton; 
    private TextView displayTextView; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     sendButton = (Button)findViewById(R.id.send); 
     displayTextView = (TextView)findViewById(R.id.display); 
    } 

    public void onClick(View view) 
    { 
     PHPConnector obj = new PHPConnector(); 
     JSONArray myArray = obj.getAll(); 
     setDisplayTextView(myArray); 
    } 

    public void setDisplayTextView(JSONArray jsonArray) 
    { 
     String s = ""; 

     for (int i=0;i<jsonArray.length();i++) 
     { 
      JSONObject jsonObject = null; 
      try { 
       jsonObject = jsonArray.getJSONObject(i); 
       s = s + "Id : "+jsonObject.getString("id")+"\n\n" 
         + "Name : "+jsonObject.getString("name")+"\n\n" 
         + "Age : "+jsonObject.getString("age")+"\n\n" 
         + "Address : "+jsonObject.getString("address")+"\n\n" 
         + "Mobile : "+jsonObject.getString("mobile")+"\n\n"; 
       displayTextView.setText(s); 

      } 
      catch (JSONException exp) 
      { 

      } 
     } 
    } 

} 




****************************************************************************** 


package com.lnt.swapnil; 

    import android.util.Log; 

    import org.json.JSONArray; 

    import java.io.BufferedReader; 
    import java.io.InputStream; 
    import java.io.InputStreamReader; 
    import java.net.HttpURLConnection; 
    import java.net.URL; 

    /** 
    * Created by SWAPNIL on 20-08-2015. 
    */ 
    public class PHPConnector { 
    private JSONArray jsonArray; 

     public JSONArray getAll() 
     { 
     try { 
      URL url = new URL("http://127.0.0.1/Android/test.php"); 
      HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); 
      urlConnection.setRequestMethod("POST"); 

      InputStream is = urlConnection.getInputStream(); 
      BufferedReader streamReader = new BufferedReader(new InputStreamReader(is, "UTF-8")); 
      StringBuilder responseStrBuilder = new StringBuilder(); 

      String inputStr; 
      while ((inputStr = streamReader.readLine()) != null) 
       responseStrBuilder.append(inputStr); 

      jsonArray = new JSONArray(responseStrBuilder.toString()); 

     } 
     catch (Exception e) 
     { 
      e.getMessage(); 
      Log.i("Exception : ",e.getMessage()); 

     } 
      return jsonArray; 
     } 
    } 

*************************************************************************** 

**GetMember.java** 

package com.lnt.swapnil; 

import android.os.AsyncTask; 

import org.json.JSONArray; 

/** 
* Created by SWAPNIL on 20-08-2015. 
*/ 
public class GetMembers extends AsyncTask<PHPConnector,Long,JSONArray> { 
    @Override 
    protected JSONArray doInBackground(PHPConnector... phpConnectors) { 
     return phpConnectors[0].getAll(); 
    } 


} 

---

** ** manifest.xml中

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.lnt.swapnil" > 
<uses-permission android:name="android.permission.INTERNET"/> 
    <application 
     android:allowBackup="true" 
     android:icon="@mipmap/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name=".MainActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
    </application> 

</manifest> 

---

**登錄貓**

Process: com.lnt.swapnil, PID: 2288 
    java.lang.IllegalStateException: Could not execute method of the activity 
      at android.view.View$1.onClick(View.java:4007) 
      at android.view.View.performClick(View.java:4756) 
      at android.view.View$PerformClick.run(View.java:19749) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5221) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
    Caused by: java.lang.reflect.InvocationTargetException 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at android.view.View$1.onClick(View.java:4002) 
            at android.view.View.performClick(View.java:4756) 
            at android.view.View$PerformClick.run(View.java:19749) 
            at android.os.Handler.handleCallback(Handler.java:739) 
            at android.os.Handler.dispatchMessage(Handler.java:95) 
            at android.os.Looper.loop(Looper.java:135) 
            at android.app.ActivityThread.main(ActivityThread.java:5221) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at java.lang.reflect.Method.invoke(Method.java:372) 
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
    Caused by: java.lang.NullPointerException: println needs a message 
      at android.util.Log.println_native(Native Method) 
      at android.util.Log.i(Log.java:160) 
      at com.lnt.swapnil.PHPConnector.getAll(PHPConnector.java:40) 
      at com.lnt.swapnil.MainActivity.onClick(MainActivity.java:30) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at java.lang.reflect.Method.invoke(Method.java:372) 
            at android.view.View$1.onClick(View.java:4002) 
            at android.view.View.performClick(View.java:4756) 
            at android.view.View$PerformClick.run(View.java:19749) 
            at android.os.Handler.handleCallback(Handler.java:739) 
            at android.os.Handler.dispatchMessage(Handler.java:95) 
            at android.os.Looper.loop(Looper.java:135) 
            at android.app.ActivityThread.main(ActivityThread.java:5221) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at java.lang.reflect.Method.invoke(Method.java:372) 
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
08-21 23:00:10.317 2288-2295/com.lnt.swapnil W/art﹕ Suspending all threads took: 44.072ms 

Answer 1

補充一點：

 urlConnection.setDoInput(true); 
     urlConnection.setDoOutput(true); 
     urlConnection.connect(); 

後

URL url = new URL("http://127.0.0.1/Android/test.php"); 
      HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); 
      urlConnection.setRequestMethod("POST");