轉換結果java.lang.NullPointerException時出錯，並且解析數據org.json.JSONException時出錯：字符0的輸入結束

Question

您好，我是Android的新手，我目前正在使用MySql，PHP和JSON開發一個簡單的登錄和注冊android應用。 我已經在xampp（本地服務器）中創建了一個數據庫和表。 每當我嘗試注冊時，都會遇到很多錯誤。 已經有類似的問題，但是答案並沒有幫助我。 提前致謝。

這是我的代碼

1. JSONParser

    import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import java.util.List; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.utils.URLEncodedUtils; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONException; import org.json.JSONObject; import android.util.Log; public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } public JSONObject getJSONFromUrl(String url) { // Making HTTP request try { // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); 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(); } 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; } // function get json from url // by making HTTP POST or GET mehtod 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; } } 

2. 注冊.java

     import android.app.Activity; import android.os.Bundle; import java.util.ArrayList; import java.util.List; import org.apache.http.NameValuePair; import org.apache.http.message.BasicNameValuePair; import org.json.JSONException; import org.json.JSONObject; import android.app.ProgressDialog; import android.content.Intent; import android.os.AsyncTask; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; // Creating the Java class public class Register extends Activity implements OnClickListener{ // Creating variables for username and password... private EditText user,pass; private Button register; // Creating the progressDialog... private ProgressDialog pDialog; // Creating reference for the JSONParser... JSONParser jsonparser = new JSONParser(); // Getting the url to run the php register script.. // Here I am using a localserver since I dont have access to a real server.. private static final String LOGIN_URL = "http://http://127.0.0.1/webservice/register.php"; // Creating ids for messages... private static final String TAG_SUCCESS = "success"; private static final String TAG_MESSAGE = "message"; // Creating the onCreate method... @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.register); // getting references for the username,password and the button elements user = (EditText) findViewById(R.id.get_username); pass = (EditText) findViewById(R.id.get_password); register = (Button) findViewById(R.id.submit); // Creating onClickListener for the button... register.setOnClickListener(this); } @Override public void onClick(View v) { // getting method for create new user... new CreateUser().execute(); Intent intent = new Intent(this, Usersuccess.class); } // Creating a new class called CreateUser... class CreateUser extends AsyncTask<String, String, String>{ /** * Before starting background thread Show Progress Dialog * */ boolean failure = false; @Override protected void onPreExecute() { super.onPreExecute(); pDialog = new ProgressDialog(Register.this); pDialog.setMessage("Creating User..."); pDialog.setIndeterminate(false); pDialog.setCancelable(true); pDialog.show(); } @Override protected String doInBackground(String... params) { // Check for success tag int success; String username = user.getText().toString(); String password = pass.getText().toString(); try { // Building Parameters List<NameValuePair> params1 = new ArrayList<NameValuePair>(); params1.add(new BasicNameValuePair("username", username)); params1.add(new BasicNameValuePair("password", password)); Log.d("request!", "starting"); //Posting user data to script JSONObject json = jsonparser.makeHttpRequest( LOGIN_URL, "POST", params1); // full json response Log.d("Login attempt", json.toString()); // json success element success = json.getInt(TAG_SUCCESS); if (success == 1) { Log.d("User Created!", json.toString()); finish(); return json.getString(TAG_MESSAGE); }else{ Log.d("Login Failure!", json.getString(TAG_MESSAGE)); return json.getString(TAG_MESSAGE); } } 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 product deleted pDialog.dismiss(); if (file_url != null){ Toast.makeText(Register.this, file_url, Toast.LENGTH_LONG).show(); } } } } 

3. Login.java

    import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; //Creating the class that extends the Activity class public class LoginScreen extends Activity implements OnClickListener{ @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.login_screen); Button Signup = (Button) findViewById(R.id.signup); Signup.setOnClickListener(this); } @Override public void onClick(View v) { // Creating intent for Signup process.. Intent i = new Intent(LoginScreen.this,Register.class); startActivity(i); } } 

這是我的日志：

 10-31 12:45:28.441: D/request!(359): starting 10-31 12:45:30.041: W/System.err(359): java.net.UnknownHostException: http 10-31 12:45:30.041: W/System.err(359): at java.net.InetAddress.lookupHostByName(InetAddress.java:506) 10-31 12:45:30.051: W/System.err(359): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:294) 10-31 12:45:30.051: W/System.err(359): at java.net.InetAddress.getAllByName(InetAddress.java:256) 10-31 12:45:30.051: W/System.err(359): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:136) 10-31 12:45:30.051: W/System.err(359): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 10-31 12:45:30.061: W/System.err(359): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 10-31 12:45:30.061: W/System.err(359): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:359) 10-31 12:45:30.071: W/System.err(359): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 10-31 12:45:30.071: W/System.err(359): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 10-31 12:45:30.080: W/System.err(359): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 10-31 12:45:30.080: W/System.err(359): at com.augustasoftsol.gmoapp.JSONParser.makeHttpRequest(JSONParser.java:96) 10-31 12:45:30.080: W/System.err(359): at com.augustasoftsol.gmoapp.Register$CreateUser.doInBackground(Register.java:99) 10-31 12:45:30.080: W/System.err(359): at com.augustasoftsol.gmoapp.Register$CreateUser.doInBackground(Register.java:1) 10-31 12:45:30.091: W/System.err(359): at android.os.AsyncTask$2.call(AsyncTask.java:185) 10-31 12:45:30.101: W/System.err(359): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306) 10-31 12:45:30.101: W/System.err(359): at java.util.concurrent.FutureTask.run(FutureTask.java:138) 10-31 12:45:30.101: W/System.err(359): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 10-31 12:45:30.132: W/System.err(359): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 10-31 12:45:30.132: W/System.err(359): at java.lang.Thread.run(Thread.java:1019) 10-31 12:45:30.132: E/Buffer Error(359): Error converting result java.lang.NullPointerException 10-31 12:45:30.141: E/JSON Parser(359): Error parsing data org.json.JSONException: End of input at character 0 of 10-31 12:45:30.151: W/dalvikvm(359): threadid=9: thread exiting with uncaught exception (group=0x40015560) 10-31 12:45:30.171: E/AndroidRuntime(359): FATAL EXCEPTION: AsyncTask #1 10-31 12:45:30.171: E/AndroidRuntime(359): java.lang.RuntimeException: An error occured while executing doInBackground() 10-31 12:45:30.171: E/AndroidRuntime(359): at android.os.AsyncTask$3.done(AsyncTask.java:200) 10-31 12:45:30.171: E/AndroidRuntime(359): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274) 10-31 12:45:30.171: E/AndroidRuntime(359): at java.util.concurrent.FutureTask.setException(FutureTask.java:125) 10-31 12:45:30.171: E/AndroidRuntime(359): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308) 10-31 12:45:30.171: E/AndroidRuntime(359): at java.util.concurrent.FutureTask.run(FutureTask.java:138) 10-31 12:45:30.171: E/AndroidRuntime(359): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 10-31 12:45:30.171: E/AndroidRuntime(359): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 10-31 12:45:30.171: E/AndroidRuntime(359): at java.lang.Thread.run(Thread.java:1019) 10-31 12:45:30.171: E/AndroidRuntime(359): Caused by: java.lang.NullPointerException 10-31 12:45:30.171: E/AndroidRuntime(359): at com.augustasoftsol.gmoapp.Register$CreateUser.doInBackground(Register.java:103) 10-31 12:45:30.171: E/AndroidRuntime(359): at com.augustasoftsol.gmoapp.Register$CreateUser.doInBackground(Register.java:1) 10-31 12:45:30.171: E/AndroidRuntime(359): at android.os.AsyncTask$2.call(AsyncTask.java:185) 10-31 12:45:30.171: E/AndroidRuntime(359): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306) 10-31 12:45:30.171: E/AndroidRuntime(359): ... 4 more 10-31 12:45:32.121: E/WindowManager(359): Activity com.augustasoftsol.gmoapp.Register has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@405a3fe0 that was originally added here 10-31 12:45:32.121: E/WindowManager(359): android.view.WindowLeaked: Activity com.augustasoftsol.gmoapp.Register has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@405a3fe0 that was originally added here 10-31 12:45:32.121: E/WindowManager(359): at android.view.ViewRoot.<init>(ViewRoot.java:258) 10-31 12:45:32.121: E/WindowManager(359): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148) 10-31 12:45:32.121: E/WindowManager(359): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91) 10-31 12:45:32.121: E/WindowManager(359): at android.view.Window$LocalWindowManager.addView(Window.java:424) 10-31 12:45:32.121: E/WindowManager(359): at android.app.Dialog.show(Dialog.java:241) 10-31 12:45:32.121: E/WindowManager(359): at com.augustasoftsol.gmoapp.Register$CreateUser.onPreExecute(Register.java:82) 10-31 12:45:32.121: E/WindowManager(359): at android.os.AsyncTask.execute(AsyncTask.java:391) 10-31 12:45:32.121: E/WindowManager(359): at com.augustasoftsol.gmoapp.Register.onClick(Register.java:63) 10-31 12:45:32.121: E/WindowManager(359): at android.view.View.performClick(View.java:2485) 10-31 12:45:32.121: E/WindowManager(359): at android.view.View$PerformClick.run(View.java:9080) 10-31 12:45:32.121: E/WindowManager(359): at android.os.Handler.handleCallback(Handler.java:587) 10-31 12:45:32.121: E/WindowManager(359): at android.os.Handler.dispatchMessage(Handler.java:92) 10-31 12:45:32.121: E/WindowManager(359): at android.os.Looper.loop(Looper.java:123) 10-31 12:45:32.121: E/WindowManager(359): at android.app.ActivityThread.main(ActivityThread.java:3683) 10-31 12:45:32.121: E/WindowManager(359): at java.lang.reflect.Method.invokeNative(Native Method) 10-31 12:45:32.121: E/WindowManager(359): at java.lang.reflect.Method.invoke(Method.java:507) 10-31 12:45:32.121: E/WindowManager(359): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 10-31 12:45:32.121: E/WindowManager(359): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 10-31 12:45:32.121: E/WindowManager(359): at dalvik.system.NativeStart.main(Native Method) 10-31 12:45:35.381: I/Process(359): Sending signal. PID: 359 SIG: 9 

Answer 1

使用本地服務器並在模擬器上進行測試時

采用，

private static final String LOGIN_URL = "http://10.0.2.2/webservice/register.php";

並且，如果要在真實設備上測試該應用程序，請使用承載本地服務器的計算機的IP。

希望對您有所幫助！