java Android应用程序在打开链接时崩溃

Question

嗯，我不知道为什么，但每次我在登录活动中点击提交按钮时，我的应用程序都会崩溃。主要活动效果良好

我的登录活动：

package de.blender4me.einkaufsliste;

import 安卓.app.Activity;
import 安卓.os.AsyncTask;
import 安卓.os.Bundle;
import 安卓.view.MenuItem;
import 安卓.view.View;
import 安卓.view.View.OnClickListener;
import 安卓.widget.Button;
import 安卓.widget.EditText;
import 安卓.widget.TextView;

public class LoginActivity extends Activity {

EditText password;
EditText username;
Button submit;
TextView userPass;

String usernameString;
String passwordString;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    submit = (Button) findViewById(R.id.buttonSubmitLogin);
    submit.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            password = (EditText) findViewById(R.id.editTextPassword);
            passwordString = password.getText().toString();

            username = (EditText) findViewById(R.id.editTextUsername);
            usernameString = username.getText().toString();

            userPass = (TextView) findViewById(R.id.textPassUser);

            LongOperation lo = new LongOperation();
            lo.execute();
        }
    });
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);



}
private class LongOperation extends AsyncTask<Void, Void, String> {

    private String[] values = null;

    @Override
    protected String doInBackground(Void... params) {
        internetHandler ih = new internetHandler();
        values = ih.getList(usernameString,passwordString,"","");

        userPass.setText(values[0]);

        if(!values[0].equalsIgnoreCase("error")&&!values[0].equalsIgnoreCase("401")&&!values[0].equalsIgnoreCase("404")){
            userPass.setText("Yep");
        }else{
            userPass.setText(values[0]);
        }

        return null;
    }

    @Override
    protected void onPostExecute(String result) {
    }   
  }
}

我的主要活动：

package de.blender4me.einkaufsliste;

import 安卓.app.Activity;
import 安卓.app.AlertDialog;
import 安卓.content.DialogInterface;
import 安卓.content.Intent;
import 安卓.os.AsyncTask;
import 安卓.os.Bundle;
import 安卓.view.Menu;
import 安卓.view.MenuItem;
import 安卓.view.View;
import 安卓.widget.ArrayAdapter;
import 安卓.widget.Button;
import 安卓.widget.EditText;
import 安卓.widget.ListView;


public class MainActivity extends Activity {

//Widgets
Button addItem;
Button loginMenu;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //listView
        LongOperation lo = new LongOperation();
        lo.execute();

        //register Widgets
        addItem =(Button) findViewById(R.id.addItem);
        addItem.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openDialog();
            }
        });

        loginMenu = (Button) findViewById(R.id.loginMenu);
        loginMenu.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent i = new Intent(getApplicationContext(), LoginActivity.class);
                startActivity(i);
            }
        });
    }

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

//Alert
public void openDialog(){
    AlertDialog.Builder alert = new AlertDialog.Builder(this);

    alert.setTitle("Zur Einkaufsliste hinzufügen");
    alert.setMessage(" ");

    // Set an EditText view to get user input 
    final EditText input = new EditText(this);
    alert.setView(input);

    alert.setPositiveButton("Bestätigen", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {
      String value = input.getText().toString();
      // Do something with value!
      }
    });

    alert.setNegativeButton("Abbrechen", new DialogInterface.OnClickListener() {
      public void onClick(DialogInterface dialog, int whichButton) {
        // Canceled.
      }
    });

    alert.show();
}

//listView erstellen
private class LongOperation extends AsyncTask<Void, Void, String> {

    private String[] values = null;

    @Override
    protected String doInBackground(Void... params) {
        internetHandler ih = new internetHandler();
        values = ih.getList("TestUser","TestPass","TestValue","");
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        //Liste konvertieren
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this, 
            R.layout.listview_item, //Genutztes Layout
            values); //Genutzter Array

        //listView einstellen
        ListView list = (ListView) findViewById(R.id.listView);
        list.setAdapter(adapter);
    }

    @Override
    protected void onPreExecute() {}

    @Override
    protected void onProgressUpdate(Void... values) {}
  }
}

我的互联网管理员：

package de.blender4me.einkaufsliste;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.regex.Pattern;

public class internetHandler {

    //Einkaufsplaner-API aufrufen
        public static String[] getList(String name, String pass, String addValue, String removeValue){

            InputStream is = null;

            try
            {
              URL url = new URL("https://einkaufsplaner.blender4me.de/api.php?name="+name+"&pass="+pass+"&addValue="+addValue+"&removeValue="+removeValue);
              BufferedReader in = new BufferedReader(
              new InputStreamReader(url.openStream()));

              String Values = null;

              for(int i = 0; i < 4; ++i){
                  Values = in.readLine();
              }
              in.close();

              String[] List = Values.split( Pattern.quote( ";" ) );
              return List;

            }
            catch ( Exception e ) {
              e.printStackTrace();
            }
            finally {
              if ( is != null )
                try { is.close(); } catch ( IOException e ) { }
            }
            String[] error = {"error"};
            return error;
        }
}

错误：

11-07 21:34:29.474: E/Trace(1223): error opening trace file: No such file or directory (2) 11-07 21:34:32.785: D/gralloc_goldfish(1223): Emulator without GPU emulation detected. 11-07 21:34:34.074: D/dalvikvm(1223): GC_CONCURRENT freed 260K, 10% free 7393K/8135K, paused 16ms+15ms, total 59ms 11-07 21:34:39.964: I/Choreographer(1223): Skipped 248 frames! The application may be doing too much work on its main thread. 11-07 21:34:40.504: W/dalvikvm(1223): threadid=12: thread exiting with uncaught exception (group=0x40a13300) 11-07 21:34:40.564: E/AndroidRuntime(1223): FATAL EXCEPTION: AsyncTask #2 11-07 21:34:40.564: E/AndroidRuntime(1223): java.lang.RuntimeException: An error occured while executing doInBackground() 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.os.AsyncTask$3.done(AsyncTask.java:299) 11-07 21:34:40.564: E/AndroidRuntime(1223): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273) 11-07 21:34:40.564: E/AndroidRuntime(1223): at java.util.concurrent.FutureTask.setException(FutureTask.java:124) 11-07 21:34:40.564: E/AndroidRuntime(1223): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307) 11-07 21:34:40.564: E/AndroidRuntime(1223): at java.util.concurrent.FutureTask.run(FutureTask.java:137) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 11-07 21:34:40.564: E/AndroidRuntime(1223): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076) 11-07 21:34:40.564: E/AndroidRuntime(1223): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569) 11-07 21:34:40.564: E/AndroidRuntime(1223): at java.lang.Thread.run(Thread.java:856) 11-07 21:34:40.564: E/AndroidRuntime(1223): Caused by: 安卓.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.view.ViewRootImpl.checkThread(ViewRootImpl.java:4609) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.view.ViewRootImpl.requestLayout(ViewRootImpl.java:835) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.view.View.requestLayout(View.java:15129) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.view.View.requestLayout(View.java:15129) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.view.View.requestLayout(View.java:15129) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.view.View.requestLayout(View.java:15129) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.widget.RelativeLayout.requestLayout(RelativeLayout.java:292) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.view.View.requestLayout(View.java:15129) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.widget.TextView.checkForRelayout(TextView.java:6309) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.widget.TextView.setText(TextView.java:3547) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.widget.TextView.setText(TextView.java:3405) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.widget.TextView.setText(TextView.java:3380) 11-07 21:34:40.564: E/AndroidRuntime(1223): at de.blender4me.einkaufsliste.LoginActivity$LongOperation.doInBackground(LoginActivity.java:71) 11-07 21:34:40.564: E/AndroidRuntime(1223): at de.blender4me.einkaufsliste.LoginActivity$LongOperation.doInBackground(LoginActivity.java:1) 11-07 21:34:40.564: E/AndroidRuntime(1223): at 安卓.os.AsyncTask$2.call(AsyncTask.java:287) 11-07 21:34:40.564: E/AndroidRuntime(1223): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305) 11-07 21:34:40.564: E/AndroidRuntime(1223): ... 5 more 11-07 21:34:42.315: I/Process(1223): Sending signal. PID: 1223 SIG: 9

Answer 1

实际上，您正试图从AsyncTask中的doInBackground()更新应用程序UI，这会导致此错误

所以把你的代码改成

@Override
protected String doInBackground(Void... params) {
    internetHandler ih = new internetHandler();
    values = ih.getList(usernameString,passwordString,"","");
    return values[0];    
}

@Override
protected void onPostExecute(String result) {
   if(!result.equalsIgnoreCase("error") && !result.equalsIgnoreCase("401") && !result.equalsIgnoreCase("404")){
        userPass.setText("Yep");
    }else{
        userPass.setText(result);
    }
}   

由于doInBackground()在工作线程中运行，所以您无法从它访问android的主应用程序UI线程，因此您必须从运行在UI线程上的onPostExecute()更新UI部分