Question

简单代码：

public class ZSEEActivity extends TabActivity {
private WebView webview ; 
private WebView webviewtwo;
private TabHost mTabHost;
private int a;


protected void onStart() {
    super.onStart();
    // The activity is about to become visible.
}
protected void onStop() {
    super.onStop();
    // The activity is about to become visible.
}
protected void onRestart() {
    super.onRestart();
}
protected void onDestroy(){
    super.onDestroy();
}
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    final Activity activity = this;


    mTabHost = getTabHost();

    mTabHost.addTab(mTabHost.newTabSpec("tab_test1").setIndicator("Zastępstwa").setContent(R.id.tab1));
    mTabHost.addTab(mTabHost.newTabSpec("tab_test2").setIndicator("Plan Lekcji").setContent(R.id.tab2));
    mTabHost.addTab(mTabHost.newTabSpec("tab_test3").setIndicator("O programie").setContent(R.id.tab3));



    webview = (WebView) findViewById(R.id.webView1);
    webviewtwo = (WebView) findViewById(R.id.webView2);
    final WebSettings webviewtwoSettings = webviewtwo.getSettings();
        if (savedInstanceState != null){
            webview.restoreState(savedInstanceState.getBundle("stateone"));
            webviewtwo.restoreState(savedInstanceState.getBundle("statetwo"));
            webviewtwoSettings.setTextSize(TextSize.LARGER);
            mTabHost.setCurrentTab(savedInstanceState.getInt("CURRENT_TAB"));

        }
        else{
            webview.loadUrl("http://zsee.bytom.pl/ogloszenia.php");
            webviewtwo.loadUrl("http://zsee.bytom.pl/plannew/index.html");
            webviewtwoSettings.setTextSize(TextSize.LARGER);
            mTabHost.setCurrentTab(0);
        }


    webview.setWebViewClient(new WebViewClient() {
           public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
               String summary = "<html><body><meta http-equiv=\"Content-Type\" content=\"text/html;charset=utf-8\" ><center>Coś się zepsuło :(</center></body></html>";
               webview.loadData(summary, "text/html","utf-8");
             Toast.makeText(activity, "O nie! " + description, Toast.LENGTH_SHORT).show();
           }
         });

    webviewtwo.setWebViewClient(new WebViewClient() {
       public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
           String summary = "<html><body><meta http-equiv=\"Content-Type\" content=\"text/html;charset=utf-8\" ><center>Coś się zepsuło :(</center></body></html>";
           webviewtwo.loadData(summary, "text/html","utf-8");
           webviewtwoSettings.setTextSize(TextSize.NORMAL);
         Toast.makeText(activity, "O nie! " + description, Toast.LENGTH_SHORT).show();
       }
     });

    }
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.main, menu);
    return true;
}

protected void onSaveInstanceState(Bundle outState) {
    Bundle outStateone = new Bundle();
    Bundle outStatetwo = new Bundle();
    webview.saveState(outStateone);
    webviewtwo.saveState(outStatetwo);


    outState.putBundle("stateone", outStateone);
    outState.putBundle("statetwo", outStatetwo);
    outState.putInt("CURRENT_TAB", mTabHost.getCurrentTab());
}



public boolean onOptionsItemSelected(MenuItem item) {
    // Handle item selection
    switch (item.getItemId()) {
    case R.id.item1:
        final AlertDialog alertdialog= new AlertDialog.Builder(this).create();
        alertdialog.setTitle("O Programie");
        alertdialog.setMessage("Zmiany w 1.0.1: \n-Obsługa planu z dnia 17.10.2011\n-Drobne Poprawki");
        alertdialog.setButton("Fajno", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
                alertdialog.cancel();
           }
       });
        alertdialog.show();
        return true;
    case R.id.item2:
        finish();
    case R.id.item3:
        if(mTabHost.getCurrentTab() == 0){
        webview.loadUrl("http://zsee.bytom.pl/ogloszenia.php");
        }
        else if(mTabHost.getCurrentTab() == 1)
        {
        webviewtwo.loadUrl("http://zsee.bytom.pl/plannew/index.html");
        }
    default:
        return super.onOptionsItemSelected(item);
    }
}
}

现在我的问题。按下后退按钮onStop（）执行代码和onDestroy。我怎么能不杀app？我想在后台使用这个应用程序。现在，当我按下后退按钮并打开应用程序时，所有数据将再次下载并加载到webview。那么如何使这个过程在后台工作呢？

抱歉我的haotic英语：）

Sierran

Answer 1

使用Android service在后台而不是活动中执行某些操作。

并使用Broadcast receiver从服务中调用您的活动。当你的背景工作完成时。

Android - Service

如果你想做一点，那么只需override onKeyDown()

@Override     
 public boolean onKeyDown(int keyCode, KeyEvent event) 
  {         
    if (keyCode == KeyEvent.KEYCODE_BACK) 
       {            
     // put your stuff here or just block the back button for perticular activity             
           return true;        
       }         
     return super.onKeyDown(keyCode, event); 
   }

Answer 2

如果您想在后台执行某些操作并且需要它始终或多或少地运行，我建议您使用Service。在这里查看Service文档：

http://developer.android.com/reference/android/app/Service.html

在您的情况下，另一种方法是创建网站的本地缓存。

如何在onStop之后杀死进程？

2 个答案: