我被警告不要在主线程上使用网络操作。
但我有这样一个案例；
我需要检查该值是否存在于数据库中，
如果是，我将继续进行另一项活动。
但我要破例。请帮我解决这个问题我更新的代码
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.initial);
if(!isNetworkAvailable())
{
final Dialog dialog = new Dialog(context);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.customlayoutnetconnection);
Button dialogButton = (Button) dialog.findViewById(R.id.Ok);
Button dialogButton2 = (Button) dialog.findViewById(R.id.OpenCon);
dialogButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
finish();
}});
dialogButton2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
ConnectivityManager manager = (ConnectivityManager)getSystemService(InitialActivity.CONNECTIVITY_SERVICE);
Boolean is3g = manager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).isConnectedOrConnecting();
Boolean isWifi = manager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).isConnectedOrConnecting();
if(is3g){
Toast.makeText(context, "3G", Toast.LENGTH_LONG);
}else if(isWifi){
Toast.makeText(context, "wifi", Toast.LENGTH_LONG);
}else{
Toast.makeText(context, "nothing", Toast.LENGTH_LONG);
startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));
}
}});
dialog.show();
}
lost = (Button) findViewById(R.id.imlost);
lost.setOnClickListener(this);
looking = (Button) findViewById(R.id.imlookingfor);
looking.setOnClickListener(this);
about = (Button) findViewById(R.id.about);
about.setOnClickListener(this);
howto = (Button) findViewById(R.id.howto);
howto.setOnClickListener(this);
}
@Override
public void onClick(View v) {
if(v==lost)
{
Intent i = new Intent(getApplicationContext(),IamLostActivity.class);
startActivity(i);
}
else if(v==looking)
{
final Dialog dialog = new Dialog(context);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.customlayout);
Button dialogButton = (Button) dialog.findViewById(R.id.Find);
code = (EditText) dialog.findViewById(R.id.codeToFind);
code.requestFocus();
dialogButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if(code.getText().toString().contentEquals(""))
{
final Dialog dialog2 = new Dialog(context);
dialog2.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog2.setContentView(R.layout.customlayoutinfo);
TextView tv = (TextView) dialog2.findViewById(R.id.customInfo);
tv.setText(context.getString(R.string.BlankField));
Button dialogButton2 = (Button) dialog2.findViewById(R.id.Ok);
dialogButton2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog2.dismiss();
} });
dialog2.show();
}
else
{
findFriend = new Runnable() {
@Override
public void run() {
httpclnt = new DefaultHttpClient();
httppst = new HttpPost(url);
try {
nameValuePairs = new ArrayList<NameValuePair>(1);
nameValuePairs.add((new BasicNameValuePair("code", code.getText().toString())));
httppst.setEntity(new UrlEncodedFormEntity(nameValuePairs));
ResponseHandler<String> responseHandler = new BasicResponseHandler();
response = httpclnt.execute(httppst, responseHandler);
//message = response;
}
catch (ClientProtocolException e) {
Toast.makeText(InitialActivity.this, "Client protocol exception ", Toast.LENGTH_LONG).show();
} catch (IOException e) {
Toast.makeText(InitialActivity.this, "IO exception "+e.getMessage(), Toast.LENGTH_LONG).show();
}
}
};
Thread thread = new Thread(null, findFriend, "FindFriend");
thread.start();
if(response.contentEquals(","))
{
final Dialog dialog4 = new Dialog(context);
dialog4.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog4.setContentView(R.layout.customlayoutinfo);
TextView tv = (TextView) dialog4.findViewById(R.id.customInfo);
tv.setText(context.getString(R.string.CheckCorrectness));
Button dialogButton2 = (Button) dialog4.findViewById(R.id.Ok);
dialogButton2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog4.dismiss();
} });
dialog4.show();
}
else
{
Intent in = new Intent(getApplicationContext(),IamLookingForActivity.class);
in.putExtra("message", response.toString());
startActivity(in);
}
};
}
}
);
Button dialogButton2 = (Button) dialog.findViewById(R.id.Cancel);
dialogButton2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
}
});
dialog.show();
}
else if(v==about)
{
final Dialog dialog = new Dialog(context);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.customlayoutabout);
ImageButton dialogButton = (ImageButton) dialog.findViewById(R.id.kodatolye);
Button dialogButton2 = (Button) dialog.findViewById(R.id.Back);
dialogButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
final Dialog dialog2 = new Dialog(context);
dialog2.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog2.setContentView(R.layout.customlayoutinfo);
TextView tv = (TextView) dialog2.findViewById(R.id.customInfo);
tv.setText("www.kodatolye.com");
Button dialogButton3 = (Button) dialog2.findViewById(R.id.Ok);
dialogButton3.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog2.dismiss();
} });
dialog2.show();
} });
dialogButton2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
} });
dialog.show();
}
else if(v==howto)
{
final Dialog dialog2 = new Dialog(context);
dialog2.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog2.setContentView(R.layout.customlayouthowto);
Button dialogButton3 = (Button) dialog2.findViewById(R.id.Back);
dialogButton3.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog2.dismiss();
} });
dialog2.show();
}
}
}
您不能在主线程上执行网络代码。同样，您不能尝试从主线程以外的任何更新UI。您（正确地）为网络操作启动了一个单独的线程，但您没有等待它完成。您应该将启动if(response.contentEquals(...))的代码移到Runnable中，直到网络活动完成并得到响应后，该代码才会运行。然后，您可以通过处理程序将Runnable发布到主线程，以启动新活动（或者根据需要显示错误消息）。您可能希望显示一个对话框，告诉用户在启动网络线程之前等待。
AsyncTask为您完成了大部分记账工作，使这一切变得更容易。有关更多信息，请参阅博客文章Painless Threading。