重写android返回键

在Activity里面加入下面代码：

@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {showDialog(APP_EXIT);return true;} elsereturn super.onKeyDown(keyCode, event);}@Overrideprotected Dialog onCreateDialog(int id) {if (id == APP_EXIT) {return new AlertDialog.Builder(BaseActivity.this).setMessage("是否退出程序?").setTitle("用户退出").setPositiveButton("确定",new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog,int which) {dialog.dismiss();android.os.Process.killProcess(android.os.Process.myPid());finish();}}).setNegativeButton("取消",new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog,int which) {dialog.dismiss();}}).create();}return null;}