andoird 按返回键退出

@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if (keyCode == KeyEvent.KEYCODE_BACK&& event.getAction() == KeyEvent.ACTION_DOWN) {//DialogAPI.showExit(this);new AlertDialog.Builder(this).setTitle("提示").setMessage("确定退出?").setIcon(R.drawable.tab1).setPositiveButton("确定",new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog,int whichButton) {setResult(RESULT_OK);// 确定按钮事件finish();}}).setNegativeButton("取消",new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog,int whichButton) {// 取消按钮事件}}).show();return true;}return super.onKeyDown(keyCode, event);}