重寫Android返回鍵

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {

	//點擊完返回鍵，執行的動作
        ((MyApp) getApplication()).tag = 0;
        Intent intent = new Intent(this, DibuDaohangActivity.class);
        startActivity(intent);
        finish();
    }
    return true;
}