安卓屏蔽返回键

//屏蔽返回键
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK){
//TODO
//return false;
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("提示");
builder.setIcon(android.R.drawable.ic_dialog_info);
builder.setMessage("确定退出？");
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
android.os.Process.killProcess(android.os.Process.myPid());
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
builder.create().show();
}
return false;
}