《Android编程权威指南（第3版）》：5.5挑战练习：堵住漏洞

作弊者是注定会失败的。当然，如果他们能一直避开反作弊手段，那就另当别论了。正所谓 道高一尺，魔高一丈，也许他们能做到。 GeoQuiz应用有些大漏洞，你的任务就是堵住它们。从易到难，以下为待解决的三个漏洞。

 用户作弊后，可以旋转CheatActivity来清除作弊痕迹。

CheatActivity中添加：

public class CheatActivity extends AppCompatActivity {

    //漏洞1
    private boolean mIsShowAnswer;
    private static final String bug1 = "bug1";
}

    @Override
    protected void onSaveInstanceState(Bundle saveInstanceState){
        super.onSaveInstanceState(saveInstanceState);
        saveInstanceState.putBoolean(bug1, mIsShowAnswer);
    }

public class CheatActivity extends AppCompatActivity {

        if (savedInstanceState != null){
            mIsShowAnswer = savedInstanceState.getBoolean(bug1, false);
            if (mIsShowAnswer){
                setAnswerShownResult(mIsShowAnswer);
            }
        }
}

可能多次调用setResult(int resultCode, Intent data)（竖屏时点击cheat-showanswer，这里调用一次setResult函数，然后旋转屏幕，点击后退键，这里又调用一次setResult函数），简单的测试似乎没有什么问题？

 

 作弊返回后，用户可以旋转QuizActivity来清除mIsCheater变量值。

QuizActivity中添加：

private boolean mIsCheater = false;

//漏洞2
private static final String bug2 = "bug2";

@Override
protected void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Log.d(TAG, "onCreate(Bundle) called");
    setContentView(R.layout.activity_quiz);

    if (savedInstanceState != null){
        mCurrentIndex = savedInstanceState.getInt(KEY_INDEX, 0);
        mIsCheater = savedInstanceState.getBoolean(bug2, false);
    }

    mShowAnswerButton.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v){
            if (mAnswerIsTrue)
                mAnswerTextView.setText(R.string.true_button);
            else
                mAnswerTextView.setText(R.string.false_button);
                mIsShowAnswer = true;
                setAnswerShownResult(true);
            }
    });
}

    @Override
    protected void onSaveInstanceState(Bundle saveInstanceState){
            super.onSaveInstanceState(saveInstanceState);
            Log.i(TAG, "onSaveInstanceState");
            saveInstanceState.putInt(KEY_INDEX, mCurrentIndex);
            saveInstanceState.putBoolean(bug2, mIsCheater);
    }

 

 用户可以不断单击NEXT按钮，跳到偷看过答案的问题，从而使作弊纪录丢失。 祝好运！ 

这里保留堵住漏洞1的代码，在此基础上添加代码

在QuizActivity中添加：

public class QuizActivity extends AppCompatActivity {

    //漏洞3
    private boolean[] mIsCheater = new boolean[mQuestionBank.length];
    private static final String bug3 = "bug3";
}

    @Override
    protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "onCreate(Bundle) called");
        setContentView(R.layout.activity_quiz);
        for (int i = 0; i < mQuestionBank.length; i++)
            mIsCheater[i] = false;

        if (savedInstanceState != null){
            mCurrentIndex = savedInstanceState.getInt(KEY_INDEX, 0);
            mIsCheater = savedInstanceState.getBooleanArray(bug3);
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data){
        if (resultCode != Activity.RESULT_OK){
            return;
        }
        if (requestCode == REQUEST_CODE_CHEAT){
            if (data == null){
                return;
            }
            mIsCheater[mCurrentIndex] = CheatActivity.wasAnswerShown(data);
        }
    }

    private void checkAnswer(boolean userPressedTrue) {
        boolean answerIsTrue = mQuestionBank[mCurrentIndex].isAnswerTrue();
        int messageResId = 0;
        mQuestionBank[mCurrentIndex].setAnswered(1);

        if (mIsCheater[mCurrentIndex]) {
            messageResId = R.string.judgment_toast;
        } else {
            if (userPressedTrue == answerIsTrue) {
                messageResId = R.string.correct_toast;
            } else {
                messageResId = R.string.incorrect_toast;
            }
        }
        Toast.makeText(this, messageResId, Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onSaveInstanceState(Bundle saveInstanceState){
            super.onSaveInstanceState(saveInstanceState);
            Log.i(TAG, "onSaveInstanceState");
            saveInstanceState.putInt(KEY_INDEX, mCurrentIndex);
            saveInstanceState.putBooleanArray(bug3, mIsCheater);
    }