Android自己绘制验证码

为了避免自己的代码被别人反编译后拿到短信验证码的接口做恶意攻击，不断的发送验证码请求给服务器带来压力，需要我们自己绘制验证码。以下是所需代码，直接拿走！
MainActivity

public class MainActivity extends AppCompatActivity {
    private ImageView mIvYanzheng;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Bitmap mBitmap=CodeUtils.getInstance().createBitmap();
        mIvYanzheng = (ImageView) findViewById(R.id.iv_yanzheng);
        mIvYanzheng.setImageBitmap(mBitmap);
    }
}

CodeUtils代码工具类

public class CodeUtils {
    private static final char[] CHARS = {
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
            'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
            'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'
    };

    private static CodeUtils mCodeUtils;
    private int mPaddingLeft, mPaddingTop;
    private StringBuilder mBuilder = new StringBuilder();
    private Random mRandom = new Random();

    //Default Settings
    private static final int DEFAULT_CODE_LENGTH = 4;//验证码的长度  这里是4位
    private static final int DEFAULT_FONT_SIZE = 60;//字体大小
    private static final int DEFAULT_LINE_NUMBER = 3;//多少条干扰线
    private static final int BASE_PADDING_LEFT = 20; //左边距
    private static final int RANGE_PADDING_LEFT = 35;//左边距范围值
    private static final int BASE_PADDING_TOP = 42;//上边距
    private static final int RANGE_PADDING_TOP = 15;//上边距范围值
    private static final int DEFAULT_WIDTH = 200;//默认宽度.图片的总宽
    private static final int DEFAULT_HEIGHT = 100;//默认高度.图片的总高
    private static final int DEFAULT_COLOR = 0xD;//默认背景颜色值

    public static CodeUtils getInstance() {
        if(mCodeUtils == null) {
            mCodeUtils = new CodeUtils();
        }
        return mCodeUtils;
    }

    //生成验证码图片
    public Bitmap createBitmap() {
        mPaddingLeft = 0; //每次生成验证码图片时初始化
        mPaddingTop = 0;

        Bitmap bitmap = Bitmap.createBitmap(DEFAULT_WIDTH, DEFAULT_HEIGHT, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);

        //生成的验证码
        String code = createCode();

        canvas.drawColor(Color.rgb(DEFAULT_COLOR, DEFAULT_COLOR, DEFAULT_COLOR));
        Paint paint = new Paint();
        paint.setTextSize(DEFAULT_FONT_SIZE);

        for (int i = 0; i < code.length(); i++) {
            randomTextStyle(paint);
            randomPadding();
            canvas.drawText(code.charAt(i) + "" , mPaddingLeft, mPaddingTop, paint);
        }

        //干扰线
        for (int i = 0; i < DEFAULT_LINE_NUMBER; i++) {
            drawLine(canvas, paint);
        }

        canvas.save(Canvas.ALL_SAVE_FLAG);//保存
        canvas.restore();
        return bitmap;
    }

    //生成验证码
    public String createCode() {
        mBuilder.delete(0, mBuilder.length()); //使用之前首先清空内容

        for (int i = 0; i < DEFAULT_CODE_LENGTH; i++) {
            mBuilder.append(CHARS[mRandom.nextInt(CHARS.length)]);
        }

        return mBuilder.toString();
    }

    //生成干扰线
    private void drawLine(Canvas canvas, Paint paint) {
        int color = randomColor();
        int startX = mRandom.nextInt(DEFAULT_WIDTH);
        int startY = mRandom.nextInt(DEFAULT_HEIGHT);
        int stopX = mRandom.nextInt(DEFAULT_WIDTH);
        int stopY = mRandom.nextInt(DEFAULT_HEIGHT);
        paint.setStrokeWidth(1);
        paint.setColor(color);
        canvas.drawLine(startX, startY, stopX, stopY, paint);
    }

    //随机颜色
    private int randomColor() {
        mBuilder.delete(0, mBuilder.length()); //使用之前首先清空内容

        String haxString;
        for (int i = 0; i < 3; i++) {
            haxString = Integer.toHexString(mRandom.nextInt(0xFF));
            if (haxString.length() == 1) {
                haxString = "0" + haxString;
            }

            mBuilder.append(haxString);
        }

        return Color.parseColor("#" + mBuilder.toString());
    }

    //随机文本样式
    private void randomTextStyle(Paint paint) {
        int color = randomColor();
        paint.setColor(color);
        paint.setFakeBoldText(mRandom.nextBoolean());  //true为粗体，false为非粗体
        float skewX = mRandom.nextInt(11) / 10;
        skewX = mRandom.nextBoolean() ? skewX : -skewX;
        paint.setTextSkewX(skewX); //float类型参数，负数表示右斜，整数左斜
//        paint.setUnderlineText(true); //true为下划线，false为非下划线
//        paint.setStrikeThruText(true); //true为删除线，false为非删除线
    }

    //随机间距
    private void randomPadding() {
        mPaddingLeft += BASE_PADDING_LEFT + mRandom.nextInt(RANGE_PADDING_LEFT);
        mPaddingTop = BASE_PADDING_TOP + mRandom.nextInt(RANGE_PADDING_TOP);
    }
}

布局文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.drawyanzhengma2.MainActivity">

    <ImageView
        android:id="@+id/iv_yanzheng"
        android:layout_width="200dp"
        android:layout_height="100dp"
        />
</RelativeLayout>