图形验证码

思路：随机生成几个字符，绘制字符，加干扰线或者是一些其他的图形，为了美观，需要绘制一下背景，或者边框。保存该Bitmap对象，就可以使用了。见代码

public class BitmapCode {
    private static final char[] CHARS = {
            '0','1',  '2', '3', '4', '5', '6', '7', '8', '9'
    };

    private static BitmapCode bmpCode;

    public static BitmapCode getInstance() {
        if(bmpCode == null)
            bmpCode = new BitmapCode();
        return bmpCode;
    }

    private final static int DEFAULT_WIDTH=100;//图片的宽
    private final static int DEFAULT_HEIGHT=40;//图片的高度
    private final static int CODE_LENGTH=4;//验证码的长度
    private int width=DEFAULT_WIDTH;
    private int height=DEFAULT_HEIGHT;
    private int codeLength=CODE_LENGTH;
    private int lineNum=10;

    private Random random=new Random();

    private String code;
    public Bitmap createBitmap(){
        createCode();
        Bitmap bp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvas=new Canvas(bp);
        canvas.drawColor(Color.rgb(241,252,243));//绘制背景色
        Rect rect=new Rect(0,0,width,height);
        //绘制边框
        {
            Paint paint = new Paint();
            paint.setColor(Color.GRAY);
            paint.setStyle(Paint.Style.STROKE);
            paint.setStrokeWidth(3);
            canvas.drawRect(rect, paint);
        }
        //绘制随机验证码
        {
            Paint textPaint=new Paint();
            textPaint.setTextSize(24);
            textPaint.setColor(Color.BLUE);
            //测量字体宽度
            float textWidth=textPaint.measureText("0");
            //测量字体高度
            float textHeight=textPaint.ascent()+textPaint.descent();
            //离顶部的标准距离
            float paddingTop=(height-textHeight)/2;
            //离左侧的标准距离
            float paddingLeft=(width/4f-textWidth)/2;
            for(int i=0;i<code.length();i++){
                float skewX = random.nextInt(12) / 10;
                skewX = random.nextBoolean() ? skewX : -skewX;
                textPaint.setTextSkewX(skewX); //float类型参数，负数表示右斜，整数左斜                canvas.drawText(code.charAt(i)+"",paddingLeft+i*width/4,paddingTop+random.nextInt(10)-5,textPaint);//让字体倾斜，垂直位置离中间位置随机偏移
            }
        }
        //绘制干扰线条
        {
            Paint linePaint = new Paint();
            drawLine(canvas, linePaint);
        }
        canvas.save(Canvas.ALL_SAVE_FLAG );
        canvas.restore();
        return bp;
    }

    /**
     * 生成随机验证码
     * @return
     */
    private void createCode(){
        StringBuilder builder=new StringBuilder();
        for(int i=0;i<codeLength;i++) {
            builder.append(CHARS[random.nextInt(CHARS.length)]);
        }
        this.code=builder.toString();
    }

    //利用此方法返回生成的字符，供与用户的输入进行核对
    public String getCode(){
        return this.code;
    }

    private void drawLine(Canvas canvas,Paint paint){
        for(int i=0;i<lineNum;i++){
            paint.setColor(randomColor());
            int startX=random.nextInt(width);
            int startY=random.nextInt(height);
            int endX=random.nextInt(width);
            int endY=random.nextInt(height);
            canvas.drawLine(startX,startY,endX,endY,paint);
        }
    }
//生成随机颜色
    private int randomColor(){
        int red=random.nextInt(256);
        int green=random.nextInt(256);
        int blue=random.nextInt(256);
        return Color.rgb(red,green,blue);
    }
}

以上类可以作为工具类使用，接下来就是使用了，我的注册页面是在Fragment中：

public class RegisterFragment1 extends Fragment {
    private TextView land;
    private TextView register;
    private ImageView code;//验证码ImageView
    private EditText phone;
    private EditText checkCode;
    private BitmapCode bitmapCode=BitmapCode.getInstance();//此处得到BitmapCode对象
    private RegisterCallBack mCallBack=null;
    private PopupWindow popupWindow;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View root=inflater.inflate(R.layout.register_frag1,null);
        land=(TextView) root.findViewById(R.id.tv_land);
        register=(TextView) root.findViewById(R.id.tv_register);
        code=(ImageView) root.findViewById(R.id.iv_code);
        phone=(EditText) root.findViewById(R.id.et_phone);
        checkCode=(EditText) root.findViewById(R.id.et_check_code);
        /**通过createBitmap()方法生成图形验证码*/
        code.setImageBitmap(bitmapCode.createBitmap());
        code.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            //点击ImageView，通过createBitmap生成新图片
                code.setImageBitmap(bitmapCode.createBitmap());
            }
        });
        land.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                RegisterFragment1.this.getActivity().finish();
                Intent intent=new Intent( RegisterFragment1.this.getActivity(),LandActivity.class);
                startActivity(intent);
            }
        });
        /**注册按钮的点击事件，根据bitmapCode.getCode()得到实际生成的验证码与用户的输入进行比对*/
        register.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(phone.getText().toString().length()!=11){
                    mCallBack.show("请输入正确的手机号码");
                }else if(!checkCode.getText().toString().equals(bitmapCode.getCode())){
                    mCallBack.show("验证码输入错误");
                }else if(mCallBack!=null)
                    mCallBack.toNext(phone.getText().toString());
            }
        });
        return root;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        this.mCallBack=(RegisterCallBack) context;
    }
}

我的注册页面效果如下