Android Realizes Random Generation of Verification Codes

In this paper, we share the random generation code of Android verification code for your reference. The specific contents are as follows

Code.java

package com.example.myapp;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;

import java.util.Random;

public class Code {
    /**
     *  Random number array 
     *  Remove confusing   Figures  0  And   Alphabet  o O
     *                 Figures  1  And   Alphabet  i I l L
     *                 Figures  6  And   Alphabet  b
     *                 Figures  9  And   Alphabet  q
     *                 Alphabet  c C  And  G
     *                 Alphabet  t  (Often mixed with random lines 1 Can't see clearly) 
     */
    private static final char[] CHARS = {
            '2', '3', '4', '5',  '7', '8',
            'a',  'd', 'e', 'f', 'g', 'h', 'j', 'k', 'm',
            'n', 'p',  'r', 's',  'u', 'v', 'w', 'x', 'y', 'z',
            'A', 'B',  'D', 'E', 'F',  'H',  'J', 'K', 'M',
            'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'
    };

    private static Code bmpCode;

    public static Code getInstance() {
        if(bmpCode == null)
            bmpCode = new Code();
        return bmpCode;
    }
    //default settings
    // Number of default random numbers of verification code 
    private static final int DEFAULT_CODE_LENGTH = 4;
    // Default font size 
    private static final int DEFAULT_FONT_SIZE = 25;
    // Default number of lines 
    private static final int DEFAULT_LINE_NUMBER = 5;
    //padding Value 
    private static final int BASE_PADDING_LEFT = 10, RANGE_PADDING_LEFT = 15, BASE_PADDING_TOP = 15, RANGE_PADDING_TOP = 20;
    // Default width and height of verification code 
    private static final int DEFAULT_WIDTH = 100, DEFAULT_HEIGHT = 40;

    //settings decided by the layout xml
    //canvas width and height
    private int width = DEFAULT_WIDTH, height = DEFAULT_HEIGHT;

    //random word space and pading_top
    private int base_padding_left = BASE_PADDING_LEFT, range_padding_left = RANGE_PADDING_LEFT,
            base_padding_top = BASE_PADDING_TOP, range_padding_top = RANGE_PADDING_TOP;

    //number of chars, lines; font size
    private int codeLength = DEFAULT_CODE_LENGTH, line_number = DEFAULT_LINE_NUMBER, font_size = DEFAULT_FONT_SIZE;

    //variables
    private String code;
    private int padding_left, padding_top;
    private Random random = new Random();
    // Verification code picture 
    public Bitmap createBitmap() {
        padding_left = 0;

        Bitmap bp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(bp);

        code = createCode();

        c.drawColor(Color.WHITE);
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setTextSize(font_size);
        // Draw verification code 
        for (int i = 0; i < code.length(); i++) {
            randomTextStyle(paint);
            randomPadding();
            c.drawText(code.charAt(i) + "", padding_left, padding_top, paint);
        }
        // Draw lines 
        for (int i = 0; i < line_number; i++) {
            drawLine(c, paint);
        }

//        c.save( Canvas.ALL_SAVE_FLAG );// Save 
        c.save();// Save 
        c.restore();//
        return bp;
    }
    public String getCode() {
        return code;
    }

    // Generate verification code 
    private String createCode() {
        StringBuilder buffer = new StringBuilder();
        for (int i = 0; i < codeLength; i++) {
            buffer.append(CHARS[random.nextInt(CHARS.length)]);
        }
        return buffer.toString();
    }
    // Draw interference lines 
    private void drawLine(Canvas canvas, Paint paint) {
        int color = randomColor();
        int startX = random.nextInt(width);
        int startY = random.nextInt(height);
        int stopX = random.nextInt(width);
        int stopY = random.nextInt(height);
        paint.setStrokeWidth(1);
        paint.setColor(color);
        canvas.drawLine(startX, startY, stopX, stopY, paint);
    }
    // Generate random colors 
    private int randomColor() {
        return randomColor(1);
    }

    private int randomColor(int rate) {
        int red = random.nextInt(256) / rate;
        int green = random.nextInt(256) / rate;
        int blue = random.nextInt(256) / rate;
        return Color.rgb(red, green, blue);
    }
    // Randomly generate text style, color, thickness and inclination 
    private void randomTextStyle(Paint paint) {
        int color = randomColor();
        paint.setColor(color);
        paint.setFakeBoldText(random.nextBoolean());  //true Is bold, false Is non-bold 
        float skewX = random.nextInt(11) / 10;
        skewX = random.nextBoolean() ? skewX : -skewX;
        paint.setTextSkewX(skewX); //float Type parameter, negative number indicates right slant and integer left slant 
        //paint.setUnderlineText(true); //true To underline, false Is not underlined 
        //paint.setStrikeThruText(true); //true For strikethrough, false Is a non-strikeout line 
    }
    // Random generation padding Value 
    private void randomPadding() {
        padding_left += base_padding_left + random.nextInt(range_padding_left);
        padding_top = base_padding_top + random.nextInt(range_padding_top);
    }
}

Call

// Display the verification code in the form of pictures 
RegisteractivityShowcode.setImageBitmap(Code.getInstance().createBitmap());
realCode = Code.getInstance().getCode().toLowerCase();