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Android验证码的生成

验证码是我们在程序开发中不可或缺的一个功能模块，这里我为大家推荐一个比较简洁的验证码图片生成方法(已注释)。
1.新建一个BPUtil验证码工具类，作用是生成验证码图片，代码如下：

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package com.my.nask.captcha.utils;import java.util.Random;import com.my.captcha.R;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Bitmap.Config;/** * 验证码工具类 */public class BPUtil {    /** 生成验证码的字符数组集合 **/    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 BPUtil bpUtil;    public static BPUtil getInstance() {        if (bpUtil == null)            bpUtil = new BPUtil();        return bpUtil;    }    // width="60" height="30"    // base_padding_left="5"    // range_padding_left="10"    // base_padding_top="15"    // range_padding_top="10"    // codeLength="4"    // line_number="3"    // font_size="20"    // default settings    private static final int DEFAULT_CODE_LENGTH = 4;    private static final int DEFAULT_FONT_SIZE = 20;    private static final int DEFAULT_LINE_NUMBER = 3;    private static final int BASE_PADDING_LEFT = 5, RANGE_PADDING_LEFT = 10,            BASE_PADDING_TOP = 15, RANGE_PADDING_TOP = 10;    private static final int DEFAULT_WIDTH = 60, DEFAULT_HEIGHT = 30;    // 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();    /**     * 新建一个Bitmap对象     */    public Bitmap createBitmap() {        padding_left = 0;        Bitmap bp = Bitmap.createBitmap(width, height, Config.ARGB_8888);        Canvas c = new Canvas(bp);        code = createCode();        // 验证码图片背景色        c.drawColor(R.color.whiteColor);        Paint paint = new Paint();        paint.setTextSize(font_size);        for (int i = 0; i < code.length(); i++) {            randomTextStyle(paint);            randomPadding();            c.drawText(code.charAt(i) + "", padding_left, padding_top, paint);        }        for (int i = 0; i < line_number; i++) {            drawLine(c, paint);        }        c.save(Canvas.ALL_SAVE_FLAG);// 保存        c.restore();//        return bp;    }    /**     * 获取生成的验证码结果     */    public String getCode() {        return bpUtil.code;    }    /**     * 随机生成验证码     */    private String createCode() {        StringBuilder buffer = new StringBuilder();        for (int i = 0; i < codeLength; i++) {            buffer.append(CHARS[random.nextInt(CHARS.length)]);        }        return buffer.toString();    }    /**     * 绘制验证码     */    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);    }    /**     * 随机验证码颜色     */    private int randomColor() {        return randomColor(1);    }    /**     * 随机生成对应的颜色     */    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);    }    /**     * 设置字体样式     */    private void randomTextStyle(Paint paint) {        int color = randomColor();        paint.setColor(color);        paint.setFakeBoldText(random.nextBoolean()); // true为粗体，false为非粗体        float skewX = random.nextInt(11) / 10;        skewX = random.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    }    /**     * 字符间距填充     */    private void randomPadding() {        padding_left += base_padding_left + random.nextInt(range_padding_left);        padding_top = base_padding_top + random.nextInt(range_padding_top);    }}

2.调用方法生成验证码图片,执行代码如下：
// 生成验证码并显示

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img.setImageBitmap(BPUtil.getInstance().createBitmap());

就这样简单的两步，我们就可以完成验证码图片的生成了，具体需求大家可根据实际情况改写