Android应用中怎么对随机验证码进行获取

 package cn.hk.image; import java.awt.BasicStroke; import java.awt.Color; import java.awt.Font; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.IOException; import java.io.OutputStream; import java.util.Random; import javax.imageio.ImageIO; public class VerifyCode {   private int w = 70;   private int h = 35;   private Random r = new Random();   // {"宋体", "华文楷体", "黑体", "华文新魏", "华文隶书", "微软雅黑", "楷体_GB2312"}   private String[] fontNames = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};   // 可选字符   private String codes = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";   // 背景色   private Color bgColor = new Color(255, 255, 255);   // 验证码上的文本   private String text ;   // 生成随机的颜色   private Color randomColor () {     int red = r.nextInt(150);     int green = r.nextInt(150);     int blue = r.nextInt(150);     return new Color(red, green, blue);   }   // 生成随机的字体   private Font randomFont () {     int index = r.nextInt(fontNames.length);     String fontName = fontNames[index];//生成随机的字体名称     int style = r.nextInt(4);//生成随机的样式, 0(无样式), 1(粗体), 2(斜体), 3(粗体+斜体)     int size = r.nextInt(5) + 24; //生成随机字号, 24 ~ 28     return new Font(fontName, style, size);   }   // 画干扰线   private void drawLine (BufferedImage image) {     int num = 3;//一共画3条     Graphics2D g2 = (Graphics2D)image.getGraphics();     for(int i = 0; i < num; i++) {//生成两个点的坐标，即4个值       int x1 = r.nextInt(w);       int y1 = r.nextInt(h);       int x2 = r.nextInt(w);       int y2 = r.nextInt(h);        g2.setStroke(new BasicStroke(1.5F));        g2.setColor(Color.BLUE); //干扰线是蓝色       g2.drawLine(x1, y1, x2, y2);//画线     }   }   // 随机生成一个字符   private char randomChar () {     int index = r.nextInt(codes.length());     return codes.charAt(index);   }   // 创建BufferedImage，图片缓存区   private BufferedImage createImage () {     BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);      Graphics2D g2 = (Graphics2D)image.getGraphics();      g2.setColor(this.bgColor);     g2.fillRect(0, 0, w, h);     return image;   }   // 调用这个方法得到验证码   public BufferedImage getImage () {     BufferedImage image = createImage();//创建图片缓冲区      Graphics2D g2 = (Graphics2D)image.getGraphics();//得到绘制环境     StringBuilder sb = new StringBuilder();//用来装载生成的验证码文本     // 向图片中画4个字符     for(int i = 0; i < 4; i++) {//循环四次，每次生成一个字符       String s = randomChar() + "";//随机生成一个字母        sb.append(s); //把字母添加到sb中       float x = i * 1.0F * w / 4; //设置当前字符的x轴坐标       g2.setFont(randomFont()); //设置随机字体       g2.setColor(randomColor()); //设置随机颜色       g2.drawString(s, x, h-5); //画图     }     this.text = sb.toString(); //把生成的字符串赋给了this.text     drawLine(image); //添加干扰线     return image;       }   // 返回验证码图片上的文本   public String getText () {     return text;   }   // 保存图片到指定的输出流   public static void output (BufferedImage image, OutputStream out)          throws IOException {     ImageIO.write(image, "JPEG", out);   } }