Android 获取随机验证码功能示例

验证码功能在各大网站都能用到，下面小编通过实例代码给大家分享Android 获取随机验证码功能，具体代码如下所示：

 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);
  }
} 

以上所述是小编给大家介绍的Android 获取随机验证码功能示例，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！