生成驗證碼程式碼： 

package test;

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();
 	// {"宋體", "華文楷體", "黑體", "華文新魏", "華文隸書", "微軟雅黑", "楷體_GB2312"}
	private String[] fontNames  = {"宋體", "華文楷體", "黑體", "微軟雅黑", "楷體_GB2312"};
	// 可選字元
	private String codes  = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
	// 背景色
	private Color bgColor  = new Color(255, 255, 255);
	// 驗證碼上的文字
	private String text ;
	
	// 生成隨機的顏色
	private Color randomColor () {
		int red = r.nextInt(150);
		int green = r.nextInt(150);
		int blue = r.nextInt(150);
		return new Color(red, green, blue);
	}
	
	// 生成隨機的字型
	private Font randomFont () {
		int index = r.nextInt(fontNames.length);
		String fontName = fontNames[index];//生成隨機的字型名稱
		int style = r.nextInt(4);//生成隨機的樣式, 0(無樣式), 1(粗體), 2(斜體), 3(粗體+斜體)
		int size = r.nextInt(5) + 24; //生成隨機字號, 24 ~ 28
		return new Font(fontName, style, size);
	}
	
	// 畫干擾線
	private void drawLine (BufferedImage image) {
		int num  = 3;//一共畫3條
		Graphics2D g2 = (Graphics2D)image.getGraphics();
		for(int i = 0; i < num; i++) {//生成兩個點的座標，即4個值
			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); //干擾線是藍色
			g2.drawLine(x1, y1, x2, y2);//畫線
		}
	}
	
	// 隨機生成一個字元
	private char randomChar () {
		int index = r.nextInt(codes.length());
		return codes.charAt(index);
	}
	
	// 建立BufferedImage
	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;
	}
	
	// 呼叫這個方法得到驗證碼
	public BufferedImage getImage () {
		BufferedImage image = createImage();//建立圖片緩衝區 
		Graphics2D g2 = (Graphics2D)image.getGraphics();//得到繪製環境
		StringBuilder sb = new StringBuilder();//用來裝載生成的驗證碼文字
		// 向圖片中畫4個字元
		for(int i = 0; i < 4; i++)  {//迴圈四次，每次生成一個字元
			String s = randomChar() + "";//隨機生成一個字母 
			sb.append(s); //把字母新增到sb中
			float x = i * 1.0F * w / 4; //設定當前字元的x軸座標
			g2.setFont(randomFont()); //設定隨機字型
			g2.setColor(randomColor()); //設定隨機顏色
			g2.drawString(s, x, h-5); //畫圖
		}
		this.text = sb.toString(); //把生成的字串賦給了this.text
		drawLine(image); //新增干擾線
		return image;		
	}
	
	// 返回驗證碼圖片上的文字
	public String getText () {
		return text;
	}
	
	// 儲存圖片到指定的輸出流
	public static void output (BufferedImage image, OutputStream out) 
				throws IOException {
		ImageIO.write(image, "JPEG", out);
	}
}


 

測試程式碼：

@Test
	public void fun2() throws FileNotFoundException, IOException {
		VerifyCode vc = new VerifyCode();
		BufferedImage bi =   vc.getImage();
		VerifyCode.output(bi,  new FileOutputStream("F:/xxx.jpg"));
		System.out.println(vc.getText());
	}

 輸出結果：