这里只有一个文件，可以在<img />的src属性里直接调用显示，适用于各种项目的表单安全验证

jsp页面代码：

<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %> <%! Color getRandColor(int fc,int bc){ Random random = new Random(); if(fc>255) fc=255; if(bc>255) bc=255; int r=fc+random.nextInt(bc-fc); int g=fc+random.nextInt(bc-fc); int b=fc+random.nextInt(bc-fc); return new Color(r,g,b); } %> <% response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); int width=60, height=20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); Random random = new Random(); g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); g.setFont(new Font("Times New Roman",Font.PLAIN,18)); g.setColor(getRandColor(160,200)); for (int i=0;i<155;i++){ int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x,y,x+xl,y+yl); } String sRand=""; for (int i=0;i<4;i++){ String rand=String.valueOf(random.nextInt(10)); sRand+=rand; g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); g.drawString(rand,13*i+6,16); } session.setAttribute("rand",sRand); g.dispose(); ImageIO.write(image, "JPEG", response.getOutputStream()); response.getOutputStream().flush(); response.getOutputStream().close(); out.clear(); out=pageContext.pushBody(); %>