javaweb必会_网页验证码制作

来源：互联网发布：起点09服饰淘宝店编辑：程序博客网时间：2024/06/05 07:20

准备

将常用的Unicode编码的汉字准备好

如下:

\u96d5\u864e\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u9ec4\u4e94\u7b2c\u4f7f\u5199\u519b\u6728\u73cd\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u6885\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904

实现功能的逻辑顺序

<span style="font-size:14px;">         //1设置背景              setBackGround(g);//2设置边框         setBorder(g);//3设置干扰线           drawRandomLine(g);//4随机数        drawRandomNum((Graphics2D)g);//5图形写给浏览器//6控制浏览器用图片形式打开</span>

<span style="font-size:14px;">        //7控制缓冲        response.setContentType("image/jpeg");        response. setDateHeader("expries",-1);        response.setHeader("Cache-Control","no-cache");        response.setHeader("Pragma","no-cache");        ImageIO.write(bi,"jpg", response.getOutputStream());</span>

编码

以此实现上述逻辑的方法

private void drawRandomNum(Graphics2D g) {g.setColor(Color.RED);g.setFont(new Font("宋体",Font.BOLD,20));String base="\u7684\u4e00\u4e86\u662f\u4e0d\u5728\u4e04\u8526\u555e\u55ae";int x=10;for(int i=0;i<4;i++){   int deg=new Random().nextInt()%30;String str=base.charAt(new Random().nextInt(base.length()))+"";g.rotate(deg*Math.PI/180, x, 20);g.drawString(str, x, 20);g.rotate(-deg*Math.PI/180, x, 20);x+=30;}}private void drawRandomLine(Graphics g) {g.setColor(Color.GREEN);for(int i=0;i<5;i++){int x1=new Random().nextInt(WIDTH);int y1=new Random().nextInt(HEIGHT);int x2=new Random().nextInt(WIDTH);int y2=new Random().nextInt(HEIGHT);g.drawLine(x1, y1, x2, y2);}}private void setBorder(Graphics g) {g.setColor(Color.BLUE);g.drawRect(1, 1, WIDTH-2,HEIGHT-2);}private void setBackGround(Graphics g) {g.setColor(Color.WHITE);g.fillRect(0, 0,WIDTH, HEIGHT);}

源码

<span style="font-size:18px;">package com.test.response;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.image.*;import java.io.IOException;import java.io.PrintWriter;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class demo1 extends HttpServlet {public static final int WIDTH=120;public static final int HEIGHT=25;public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {          BufferedImage bi=new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);          Graphics  g=bi.getGraphics();//1设置背景  setBackGround;         setBackGround(g);//2设置边框  setBorder         setBorder(g);//3设置干扰线  draw         drawRandomLine(g);//4随机数        drawRandomNum((Graphics2D)g);//5图形写给浏览器        //6控制浏览器用图片形式打开        response.setContentType("image/jpeg");        response. setDateHeader("expries",-1);        response.setHeader("Cache-Control","no-cache");        response.setHeader("Pragma","no-cache");        ImageIO.write(bi,"jpg", response.getOutputStream());}private void drawRandomNum(Graphics2D g) {g.setColor(Color.RED);g.setFont(new Font("宋体",Font.BOLD,20));String base="</span><p>\u96d5\u864e\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u9ec4\u4e94\u7b2c\u4f7f\u5199\u519b\u6728\u73cd\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u6885\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904</p>";int x=10;for(int i=0;i<4;i++){   int deg=new Random().nextInt()%30;String str=base.charAt(new Random().nextInt(base.length()))+"";g.rotate(deg*Math.PI/180, x, 20);g.drawString(str, x, 20);g.rotate(-deg*Math.PI/180, x, 20);x+=30;}}private void drawRandomLine(Graphics g) {g.setColor(Color.GREEN);for(int i=0;i<5;i++){int x1=new Random().nextInt(WIDTH);int y1=new Random().nextInt(HEIGHT);int x2=new Random().nextInt(WIDTH);int y2=new Random().nextInt(HEIGHT);g.drawLine(x1, y1, x2, y2);}}private void setBorder(Graphics g) {g.setColor(Color.BLUE);g.drawRect(1, 1, WIDTH-2,HEIGHT-2);}private void setBackGround(Graphics g) {g.setColor(Color.WHITE);g.fillRect(0, 0,WIDTH, HEIGHT);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {}}

结果

特别注意

1. g.rotate(deg*Math.PI/180, x, 20);

g.drawString(str, x, 20);

g.rotate(-deg*Math.PI/180, x, 20);

注意,在旋转一定角度后,必须把原来的纠正过来,否则第二个字会在没有纠正的状态下继续旋转

2.浏览器默认是带有缓冲的有些网页在重新加载文件时,是使用缓冲里面的图片,造成图片没有更改

response. setDateHeader("expries",-1);

response.setHeader("Cache-Control","no-cache");

response.setHeader("Pragma","no-cache");

2 0