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servlet 验证码生成
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内容图文
servlet
package com.htpo.net;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
public class testget extends HttpServlet {
/**
* Constructor of the object.
*/
public testget() {
super();
}
public static final char[] CHARS = { ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘,
‘9‘, ‘0‘, ‘A‘, ‘Q‘, ‘W‘, ‘E‘, ‘R‘, ‘T‘, ‘G‘, ‘D‘, ‘S‘, ‘W‘, ‘G‘,
‘H‘ };// 随机字符的字典
public static Random random = new Random();// 随机数
public static String getRandomString() {
// 字符的缓存
StringBuffer buf = new StringBuffer();
for (int i = 0; i < 6; i++) {// 循环 六次
buf.append(CHARS[random.nextInt(CHARS.length)]);
}
return buf.toString();
}
public static Color getRandomColor() {
return new Color(random.nextInt(255), random.nextInt(255),
random.nextInt(255));
}
public static Color getReverseColor(Color c) {
return new Color(255 - c.getRed(), 255 - c.getGreen(),
255 - c.getBlue());
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
* response.setContentType("text/html"); String re =
* request.getParameter("username"); System.out.println(re); PrintWriter
* out = response.getWriter();
*
* // response.sendRedirect("test.jsp"); // String s =
* "[{ id:1, pId:0, name:"pNode
* 1", open:true},{ id:11, pId:1, name:"pNode
* 11"},{ id:111, pId:11, name:"leaf node
* 111"},{ id:112, pId:11, name:"leaf node
* 112"},{ id:113, pId:11, name:"leaf node
* 113"},{ id:114, pId:11, name:"leaf node
* 114"},{ id:12, pId:1, name:"pNode 12"},{ id:121, pId:12, name:"leaf
* node 121"},{ id:122, pId:12, name:"leaf node
* 122"},{ id:123, pId:12, name:"leaf node
* 123"},{ id:124, pId:12, name:"leaf node
* 124"},{ id:13, pId:1, name:"pNode 13 - no
* child", isParent:true},{ id:2, pId:0, name:"pNode
* 2"},{ id:21, pId:2, name:"pNode
* 21", open:true},{ id:211, pId:21, name:"leaf node
* 211"},{ id:212, pId:21, name:"leaf node
* 212"},{ id:213, pId:21, name:"leaf node
* 213"},{ id:214, pId:21, name:"leaf node
* 214"},{ id:22, pId:2, name:"pNode 22"},{ id:221, pId:22, name:"leaf
* node 221"},{ id:222, pId:22, name:"leaf node
* 222"},{ id:223, pId:22, name:"leaf node
* 223"},{ id:224, pId:22, name:"leaf node
* 224"},{ id:23, pId:2, name:"pNode 23"},{ id:231, pId:23, name:"leaf
* node 231"},{ id:232, pId:23, name:"leaf node
* 232"},{ id:233, pId:23, name:"leaf node
* 233"},{ id:234, pId:23, name:"leaf node
* 234"},{ id:3, pId:0, name:"pNode 3 - no child", isParent:true}]";
* out.write(s);
*
* out.println(
* "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
* out.println("<HTML>");
* out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
* out.println(" <BODY>"); out.print(" This is ");
* out.print(this.getClass()); out.println(", using the GET method");
* out.println(" </BODY>"); out.println("</HTML>");
*
* out.flush(); out.close();
*/
String s = request.getParameter("username");
System.out.println(s);
response.setContentType("image/jpeg");// 设置输出的类型
String randomString = getRandomString();// 得到返回的字符集
request.getSession(true).setAttribute("randomString", randomString);
int with = 100;
int hight = 30;// 生成图片的大小
Color color = getRandomColor();// 用于背景色
Color reverse = getReverseColor(color);// 用于前景色
BufferedImage bi = new BufferedImage(with, hight,
BufferedImage.TYPE_INT_RGB);// 创建一个彩色的图片
Graphics2D g = bi.createGraphics();// 获取到绘图对象
g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 16));// 设置字体
g.setColor(color);// 设置颜色
g.fillRect(0, 0, with, hight);// 绘制背景
g.setColor(reverse);// 设置颜色
g.drawString(randomString, 18, 20);// 绘制随机字符
for (int i = 0, n = random.nextInt(100); i < n; i++) {// 画最多100个噪音点
g.drawRect(random.nextInt(with), random.nextInt(hight), 1, 1);// 随机噪音点
}
ServletOutputStream out = response.getOutputStream();
// 转换图片格式
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(bi);// 对图片进行编码
out.flush();// 输出
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
/**
* Initialization of the servlet. <br>
*
* @throws ServletException
* if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
---------------------------------------
jsp
function reloadImage(){
document.getElementByIdx_x_x("btn").disabled=false;
document.getElementByIdx_x_x("Identity").src=‘testget?ts=‘+new Date().getTime();
}
function yanzheng() {
}
</script>
<img src="testget" id="Identity" />
<input type="button" id="btn" value="换个图片" onclick="reloadImage()"/>
原文：http://www.cnblogs.com/L0VEGP/p/5042302.html
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