<%@ page autoFlush="false" import="java.awt.*,java.awt.image.*,com.sun.image.codec.jpeg.*,java.util.*"%> <%@ page import="org.apache.commons.lang.RandomStringUtils"%> <% RandomStringUtils rs=new RandomStringUtils(); String random=rs.randomAlphanumeric(4); session.setAttribute("random",random); %> <%
out.clear(); response.setContentType("image/jpeg"); response.addHeader("pragma","NO-cache"); response.addHeader("Cache-Control","no-cache"); response.addDateHeader("Expries",0); int width=100, height=40; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); //以下填充背景?色 g.setColor(Color.GRAY); Font DeFont=new Font("SansSerif", Font.PLAIN, 32); g.setFont(DeFont); g.fillRect(0, 0, width, height); //?置字体?色 g.setColor(Color.RED); g.drawString(random,3,30); g.dispose(); ServletOutputStream outStream = response.getOutputStream(); JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(outStream); encoder.encode(image); outStream.close(); %>
test.jsp文件代码如下: <%@ page contentType="text/html; charset=UTF-8" language="java" import="java.sql.*" errorPage="" %> <html> <head> <title>Untitled Document</title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> </head>
<body> <img src="random.jsp"> </body> </html>
如果不想导入Apache的包可以自己编译下面这个文件 // FrontEnd Plus GUI for JAD // DeCompiled : RandomStringUtils.class
package org.apache.commons.lang;
import java.util.Random;
public class RandomStringUtils {
private static final Random RANDOM = new Random();
public RandomStringUtils() { }
public static String random(int count) { return random(count, false, false); }
public static String randomAscii(int count) { return random(count, 32, 127, false, false); }
public static String randomAlphabetic(int count) { return random(count, true, false); }
public static String randomAlphanumeric(int count) { return random(count, true, true); }
public static String randomNumeric(int count) { return random(count, false, true); }
public static String random(int count, boolean letters, boolean numbers) { return random(count, 0, 0, letters, numbers); }
public static String random(int count, int start, int end, boolean letters, boolean numbers) { return random(count, start, end, letters, numbers, null); }
public static String random(int count, int start, int end, boolean letters, boolean numbers, char set[]) { if(start == 0 && end == 0) { end = 122; start = 32; if(!letters && !numbers) { start = 0; end = 0x7fffffff; } } StringBuffer buffer = new StringBuffer(); int gap = end - start; while(count-- != 0) { char ch; if(set == null) ch = (char)(RANDOM.nextInt(gap) + start); else ch = set[RANDOM.nextInt(gap) + start]; if(letters && numbers && Character.isLetterOrDigit(ch) || letters && Character.isLetter(ch) || numbers && Character.isDigit(ch) || !letters && !numbers) buffer.append(ch); else count++; } return buffer.toString(); }
public static String random(int count, String set) { return random(count, set.toCharArray()); }
public static String random(int count, char set[]) { return random(count, 0, set.length - 1, false, false, set); }
}