[求助]有关于JSP彩色验证码的一些问题，哪位大侠帮帮忙？
我最近在弄毕业设计，对于验证部分。我希望加入彩色验证码。便从网上寻找，运行后有一些问题。 //image.jsp
<%@ page contentType="image/jpeg"%>
<%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%>
<%!
Color getRandColor(int fc,int bc){//给定范围获得随机颜色
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);
}
%>
<%
//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font("Comic Sans MS",Font.PLAIN,20));
//画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
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);
}
// 取随机产生的认证码(4位数字)
String sRand="";
for(int i=0;i<4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
//将认证码显示到图象中
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute("rand",sRand);
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
//check.jsp
<%@ page contentType="text/html; charset=gb2312" language="java" %>
<html>
<head>
<title>check</title>
<SCRIPT language="javascript">
function chkMsg(){
if(login.username.value == '' || login.password.value == '' || login.secr.value == ''){
alert('请输入完整信息');
return false;
}
return true;
}
</SCRIPT>
</head>
<body>
<form name="login" method="POST" action="confirm.jsp" onSubmit="return chkMsg()">
<table>
<tr>
<td>帐户<input type="text" name="username"></td>
<td>密码<input type="password" name="password"></td>
<td>验证码<input type="text" name="secr" ></td>
<td><img border="0" src="image.jsp"></td>
<td><input type="submit" name="sub" value="确定"></td>
</tr>
</table>
</form>
</body>
</html>
//confirm.jsp
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" import="java.util.*" import="java.text.*" import="*" errorPage="" %>
<jsp:useBean id="chklogin" class="test.firm" scope="page" />
<%
String adminname = request.getParameter("username");
String adminpass = request.getParameter("password");
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("secr");
String sql = "SELECT * FROM custom where custid='"+adminname+"' and custpass='"+adminpass+"'";
ResultSet rs = chklogin.executeQuery(sql);
if(!rand.equals(input))
{
out.println("<script language=javascript> alert('你输入的验证码不正确！'); location.href='index.jsp';</script>");
}
else if (rs.next())
{
String cash = rs.getString("custcash");
rs.close();
session.setAttribute("adminname",adminname);
session.setAttribute("cash",cash);
response.sendRedirect("jump.jsp");
}
else
{
out.println("<script language=javascript> alert('你输入的用户名或密码不正确！'); location.href='index.jsp';</script>");
}
%>
<%
chklogin.closeStmt();
chklogin.closeConn();
%>
//jump.jsp
<%@ page contentType="text/html; charset=GB2312"%>
<html>
<head>
<title>jump</title>
</head>
<body>
<h1>ok，您验证以成功</h1>
</body>
</html>
//test.firm
ackage test;
import java.awt.*;
import javax.swing.JPanel;
import java.sql.*;
public class firm
{
String strDBDriver="sun.jdbc.odbc.JdbcOdbcDriver";
String strDBUrl="jdbc:odbc:MYSQL";
public Connection conn=null;
public Statement stmt=null;
ResultSet rs=null;
//<!--注册数据库驱动程序-->
public firm(){
try{
Class.forName(strDBDriver);
}catch(java.lang.ClassNotFoundException e){
System.err.println("firm():"+e.getMessage());
}
}
//<!--建立数据库连接及定义数据查询-->
public ResultSet executeQuery(String sql){
rs=null;
try{
conn=DriverManager.getConnection(strDBUrl,"sa","");//创建数据库连接对象
stmt=conn.createStatement();
rs=stmt.executeQuery(sql);
}catch(SQLException ex){
System.err.println("aq.executeQuery:"+ex.getMessage());
}
return rs;
}
//<!--定义数据操作-->
public void executeUpdate(String sql){
stmt=null;
rs=null;
try{
conn=DriverManager.getConnection(strDBUrl,"sa","");
stmt=conn.createStatement();
stmt.executeQuery(sql);
rs.close();
stmt.close();
conn.close();
}catch(SQLException ex){
System.err.println("aq.executeUpdate:"+ex.getMessage());
}
}
//<!--关闭数据库连接-->
public void closeStmt(){
try{
stmt.close();
}catch(SQLException e){
e.printStackTrace();
}
}
public void closeConn(){
try{
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
}
public String ex_chinese(String str){
if(str==null){
str ="" ;
}else{
try{
str = new String(str.getBytes("iso-8859-1"),"gb2312");
}catch (Exception ex) {
}
}
return str ;
}
public static void main(String args[]){
firm fm= new firm();
}
}
数据源为MYSQL 表为custom 其中列名分别为custid,custpass,custcash
运行后问题为：
StandardWrapperValve[debugjsp]: Servlet.service() for servlet debugjsp threw exception
java.lang.IllegalStateException: getOutputStream() has already been called for this response
java.lang.IllegalStateException: getOutputStream() has already been called for this response
??at org.apache.catalina.connector.ResponseBase.getWriter(ResponseBase.java:755)
??at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:165)
??at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:166)
??at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:158)
??at org.apache.jasper.runtime.JspWriterImpl.flush(JspWriterImpl.java:205)
??at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:177)
??at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:198)
??at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:193)
??at org.apache.jsp.image$jsp._jspService(image$jsp.java:145)
??at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:107)
??at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
??at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:202)
??at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:382)
??at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:474)
??at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
??at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
??at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
??at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
??at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
??at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
??at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
??at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
??at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
??at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
??at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
??at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
??at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
??at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2343)
??at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
??at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
??at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
??at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
??at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
??at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
??at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
??at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
??at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
??at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
??at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
??at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
??at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1012)
??at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1107)
??at java.lang.Thread.run(Thread.java:536)
