Tomcat下jsp中出现getOutputStream() has already been called for this response异常的原因和解决方法
在tomcat5下jsp中出现此错误一般都是在jsp中使用了输出流(如输出图片验证码,文件下载等),
没有妥善处理好的原因。
具体的原因就是
在tomcat中jsp编译成servlet之后在函数_jspService(HttpServletRequest request, HttpServletResponse response)的最后
有一段这样的代码
finally {
if (_jspxFactory != null) _jspxFactory.releasePageContext(_jspx_page_context);
}
这里是在释放在jsp中使用的对象,会调用response.getWriter(),因为这个方法是和
response.getOutputStream()相冲突的!所以会出现以上这个异常。
然后当然是要提出解决的办法,其实挺简单的(并不是和某些朋友说的那样--
将jsp内的所有空格和回车符号所有都删除掉),
在使用完输出流以后调用以下两行代码即可:
out.clear();
out = pageContext.pushBody();
输出彩色验证码例子:
image.jsp
<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="GB18030"%>
<%!
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("Times New Roman",Font.PLAIN,18));
//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 rand = request.getParameter("rand");
//rand = rand.substring(0,rand.indexOf("."));
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("ccode",sRand);
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
分享到:
相关推荐
NULL 博文链接:https://javal.iteye.com/blog/1993903
1.在tomcat6.0下jsp出现getOutputStream() has already been called for this response异常的原因和解决方法 在tomcat6.0下jsp中出现此错误一般都是在jsp中使用了输出流(如输出图片验证码,文件下载等),没有...
纠结了半天的 java.lang.IllegalStateException: getOutputStream() has already。这个问题困扰了半天,在网上查阅了大量资料 出这个错误一般就是下面2个.....
验证码出现getOutputStream() has already been called for this response错误解决
解决了getOutputStream() has already been called for this response. 并将产生验证码的逻辑从JSP页面中分离出来,单独写了一个类 便于重用。
NULL 博文链接:https://nethub2.iteye.com/blog/2023937
Returns a boolean indicating whether the named response header has already been set. contextDestroyed(ServletContextEvent) - Method in interface javax.servlet.ServletContextListener Notification ...
* 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 ...
this.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { try { MsgBean bean = new MsgBean(); bean.setType("请求下线"); bean.setSource(ClientFrame...
BufferedWriter wrbuf = new BufferedWriter(new OutputStreamWriter(s1.getOutputStream())); wrbuf.write("false\n"); wrbuf.flush(); }else{ Socket s2 = clients.get(str[0]); ...
servlet的response可以对返回的内容和格式进行一些设置。
outputS = new ObjectOutputStream(connection.getOutputStream()); beConnected = true; } catch (IOException e) { System.out.println("无法获取连接的输入输出流"); } } ...
if ((su.waitFor() != 0) || !device.canRead() || !device.canWrite()) { throw new SecurityException(); } } catch (Exception e) { e.printStackTrace(); throw new ...
PrintStream ps = new PrintStream(s.getOutputStream()); /* 产生发消息的时刻 */ Date date = new Date(); SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss"); /* 向客户端发消息,消息...
String s=this.jTextField3.getText().trim(); sendData(s); } } private void listenClient(int port){//侦听 try{ if(jButton1.getText().trim().equals("侦听")){ server = new ServerSocket(port); ...
dataOut = new ObjectOutputStream(socket.getOutputStream()); listener = new Thread(this); listener.start(); } catch (IOException ioException) { ioException.printStackTrace(); } } } public ...
for (int i = 0; i; i++){ // 设置压缩文件入口entry,为被读取的文件创建压缩条目 File tempFile = new File(fileArray[i].toString()); String rootStr = file.getPath(); String entryStr = ...
heads是excel表头,datalist是数据public void createExcelStream(HttpServletResponse response,String filename,String[] heads,List[]> datalist){ try{ OutputStream os = response.getOutputStream();...
this.client=c; } public void run(){ try{ BufferedReader in=new BufferedReader(new InputStreamReader(client.getInputStream())); PrintWriter out=new PrintWriter(client.getOutputStream...