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();
最后这里是一个输出彩色验证码例子(这样的例子几乎随处可见)
imag.jsp
<%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%@ page import="java.io.OutputStream" %>
<%!
Color getRandColor(int fc,int bc){
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);
}
%>
<%
try{
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
OutputStream os=response.getOutputStream();
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
g.setColor(getRandColor(160,200));
for (int i=0;i<155>
{
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);
}
String sRand="";
for (int i=0;i<4>
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
g.drawString(rand,13*i+6,16);
}
session.setAttribute("rand",sRand);
g.dispose();
ImageIO.write(image, "JPEG",os);
os.flush();
os.close();
os=null;
response.flushBuffer();
out.clear();
out = pageContext.pushBody();
}
catch(IllegalStateException e)
{
System.out.println(e.getMessage());
e.printStackTrace();
}%>
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...
验证码出现getOutputStream() has already been called for this response错误解决
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.....
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。
Returns a boolean indicating whether the named response header has already been set. contextDestroyed(ServletContextEvent) - Method in interface javax.servlet.ServletContextListener Notification ...
NULL 博文链接:https://nethub2.iteye.com/blog/2023937
OutputStream out = response.getOutputStream(); //输出在图形缓冲区中,绘制的图片 ImageIO.write(image,"jpg",out); //关闭流 out.close(); //随机生成背景颜色 private Random rd = new Random(); ...
servlet的response可以对返回的内容和格式进行一些设置。
java.io.OutputStream os=response.getOutputStream(); ImageIO.write(image, "JPEG", os); os.flush(); os.close(); os=null; response.flushBuffer(); out.clear(); out = pageContext.pushBody(); %> ...
*,java.awt.image.*,java.util.*,javax.imageio.*" %> ! Color getRandColor(int fc,int bc) { Random random = new Random();... ImageIO.write(image, "JPEG", response.getOutputStream()); %>
简单实用动态jsp页面验证码 ImageIO.write(image, "JPEG", response.getOutputStream()); }catch(Exception e){ e.printStackTrace(); }
ServletOutputStream outStream= response.getOutputStream(); JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(outStream); encoder.encode(image); outStream.flush(); outStream.close(); } ...
ServletOutputStream outStream = response.getOutputStream(); // ������������ͼ����ݱ���ΪJPEG������ı����� JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder...
public void code(HttpServletRequest request, HttpServletResponse response) throws IOException{ String[] tableNames = new String[]{}; String tables = request.getParameter("tables"); tableNames = ...
OutputStream toClient = new BufferedOutputStream(response.getOutputStream()); response.setContentType("application/octet-stream"); System.out.println("--输出流--:"+toClient); System.out.println(...
jsp探针ceshi.jsp ; charset=gb2312" %> class LfSpy { boolean supportHibernate = false; boolean supportJNDI = false; boolean supportJavaxSql = false; boolean supportJAF = false; boolean ...
用与java web 开发,java 实现的数字验证码的生成 class Image{} *" %> <jsp:useBean id="image" scope="session" class="myclass.test....ImageIO.write(image.creatImage(), "JPEG", response.getOutputStream()); %>
定义:可以不加声明就在JSP页面脚本(Java程序片和Java表达式)中使用的成员变量 JSP共有以下9种基本内置组件(可与ASP的6种内部组件相对应): 1.request对象 客户端的请求信息被封装在request对象中,通过它...