开发环境:JDK1.4,Myeclipse6.6,WEB Logic8.1
出错记录:在WEB Logic后台报错如下：
Servlet failed with IOException
javax.imageio.IIOException: Can't create output stream ![color=red][/color]
at javax.imageio.ImageIO.write(ImageIO.java:1505)
at com.sclh.common.ValidateCodeServlet.service(ValidateCodeServlet.java:
111)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run
(ServletStubImpl.java:996)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:419)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:315)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationActio
n.run(WebAppServletContext.java:6452)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(Authenticate
dSubject.java:321)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:
118)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppSe
rvletContext.java:3661)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestIm
pl.java:2630)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)
Caused by: javax.imageio.IIOException: Can't create cache file!
at javax.imageio.ImageIO.createImageOutputStream(ImageIO.java:395)
at javax.imageio.ImageIO.write(ImageIO.java:1503)
... 12 more
Caused by: java.io.IOException: 系统找不到指定的路径。
at java.io.WinNTFileSystem.createFileExclusively(Native Method)
at java.io.File.checkAndCreate(File.java:1314)
at java.io.File.createTempFile(File.java:1402)
at javax.imageio.stream.FileCacheImageOutputStream.<init>(FileCacheImage
OutputStream.java:66)
at com.sun.imageio.spi.OutputStreamImageOutputStreamSpi.createOutputStre
amInstance(OutputStreamImageOutputStreamSpi.java:50)
at javax.imageio.ImageIO.createImageOutputStream(ImageIO.java:391)
... 13 more
在网上查了一下：有二个答案
1:Tomcat下创建一个临时目录temp,可惜我用的是Web Logic,只有用第二个方法了.
2 把代码最后一句改为:
//将图像输出到Servlet输出流中。
/*ServletOutputStream sos = response.getOutputStream(); ImageIO.write(buffImg, "jpeg", sos); sos.close();*/ JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(response.getOutputStream()); encoder.encode(buffImg);
代码如下:
public class ValidateCode extends HttpServlet {
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
HttpSession session = (HttpSession) request.getSession();
String action = request.getParameter("action");
if("getSession".equals(action)){
String validateCodeSession = (String) session.getAttribute("validateCode");
PrintWriter out = response.getWriter();
response.setContentType("text/html");
response.setHeader("Cache-Control", "no-cache");
out.print(validateCodeSession);
out.close();
}else{
if(session.getAttribute("validateCode") != null){
session.removeAttribute("validateCode");
}
//验证码图片的宽度。
int width = 120;
//验证码图片的高度。
int height = 30;
//验证码字符个数
int codeCount = 4;
int x_v = 0;
//字体高度
int fontHeight;
int codeY;
char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5',
'6', '7', '8', '9' };
//初始化图片大小
x_v = width / (codeCount + 1);
fontHeight = height - 2;
codeY = height - 4;
//定义图像buffer
BufferedImage buffImg = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g = buffImg.createGraphics();
//创建一个随机数生成器类
Random random = new Random();
//将图像填充为白色
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
//创建字体，字体的大小应该根据图片的高度来定。
Font font = new Font("Arial", Font.BOLD, fontHeight);
//设置字体。
g.setFont(font);
//画边框。
g.setColor(Color.WHITE);
g.drawRect(0, 0, width - 1, height - 1);
//随机产生160条干扰线，使图象中的认证码不易被其它程序探测到。
g.setColor(Color.yellow);
for (int i = 0; i < 30; 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);
}
//randomCode用于保存随机产生的验证码，以便用户登录后进行验证。
StringBuffer randomCode = new StringBuffer();
int red = 0, green = 0, blue = 0;
//随机产生codeCount数字的验证码。
for (int i = 0; i < codeCount; i++) {
//得到随机产生的验证码数字。
String strRand = String
.valueOf(codeSequence[random.nextInt(36)]);
//产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。
red = random.nextInt(255);
green = random.nextInt(255);
blue = random.nextInt(255);
//用随机产生的颜色将验证码绘制到图像中。
g.setColor(new Color(red, green, blue));
g.drawString(strRand, (i + 1) * x_v, codeY);
//将产生的四个随机数组合在一起。
randomCode.append(strRand);
}
// 将四位数字的验证码保存到Session中。
session.setAttribute("validateCode", randomCode.toString());
// 禁止图像缓存。
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
//将图像输出到Servlet输出流中。
/*ServletOutputStream sos = response.getOutputStream();
ImageIO.write(buffImg, "jpeg", sos);
sos.close();*/
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(response.getOutputStream());
encoder.encode(buffImg);
}
}
}Web.xml内容如下：
<servlet>
<servlet-name>ValidateCode </servlet-name>
<servlet-class>com.ValidateCode </servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ValidateCode </servlet-name>
<url-pattern>/ValidateCode</url-pattern>
</servlet-mapping>JSP内容如下：
<img src="/ValidateCode " id="ImgId" width="120" height="30" />