【发布时间】：2015-02-21 03:47:50
【问题描述】：
我将尝试解释我想在这里做什么以及为什么我需要这样做。
我知道我可以使用 servlet 将我的上下文路径内部重定向到上下文路径外部，就像我在这里某个地方得到的下一个一样，它工作得很好：
@WebServlet("/images/*")
public class ImageServlet extends HttpServlet {
// Properties ---------------------------------------------------------------------------------
private String imagePath;
// Init ---------------------------------------------------------------------------------------
public void init() throws ServletException {
// Define base path somehow. You can define it as init-param of the servlet.
this.imagePath = "/home/mycomp/images/";
// In a Windows environment with the Applicationserver running on the
// c: volume, the above path is exactly the same as "c:\var\webapp\images".
// In Linux/Mac/UNIX, it is just straightforward "/var/webapp/images".
}
// Actions ------------------------------------------------------------------------------------
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// Get requested image by path info.
String requestedImage = request.getPathInfo();
// Check if file name is actually supplied to the request URI.
if (requestedImage == null) {
// Do your thing if the image is not supplied to the request URI.
// Throw an exception, or send 404, or show default/warning image, or just ignore it.
response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
return;
}
// Decode the file name (might contain spaces and on) and prepare file object.
File image = new File(imagePath, URLDecoder.decode(requestedImage, "UTF-8"));
// Check if file actually exists in filesystem.
if (!image.exists()) {
// Do your thing if the file appears to be non-existing.
// Throw an exception, or send 404, or show default/warning image, or just ignore it.
response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
return;
}
// Get content type by filename.
String contentType = getServletContext().getMimeType(image.getName());
// Check if file is actually an image (avoid download of other files by hackers!).
// For all content types, see: http://www.w3schools.com/media/media_mimeref.asp
if (contentType == null || !contentType.startsWith("image")) {
// Do your thing if the file appears not being a real image.
// Throw an exception, or send 404, or show default/warning image, or just ignore it.
response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
return;
}
// Init servlet response.
response.reset();
response.setContentType(contentType);
response.setHeader("Content-Length", String.valueOf(image.length()));
// Write image content to response.
Files.copy(image.toPath(), response.getOutputStream());
}
}
因此，每当我使用上下文“/webApp/images/mypic.jpg”中的路径时，它实际上会从我的上下文图像文件夹“/home/mycomp/images/”之外获取图像。
这很好，因为我不能修改原始代码，我只需要添加这个 servlet 就可以将它重定向到上下文之外。这就是为什么我试图做同样的事情，但要上传。我得到了下一段代码来获取保存图像的路径并保存它，目前在上下文中：
String file = "imagen" + (1 + (int) (Math.random() * 100000));
String path = httpServletRequest.getSession().getServletContext().getRealPath("/images/");
InputStream in = imagen.getInputStream();
OutputStream bos = new FileOutputStream(path + "/" + file);
int byteRead = 0;
byte[] buffer = new byte[8192];
while ((byteRead = in.read(buffer, 0, 8192)) != -1) {
bos.write(buffer, 0, byteRead);
}
bos.close();
in.close();
（我知道我错过了实际获取图像的部分，但我不需要显示。）这会将图像保存在“/home/mycomp/project/webApp/images/”中，因为那是getRealPath 的结果，显然是在上下文中。
编辑：这是在 struts1 动作中完成的，这使事情有点复杂，因为现在我已经明白我不能从 servlet 中调用动作，或者我可以吗？强>
这引出了一个问题，是否可以在不修改使用 servlet 之类的东西保存图像的代码的情况下将其保存在上下文之外，而不是将其保存到“/home/mycomp/project/webApp/ images/”，它会保存到“/home/mycomp/images/”吗？
【问题讨论】：