part.write(path+ File.separator+filename);
时间: 2024-05-17 09:16:47 浏览: 15
这段代码将上传的文件写入磁盘上的指定路径中。假设`part`是一个`javax.servlet.http.Part`对象,表示上传的文件,`path`是文件要写入的目录路径,`filename`是上传文件的文件名。
`write()`方法是`Part`接口中的一个方法,用于将上传文件写入指定路径中。在这个实现中,我们将`path`和`filename`连接起来,并使用`File.separator`作为分隔符,以保证跨平台的兼容性。例如,如果`path`是`/home/user`,`filename`是`myfile.txt`,那么写入的文件路径为`/home/user/myfile.txt`。
请确保您的应用程序对目标目录有足够的写入权限,否则文件写入可能会失败。
另外,上传的文件可能包含恶意代码,因此在将文件写入磁盘之前,您应该对文件进行检查和验证。例如,您可以使用文件类型检查、文件大小限制、文件扩展名过滤、病毒扫描等技术来确保上传的文件是安全的。
相关问题
用java写一个文件上传图片
好的,以下是一个简单的Java文件上传图片的示例代码:
```java
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
@WebServlet("/uploadImage")
@MultipartConfig
public class ImageUploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final String UPLOAD_DIR = "uploads";
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String applicationPath = request.getServletContext().getRealPath("");
String uploadFilePath = applicationPath + File.separator + UPLOAD_DIR;
File fileSaveDir = new File(uploadFilePath);
if (!fileSaveDir.exists()) {
fileSaveDir.mkdirs();
}
String fileName = "";
for (Part part : request.getParts()) {
fileName = getFileName(part);
if (!fileName.isEmpty()) {
Path path = Paths.get(uploadFilePath + File.separator + fileName);
try (InputStream inputStream = part.getInputStream()) {
Files.copy(inputStream, path);
} catch (IOException e) {
e.printStackTrace();
}
}
}
response.getWriter().write(fileName + " uploaded successfully!");
}
private String getFileName(Part part) {
String contentDisp = part.getHeader("content-disposition");
String[] tokens = contentDisp.split(";");
for (String token : tokens) {
if (token.trim().startsWith("filename")) {
return token.substring(token.indexOf("=") + 2, token.length() - 1);
}
}
return "";
}
}
```
这个示例代码使用了Java Servlet API提供的MultipartConfig注解和Part接口来处理文件上传。在上传文件时,服务器会将文件保存在指定的目录下,并返回文件名给客户端。在客户端可以根据返回的文件名来下载或显示上传的图片。
你可以把这个代码保存为一个Java文件,然后使用Java编译器将它编译成一个class文件,最后部署到Web服务器中去。当客户端上传图片时,就可以访问这个Servlet来处理图片上传了。
使用java写出图片的上传下载
图片上传:
```java
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
@WebServlet("/uploadImage")
@MultipartConfig
public class UploadImageServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final String UPLOAD_DIR = "uploads";
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String applicationPath = request.getServletContext().getRealPath("");
String uploadPath = applicationPath + File.separator + UPLOAD_DIR;
File fileUploadDirectory = new File(uploadPath);
if (!fileUploadDirectory.exists()) {
fileUploadDirectory.mkdirs();
}
final Part filePart = request.getPart("image");
final String fileName = getFileName(filePart);
Path path = Paths.get(uploadPath + File.separator + fileName);
try (InputStream inputStream = filePart.getInputStream()) {
Files.copy(inputStream, path);
}
response.getWriter().print("Image uploaded successfully!");
}
private String getFileName(final Part part) {
final String partHeader = part.getHeader("content-disposition");
for (String content : partHeader.split(";")) {
if (content.trim().startsWith("filename")) {
return content.substring(content.indexOf("=") + 2, content.length() - 1);
}
}
return null;
}
}
```
图片下载:
```java
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/downloadImage")
public class DownloadImageServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final String UPLOAD_DIR = "uploads";
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String fileName = request.getParameter("name");
String applicationPath = request.getServletContext().getRealPath("");
String downloadPath = applicationPath + File.separator + UPLOAD_DIR + File.separator + fileName;
File file = new File(downloadPath);
FileInputStream inputStream = new FileInputStream(file);
response.setContentType("image/jpeg");
response.setHeader("Content-Disposition", "attachment; filename=\"" + file.getName() + "\"");
OutputStream outputStream = response.getOutputStream();
byte[] buffer = new byte[1024];
int bytesRead = -1;
while ((bytesRead = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
inputStream.close();
outputStream.close();
}
}
```
注意事项:
1. 这里使用的是 Servlet 3.0 的注解,所以需要在 web.xml 中添加 `<web-app version="3.0">`。
2. form 表单中的 `enctype` 必须是 `multipart/form-data`。
3. `getFileName` 方法可以获取上传文件的文件名。
4. `response.setContentType` 要设置成图片的 MIME 类型,如 `image/jpeg`。
5. `response.setHeader("Content-Disposition", "attachment; filename=\"" + file.getName() + "\"");` 中的 `filename` 参数可以指定下载时的文件名。
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