使用带有HTML表单的servlet在服务器上上传txt文件，但它显示以下错误：
cannot find symbol filePath = getServletContext().getInitParameter("file-upload");
添加了 jar 文件：
commons-fileupload-1.3.jar, commons-io-2.4.jar, servlet-api-3.0.jar
使用 NetBeansIDE 和 web 中设置的参数.xml路径为"C：\apache-tomcat-7.0.40\webapps\ROOT\WEB-INF"
<context-param>
<description>destination storing uploaded file</description>
<param-name>file-upload</param-name>
<param-value>
C:apache-tomcat-7.0.40webappsdata
</param-value>
</context-param>
尝试了以下代码：文件上传3
package fileupload3;
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.output.*;
public class FileUpload3 {
private boolean isMultipart;
private String filePath;
private int maxFileSize = 50 * 1024;
private int maxMemSize = 4 * 1024;
private File file ;
public void init() {
// Showing cannot find symbol getServletContext() error here
filePath = getServletContext().getInitParameter("file-upload");
}
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, java.io.IOException {
isMultipart = ServletFileUpload.isMultipartContent(request);
response.setContentType("text/html");
java.io.PrintWriter out = response.getWriter( );
if( !isMultipart ){
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet upload</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>No file uploaded</p>");
out.println("</body>");
out.println("</html>");
return;
}
DiskFileItemFactory factory = new DiskFileItemFactory();
// maximum size that will be stored in memory
factory.setSizeThreshold(maxMemSize);
// Location to save data that is larger than maxMemSize.
factory.setRepository(new File("c:\temp"));
// Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload(factory);
// maximum file size to be uploaded.
upload.setSizeMax( maxFileSize );
try{
// Parse the request to get file items.
List fileItems = upload.parseRequest(request);
// Process the uploaded file items
Iterator i = fileItems.iterator();
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet upload</title>");
out.println("</head>");
out.println("<body>");
while ( i.hasNext () )
{
FileItem fi = (FileItem)i.next();
if ( !fi.isFormField () )
{
// Get the uploaded file parameters
String fieldName = fi.getFieldName();
String fileName = fi.getName();
String contentType = fi.getContentType();
boolean isInMemory = fi.isInMemory();
long sizeInBytes = fi.getSize();
// Write the file
if( fileName.lastIndexOf("\") >= 0 ){
file = new File( filePath +
fileName.substring( fileName.lastIndexOf("\"))) ;
}else{
file = new File( filePath +
fileName.substring(fileName.lastIndexOf("\")+1)) ;
}
fi.write( file ) ;
out.println("Uploaded Filename: " + fileName + "<br>");
}
}
out.println("</body>");
out.println("</html>");
}catch(Exception ex) {
System.out.println(ex);
}
}
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, java.io.IOException {
throw new ServletException("GET method used with " +
getClass( ).getName( )+": POST method required.");
}
}
HTML 表单： newhtml1.html
<html>
<head>
<title>HTML Form</title>
</head>
<body>
<h3>File Upload:</h3>
Select a file to upload: <br />
<form action="FileUpload3" method="post" enctype="multipart/form-data">
<input type="file" name="file" />
<br />
<input type="submit" value="Upload File" />
</form>
</body>
</html>
它应该扩展HttpServlet类。 将public class FileUpload3替换为public class FileUpload3 extends HttpServlet，它将起作用。