Servlet中的文件上传_servlet中的上传-优快云博客

本文介绍如何使用Apache Commons FileUpload库实现文件上传功能，包括初始化配置、检查是否为文件上传请求、解析请求获取文件项并进行相应处理。

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上传表单中的注意事项：

表单 method 属性应该设置为 POST 方法，不能使用 GET 方法

表单 enctype 属性应该设置为multipart/form-data

下面的实例是借助于commons-fileupload和commons-io相关包来实现的

[java] view plain copy print ?

importjava.io.*;
import java.util.*;
importjavax.servlet.ServletConfig;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
importorg.apache.commons.fileupload.FileItem;
importorg.apache.commons.fileupload.FileUploadException;
importorg.apache.commons.fileupload.disk.DiskFileItemFactory;
importorg.apache.commons.fileupload.servlet.ServletFileUpload;
importorg.apache.commons.io.output.*;
public class UploadServletextends HttpServlet {
private boolean isMultipart;
private String filePath;
private int maxFileSize = 50 * 1024;
private int maxMemSize = 4 * 1024;
private File file ;
public void init( ){
// 获取文件将被存储的位置
filePath =
getServletContext().getInitParameter("file-upload");
}
public void doPost(HttpServletRequestrequest,
HttpServletResponse response)
throws ServletException,java.io.IOException {
// 检查我们有一个文件上传请求
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>Servletupload</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>No fileuploaded</p>");
out.println("</body>");
out.println("</html>");
return;
}
DiskFileItemFactoryfactory = new DiskFileItemFactory();
//设置上传文件时用于临时存放文件的内存大小
factory.setSizeThreshold(maxMemSize);
//设置存放临时文件的目录，这个目录需要事先建立好
factory.setRepository(new File("c:\\temp"));
// 创建一个新的文件上传处理程序
ServletFileUploadupload = new ServletFileUpload(factory);
// 允许上传的文件大小的最大值
upload.setSizeMax( maxFileSize );
try{
// 解析请求，获取文件项
List fileItems = upload.parseRequest(request);
// 处理上传的文件项
Iterator i = fileItems.iterator();
out.println("<html>");
out.println("<head>");
out.println("<title>Servletupload</title>");
out.println("</head>");
out.println("<body>");
while ( i.hasNext () )
{
FileItem fi = (FileItem)i.next();
if ( !fi.isFormField () ) //是文件域
{
// 获取上传文件的参数
String fieldName = fi.getFieldName();
String fileName = fi.getName(); //文件的全路径
String contentType = fi.getContentType();
boolean isInMemory =fi.isInMemory();
long sizeInBytes = fi.getSize();
//得到去除路径的文件名
if(fileName.lastIndexOf("\\") >= 0 ){ //路径中包含“\”时
file = new File( filePath +
fileName.substring( fileName.lastIndexOf("\\")));
}else{ //路径中不包含“\”时
file = new File( filePath +
fileName.substring(fileName.lastIndexOf("\\")+1)) ;
}
fi.write( file ) ; // 写入文件
out.println("UploadedFilename: " + fileName + "<br>");
}
}
out.println("</body>");
out.println("</html>");
}catch(Exception ex) {
System.out.println(ex);
}
}
public void doGet(HttpServletRequestrequest,
HttpServletResponseresponse)
throws ServletException,java.io.IOException {
throw new ServletException("GETmethod used with " +
getClass( ).getName( )+":POST method required.");
}
}

importjava.io.*;
import java.util.*;
 
importjavax.servlet.ServletConfig;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
 
importorg.apache.commons.fileupload.FileItem;
importorg.apache.commons.fileupload.FileUploadException;
importorg.apache.commons.fileupload.disk.DiskFileItemFactory;
importorg.apache.commons.fileupload.servlet.ServletFileUpload;
importorg.apache.commons.io.output.*;
 
public class UploadServletextends HttpServlet {
  
   private boolean isMultipart;
   private String filePath;
   private int maxFileSize = 50 * 1024;
   private int maxMemSize = 4 * 1024;
   private File file ;
 
   public void init( ){
      // 获取文件将被存储的位置
      filePath =
            getServletContext().getInitParameter("file-upload");
   }
   public void doPost(HttpServletRequestrequest,
               HttpServletResponse response)
              throws ServletException,java.io.IOException {
      // 检查我们有一个文件上传请求
      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>Servletupload</title>"); 
        out.println("</head>");
         out.println("<body>");
         out.println("<p>No fileuploaded</p>");
        out.println("</body>");
        out.println("</html>");
         return;
      }
      DiskFileItemFactoryfactory = new DiskFileItemFactory();
      //设置上传文件时用于临时存放文件的内存大小
      factory.setSizeThreshold(maxMemSize);
      //设置存放临时文件的目录，这个目录需要事先建立好
      factory.setRepository(new File("c:\\temp"));
 
      // 创建一个新的文件上传处理程序
      ServletFileUploadupload = new ServletFileUpload(factory);
      // 允许上传的文件大小的最大值
      upload.setSizeMax( maxFileSize );
 
      try{
      // 解析请求，获取文件项
      List fileItems = upload.parseRequest(request);
     
      // 处理上传的文件项
      Iterator i = fileItems.iterator();
 
      out.println("<html>");
      out.println("<head>");
      out.println("<title>Servletupload</title>"); 
      out.println("</head>");
      out.println("<body>");
      while ( i.hasNext () )
      {
         FileItem fi = (FileItem)i.next();
         if ( !fi.isFormField () )  //是文件域
         {
            // 获取上传文件的参数
            String fieldName = fi.getFieldName();
            String fileName = fi.getName();  //文件的全路径
            String contentType = fi.getContentType();
            boolean isInMemory =fi.isInMemory();
            long sizeInBytes = fi.getSize();
           //得到去除路径的文件名
            if(fileName.lastIndexOf("\\") >= 0 ){   //路径中包含“\”时
               file = new File( filePath +
               fileName.substring( fileName.lastIndexOf("\\")));
            }else{   //路径中不包含“\”时
               file = new File( filePath +
              fileName.substring(fileName.lastIndexOf("\\")+1)) ;
            }
            fi.write( file ) ;   // 写入文件
            out.println("UploadedFilename: " + fileName + "<br>");
         }
      }
      out.println("</body>");
      out.println("</html>");
   }catch(Exception ex) {
       System.out.println(ex);
   }
   }
   public void doGet(HttpServletRequestrequest,
                       HttpServletResponseresponse)
        throws ServletException,java.io.IOException {
       
        throw new ServletException("GETmethod used with " +
                getClass( ).getName( )+":POST method required.");
   }
}