文件上传file upload

使用fileupload组件实现文件上传：

导入

commons-fileupload-1.2.2.jar

commons-io-2.1.jar

官方文档：

// Check that we have a file upload request 检测是否有文件上传的请求
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
/**************************************************************/

// Create a factory for disk-based file items 创建一个基于磁盘文件项目的工厂
DiskFileItemFactory factory = new DiskFileItemFactory();

// Configure a repository 配置存储库(to ensure a secure temp location is used 确保一个安全的临时位置被利用)
ServletContext servletContext = this.getServletConfig().getServletContext();
File repository = (File) servletContext.getAttribute("javax.servlet.context.tempdir");
factory.setRepository(repository);

// Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload(factory);

// Parse the request
List<FileItem> items = upload.parseRequest(request);

/******************************************************************************/

// Create a factory for disk-based file items
DiskFileItemFactory factory = new DiskFileItemFactory();

// Set factory constraints 设置工厂约束
factory.setSizeThreshold(yourMaxMemorySize);  //
factory.setRepository(yourTempDirectory);   //

// Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload(factory);

// Set overall request size constraint 设置整体请求大小的约束
upload.setSizeMax(yourMaxRequestSize);

// Parse the request
List<FileItem> items = upload.parseRequest(request);

/***********************************************************************/

// Process the uploaded items
Iterator<FileItem> iter = items.iterator();
while (iter.hasNext()) {
    FileItem item = iter.next();

    if (item.isFormField()) {
        processFormField(item);
    } else {
        processUploadedFile(item);
    }
}

/*****************************************************************************/

// Process the uploaded items
Iterator<FileItem> iter = items.iterator();
while (iter.hasNext()) {
    FileItem item = iter.next();

    if (item.isFormField()) {
        processFormField(item);
    } else {
        processUploadedFile(item);
    }
}

/*********************************************************/

package com.servlet;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;

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;

public class FileUploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    public FileUploadServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            
        
        boolean isMultipart = ServletFileUpload.isMultipartContent(request);
        System.out.println("是否有文件上传："+isMultipart);
        
        DiskFileItemFactory factory = new DiskFileItemFactory();
        
        factory.setSizeThreshold(1024*512);  // 设置内存缓冲区的阀值512k
        //设置临时存储文件的目录
        File tempDir = new File("E:\upload");
        factory.setRepository(tempDir);
        
        ServletFileUpload upload = new ServletFileUpload(factory);
        upload.setSizeMax(1024*1024*5);  //设置上传文件的最大值 5M
        try {
            //解析上传文件流，获取FileItem的对象列表
            List<FileItem> items = upload.parseRequest(request);
            
            for(FileItem item :items){
                if(item.isFormField()){
                    String name = item.getName();
                    String value = item.getString();
                    System.out.println(name+":"+value);
                }else{//如果是文件域则将文件保存到d:\file
                    String fieldName = item.getFieldName();
                    String fileName = item.getName();
                    String contentType = item.getContentType();
                    long sizeInBytes = item.getSize();
                    
                    System.out.println("fieldName:"+fieldName);
                    System.out.println("fileName:"+fileName);
                    System.out.println("contentType:"+contentType);
                    System.out.println("sizeInBytes:"+sizeInBytes);
                    
                    
                    InputStream is = item.getInputStream();
                    byte [] buffer = new byte[1024];
                    int len = 0;
                    fileName = "E:\file\"+fileName;
                    OutputStream out = new FileOutputStream(fileName);
                    while ((len = is.read(buffer))!=-1){
                        out.write(buffer,0,len);
                    }
                    out.close();is.close();
                    
                }
            }
        } catch (FileUploadException e) {
            e.printStackTrace();
        }    
            
    }

}

<form action="FileUploadServlet" method="post" enctype="multipart/form-data">
        file:<input type="file" name="file"/>
        <input type="submit" value="Submit"/>
</form>