通过Servlet文件上传理解Struts2文件上传原理(附源码)
package mypack;import java.io.File;import java.io.IOException;import java.io.PrintWriter;import java.util.Iterator;import java.util.List;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.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;public class UploadServlet extends HttpServlet{private String filePath;// 存放上传文件的目录private String tempFilePath;// 存放临时文件的目录@Overridepublic void init(ServletConfig config) throws ServletException{super.init(config);filePath = config.getInitParameter("filePath");System.out.println("filePath1::"+filePath);tempFilePath = config.getInitParameter("tempFilePath");//上面从web.xml中得到临时文件和保存文件的目录名System.out.println("tempFilePath1::"+tempFilePath);filePath = this.getServletContext().getRealPath(filePath);System.out.println("filePath2::"+filePath);tempFilePath = this.getServletContext().getRealPath(tempFilePath);System.out.println("tempFilePath2::"+tempFilePath);//上面从web.xml中得到临时文件和保存文件的完整路径}@Overrideprotected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{response.setContentType("text/plain");// 向客户端发送响应正文//得到response输出流PrintWriter outNet = response.getWriter();try{// 创建一个基于硬盘的FileItem工厂DiskFileItemFactory factory = new DiskFileItemFactory();// 设置向硬盘写数据时所用的缓冲区的大小，此处为4Kfactory.setSizeThreshold(4*1024);// 设置临时目录factory.setRepository(new File(tempFilePath));// 创建一个文件上传处理器ServletFileUpload upload = new ServletFileUpload(factory);// 设置允许上传的文件的最大尺寸，此处为4Mupload.setSizeMax(4*1024*1024);List items = upload.parseRequest(request);Iterator iter = items.iterator();while(iter.hasNext()){FileItem item = (FileItem)iter.next();if(item.isFormField()){processFormField(item,outNet); // 处理普通的表单域}else{processUploadedFile(item,outNet); // 处理上传文件}}outNet.close();}catch(Exception ex){ex.printStackTrace();}}private void processFormField(FileItem item,PrintWriter outNet){String name = item.getFieldName();String value = item.getString();outNet.println(name+":"+value+"\r\n");}private void processUploadedFile(FileItem item,PrintWriter outNet)throws Exception{String filename = item.getName();int index = filename.lastIndexOf("\\");filename = filename.substring(index+1,filename.length());long fileSize = item.getSize();if(filename.equals("")&&fileSize==0)return;File uploadFile = new File(filePath+"/"+filename);item.write(uploadFile);outNet.println(filename+" is saved.");outNet.println("The size of "+filename+" is "+fileSize+"\r\n");}}?
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"><servlet><servlet-name>UploadServlet</servlet-name><servlet-class>mypack.UploadServlet</servlet-class><init-param><param-name>filePath</param-name><param-value>store</param-value></init-param><init-param><param-name>tempFilePath</param-name><param-value>temp</param-value></init-param></servlet><servlet-mapping><servlet-name>UploadServlet</servlet-name><url-pattern>/upload</url-pattern></servlet-mapping><welcome-file-list><welcome-file>upload.htm</welcome-file></welcome-file-list></web-app>
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<html><head><title>Upload</title></head><body><form name="uploadForm" method="POST" enctype="MULTIPART/FORM-DATA" action="upload"><table><tr><td><div align="right">User Name:</div></td><td><input type="text" name="username" size="30" /></td></tr><tr><td><div align="right">Upload File1:</div></td><td><input type="file" name="file1" size="30" /></td></tr><tr><td><div align="right">Upload File2:</div></td><td><input type="file" name="file2" size="30" /></td></tr><tr><td><input type="submit" name="submit" value="upload"></td><td><input type="reset" name="reset" value="reset"></td></tr></table></form></body></html>