java组件commons-fileupload实现文件上传

2019-11-26 13:42:56

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一、所需要的包：
1、commons-fileupload-1.2.1.jar：
下载地址
http://commons.apache.org/downloads/download_fileupload.cgi
2、commons-io-1.4.jar：
下载地址
http://commons.apache.org/downloads/download_io.cgi

二、注意事项：
form表单里面要加上enctype="multipart/form-data"

三、代码示例

1、jsp代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"  pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>upload</title> </head> <body> <form action="uploadServlet" method="post" enctype="multipart/form-data">  <table>  <caption>上传实例</caption>  <tr>   <td>姓名</td>   <td>   <input type="text" name="name">   </td>  </tr>  <tr>   <td>年龄</td>   <td>   <input type="text" name="age">   </td>  </tr>  <tr>   <td>照片</td>   <td>   <input type="file" name="image">   </td>  </tr>  <tr>   <td></td>   <td>   <input type="submit" value="提交">   </td>  </tr>  </table> </form> </body> </html>

2、UploadServlet代码

package servlet;  import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.Writer; import java.util.Iterator; 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.FileUploadBase.SizeLimitExceededException; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; import org.apache.commons.fileupload.util.Streams;  /**  * 上传servlet  * @author lisanlai  *  */ public class UploadServlet extends HttpServlet {  private static final long serialVersionUID = 1L;    public UploadServlet() {  super();  }   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  this.doPost(request, response);  }   @SuppressWarnings("unchecked")  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    response.setContentType("text/html");  // 设置字符编码为UTF-8, 这样支持汉字显示  response.setCharacterEncoding("UTF-8");  Writer o = response.getWriter();    /**   * 首先判断form的enctype是不是multipart/form-data   * 同时也判断了form的提交方式是不是post   * 方法：isMultipartContent(request)   */   if(ServletFileUpload.isMultipartContent(request)){   request.setCharacterEncoding("utf-8");     // 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload   DiskFileItemFactory factory = new DiskFileItemFactory();     //设置文件存放的临时文件夹，这个文件夹要真实存在   File fileDir = new File("../webapps/fileupload/tmp/");   if(fileDir.isDirectory() && fileDir.exists()==false){   fileDir.mkdir();   }   factory.setRepository(fileDir);     //设置最大占用的内存   factory.setSizeThreshold(1024000);     //创建ServletFileUpload对象   ServletFileUpload sfu = new ServletFileUpload(factory);   sfu.setHeaderEncoding("utf-8");     //设置单个文件最大值byte   sfu.setFileSizeMax(102400000);     //所有上传文件的总和最大值byte   sfu.setSizeMax(204800000);     List<FileItem> items = null;     try {   items = sfu.parseRequest(request);   }catch (SizeLimitExceededException e) {   System.out.println("文件大小超过了最大值");   } catch(FileUploadException e) {   e.printStackTrace();   }     //取得items的迭代器   Iterator<FileItem> iter = items==null?null:items.iterator();     //图片上传后存放的路径目录   File images = new File("D:/upload/images/");   if(images.exists()==false){   images.mkdirs();   }   //迭代items   while(iter!=null && iter.hasNext()){   FileItem item = (FileItem) iter.next();      //如果传过来的是普通的表单域   if(item.isFormField()){    System.out.print("普通的表单域:");    System.out.print(new String(item.getFieldName()) + " ");    System.out.println(new String(item.getString("UTF-8")));   }   //文件域   else if(!item.isFormField()){    System.out.println("源图片:" + item.getName());    String fileName = item.getName().substring(item.getName().lastIndexOf("//"));    BufferedInputStream in = new BufferedInputStream(item.getInputStream());    //文件存储在D:/upload/images目录下,这个目录也得存在    BufferedOutputStream out = new BufferedOutputStream(     new FileOutputStream(new File(images.getAbsolutePath()+ fileName)));    Streams.copy(in, out, true);    o.write("文件上传成功");   }   }  }else {   System.out.println("表单的enctype 类型错误");  }  }  }

3、web.xml

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">  <display-name>UploadTest</display-name>  <welcome-file-list>  <welcome-file>upload.jsp</welcome-file>  </welcome-file-list>  <servlet>  <description></description>  <display-name>UploadServlet</display-name>  <servlet-name>UploadServlet</servlet-name>  <servlet-class>servlet.UploadServlet</servlet-class>  </servlet>  <servlet-mapping>  <servlet-name>UploadServlet</servlet-name>  <url-pattern>/uploadServlet</url-pattern>  </servlet-mapping> </web-app>

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