J2EE Servlet上传文件到服务器并相应显示功能的实现代码

2019-11-26 09:51:24

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编辑上传文件的页面upload.html

注意事项：上传方式使用POST不能使用GET（GET不能上传文件）

表单 enctype 属性应该设置为 multipart/form-data.（表示提交的数据是二进制文件）

upload.html

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>文件上传</title></head><body>  <form action="UploadPhotoServlet" method="POST" enctype="multipart/form-data">    人物名称:<input type="text" name="heroName"/><br>    上传头像:<input type="file" name="filepath"/><br>    <input type="submit" value="上传">  </form></body></html>

UPloadPtotoServlet文件上传类--上传功能的开发

将commons-io-1.4.jar和commons-fileupload-1.2.2.jar 两个jar包放到WEB-INF/lib 目录下。

import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.PrintWriter;import java.util.Iterator;import java.util.List;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;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;/** * Servlet implementation class UploadPhotoServlet */@WebServlet("/UploadPhotoServlet")public class UploadPhotoServlet extends HttpServlet {  private static final long serialVersionUID = 1L;  /**   * @see HttpServlet#HttpServlet()   */  public UploadPhotoServlet() {    super();    // TODO Auto-generated constructor stub  }  /**   * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)   */  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    // TODO Auto-generated method stub//    response.getWriter().append("Served at: ").append(request.getContextPath());    String filename=null;    DiskFileItemFactory factory=new DiskFileItemFactory();  //磁盘文件条目工厂    ServletFileUpload upload=new ServletFileUpload(factory); //负责处理上传的文件数据，并将表单中每个输入项封装成一个fileitem对象中    //设置上传文件的大小为10M    factory.setSizeThreshold(2*1024*1024);    List items=null;    try {      //parse 解析      items=upload.parseRequest(request);  //得到一个保存了所有上传内容的List对象    } catch (FileUploadException e) {      // TODO Auto-generated catch block      e.printStackTrace();    }    Iterator iter=items.iterator();  //迭代上传的文件数据    while(iter.hasNext()){      FileItem item=(FileItem) iter.next();      if(!item.isFormField()){ //如果不是上传的        //根据时间戳创建头像文件        filename=System.currentTimeMillis()+".jpg";        //通过getrealpath获取上传文件夹，如果项目存在将存在当前项目下 不存在的话创建项目文件夹        //图片文件夹        String photoFolder=request.getServletContext().getRealPath("uploaded");        File f=new File(photoFolder,filename);        f.getParentFile().mkdirs(); //如果父文件夹不存在则自动创建        //通过item.getInputStream() 获取浏览器上传的文件        InputStream is = item.getInputStream();  //将文件读进来        //复制文件        FileOutputStream fos=new FileOutputStream(f); //往界面上显示        byte[] b=new byte[2*1024*1024];        int len=0;        while((len=is.read(b))!=-1){          fos.write(b, 0, len);        }        fos.close();      }else{        System.out.println(item.getFieldName());//heroName        String value=item.getString();          value=new String(value.getBytes("ISO-8859-1"), "UTF-8");        System.out.println(value);  //桑葚      }    }    String html="<img width='200' height='150' src='uploaded/%s'/>";    response.setContentType("text/html");    PrintWriter pw=response.getWriter();    pw.format(html, filename);  }  /**   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)   */  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    // TODO Auto-generated method stub    doGet(request, response);  }}

运行结果：