J2EE:Servlet上传文件到服务器，并相应显示
Servlet 可以与HTML一起使用来允许用户上传文件到服务器
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：
