J2EE Servlet上传文件到服务器并相应显示功能的实现代码

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：

总结

以上所述是小编给大家介绍的J2EE Servlet上传文件到服务器并相应显示功能的实现代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！