java servlet上传文件并把文件内容显示在网页中

servlet3.0(JDK1.6)自带的API即可实现本地文件的上传，Servlet3.0新增了Part接口，HttpServletRequest的getPart()方法取得Part实现对象。下面我实现了文件的上传以及将上传的文件显示在网页上（主要目的是实现本地文件在网页上的显示，我采取了先上传文件，在读取上传的文件，将读取的内容显示在网页上）。

Java代码实现：

  1 package FileUpload.servlet;
  2 
  3 import java.io.BufferedReader;
  4 import java.io.File;
  5 import java.io.FileReader;
  6 import java.io.IOException;
  7 import java.io.PrintWriter;
  8 
  9 import javax.servlet.ServletException;
 10 import javax.servlet.annotation.*;
 11 import javax.servlet.http.HttpServlet;
 12 import javax.servlet.http.HttpServletRequest;
 13 import javax.servlet.http.HttpServletResponse;
 14 import javax.servlet.http.Part;
 15 
 16 /**
 17  * Servlet implementation class FileUploadServlet
 18  */
 19 //上传文件被保存的路径
 20 @MultipartConfig(
 21         location="E:\\eclipse\\workspace\\TestAceEditor\\FileUpload"
 22         )
 23 @WebServlet(urlPatterns={"/fileUpload"})
 24 
 25 public class FileUploadServlet extends HttpServlet {
 26     private static final long serialVersionUID = 1L;
 27     //private static final Log log = LogFactory.getLog(UploadFileAction.class);
 28     //private String fileNameExtractorRegex = "filename=\".+\"";
 29     
 30     /**
 31      * @see HttpServlet#HttpServlet()
 32      */
 33     public FileUploadServlet() {
 34         super();
 35         // TODO Auto-generated constructor stub
 36     }
 37 
 38     //获得指定文件的内容
 39     private String getFileContent(String fileName){
 40         File file = new File(fileName);
 41         BufferedReader reader = null;
 42         String ans = "";
 43         try{
 44             reader = new BufferedReader(new FileReader(file));
 45             String tmpString = null;
 46             //一行一行的读取文件里面的内容
 47             while((tmpString = reader.readLine()) != null){
 48                 ans += tmpString + "\n";//保存在ans里面
 49             }
 50         }catch(IOException e){
 51             e.printStackTrace();
 52         }finally{
 53             if(reader != null)
 54             {
 55                 try{
 56                     reader.close();
 57                 }catch(IOException e1){
 58                     e1.printStackTrace();
 59                 }
 60             }
 61         }
 62         //返回获得的文件内容
 63         return ans;
 64     }
 65     //获得上传文件的文件名
 66     private String getFilename(Part part){
 67         
 68         if(part == null){
 69             return null;
 70         }
 71         //获得文件名的方法是根据一本书上的代码来的，忘记书名了，以后补上
 72         String contentDispositionHeader = part.getHeader("content-disposition");
 73         
 74         String fileName = null;
 75         String[] elements = contentDispositionHeader.split(";");
 76         for(String element:elements){
 77             if(element.trim().startsWith("filename")){
 78                 fileName = element.substring(element.indexOf('=') + 1).trim().replace("\"", "");
 79                 break;
 80             }
 81         }
 82         fileName = fileName.substring(fileName.lastIndexOf('\\') + 1);
 83 //        Pattern pattern = Pattern.compile(fileNameExtractorRegex);  
 84 //        Matcher matcher = pattern.matcher(contentDispositionHeader); 
 85 //        String fileName = null;
 86 //        if(matcher.find()){  
 87 //            fileName = matcher.group();  
 88 //            fileName = fileName.substring(10, fileName.length()-1);  
 89 //        }  
 90         
 91         return fileName;
 92     }
 93     
 94     /**
 95      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 96      */
 97     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 98         // TODO Auto-generated method stub
 99         request.getRequestDispatcher("fileUpload.jsp").forward(request, response);
100     }
101 
102     /**
103      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
104      */
105     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
106         // TODO Auto-generated method stub
107         //set the encoding
108         request.setCharacterEncoding("UTF-8");
109         
110         //请求（form中为file类型的输入框的名字为filename）发送过来时，使用getPart()方法取得Part实现对象
111         Part part = request.getPart("filename");
112         String fileName = getFilename(part);
113         
114         
115         if(fileName != null && !fileName.isEmpty()){
116             part.write(fileName);
117         }
118         
119         //从指定文件路径获得文件内容
120         String filePath = "E:\\eclipse\\workspace\\TestAceEditor\\FileUpload" + "\\" + fileName;
121         String fileContent = getFileContent(filePath);
122         
123         //write to browser
124 //        response.setContentType("text/html");
125 //        PrintWriter writer = response.getWriter();
126 //        writer.print("<br/>Uploaded file name: "+ fileName);
127 //        writer.print("<br/>Size: "+part.getSize());
128 //        
129 //        String author = request.getParameter("author");
130 //        writer.print("<br/>Author: "+author);
131         //设置属性，在jsp文件中可以使用EL获得fileContent对象里的内容
132         request.setAttribute("fileContent", fileContent);
133         request.getRequestDispatcher("fileUpload.jsp").forward(request, response);
134         
135     }
136 
137 }

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