java基於servlet編寫上傳下載功能 類似檔案伺服器_java

本人閑來無事，寫了個servlet，實現上傳下載功能。啟動服務後，可以在一個區域網路內當一個小小的檔案伺服器。 

一、準備工作
下載兩個jar包： 

commons-fileupload-1.3.1.jar
commons-io-2.2.jar 

二、建立一個web工程
我的工程名叫：z-upload 

三、配置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" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>z-upload</display-name> <servlet> <servlet-name>UploadService</servlet-name> <servlet-class>com.syz.servlet.UploadService</servlet-class> </servlet> <servlet-mapping> <servlet-name>UploadService</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping></web-app>

 從以上配置可以看出，我的servlet類是UploadService，匹配的url是/*，意思是匹配所有訪問url。 

四、寫servlet類

 package com.syz.servlet;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.io.PrintWriter;import java.text.SimpleDateFormat;import java.util.Date;import java.util.Iterator;import java.util.List;import javax.servlet.ServletContext;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.ProgressListener;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;public class UploadService extends HttpServlet {  public static final String LIST = "/list";  public static final String FORM = "/form";  public static final String HANDLE = "/handle";  public static final String DOWNLOAD = "/download";  public static final String DELETE = "/delete";  public static final String UPLOAD_DIR = "/upload";  private static final long serialVersionUID = 2170797039752860765L;  public void execute(HttpServletRequest req, HttpServletResponse resp)      throws ServletException, IOException {    System.out.println("execute...");    System.out.println("------------begin---------------");    req.setCharacterEncoding("UTF-8");    String host = req.getRemoteHost();    System.out.println("host:" + host);    String uri = req.getRequestURI();    System.out.println("uri:" + uri);    ServletContext servletContext = this.getServletConfig()        .getServletContext();    // 上傳檔案的基本路徑    String basePath = servletContext.getRealPath(UPLOAD_DIR);    // 上下文路徑    String contextPath = servletContext.getContextPath();    System.out.println("contextPath:" + contextPath);    // 截取上下文之後的路徑    String action = uri.substring(contextPath.length());    System.out.println("action:" + action);    // 依據action不同進行不同的處理    if (action.equals(FORM)) {      form(contextPath, resp);    }    else if (action.equals(HANDLE)) {      boolean isMultipart = ServletFileUpload.isMultipartContent(req);      System.out.println("isMultipart:" + isMultipart);      if (!isMultipart) {        return;      }      DiskFileItemFactory factory = new DiskFileItemFactory();      File repository = (File) servletContext          .getAttribute(ServletContext.TEMPDIR);      System.out.println("repository:" + repository.getAbsolutePath());      System.out.println("basePath:" + basePath);      factory.setSizeThreshold(1024 * 100);      factory.setRepository(repository);      ServletFileUpload upload = new ServletFileUpload(factory);      // 建立監聽      ProgressListener progressListener = new ProgressListener() {        public void update(long pBytesRead, long pContentLength,            int pItems) {          System.out.println("當前檔案大小:" + pContentLength + "\t已經處理:"              + pBytesRead);        }      };      upload.setProgressListener(progressListener);      List<FileItem> items = null;      try {        items = upload.parseRequest(req);        System.out.println("items size:" + items.size());        Iterator<FileItem> ite = items.iterator();        while(ite.hasNext()){          FileItem item = ite.next();          if(item.isFormField()){            // handle FormField          }else{            // handle file            String fieldName = item.getFieldName();            String fileName = item.getName();            fileName = fileName.substring(                fileName.lastIndexOf(File.separator) + 1);            String contentType = item.getContentType();            boolean isInMemory = item.isInMemory();            long sizeInBytes = item.getSize();            System.out.println(fieldName + "\t" + fileName + "\t"                + contentType + "\t" + isInMemory + "\t"                + sizeInBytes);            File file = new File(                basePath + "/" + fileName + "_" + getSuffix());            // item.write(file);            InputStream in = item.getInputStream();            OutputStream out = new FileOutputStream(file);            byte[] b = new byte[1024];            int n = 0;            while ((n = in.read(b)) != -1) {              out.write(b, 0, n);            }            out.flush();            in.close();            out.close();          }        }        // 處理完後重新導向到檔案清單頁面        String href1 = contextPath + LIST;        resp.sendRedirect(href1);      }      catch (FileUploadException e) {        e.printStackTrace();      }      catch (Exception e) {        e.printStackTrace();      }    }    else if (action.equals(LIST)) {      list(contextPath, basePath, resp);    }    else if (action.equals(DOWNLOAD)) {      String id = req.getParameter("id");      System.out.println("id:" + id);      if (id == null) {        return;      }      File file = new File(basePath);      File[] list = file.listFiles();      int len = list.length;      boolean flag = false;      for (int i = 0; i < len; i++) {        File f = list[i];        String fn = f.getName();        if (f.isFile() && fn.lastIndexOf("_") > -1) {          String fid = fn.substring(fn.lastIndexOf("_"));          if (id.equals(fid)) {            download(f, resp);            flag = true;            break;          }        }      }      if (!flag) {        notfound(contextPath, resp);      }    }    else if (action.equals(DELETE)) {      String id = req.getParameter("id");      System.out.println("id:" + id);      if (id == null) {        return;      }      File file = new File(basePath);      File[] list = file.listFiles();      int len = list.length;      boolean flag = false;      for (int i = 0; i < len; i++) {        File f = list[i];        String fn = f.getName();        if (f.isFile() && fn.lastIndexOf("_") > -1) {          String fid = fn.substring(fn.lastIndexOf("_"));          if (id.equals(fid)) {            f.delete();            flag = true;            break;          }        }      }      if (flag) {        // 處理完後重新導向到檔案清單頁面        String href1 = contextPath + LIST;        resp.sendRedirect(href1);      }      else {        notfound(contextPath, resp);      }    }    else {      show404(contextPath, resp);    }    System.out.println("------------end---------------");  }  private void show404(String contextPath, HttpServletResponse resp)      throws IOException {    resp.setContentType("text/html;charset=utf-8");    PrintWriter out = resp.getWriter();    String href1 = contextPath + LIST;    out.write("<html>");    out.write("<head><title>404</title></thead>");    out.write("<body>");    out.write("<b>您所訪問的頁面不存在！<a href='" + href1 + "'>點擊</a>返迴文件列表</b>");    out.write("</body>");    out.write("</html>");    out.close();  }  private void form(String contextPath, HttpServletResponse resp)      throws IOException {    resp.setContentType("text/html;charset=utf-8");    PrintWriter out = resp.getWriter();    String href1 = contextPath + LIST;    out.write("<html>");    out.write("<head><title>form</title></thead>");    out.write("<body>");    out.write("<b><a href='" + href1 + "'>點擊</a>返迴文件列表</b>");    out.write(        "<form action='handle' method='post' enctype='multipart/form-data' style='margin-top:20px;'>");    out.write("<input name='file' type='file'/><br>");    out.write("<input type='submit' value='上傳'/><br>");    out.write("</form>");    out.write("</body>");    out.write("</html>");    out.close();  }  private void notfound(String contextPath, HttpServletResponse resp)      throws IOException {    resp.setContentType("text/html;charset=utf-8");    PrintWriter out = resp.getWriter();    String href1 = contextPath + LIST;    out.write("<html><body><b>操作失敗！檔案不存在或檔案已經被刪除！<a href='" + href1        + "'>點擊</a>返迴文件列表</b></body></html>");    out.close();  }  private void download(File f, HttpServletResponse resp)      throws IOException {    String fn = f.getName();    String fileName = fn.substring(0, fn.lastIndexOf("_"));    System.out.println("fileName:" + fileName);    resp.reset();    resp.setContentType("application/octet-stream");    String encodingFilename = new String(fileName.getBytes("GBK"),        "ISO8859-1");    System.out.println("encodingFilename:" + encodingFilename);    resp.setHeader("content-disposition",        "attachment;filename=" + encodingFilename);    InputStream in = new FileInputStream(f);    OutputStream out = resp.getOutputStream();    byte[] b = new byte[1024];    int n = 0;    while ((n = in.read(b)) != -1) {      out.write(b, 0, n);    }    out.flush();    in.close();    out.close();  }  private void list(String contextPath, String basePath,      HttpServletResponse resp)      throws IOException {    String href_u = contextPath + FORM;    resp.setContentType("text/html;charset=utf-8");    PrintWriter out = resp.getWriter();    out.write("<html>");    out.write("<head><title>list</title></thead>");    out.write("<body>");    out.write("<b>我要<a href='" + href_u + "'>上傳</a></b><br>");    out.write(        "<table border='1' style='border-collapse:collapse;width:100%;margin-top:20px;'>");    out.write("<thead>");    out.write("<tr>");    out.write("<th>序號</th><th>檔案名稱</th><th>操作</th>");    out.write("</tr>");    out.write("</thead>");    out.write("<tbody>");    File file = new File(basePath);    File[] list = file.listFiles();    System.out        .println("basePath:" + basePath + "\tlist.size:" + list.length);    int len = list.length;    int no = 1;    for (int i = 0; i < len; i++) {      File f = list[i];      System.out.println(i + "\t" + f.getName());      String fn = f.getName();      if (f.isFile() && fn.lastIndexOf("_") > -1) {        String filename = fn.substring(0, fn.lastIndexOf("_"));        String id = fn.substring(fn.lastIndexOf("_"));        String href1 = contextPath + DOWNLOAD + "?id=" + id;        String href2 = contextPath + DELETE + "?id=" + id;        StringBuilder sb = new StringBuilder();        sb.append("<tr>");        sb.append("<td>");        sb.append(no++);        sb.append("</td>");        sb.append("<td>");        sb.append(filename);        sb.append("</td>");        sb.append("<td>");        sb.append("<a href='");        sb.append(href1);        sb.append("'>下載</a> <a href='");        sb.append(href2);        sb.append("' onclick='return confirm(\"您確定要刪除嗎？\");'>刪除</a>");        sb.append("</td>");        sb.append("</tr>");        out.write(sb.toString());      }    }    out.write("</tbody>");    out.write("</table>");    out.write("</body>");    out.write("</html>");    out.close();  }  public void doGet(HttpServletRequest req, HttpServletResponse resp)      throws ServletException, IOException {    System.out.println("doGet...");    execute(req, resp);  }  public void doPost(HttpServletRequest req, HttpServletResponse resp)      throws ServletException, IOException {    System.out.println("doPost...");    execute(req, resp);  }  private String getSuffix() {    Date date = new Date();    SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssSSS");    String suffix = sdf.format(date);    return suffix;  }}

其實UploadService類可以直接實現service方法，而不用實現doGet、doPost方法。

以上servlet我也不想多解釋什麼，自己看代碼吧。

五、效果圖

1.項目結構圖

2.404頁面

/*會匹配所有包括Null 字元，所以圖片中的路徑會匹配，在UploadService中的if判斷中出現在else中，因為此時的action是Null 字元。

3.檔案清單頁面

4.上傳表單頁面

5.下載

6.刪除

7.檔案找不到，如果你點刪除時，檔案在伺服器上已經不存在，那麼會進入此頁面

8.打包的源碼工程和war包

其中z-upload是eclipse源碼工程，z-upload.war是打好的war包

全工程就兩個jar包，一個web.xml和一個servlet類，可以自己從文章中拷貝過去測試一下，如果是懶人，可以下載

http://download.csdn.net/detail/yunsyz/9569680，特別提醒，下載要1分哦。

以上就是本文的全部內容，希望對大家的學習有所協助，也希望大家多多支援雲棲社區。