Java Servlet简单实例分享(文件上传下载demo)

2024-07-13 10:08:19

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项目结构

src  com    servletdemo        DownloadServlet.java        ShowServlet.java        UploadServlet.java        WebContent  jsp    servlet        download.html        fileupload.jsp        input.jsp          WEB-INF    lib        commons-fileupload-1.3.1.jar        commons-io-2.4.jar

1.简单实例

ShowServlet.java

package com.servletdemo;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class ShowServlet */@WebServlet("/ShowServlet")public class ShowServlet extends HttpServlet {  private static final long serialVersionUID = 1L;  PrintWriter pw=null;    /**   * @see HttpServlet#HttpServlet()   */  public ShowServlet() {    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    this.doPost(request, response);  }  /**   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)   */  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    // TODO Auto-generated method stub    request.setCharacterEncoding("gb2312");    response.setContentType("text/html;charset=gb2312");    pw=response.getWriter();    String name=request.getParameter("username");    String password=request.getParameter("password");    pw.println("user name:" + name);    pw.println("<br>");    pw.println("user password:" + password);  }}

input.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"  pageEncoding="ISO-8859-1"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>servlet demo</title></head><body><form action="<%=request.getContextPath()%>/ShowServlet">     <table>       <tr>         <td>name</td>         <td><input type="text" name="username"></td>       </tr>       <tr>         <td>password</td>         <td><input type="text" name="password"></td>       </tr>       <tr>         <td><input type="submit" value="login"></td>         <td><input type="reset" value="cancel"></td>       </tr>     </table>   </form></body></html>

2.文件上传实例

UploadServlet.java

package com.servletdemo;import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.PrintWriter; import java.text.DateFormat; import java.util.Date; import java.util.List; import java.util.UUID; 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.ProgressListener; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload;/** * Servlet implementation class UploadServlet */@WebServlet("/servlet/UploadServlet")public class UploadServlet extends HttpServlet {  private static final long serialVersionUID = 1L;      /**   * @see HttpServlet#HttpServlet()   */  public UploadServlet() {    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    //设置编码     request.setCharacterEncoding("UTF-8");     response.setContentType("text/html;charset=UTF-8");     PrintWriter pw = response.getWriter();     try {       //设置系统环境       DiskFileItemFactory factory = new DiskFileItemFactory();       //文件存储的路径       String storePath = getServletContext().getRealPath("/WEB-INF/files");       //判断传输方式 form enctype=multipart/form-data       boolean isMultipart = ServletFileUpload.isMultipartContent(request);       if(!isMultipart)       {         pw.write("传输方式有错误！");         return;       }       ServletFileUpload upload = new ServletFileUpload(factory);       upload.setFileSizeMax(4*1024*1024);//设置单个文件大小不能超过4M       upload.setSizeMax(4*1024*1024);//设置总文件上传大小不能超过6M       //监听上传进度       upload.setProgressListener(new ProgressListener() {          //pBytesRead：当前以读取到的字节数         //pContentLength：文件的长度         //pItems:第几项         public void update(long pBytesRead, long pContentLength,             int pItems) {           System.out.println("已读去文件字节 :"+pBytesRead+" 文件总长度："+pContentLength+"  第"+pItems+"项");                    }       });       //解析       List<FileItem> items = upload.parseRequest(request);       for(FileItem item: items)       {         if(item.isFormField())//普通字段，表单提交过来的         {           String name = item.getFieldName();           String value = item.getString("UTF-8");           System.out.println(name+"=="+value);         }else         { //         String mimeType = item.getContentType(); 获取上传文件类型 //         if(mimeType.startsWith("image")){           InputStream in =item.getInputStream();           String fileName = item.getName();            if(fileName==null || "".equals(fileName.trim()))           {             continue;           }           fileName = fileName.substring(fileName.lastIndexOf("//")+1);           fileName = UUID.randomUUID()+"_"+fileName;                      //按日期来建文件夹           String newStorePath = makeStorePath(storePath);           String storeFile = newStorePath+"//"+fileName;           OutputStream out = new FileOutputStream(storeFile);           byte[] b = new byte[1024];           int len = -1;           while((len = in.read(b))!=-1)           {              out.write(b,0,len);               }           in.close();           out.close();           item.delete();//删除临时文件         }        } //     }     }catch(org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException e){         //单个文件超出异常       pw.write("单个文件不能超过4M");     }catch(org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException e){       //总文件超出异常       pw.write("总文件不能超过6M");            }catch (FileUploadException e) {       e.printStackTrace();     }  }  /**   * @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);  }    private String makeStorePath(String storePath) {         Date date = new Date();     DateFormat df = DateFormat.getDateInstance(DateFormat.MEDIUM);     String s = df.format(date);     String path = storePath+"//"+s;     File file = new File(path);     if(!file.exists())     {       file.mkdirs();//创建多级目录，mkdir只创建一级目录     }     return path;         }   private String makeStorePath2(String storePath, String fileName) {     int hashCode = fileName.hashCode();     int dir1 = hashCode & 0xf;// 0000~1111：整数0~15共16个     int dir2 = (hashCode & 0xf0) >> 4;// 0000~1111：整数0~15共16个        String path = storePath + "//" + dir1 + "//" + dir2; // WEB-INF/files/1/12     File file = new File(path);     if (!file.exists())       file.mkdirs();        return path;   } }

fileupload.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"  pageEncoding="ISO-8859-1"%><% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Upload File Demo</title></head><body><form action="${pageContext.request.contextPath}/servlet/UploadServlet" method="post" enctype="multipart/form-data">   user name<input type="text" name="username"/> <br/>   <input type="file" name="f1"/><br/>   <input type="file" name="f2"/><br/>   <input type="submit" value="save"/>  </form></body></html>

3.文件下载实例

DownloadServlet.java

package com.servletdemo;import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStream; import java.io.PrintWriter; import java.net.URLEncoder;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 javax.servlet.ServletResponse; /** * Servlet implementation class DownloadServlet */@WebServlet("/DownloadServlet")public class DownloadServlet extends HttpServlet {  private static final long serialVersionUID = 1L;      /**   * @see HttpServlet#HttpServlet()   */  public DownloadServlet() {    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    download1(response);   }  /**   * @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);  }    public void download1(HttpServletResponse response) throws IOException{     //获取所要下载文件的路径      String path = this.getServletContext().getRealPath("/files/web配置.xml");      String realPath = path.substring(path.lastIndexOf("//")+1);         //告诉浏览器是以下载的方法获取到资源      //告诉浏览器以此种编码来解析URLEncoder.encode(realPath, "utf-8"))     response.setHeader("content-disposition","attachment; filename="+URLEncoder.encode(realPath, "utf-8"));     //获取到所下载的资源      FileInputStream fis = new FileInputStream(path);      int len = 0;       byte [] buf = new byte[1024];       while((len=fis.read(buf))!=-1){         response.getOutputStream().write(buf,0,len);       }    }}

download.html

<!DOCTYPE html><html><head><meta charset="ISO-8859-1"><title>Download Demo</title><meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="this is my page"> <meta http-equiv="content-type" content="text/html; charset=UTF-8"></head><body><a href = "/JavabeanDemo/DownloadServlet">download</a></body></html>

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