Java Servlet简单实例分享(文件上传下载demo)

程序员文章站 2024-02-16 13:46:22

项目结构 src com servletdemo downloadservlet.java showservl...

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>

以上这篇java servlet简单实例分享(文件上传下载demo)就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。

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