jsp+servlet简单实现上传文件功能(保存目录改进)

1、jsp前端

<%--
 created by intellij idea.
 user: lenovo
 date: 2020/6/19
 time: 22:53
 learn from https://www.bilibili.com/video/bv18z411i7gh?t=23&p=192
 to change this template use file | settings | file templates.
--%>
<%@ page contenttype="text/html;charset=utf-8" language="java" %>
<html>
<head>
  <title>文件上传</title>
</head>
<body>
  <!--文件上传对表单的要求-->
  <!--
    1、表单中的请求提交方式必须是post
    2、表单中应指定所提交的请求位multipart请求,通过在<form/>标签中添加enctype属性
      其值为multipart/form-data
    3、 表单
  -->
  <form method="post" action="http://localhost:8888/hello/uploadimageservlet" enctype="multipart/form-data">
    编号<input type="text" name="bno"></br>
    名字<input type="text" name="bname"></br>
    照片<input type="file" name="picutreurl"></br>
    <input type="submit" value="注册">
  </form>
</body>
</html>

2、servlet后台

package servlet.bookservlet;

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;
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 java.io.*;
import java.text.simpledateformat;
import java.util.calendar;
import java.util.date;
import java.util.list;


@webservlet(name = "uploadimageservlet")
public class uploadimageservlet extends httpservlet {
  @override
  protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
    this.dopost(request,response);
  }
  @override
  protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
    //1、判断请求是不是multipart请求
    if(!servletfileupload.ismultipartcontent(request)){
      throw new runtimeexception("当前请求不支持文件上传");
    }
    system.out.println("开始上传文件");
    //2、创建fileitem工厂==>文件写入硬盘的作用
    try {
      diskfileitemfactory factory = new diskfileitemfactory();
      //3、创建temp临时文件夹
      string temppath ="d:\\tomcat\\apache-tomcat-9.0.35-windows-x64\\apache-tomcat-9.0.35\\webapps\\librarysystem\\web\\net\\temp";
      file tempfile = new file(temppath);
      factory.setrepository(tempfile);
      //4、设置使用临时文件的边界值,大于该值,上传文件先保存在临时文件中,小于该值,则直接写入内存
      //单位是字节
      factory.setsizethreshold(1024*1024*1);

      //5、创建文件上传核心组件
      // 调用servletfileupload.parserequest方法解析request对象,得到一个保存了所有上传内容的list对象。
      servletfileupload upload = new servletfileupload(factory);
      upload.setheaderencoding("utf-8");//可以解决文件名中文乱码
      upload.setfilesizemax(1024*1024*2);

      string bno="defaultbno",bname="defaultbname";
      //6、解析请求
      list<fileitem> items =upload.parserequest(request);
      //7、遍历请求
      for(fileitem item:items){
        //普通表单项,上传名字,编号等普通信息的上i传
        if(item.isformfield()){
          string filename = item.getfieldname();// name属性值
          string filevalue = item.getstring("utf-8");// name对应的value值
          system.out.println(filename + " -- " + filevalue);
          if(filename.equalsignorecase("bno")){
            bno = filevalue;
          }
          if(filename.equalsignorecase("bname")){
            bname = filevalue;
          }
         }
        else{//上传图片等
          string filename = item.getname();
          system.out.println("上传文件名字:"+filename);
          string suffix = filename.substring(filename.lastindexof('.'));//获取文件类型
          string newfilename = bno+"_"+bname+suffix;
          system.out.println(newfilename);
          //获取输入流,其中有上传文件的内容
          inputstream is = item.getinputstream();
          //string path = this.getservletcontext().getrealpath("/net/bookimage");//获得当前项目保存服务器地址,也就是web文件夹下
          string path ="d:\\tomcat\\apache-tomcat-9.0.35-windows-x64\\apache-tomcat-9.0.35\\webapps\\librarysystem\\web\\net\\bookimage";
          //文件夹内文件数目有上限,但是可以创建子目录
            //获取当前系统时间
            calendar now = calendar.getinstance();
            int year = now.get(calendar.year);
            int month = now.get(calendar.month)+1;
            int day = now.get(calendar.day_of_month);
            path = path+"/"+year+"/"+month+"/"+day;
            //若该目录不存在,直接创建新目录
            file dirfile = new file(path);
            if(!dirfile.exists()){
              dirfile.mkdirs();
            }
          //创建目标文件,用来保存上传文件
          file desfile = new file(path,newfilename);
          //创建文件输出流
          outputstream os = new fileoutputstream(desfile);
          //将输入流数据写入到输出流中
          int len=-1;
          byte[]buf = new byte[1024];
          while((len=is.read(buf))!=-1){
            os.write(buf,0,len);
          }
          //desfile.delete();//删除临时文件
          os.close();//输出流
          is.close();//输入流
          //删除临时文件
          item.delete();
        }
      }
    } catch (fileuploadexception e) {
      e.printstacktrace();
    }
  }
}

总结

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