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java web图片上传和文件上传实例详解

程序员文章站 2024-03-09 18:05:59
java web图片上传和文件上传 图片上传和文件上传本质上是一样的,图片本身也是文件。文件上传就是将图片上传到服务器,方式虽然有很多,但底层的实现都是文件的读写操作。...

java web图片上传和文件上传

图片上传和文件上传本质上是一样的,图片本身也是文件。文件上传就是将图片上传到服务器,方式虽然有很多,但底层的实现都是文件的读写操作。

注意事项

1.form表单一定要写属性enctype="multipart/form-data"

2.为了能保证文件能上传成功file控件的name属性值要和你提交的控制层变量名一致,

例如空间名是file那么你要在后台这样定义

private file file; //file控件名

private string filecontenttype;//图片类型

private string filefilename; //文件名

1.jsp页面

<%@ page language="java" contenttype="text/html; charset=utf-8" 
  pageencoding="utf-8"%> 
<!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=utf-8"> 
<meta http-equiv="pragma" content="no-cache" /> 
<base target="_self"> 
<title>文件上传</title> 
</head>
<body>
<form method="post" action="" enctype="multipart/form-data">
<input type="file" name="file" value="file">
<input type="submit" value="确定">
</form>
</body>
</html>

1.页面数据需要提交的controller



package com.cpsec.tang.chemical.action;

import java.io.file;
import java.io.ioexception;
import java.util.random;

import javax.annotation.resource;
import javax.servlet.http.httpservletrequest;

import org.apache.commons.io.fileutils;
import org.apache.struts2.servletactioncontext;
import org.springframework.stereotype.controller;

import com.cpsec.tang.chemical.biz.lunbobiz;
import com.cpsec.tang.chemical.entity.image;
import com.opensymphony.xwork2.actionsupport;


@controller("lunboaction")
public class lunboaction extends actionsupport {
  /**
   * 
   */
  private static final long serialversionuid = 1l;
  @resource(name="lunbobiz")
  private lunbobiz lunbobiz;
  private image image;
  private file file; //file控件名
  private string filecontenttype;//图片类型
  private string filefilename; //文件名
  private integer number;
  
  public string findimage(){
    image=lunbobiz.findimage();
    return success;
  }
  
  public string alterimage(){
    image=lunbobiz.findimage();
    return success;
  }
  
  public string alterimage1(){
    httpservletrequest request = servletactioncontext.getrequest();
    string root = request.getrealpath("/upload");//图片要上传到的服务器路径
    string names[]=filefilename.split("\\.");
    string filename="";
    if(names.length>=1){
      filename=getrandomstring(20)+"."+names[names.length-1];
    }
    string picpath="upload/"+filename;//图片保存到数据库的路径
    file file1=new file(root);
    try {
      fileutils.copyfile(file, new file(file1,filename));
      }
    } catch (ioexception e) {
      e.printstacktrace();
    }
    return success;
  }
  
  /*获取一条随机字符串*/
  public string getrandomstring(int length) { //length表示生成字符串的长度 
    string base = "abcdefghijklmnopqrstuvwxyz0123456789";   
    random random = new random();   
    stringbuffer sb = new stringbuffer();   
    for (int i = 0; i < length; i++) {   
      int number = random.nextint(base.length());   
      sb.append(base.charat(number));   
    }   
    return sb.tostring();   
   }  

}

这是通过复制的方式上传文件,还有其他方式

方法二



@controller("contractaction")
public class contractaction extends actionsupport {
  
  private final static string uploaddir = "/files";//文件上传的路径,在webcontent下建立
  private file file; //input控件名一定为file 
  //上传文件名集合  
  private string filefilename;  
  //上传文件内容类型集合  
  private string filecontenttype; 
  
  private string filename;
 
  public string upload() throws filenotfoundexception, ioexception{
    string path=uploadfile();//文件保存数据库的路径
  
    return success;
  }
  
  //执行上传功能  
  @suppresswarnings("deprecation")
  public string uploadfile() throws filenotfoundexception, ioexception {  
    try {  
      inputstream in = new fileinputstream(file);  
      string dir = servletactioncontext.getrequest().getrealpath(uploaddir); 
      file filelocation = new file(dir); 
      //此处也可以在应用根目录手动建立目标上传目录 
      if(!filelocation.exists()){ 
        boolean iscreated = filelocation.mkdir(); 
        if(!iscreated) { 
          //目标上传目录创建失败,可做其他处理,例如抛出自定义异常等,一般应该不会出现这种情况。 
          return null; 
        } 
      }
      // this.setfilefilename(getrandomstring(20));
      string[] name=this.getfilefilename().split("\\.");
      string filename=getrandomstring(20)+"."+name[name.length-1];
      this.setfilefilename(filename);
      system.out.println(filename);
      file uploadfile = new file(dir, filename);
      outputstream out = new fileoutputstream(uploadfile);  
      byte[] buffer = new byte[1024 * 1024];  
      int length;  
      while ((length = in.read(buffer)) > 0) {  
        out.write(buffer, 0, length);  
      }
      in.close();  
      out.close();  
      return uploaddir.substring(1)+"\\"+filefilename;
      } catch (filenotfoundexception ex) {
        return null;  
      } catch (ioexception ex) {
        return null;  
    }  
  }
  
  
  public static string getrandomstring(int length){
    string str="abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789";
    random random=new random();
    stringbuffer sb=new stringbuffer();
    for(int i=0;i<length;i++){
     int number=random.nextint(62);
     sb.append(str.charat(number));
    }
    return sb.tostring();
  }  

}


 

除了单图上传还有多图上传,原理都是一样的

package com.cpsec.tang.chemical.action;

import java.io.file; 
import java.io.fileinputstream; 
import java.io.filenotfoundexception; 
import java.io.fileoutputstream; 
import java.io.ioexception; 
import java.io.inputstream; 
import java.io.outputstream;
import java.util.list;
import javax.servlet.http.httpservletrequest;
import org.apache.struts2.servletactioncontext;
import com.opensymphony.xwork2.actionsupport;


/**
 * 多文件上传
 */
public class filesuploadaction extends actionsupport {
     //上传文件存放路径  
     private final static string uploaddir = "/upload";  
     //上传文件集合  
     private list<file> file;  
     //上传文件名集合  
     private list<string> filefilename;  
     //上传文件内容类型集合  
     private list<string> filecontenttype;  
     
     public list<file> getfile() {  
       return file;  
     }  
 
     public void setfile(list<file> file) {  
       this.file = file;  
     }  
 
    public list<string> getfilefilename() {  
      return filefilename;  
    }  
 
     public void setfilefilename(list<string> filefilename) {  
       this.filefilename = filefilename;  
     }  
 
     public list<string> getfilecontenttype() {  
       return filecontenttype;  
     }  
 
     public void setfilecontenttype(list<string> filecontenttype) {  
       this.filecontenttype = filecontenttype;  
     }  
 
     
     public string uploadform() throws exception {
       httpservletrequest request = servletactioncontext.getrequest();
       string webpath=null;//上传路径
       for (int i = 0; i < file.size(); i++) {  
         //循环上传每个文件  
         uploadfile(i); 
         webpath="upload/"+this.getfilefilename().get(i);
       }
       return "success";
     } 
   
 
    
    //执行上传功能  
     private string uploadfile(int i) throws filenotfoundexception, ioexception {  
       try {  
         
         inputstream in = new fileinputstream(file.get(i));  
         string dir = servletactioncontext.getrequest().getrealpath(uploaddir); 
         file filelocation = new file(dir); 
         //此处也可以在应用根目录手动建立目标上传目录 
         if(!filelocation.exists()){ 
           boolean iscreated = filelocation.mkdir(); 
           if(!iscreated) { 
             //目标上传目录创建失败,可做其他处理,例如抛出自定义异常等,一般应该不会出现这种情况。 
             return null; 
           } 
         } 
         string filename=this.getfilefilename().get(i); 
         file uploadfile = new file(dir, filename);
         outputstream out = new fileoutputstream(uploadfile);  
         byte[] buffer = new byte[1024 * 1024];  
         int length;  
         while ((length = in.read(buffer)) > 0) {  
           out.write(buffer, 0, length);  
         }
         in.close();  
         out.close();  
         return uploadfile.tostring();
       } catch (filenotfoundexception ex) {
         return null;  
       } catch (ioexception ex) {
         return null;  
       }  
     }
   }

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