java web图片上传和文件上传实例详解

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;
       }
     }
   }

感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！