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SSH Struts2上传文件

Struts2 上传文件

上传文件在一个系统当中是一个很常用的功能,也是一个比较重要的功能。今天我们就一起来学习一下Struts2如何上传文件。今天讲的上传文件的方式有三种:

  • 1以字节为单位传输文件;
  • 2Struts2封装的一种方式;
  • 3以字符的方式传输文件。

其实这三种方式都差不多,都是将文件先从客户端一临时文件的形式,传输到服务器的临时文件夹下,然后在将该临时文件复制到我们要上传的目录。另外,有一个需要注意,就是上传过程中产生的这些临时文件,Struts2不会自动清理,所以我们需要手动清理临时文件,这一个下面的代码中有提到。

用Action来完成我们上传的核心功能:

package com.action;  

import java.io.BufferedReader;  
import java.io.BufferedWriter;  
import java.io.File;  
import java.io.FileInputStream;  
import java.io.FileOutputStream;  
import java.io.InputStreamReader;  
import java.io.OutputStreamWriter;  
import java.util.Map;  

import org.apache.struts2.ServletActionContext;  

import com.opensymphony.xwork2.ActionContext;  
import com.opensymphony.xwork2.ActionSupport;  

public class UploadAction extends ActionSupport {  

    private File upload;  
    private String uploadFileName;    
    private String uploadContentType;  

    private long maximumSize;  
    private String allowedTypes;  

    public File getUpload() {  
        return upload;  
    }  
    public void setUpload(File upload) {  
        this.upload = upload;  
    }  
    public String getUploadFileName() {  
        return uploadFileName;  
    }  
    public void setUploadFileName(String uploadFileName) {  
        this.uploadFileName = uploadFileName;  
    }  

    public String getUploadContentType() {  
        return uploadContentType;  
    }  
    public void setUploadContentType(String uploadContentType) {  
        this.uploadContentType = uploadContentType;  
    }  
    public long getMaximumSize() {  
        return maximumSize;  
    }  
    public void setMaximumSize(long maximumSize) {  
        this.maximumSize = maximumSize;  
    }  
    public String getAllowedTypes() {  
        return allowedTypes;  
    }  
    public void setAllowedTypes(String allowedTypes) {  
        this.allowedTypes = allowedTypes;  
    }  
    @Override  
    public String execute() throws Exception {  

        File uploadFile = new File(ServletActionContext.getServletContext().getRealPath("upload"));  
        if(!uploadFile.exists()) {  
            uploadFile.mkdir();  
        }  

        //验证文件大小及格式  
        if (maximumSize < upload.length()) {  
            return "error";  
        }  

        boolean flag =false;  
        String[]  allowedTypesStr = allowedTypes.split(",");  
        for (int i = 0; i < allowedTypesStr.length; i++) {  
            if (uploadContentType.equals(allowedTypesStr[i])) {  
                flag = true;  
            }  
        }  
        if (flag == false) {  
            Map request = (Map) ActionContext.getContext().get("request");  
            request.put("errorMassage", "文件类型不合法!");  

            System.out.println(request.toString());  
            return "error";  
        }  

        //第一种上传方式  
//      FileInputStream input = new FileInputStream(upload);  
//      FileOutputStream out = new FileOutputStream(uploadFile +"//"+ uploadFileName);  
//      try {  
//          byte[] b =new byte[1024];  
//          int i = 0;  
//          while ((i=input.read(b))>0) {  
//              out.write(b, 0, i);  
//          }  
//      } catch (Exception e) {  
//          e.printStackTrace();  
//      } finally {  
//          //关闭输入、输出流  
//          input.close();  
//          out.close();  
//          //删除临时文件  
//          upload.delete();  
//      }  

        //第二种上传方式  
//      FileUtils.copyFile(upload, new File(uploadFile+"\\"+uploadFileName));  
//      //删除临时文件  
//      upload.delete();  

        //第三种上传方式  
        BufferedReader bReader = new BufferedReader(new InputStreamReader(new FileInputStream(upload)));  
        BufferedWriter bWriter = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(uploadFile+"\\"+ uploadFileName)));  
        try {  
            char [] c =new char[1024];  
            int i = 0;  
            while ((i = bReader.read(c)) > 0) {  
                bWriter.write(c, 0, i);  
            }  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            bReader.close();  
            bWriter.close();              
            //删除临时文件  
            upload.delete();  
        }  

        return "success";  
    }     

}  

在Struts.xml文件中配置我们的Action:

<?xml version="1.0" encoding="UTF-8" ?>    
<!DOCTYPE struts PUBLIC    
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"    
    "http://struts.apache.org/dtds/struts-2.0.dtd">    

<struts>    
    <constant name="struts.action.extension" value=","></constant>    
    <!-- 上传文件最大限制(如果为多文件上传,则为多个文件的总大小) -->    
    <constant name="struts.multipart.maxSize" value="40000000"></constant>    
    <!-- 存放上传文件的临时目录 -->    
    <constant name="struts.multipart.saveDir" value="D:\\temp"></constant>      

    <package name="upload" namespace="/file" extends="struts-default">    
        <action name="upLoad" class="com.action.UploadAction">    
            <result name="success">/success.jsp</result>    
            <result name="error" >/error.jsp</result>    
            <result name = "input" type ="redirect">/index.jsp</result>    
            <param name="maximumSize ">1000000</param>    
            <param name="allowedTypes">application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document,text/plain</param>    

            <!--用struts拦截器限制上传文件大小及类型    
            <interceptor-ref name="fileUpload">    
                单个文件的大小    
                <param name="maximumSize ">1000000</param>    
                <param name="allowedTypes">application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document,text/plain</param>    
            </interceptor-ref>    
            <interceptor-ref name="defaultStack"></interceptor-ref>    
             -->    
        </action>    

    </package>    

</struts>    

文件上传的页面:

<%@ 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">  
<title>上传文件</title>  
</head>  
<body>  
    <!-- enctype="multipart/form-data"不对字符编码。在使用包含文件上传控件的表单时,必须使用该值。 -->  
    <form action="file/upLoad" method="post" enctype="multipart/form-data">  
        <input name="upload" type="file">  
        <input name="btnUpload" type="submit" value="上传">  
    </form>  
</body>  
</html>  

上传文件之前,通常要判断一下文件的大小及类型,上面有两种方式来验证,一种是在Action里验证,一种是通过Struts2的拦截器验证。两者选其一,选择一个把另一个注释掉即可。

另外,还有一个需要注意:上传文件页面中form的enctype属性值,一定要设置成"multipart/form-data",否则就会出错。

OK,今天上传文件就向大家介绍到这里,我们下篇博客再见!

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