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：