Java IO工具类常用方法

常用的文件操作：包括文件拷贝、HTTP方式拷贝、文件下载等。 

1.创建文件夹

/**
 * 创建文件夹
 * @filePath:路径
 */
public void MakeFolder(String folderPath){
    File file =new File(folderPath);    
    //如果文件夹不存在则创建     
    if(!file.exists() && !file.isDirectory())      
    {       
        System.out.println("//不存在");  
        file.mkdirs();    
    }else {  
        System.out.println("//目录存在");  
    }  
}
//使用示例
MakeFolder("E:\Java\newFile");

2.创建文件

/**
 * 创建文件
 * @folderPath:路径
 */
public void MakeFile(String filePath){
    File file=new File(filePath);    
    if(!file.exists())    
    {    
        try {    
            file.createNewFile();    
        } catch (IOException e) {    
            // TODO Auto-generated catch block     
            e.printStackTrace();    
        }    
    } 
}
//使用示例
MakeFile("E:\Java\newFile\helloworld.txt");

3.本地拷贝文件 

    /**
     * 拷贝文件
     * @sourcePath:源文件路径
     * @destPath:目标文件路径
     * @folderName:文件夹路径
     */
    public void copyFile(String sourcePath, String destPath,String folderName) throws Exception {
        File source = new File(sourcePath);
        if(!folderName.equals("")){
            File folder = new File(folderName);
            //文件夹不存在，创建
            if(!folder.exists() && !folder.isDirectory()) {
                folder.mkdirs();
            }
        }
        File dest = new File(destPath);
        if (!dest.exists()) {
            dest.createNewFile();
        }
        FileInputStream fis = new FileInputStream(source);
        FileOutputStream fos = new FileOutputStream(dest);
        FileChannel sourceCh = fis.getChannel();
        FileChannel destCh = fos.getChannel();
        MappedByteBuffer mbb = sourceCh.map(FileChannel.MapMode.READ_ONLY, 0,sourceCh.size());
        destCh.write(mbb);
        sourceCh.close();
        destCh.close();
    }

4.下载HTTP资源文件到服务器硬盘路径

    /**
     * HTTP方式下载文件
     * @url:源文件远程地址
     * @dir:下载地址目录
     * @return:1成功 0：失败  
     */
    public int downloadFromUrl(String url,String dir) {
        try {
            URL httpurl = new URL(url);
            File f = new File(dir);
            FileUtils.copyURLToFile(httpurl, f);
        } catch (Exception e) {
            e.printStackTrace();
            return 0;
        } 
        return 1;
    }

 5.用户下载服务器资源文件 

/**
 * 下载服务器文件
 * @fullfilepath:文件所在硬盘的真实路径
 * @downloadfilename:下载的文件命名
 */
public void DownloadFile(String fullfilepath,String downloadfilename,HttpServletResponse response){
    try{
        /*读取文件*/
        File file = new File(fullfilepath);
        /*如果文件存在*/
        if (file.exists()) {
            downloadfilename = URLEncoder.encode(downloadfilename, enc);
            response.reset();
            response.setContentType(contentType);
            response.addHeader("Content-Disposition", "attachment; filename="" + downloadfilename + """);
            int fileLength = (int) file.length();
            response.setContentLength(fileLength);
            /*如果文件长度大于0*/
            if (fileLength != 0) {
                /*创建输入流*/
                InputStream inStream = new FileInputStream(file);
                byte[] buf = new byte[4096];
                /*创建输出流*/
                ServletOutputStream servletOS = response.getOutputStream();
                int readLength;
                while (((readLength = inStream.read(buf)) != -1)) {
                    servletOS.write(buf, 0, readLength);
                }
                inStream.close();
                servletOS.flush();
                servletOS.close();
            }
        }else{
            System.out.println("Error: can't find the file "+filename);
        }
    }catch(Exception e){
        System.out.println("文件下载出错!");
    }
}