SpringMVC IO 文件上传

public class FileUtil {


    /**
     * 读取文件内容，作为字符串返回
     */
    public static String readFileAsString(String filePath) throws IOException {
        File file = new File(filePath);
        if (!file.exists()) {
            throw new FileNotFoundException(filePath);
        }

        if (file.length() > 1024 * 1024 * 1024) {
            throw new IOException("File is too large");
        }

        StringBuilder sb = new StringBuilder((int) (file.length()));
        // 创建字节输入流
        FileInputStream fis = new FileInputStream(filePath);
        // 创建一个长度为10240的Buffer
        byte[] bbuf = new byte[10240];
        // 用于保存实际读取的字节数
        int hasRead = 0;
        while ( (hasRead = fis.read(bbuf)) > 0 ) {
            sb.append(new String(bbuf, 0, hasRead));
        }
        fis.close();
        return sb.toString();
    }

    /**
     * 根据文件路径读取byte[] 数组
     */
    public static byte[] readFileByBytes(String filePath) throws IOException {
        File file = new File(filePath);
        if (!file.exists()) {
            throw new FileNotFoundException(filePath);
        } else {
            ByteArrayOutputStream bos = new ByteArrayOutputStream((int) file.length());
            BufferedInputStream in = null;

            try {
                in = new BufferedInputStream(new FileInputStream(file));
                short bufSize = 1024;
                byte[] buffer = new byte[bufSize];
                int len1;
                while (-1 != (len1 = in.read(buffer, 0, bufSize))) {
                    bos.write(buffer, 0, len1);
                }

                byte[] var7 = bos.toByteArray();
                return var7;
            } finally {
                try {
                    if (in != null) {
                        in.close();
                    }
                } catch (IOException var14) {
                    var14.printStackTrace();
                }

                bos.close();
            }
        }
    }

    /*
     * 通过流的方式上传文件
     * @RequestParam("file") 将name=file控件得到的文件封装成CommonsMultipartFile 对象
     * org.springframework.web.multipart.commons.CommonsMultipartFile（类）
     * 中间会生成临时文件，会自动删除
     * 效率NO.3
     * 稍微大的文件超时，jq.js会报10254错误，前端显示404不过文件可以上传
     * 需要在在dispatcher.xml里面配置试图解析器（<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">）
     */

    public static void  fileUpload1(CommonsMultipartFile file) throws IOException {
//        FileItem fff=file.getFileItem();
//        System.out.println(fff.getName()+"<<<<getName()>>>>");
//        System.out.println(fff.getFieldName()+"<<<<getFieldName()>>>>>");    ;
//        System.out.println(fff.isFormField()+"<<<<isFormField()>>>>");
//        //在这里面规定上传文件的类型
//        System.out.println(fff.getContentType().endsWith(".doc")+"<<<<getContentType()>>>>");
//        System.out.println(fff.isInMemory()+"<<<<isInMemory()>>>>");
//        System.out.println(fff.getSize()+"<<<<getSize()>>>>");

        //用来检测程序运行时间
        long  startTime=System.currentTimeMillis();
        if(file.isEmpty()){
            System.out.println("文件不存在(或大小为0)");
            return;
        }
        String renamePath=FileUtil.renameFile(file.getOriginalFilename());
        OutputStream os = null;
        InputStream is = null;
        try {
            //获取输出流
            os=new FileOutputStream(renamePath);
            //获取输入流 CommonsMultipartFile 中可以直接得到文件的流
             is=file.getInputStream();
            int temp;
            //一个一个字节的读取并写入
            while((temp=is.read())!=(-1))
            {
                os.write(temp);
            }


        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            os.flush();
            os.close();
            is.close();
        }
        long  endTime=System.currentTimeMillis();
        System.out.println("方法一的运行时间："+String.valueOf(endTime-startTime)+"ms");
    }


    /*
     * 采用file.Transto 来保存上传的文件【速度最快】
     *     org.springframework.web.multipart.commons.CommonsMultipartFile（类）
     *中间会生成临时文件，会自动删除
     * 效率NO.2
     * 稍微大的文件超时，jq.js会报10254错误，前端显示404不过文件可以上传
     *     * 需要在在dispatcher.xml里面配置试图解析器（<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">）

     */
    public static void  fileUpload2(CommonsMultipartFile file) throws IOException {
        if(file.isEmpty()){
            System.out.println("文件不存在");
            return;
        }
        long  startTime=System.currentTimeMillis();
         String renameFilePath=FileUtil.renameFile(file.getOriginalFilename());
        try{
            File newFile=new File(renameFilePath);
            //通过CommonsMultipartFile的方法直接写文件（注意这个时候）
            file.transferTo(newFile);
        }catch (Exception e){
            System.out.println("方法2上传文件转换失败");
        }

        long  endTime=System.currentTimeMillis();
        System.out.println("方法二的运行时间："+String.valueOf(endTime-startTime)+"ms");

    }

    /*推荐使用使用
     *采用spring提供的上传文件的方法
     * package org.springframework.web.multipart.commons.CommonsMultipartResolver;
     * 需要在在dispatcher.xml里面配置试图解析器（<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">）
     * 中间会生成临时文件，会自动删除
     * 支持多文件上传
     * 速度NO.1
     */

    public static void  springUpload(HttpServletRequest request) throws IllegalStateException, IOException
    {
        long  startTime=System.currentTimeMillis();
        //将当前上下文初始化给  CommonsMutipartResolver （多部分解析器）
        CommonsMultipartResolver multipartResolver=new CommonsMultipartResolver(
                request.getSession().getServletContext());
        //检查form中是否有enctype="multipart/form-data"
        if(multipartResolver.isMultipart(request))
        {
            //将request变成多部分request
            MultipartHttpServletRequest multiRequest=(MultipartHttpServletRequest)request;
            //获取multiRequest 中所有的文件名
            Iterator iter=multiRequest.getFileNames();
//            List<FileItem>
            while(iter.hasNext())
            {
                //一次遍历所有文件
                MultipartFile file=multiRequest.getFile(iter.next().toString());
                if(file!=null)
                {
                  String renamePath=  FileUtil.renameFile(file.getOriginalFilename());
                    //上传
                    file.transferTo(new File(renamePath));
                }

            }

        }
        long  endTime=System.currentTimeMillis();
        System.out.println("方法三的运行时间："+String.valueOf(endTime-startTime)+"ms");

    }

    /***基于
     * commons-fileupload
     *commons-io
     *上传
     *需要注销spring的上传文件解析器
     * 因为protected MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException {
     *         String encoding = this.determineEncoding(request);
     *         FileUpload fileUpload = this.prepareFileUpload(encoding);已经调用FileUpload进行解析封装为自己的对象MultipartParsingResult
     *         再次List<FileItem> list = upload.parseRequest(request);解析时为空导致集合为空
     * */
       public static void fileUpload3(HttpServletRequest request, HttpServletResponse response){
        //判断是不是post提交
         boolean isMultipart =ServletFileUpload.isMultipartContent(request);
           if (isMultipart == true) {
               //初始化FiletItem工厂
               FileItemFactory fif =new DiskFileItemFactory();
               ServletFileUpload upload = new ServletFileUpload(fif);
               upload.setHeaderEncoding("utf-8");
               try {
                   //解析表单请求
                   List<FileItem> list = upload.parseRequest(request);
                   for (FileItem fi : list) {
                       //普通表单元素处理start
                       if (fi.isFormField()) {//判断是不是普通变淡属性
                           String fieldname = fi.getFieldName();
                           if (fieldname.equals("productNmae")) {
                               String projectName = null;
                               try {
                                   projectName = fi.getString("utf-8");
                               } catch (UnsupportedEncodingException e) {
                                   System.out.println("不支持utf-8编码");
                               }
                               System.out.println(projectName);
                           } else if (fieldname.equals("file")) {
                               try {
                                   System.out.println(fi.getString("utf-8"));
                               } catch (UnsupportedEncodingException e) {
                                   System.out.println("不支持utf-8编码");
                               }
                               ;
                           }
                           //普通表单元素处理end
                       } else {//是文件类型判断其大小，为0继续for循环
                           if (fi.getSize() == 0) {
                               continue;
                           }
                         String  newFileName =FileUtil.renameFile(fi.getName());
                           try {
                               fi.write(new File(newFileName));
                           } catch (Exception e) {
                               e.printStackTrace();
                           }

                       }
                   }
               } catch (FileUploadException e) {
                   e.printStackTrace();
               }

           }

       }
    /***
     * 上传文件命名公共方法
     * */
    public static synchronized String renameFile(String originalFilename){
        System.out.println("原文件名："+originalFilename);
        //桌面路径
        String prefix = originalFilename.substring(originalFilename.lastIndexOf("."));
        String newFileName =new Date().getTime()+ prefix;
        String desktopPath= FileSystemView.getFileSystemView().getHomeDirectory().getAbsolutePath()+"\"+newFileName;
        System.out.println("新文件名："+newFileName);
        return  desktopPath;

    }

//    <!-- 多部分文件上传 -->
//<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
//     <property name="maxUploadSize" value="104857600" />
//     <property name="maxInMemorySize" value="4096" />
//     <property name="defaultEncoding" value="UTF-8"></property>
//</bean>
}