Java实现FastDFS对文件上传、下载、删除_fastdfs java

在一些web应用项目实施过程，会碰到这么一个问题，例如：项目中有功能需要上传图片、文件等附件，这些附件在存储时常规的情况下是存储在一个固定的目录下，在部署多个相同的Tomcat实例集群的时候，往往需要考虑这些附件的同步问题，因此采用 FastDFS来对附件进行存储管理。

FastDFS 是一个开源的分布式文件系统，她对文件进行管理，功能包括：文件存储、文件同步、文件访问（文件上传、文件下载）等，解决了大容量存储和负载均衡的问题。FastDFS的工作原理以及相关安装流程就不做过多赘述，可以搜索相关资料了解，下面就来给大家介绍一下Java如何实现通过FastDFS上传、下载、删除附件。

首先需要在项目中导入FastDFS依赖相关的Jar包，我们使用maven的情况下，如下配置：

      <dependency>    
              <groupId>commons-io</groupId>    
          <artifactId>commons-io</artifactId>    
          <version>2.6</version>
      </dependency> 
      <dependency>    
          <groupId>commons-fileupload</groupId>    
          <artifactId>commons-fileupload</artifactId>    
          <version>1.3.1</version>    
      </dependency>
      <dependency>
           <groupId>org.csource</groupId>
           <artifactId>fastdfs-client-java</artifactId>
           <version>1.29-SNAPSHOT</version>
      </dependency>

第二步，在springboot项目中创建配置文件fdfs_client.conf

#默认值为30s
connect_timeout = 10
#默认值为30s
network_timeout = 30
charset = UTF-8
http.tracker_http_port = 8080
# token 防盗链功能
http.anti_steal_token = true
#防盗链key
http.secret_key = ZFnWLBqrX3
#服务器
tracker_server = 127.0.0.1:22122

第三步，创建一个实体类，定义附件相关的对象

public class FastDFSFile {
 
    private String name;//文件名
    private byte[] content; //文件的内容，字节数组
    private String ext; //文件扩展名，不包含（.）
    private String md5; //加密
 
    public FastDFSFile() {
    }
 
    public FastDFSFile(String name, byte[] content, String ext) {
        this.name = name;
        this.content = content;
        this.ext = ext;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public byte[] getContent() {
        return content;
    }
 
    public void setContent(byte[] content) {
        this.content = content;
    }
 
    public String getExt() {
        return ext;
    }
 
    public void setExt(String ext) {
        this.ext = ext;
    }
 
    public String getMd5() {
        return md5;
    }
 
    public void setMd5(String md5) {
        this.md5 = md5;
    }
 
    public String getAuthor() {
        return author;
    }
 
    public void setAuthor(String author) {
        this.author = author;
    }
}

第四步，创建工具类，写入相关方法

public class FastDFSClient {
 
    private final static Logger logger  = LoggerFactory.getLogger(FastDFSClient.class);
 
    //初始化
    static {
        try {
            String filePath = new ClassPathResource("fdfs_client.conf").getFile().getAbsolutePath();
            IniFileReader iniReader = new IniFileReader(filePath);
            String[] szTrackerServers = iniReader.getValues("tracker_server");
            ClientGlobal.init(filePath);
        } catch (Exception e) {
            throw new MyException(ResultEnum.FAST_DFS_ERROR);
        }
    }
 
    //上传
    public static String upload(FastDFSFile file){
        NameValuePair[] meta_list = new NameValuePair[1];
        meta_list[0] = new NameValuePair("author", file.getAuthor());
        long startTime = System.currentTimeMillis();
        String[] uploadResults = null;
        StorageClient storageClient=null;
        try {
            storageClient = getTrackerClient();
            //upload_file()三个参数：@param fileContent ①：文件的内容，字节数组 ②：文件扩展名 ③文件扩展信息 数组
            uploadResults = storageClient.upload_file(file.getContent(), file.getExt(), meta_list);
        }catch (Exception e){
            e.printStackTrace();
            throw new MyException(ResultEnum.FAST_DFS_ERROR);
        }
        if (uploadResults == null && storageClient!=null) {
            logger.error("upload file fail, error code:" + storageClient.getErrorCode());
        }
        logger.info("upload_file time used:" + (System.currentTimeMillis() - startTime) + " ms");
        String groupName = uploadResults[0];
        String remoteFileName = uploadResults[1];
        return groupName+"/"+remoteFileName;
    }
    
    //下载文件  
    public static boolean downloadFile(String localFilename, String groupName, String remoteFilename) {
        //localFilename  本地文件名
        //groupName      文件在FastDFS中的组名
        //remoteFilename 文件在FastDFS中的名称
        File file = new File(localFilename);
        if(!file.exists()) {
            if(!file.getParentFile().exists()){
                file.getParentFile().mkdirs();
            }
            try {
                file.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }else if(file.length()>0){
            logger.info("file.length()="+file.length());
            return true;
        }
        TrackerServer trackerServer;
        TrackerClient trackerClient=new TrackerClient();
        StorageServer storageServer=null;
        StorageClient storageClient=null;
        try (BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file))) {
            trackerServer = trackerClient.getTrackerServer();
            storageServer=trackerClient.getStoreStorage(trackerServer);
            storageClient= new StorageClient(trackerServer, storageServer);
            byte[] content = storageClient.download_file(groupName, remoteFilename);
            if (content == null || content.length == 0) {
                boolean flag = file.delete();
                return false;
            }
            bos.write(content);
            return true;
        } catch (IOException | MyException e) {
            e.printStackTrace();
            return false;
        }catch (Exception e){
            e.printStackTrace();
            return false;
        }
    }
 
    //删除
    public static int deleteFile(String groupName, String remoteFileName) throws Exception {
        //remoteFileName--文件路径 例如：M00/00/00/wKgRsVjtwpSAXGwkAAAweEAzRjw471.jpg
        //groupName --文件路径，例如：group1/M00/00/00/wKgRsVjtwpSAXGwkAAAweEAzRjw471.jpg中的group1
        StorageClient storageClient = getTrackerClient();
        return storageClient.delete_file(groupName, remoteFileName);
    }
 
    //查询文件信息
    public static FileInfo getFile(String groupName, String remoteFileName) {
        try {
            StorageClient storageClient = getTrackerClient();
            return storageClient.get_file_info(groupName, remoteFileName);
        } catch (IOException e) {
            logger.error("IO Exception: Get File from Fast DFS failed", e);
        } catch (Exception e) {
            logger.error("Non IO Exception: Get File from Fast DFS failed", e);
        }
        return null;
    }
}

第五步，调用示例

public class UploadDFS {
      
      //上传文件
      public static String saveFile(MultipartFile multipartFile) throws IOException {
        String fileName=multipartFile.getOriginalFilename();
        String ext = fileName.substring(fileName.lastIndexOf(".") + 1);
        byte[] file_buff = null;
        InputStream inputStream=multipartFile.getInputStream();
        if(inputStream!=null){
            int len1 = inputStream.available();
            file_buff = new byte[len1];
            inputStream.read(file_buff);
        }
        inputStream.close();
        FastDFSFile file = new FastDFSFile(fileName, file_buff, ext);
        return FastDFSClient.upload(file);
    }
 
   //下载
    public static boolean downFile(String localFilename, String groupName, String remoteFilename){
        //下载完成后到存储路径找下载的文件  localFilename 
        return FastDFSClient.downloadFile(localFilename,groupName,remoteFilename);
    }
 
 
   //删除
   public static void deleteFile(String groupName, String remoteFileName){
        try {
           int res= FastDFSClient.deleteFile(groupName,remoteFileName);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}