上篇文章介绍了如何使用 Spring Boot 上传文件，这篇文章我们介绍如何使用 Spring Boot 将文件上传到分布式文件系统 FastDFS 中。

这个项目会在上一个项目的基础上进行构建。

1、pom 包配置

<dependency>
    <groupId>org.csource</groupId>
    <artifactId>fastdfs-client-java</artifactId>
    <version>1.27-SNAPSHOT</version>
</dependency>

加入了fastdfs-client-java包，用来调用 FastDFS 相关的 API。

2、配置文件

resources 目录下添加fdfs_client.conf文件

connect_timeout = 60
network_timeout = 60
charset = UTF-8
http.tracker_http_port = 8080
http.anti_steal_token = no
http.secret_key = 123456

tracker_server = 192.168.53.85:22122
tracker_server = 192.168.53.86:22122

配置文件设置了连接的超时时间，编码格式以及 tracker_server 地址等信息

详细内容参考：fastdfs-client-java

3、封装 FastDFS 上传工具类

封装FastDFSFile，文件基础信息包括文件名、内容、文件类型、作者等。

public class FastDFSFile {
    private String name;
    private byte[] content;
    private String ext;
    private String md5;
    private String author;
    //省略getter、setter
}

封装 FastDFSClient 类，包含常用的上传、下载、删除等方法。

首先在类加载的时候读取相应的配置信息，并进行初始化。

static {
    try {
        String filePath = new ClassPathResource("fdfs_client.conf").getFile().getAbsolutePath();;
        ClientGlobal.init(filePath);
        trackerClient = new TrackerClient();
        trackerServer = trackerClient.getConnection();
        storageServer = trackerClient.getStoreStorage(trackerServer);
    } catch (Exception e) {
        logger.error("FastDFS Client Init Fail!",e);
    }
}

文件上传

public static String[] upload(FastDFSFile file) {
    logger.info("File Name: " + file.getName() + "File Length:" + file.getContent().length);

    NameValuePair[] meta_list = new NameValuePair[1];
    meta_list[0] = new NameValuePair("author", file.getAuthor());

    long startTime = System.currentTimeMillis();
    String[] uploadResults = null;
    try {
        storageClient = new StorageClient(trackerServer, storageServer);
        uploadResults = storageClient.upload_file(file.getContent(), file.getExt(), meta_list);
    } catch (IOException e) {
        logger.error("IO Exception when uploadind the file:" + file.getName(), e);
    } catch (Exception e) {
        logger.error("Non IO Exception when uploadind the file:" + file.getName(), e);
    }
    logger.info("upload_file time used:" + (System.currentTimeMillis() - startTime) + " ms");

    if (uploadResults == null) {
        logger.error("upload file fail, error code:" + storageClient.getErrorCode());
    }
    String groupName = uploadResults[0];
    String remoteFileName = uploadResults[1];

    logger.info("upload file successfully!!!" + "group_name:" + groupName + ", remoteFileName:" + " " + remoteFileName);
    return uploadResults;
}

使用 FastDFS 提供的客户端 storageClient 来进行文件上传，最后将上传结果返回。

根据 groupName 和文件名获取文件信息。

public static FileInfo getFile(String groupName, String remoteFileName) {
    try {
        storageClient = new StorageClient(trackerServer, storageServer);
        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;
}

下载文件

public static InputStream downFile(String groupName, String remoteFileName) {
    try {
        storageClient = new StorageClient(trackerServer, storageServer);
        byte[] fileByte = storageClient.download_file(groupName, remoteFileName);
        InputStream ins = new ByteArrayInputStream(fileByte);
        return ins;
    } 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;
}

删除文件

public static void deleteFile(String groupName, String remoteFileName)
        throws Exception {
    storageClient = new StorageClient(trackerServer, storageServer);
    int i = storageClient.delete_file(groupName, remoteFileName);
    logger.info("delete file successfully!!!" + i);
}

使用 FastDFS 时，直接调用 FastDFSClient 对应的方法即可。

4、编写上传控制类

从 MultipartFile 中读取文件信息，然后使用 FastDFSClient 将文件上传到 FastDFS 集群中。

public String saveFile(MultipartFile multipartFile) throws IOException {
    String[] fileAbsolutePath={};
    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);
    try {
        fileAbsolutePath = FastDFSClient.upload(file);  //upload to fastdfs
    } catch (Exception e) {
        logger.error("upload file Exception!",e);
    }
    if (fileAbsolutePath==null) {
        logger.error("upload file failed,please upload again!");
    }
    String path=FastDFSClient.getTrackerUrl()+fileAbsolutePath[0]+ "/"+fileAbsolutePath[1];
    return path;
}

请求控制，调用上面方法saveFile()。

@PostMapping("/upload") //new annotation since 4.3
public String singleFileUpload(@RequestParam("file") MultipartFile file,
                               RedirectAttributes redirectAttributes) {
    if (file.isEmpty()) {
        redirectAttributes.addFlashAttribute("message", "Please select a file to upload");
        return "redirect:uploadStatus";
    }
    try {
        // Get the file and save it somewhere
        String path=saveFile(file);
        redirectAttributes.addFlashAttribute("message",
                "You successfully uploaded '" + file.getOriginalFilename() + "'");
        redirectAttributes.addFlashAttribute("path",
                "file path url '" + path + "'");
    } catch (Exception e) {
        logger.error("upload file failed",e);
    }
    return "redirect:/uploadStatus";
}

上传成功之后，将文件的路径展示到页面，效果图如下：

在浏览器中访问此Url，可以看到成功通过FastDFS展示：