FastDFS的配置、部署与API使用解读（2）以字节方式上传文件的客户端代码

1、下载FastDFS的API FastDFS提供Java和PHP等语言的客户端API。可以到FastDFS在Google Code的项目主页 http://code.google.com/p/fastdfs/downloads/list 下载。本文以Java API为例。
2、调用API的上传接口 通过Servlet得到InputStream、文件名称和文件长度，然后通过调用FastDFS提供的Java API把文件上传到FastDFS服务器。下段代码中的getFileBuffer可参考本博客上一篇博文。（by Poechant）

/**
 * Upload File to DFS.
 * @param fileBuff, file to be uploaded.
 * @param uploadFileName, the name of the file.
 * @param fileLength, the length of the file.
 * @return the file ID in DFS.
 * @throws IOException
 */
public String uploadFile(InputStream inStream, String uploadFileName, long fileLength) throws IOException {
    byte[] fileBuff = getFileBuffer(inStream, fileLength);
    String fileId = "";
    String fileExtName = "";
    if (uploadFileName.contains(".")) {
        fileExtName = uploadFileName.substring(uploadFileName.lastIndexOf(".") + 1);
    } else {
        logger.warn("Fail to upload file, because the format of filename is illegal.");
        return fileId;
    }


    //建立连接
    TrackerClient tracker = new TrackerClient();
    TrackerServer trackerServer = tracker.getConnection();
    StorageServer storageServer = null;
    StorageClient1 client = new StorageClient1(trackerServer, storageServer);


    //设置元信息
    NameValuePair[] metaList = new NameValuePair[3];
    metaList[0] = new NameValuePair("fileName", uploadFileName);
    metaList[1] = new NameValuePair("fileExtName", fileExtName);
    metaList[2] = new NameValuePair("fileLength", String.valueOf(fileLength));


    //上传文件
    try {
        fileId = client.upload_file1(fileBuff, fileExtName, metaList);
    } catch (Exception e) {
        logger.warn("Upload file "" + uploadFileName + ""fails");
    }
    trackerServer.close();
    return fileId;
}

/**
 * Upload File to DFS.
 * @param fileBuff, file to be uploaded.
 * @param uploadFileName, the name of the file.
 * @param fileLength, the length of the file.
 * @return the file ID in DFS.
 * @throws IOException 
 */
public String uploadFile(InputStream inStream, String uploadFileName, long fileLength) throws IOException {
	byte[] fileBuff = getFileBuffer(inStream, fileLength);
	String fileId = "";
	String fileExtName = "";
	if (uploadFileName.contains(".")) {
		fileExtName = uploadFileName.substring(uploadFileName.lastIndexOf(".") + 1);
	} else {
		logger.warn("Fail to upload file, because the format of filename is illegal.");
		return fileId;
	}


	//建立连接
	TrackerClient tracker = new TrackerClient();
	TrackerServer trackerServer = tracker.getConnection();
	StorageServer storageServer = null;
	StorageClient1 client = new StorageClient1(trackerServer, storageServer);


	//设置元信息
	NameValuePair[] metaList = new NameValuePair[3];
	metaList[0] = new NameValuePair("fileName", uploadFileName);
	metaList[1] = new NameValuePair("fileExtName", fileExtName);
	metaList[2] = new NameValuePair("fileLength", String.valueOf(fileLength));


	//上传文件
	try {
		fileId = client.upload_file1(fileBuff, fileExtName, metaList);
	} catch (Exception e) {
		logger.warn("Upload file "" + uploadFileName + ""fails");
	}
	trackerServer.close();
	return fileId;
}

3、调用方式详解 （1）客户端与Tracker Server通信 根据《FastDFS的配置、部署与API使用解读（1）Get Started with FastDFS》一文中提供的FastDFS的工作原理，结合上面的代码，首先通过TrackerClient构造函数从全局配置中获取Tracker Servers的IP和端口初始化一个TrackerClient对象tracker，并与其建立连接，我们可以从API的源码中看到：

/**
* constructor with global tracker group
*/
public TrackerClient()
{
    this.tracker_group = ClientGlobal.g_tracker_group;
}
/**
* constructor with specified tracker group
* @param tracker_group the tracker group object
*/
public TrackerClient(TrackerGroup tracker_group)
{
    this.tracker_group = tracker_group;
}

/**
* constructor with global tracker group
*/
public TrackerClient()
{
	this.tracker_group = ClientGlobal.g_tracker_group;
}	
/**
* constructor with specified tracker group
* @param tracker_group the tracker group object
*/
public TrackerClient(TrackerGroup tracker_group)
{
	this.tracker_group = tracker_group;
}


上述代码中ClientGlobal是一个提供很多静态成员供外部读取的类。通过tracker这个TrackerClient建立的与Tracker Server的连接，实例化了一个trackerServer对象。

（2）客户端与Storage Server通信

通过trackerServer取得某一个可用的Storage Server的地址并用其实例化一个StorageClient1对象。这样就完成了FastDFS的客户端调用上传、下载、删除等所有操作的前期建立连接的工作。
（3）调用文件操作API 这些操作包括upload、download、append、delete等。上例中提供的是上传的实例。