一、環境搭建

1. 環境變數的配置HADOOP_HONE
2. 把HADOOP_HOME的bin新增到PATH
3. 許可權問題：新增HADOOP_USER_NAME=root環境變數

二、Eclipse的配置

1. 在Eclipse安裝目錄下dropins\plugins資料夾內新增如下hadoop-eclipse-plugin.jar包
2. 重啟Eclipse2.重啟Eclipse
3. 匯入工程必需的jar包
4. 替換工程對應的Hadoop包下的bin資料夾，使其方便操作
5. 配置，如下：

配置成功如下

找到Map/Reduce Locations

最後的配置

配置成功後

三、JavaAPI程式碼

public
 
 class TestHDFS {
	public static void main(String[] args) throws IOException {
		//操作HDFS之前得先建立配置物件
		Configuration conf = new Configuration(true);
		//建立操作HDFS的物件
		FileSystem fs = FileSystem.get(conf);
		
		//檢視檔案系統的內容
		List list = listFileSystem(fs,"/");
		//建立資料夾
		createDir(fs,"/test/abc");
		
		//上傳檔案
		uploadFileToHDFS
 
(fs,"d:/wc","/test/abc/");
		
		//下載檔案
		downLoadFileFromHDFS(fs,"/test/abc/wc","d:/");
		
		//刪除.....
		
		//重新命名
		renameFile(fs,"/test/abc/wc","/test/abc/Angelababy");
		
		//內部移動 內部複製
		innerCopyAndMoveFile(fs,conf,"/test/abc/Angelababy","/");
		
		//建立一個新檔案
		createNewFile(fs,"/test/abc/hanhong");
		
		//寫檔案
		writeToHDFSFile(
 
fs,"/test/abc/hanhong","hello world");
		//追加寫
		appendToHDFSFile(fs,"/test/abc/hanhong","\nhello world");
		
		//讀檔案內容
		readFromHDFSFile(fs,"/test/abc/hanhong");
		
		//獲取資料的位置
		getFileLocation(fs,"/install.log");
	}

	private static void getFileLocation(FileSystem fs, String string) throws IOException {
		FileStatus fileStatus = fs.getFileStatus(new Path(string));
		long len = fileStatus.getLen();
		BlockLocation[] fileBlockLocations = fs.getFileBlockLocations(fileStatus, 0, len);
		String[] hosts = fileBlockLocations[0].getHosts();
		for (String string2 : hosts) {
			System.out.println(string2);
		}
		
		HdfsBlockLocation blockLocation = (HdfsBlockLocation)fileBlockLocations[0];
		long blockId = blockLocation.getLocatedBlock().getBlock().getBlockId();
		System.out.println(blockId);
	}

	private static void readFromHDFSFile(FileSystem fs, String string) throws IllegalArgumentException, IOException {
		FSDataInputStream inputStream = fs.open(new Path(string));
		
		FileStatus fileStatus = fs.getFileStatus(new Path(string));
		
		
		
		long len = fileStatus.getLen();
		
		byte[] b = new byte[(int)len];
		int read = inputStream.read(b);
		while(read != -1){
			System.out.println(new String(b));
			read = inputStream.read(b);
		}
		
		
	}

	private static void appendToHDFSFile(FileSystem fs, String filePath, String content) throws IllegalArgumentException, IOException {
		FSDataOutputStream append = fs.append(new Path(filePath));
		append.write(content.getBytes("UTF-8"));
		append.flush();
		append.close();
	}

	private static void writeToHDFSFile(FileSystem fs, String filePath, String content) throws IllegalArgumentException, IOException {
		 FSDataOutputStream outputStream = fs.create(new Path(filePath));
		 outputStream.write(content.getBytes("UTF-8"));
		 outputStream.flush();
		 outputStream.close();
	}

	private static void createNewFile(FileSystem fs, String string) throws IllegalArgumentException, IOException {
		fs.createNewFile(new Path(string));
	}

	private static void innerCopyAndMoveFile(FileSystem fs, Configuration conf,String src, String dest) throws IOException {
		Path srcPath = new Path(src);
		Path destPath = new Path(dest);
		
		//內部拷貝
//		FileUtil.copy(srcPath.getFileSystem(conf), srcPath, destPath.getFileSystem(conf), destPath,false, conf);
		//內部移動
		FileUtil.copy(srcPath.getFileSystem(conf), srcPath, destPath.getFileSystem(conf), destPath,true, conf);
	}

	private static void renameFile(FileSystem fs, String src, String dest) throws IOException {
		Path srcPath = new Path(src);
		Path destPath = new Path(dest);
		
		fs.rename(srcPath, destPath);
	
	}

	private static void downLoadFileFromHDFS(FileSystem fs, String src, String dest) throws IOException {
		Path srcPath = new Path(src);
		Path destPath = new Path(dest);
		//copyToLocal
//		fs.copyToLocalFile(srcPath, destPath);
		//moveToLocal
		fs.copyToLocalFile(true,srcPath, destPath);
	}

	private static void uploadFileToHDFS(FileSystem fs, String src, String dest) throws IOException {
		Path srcPath = new Path(src);
		Path destPath = new Path(dest);
		//copyFromLocal
//		fs.copyFromLocalFile(srcPath, destPath);
		//moveFromLocal
		fs.copyFromLocalFile(true,srcPath, destPath);
	}

	private static void createDir(FileSystem fs, String string) throws IllegalArgumentException, IOException {
		Path path = new Path(string);
		if(fs.exists(path)){
			fs.delete(path, true);
		}
		fs.mkdirs(path);
	}

	private static List listFileSystem(FileSystem fs, String path) throws FileNotFoundException, IOException {
		Path ppath = new Path(path);
		
		FileStatus[] listStatus = fs.listStatus(ppath);
		
		for (FileStatus fileStatus : listStatus) {
			System.out.println(fileStatus.getPath());
		}
		
		return null;
	}
}