HDFSApi
package HDFSApi;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
import HDFSApi.SCP;
public class HDFSApi {
/**
* 判断路径是否存在
*/
public static boolean test(Configuration conf, String path) throws IOException {
FileSystem fs = FileSystem.get(conf);
return fs.exists(new Path(path));
}
/**
* 复制文件到指定路径
* 若路径已存在，则进行覆盖
*/
public static void copyFromLocalFile(Configuration conf, String localFilePath, String remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path localPath = new Path(localFilePath);
Path remotePath = new Path(remoteFilePath);
/* fs.copyFromLocalFile 第一个参数表示是否删除源文件，第二个参数表示是否覆盖 */
fs.copyFromLocalFile(false, true, localPath, remotePath);
fs.close();
}
/**
* 追加文件内容
*/
public static void appendToFile(Configuration conf, String localFilePath, String remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
/* 创建一个文件读入流 */
FileInputStream in = new FileInputStream(localFilePath);
/* 创建一个文件输出流，输出的内容将追加到文件末尾 */
FSDataOutputStream out = fs.append(remotePath);
/* 读写文件内容 */
byte[] data = new byte[1024];
int read = -1;
while ( (read = in.read(data)) > 0 ) {
out.write(data, 0, read);
}
out.close();
in.close();
fs.close();
}
/**
* 主函数
*
*/
public static void main(String[] args) throws IOException {
SCP.get();//通过SCP将linux上的文件下载到windows上
Configuration conf = new Configuration();
conf.set("fs.default.name","hdfs://192.168.88.101:8020");
String localFilePath = "D:\\local.txt"; // 本地路径
String remoteFilePath = "/user/hadoop/text.txt"; // HDFS 路径
String choice = "append"; // 若文件存在则追加到文件末尾
// String choice = "overwrite"; // 若文件存在则覆盖
try {
/* 判断文件是否存在 */
Boolean fileExists = false;
if (HDFSApi.test(conf, remoteFilePath)) {
fileExists = true;
System.out.println(remoteFilePath + " 已存在.");
} else {
System.out.println(remoteFilePath + " 不存在.");
}
/* 进行处理 */
if ( !fileExists) { // 文件不存在，则上传
HDFSApi.copyFromLocalFile(conf, localFilePath, remoteFilePath);
System.out.println(localFilePath + " 已上传至 " + remoteFilePath);
} else if ( choice.equals("overwrite") ) { // 选择覆盖
HDFSApi.copyFromLocalFile(conf, localFilePath, remoteFilePath);
System.out.println(localFilePath + " 已覆盖 " + remoteFilePath);
} else if ( choice.equals("append") ) { // 选择追加
HDFSApi.appendToFile(conf, localFilePath, remoteFilePath);
System.out.println(localFilePath + " 已追加至 " + remoteFilePath);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}