import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.URL;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FsUrlStreamHandlerFactory;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.junit.Test;
public class seek {
/**
* 通過API實現seek操作
*
* @author Administrator
*
* [hadoop@hadoop01 ~]$ hdfs dfs -chmod -R a+w /user/hadoop
* [hadoop@hadoop01 ~]$ hdfs dfs -ls -R /
*
*
*/
@Test
public void seekfile() throws Exception {
//創建configuration對象,有個默認的加載順序,先從core-default.xml,再到src目錄中的文件,這裏
//我們給定了
Configuration conf = new Configuration();
//通過conf的configuration對象創建了該分佈式文件系統fs,默認如果不指定文件的話爲本地文件系統
FileSystem fs = FileSystem.get(conf);
//定義一個URL的字符串
String file = "hdfs://hadoop01:9000/user/hadoop/data2/kaola.jpg";
//通過一個URL的字符串構建一個path對象
Path path = new Path(file);
FSDataInputStream in = fs.open(path);
//流對拷
IOUtils.copyBytes(in, new FileOutputStream("E:/kaola1.jpg"), 1024, false);
//重新定位到文件起始點,只有FSDataInputStream纔有實現seek接口,FSDataOutputStream沒有
in.seek(0);
IOUtils.copyBytes(in, new FileOutputStream("E:/kaola2.jpg"), 1024, true);
}
}