InputStream in = null;  
try{  
    in = new URL("hdfs://host/path").openStream();  
}finally{  
    IOUtils.closeStream(in);  
}  
 

package gucas.xiaoxia;  
import java.io.InputStream;  
import java.net.URL;  
  
import org.apache.hadoop.fs.FsUrlStreamHandlerFactory;  
import org.apache.hadoop.io.IOUtils;  
  
public class CatURL {  
static {  
    URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory());  
}  
  
    /** 
     * @param args 
     */  
    public static void main(String[] args) {  
        // TODO Auto-generated method stub  
        InputStream input = null;  
        try {  
            input = new URL("hdfs://localhost/user/hadoop/map.txt")  
                    .openStream();  
  
            IOUtils.copyBytes(input, System.out, 4096, false);  
  
        } catch (Exception e) {  
  
            e.printStackTrace();  
  
        } finally {  
  
            IOUtils.closeStream(input);  
        }  
    }  
  
}