TableBCBSPJobUtil.java

/**
 * CopyRight by Chinamobile
 * 
 * TableBCBSPJobUtil.java
 */
package com.chinamobile.bcbsp.io.db;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.util.Base64;

/**
 * Utility for TableInputFormat
 */
public class TableBCBSPJobUtil {
    static Log LOG = LogFactory.getLog(TableBCBSPJobUtil.class);

    /**
     * Writes the given scan into a Base64 encoded string.
     * 
     * @param scan
     *            The scan to write out.
     * @return The scan saved in a Base64 encoded string.
     * @throws IOException
     *             When writing the scan fails.
     */
    static String convertScanToString(Scan scan) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        DataOutputStream dos = new DataOutputStream(out);
        scan.write(dos);
        return Base64.encodeBytes(out.toByteArray());
    }

    /**
     * Converts the given Base64 string back into a Scan instance.
     * 
     * @param base64
     *            The scan details.
     * @return The newly created Scan instance.
     * @throws IOException
     *             When reading the scan instance fails.
     */
    static Scan convertStringToScan(String base64) throws IOException {
        ByteArrayInputStream bis = new ByteArrayInputStream(
                Base64.decode(base64));
        DataInputStream dis = new DataInputStream(bis);
        Scan scan = new Scan();
        scan.readFields(dis);
        return scan;
    }
}