org.apache.hadoop.sqoop.util.ResultSetPrinter.java Source code

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Here is the source code for org.apache.hadoop.sqoop.util.ResultSetPrinter.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.sqoop.util;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Utility methods to format and print ResultSet objects
 * 
 *
 */
public class ResultSetPrinter {

    public static final Log LOG = LogFactory.getLog(ResultSetPrinter.class.getName());

    // max output width to allocate to any column of the printed results.
    private static final int MAX_COL_WIDTH = 20;

    // length of the byte buffer, in bytes, to allocate.
    private static final int BUFFER_LEN = 4096;

    // maximum number of characters to deserialize from the stringbuilder
    // into the byte buffer at a time. Factor of 2 off b/c of Unicode.
    private static final int MAX_CHARS = 2048;

    private ByteBuffer bytebuf;
    private char[] charArray;

    public ResultSetPrinter() {
        bytebuf = ByteBuffer.allocate(BUFFER_LEN);
        charArray = new char[MAX_CHARS];
    }

    /**
     * Print 'str' to the string builder, padded to 'width' chars
     */
    private static void printPadded(StringBuilder sb, String str, int width) {
        int numPad;
        if (null == str) {
            sb.append("(null)");
            numPad = width - "(null)".length();
        } else {
            sb.append(str);
            numPad = width - str.length();
        }

        for (int i = 0; i < numPad; i++) {
            sb.append(' ');
        }
    }

    /**
     * Takes the contents of the StringBuilder and prints it on the OutputStream
     */
    private void sendToStream(StringBuilder sb, OutputStream os) throws IOException {

        int pos = 0; // current pos in the string builder
        int len = sb.length(); // total length (in characters) to send to os.
        CharBuffer charbuf = bytebuf.asCharBuffer();

        while (pos < len) {
            int copyLen = Math.min(sb.length(), MAX_CHARS);
            sb.getChars(pos, copyLen, charArray, 0);

            charbuf.put(charArray, 0, copyLen);
            os.write(bytebuf.array());

            pos += copyLen;
        }

    }

    private static final String COL_SEPARATOR = " | ";

    /**
     * Format the contents of the ResultSet into something that could be printed
     * neatly; the results are appended to the supplied StringBuilder.
     */
    public final void printResultSet(OutputStream os, ResultSet results) throws IOException {
        try {
            StringBuilder sbNames = new StringBuilder();
            int cols = results.getMetaData().getColumnCount();

            int[] colWidths = new int[cols];
            ResultSetMetaData metadata = results.getMetaData();
            for (int i = 1; i < cols + 1; i++) {
                String colName = metadata.getColumnName(i);
                colWidths[i - 1] = Math.min(metadata.getColumnDisplaySize(i), MAX_COL_WIDTH);
                if (colName == null || colName.equals("")) {
                    colName = metadata.getColumnLabel(i) + "*";
                }
                printPadded(sbNames, colName, colWidths[i - 1]);
                sbNames.append(COL_SEPARATOR);
            }
            sbNames.append('\n');

            StringBuilder sbPad = new StringBuilder();
            for (int i = 0; i < cols; i++) {
                for (int j = 0; j < COL_SEPARATOR.length() + colWidths[i]; j++) {
                    sbPad.append('-');
                }
            }
            sbPad.append('\n');

            sendToStream(sbPad, os);
            sendToStream(sbNames, os);
            sendToStream(sbPad, os);

            while (results.next()) {
                StringBuilder sb = new StringBuilder();
                for (int i = 1; i < cols + 1; i++) {
                    printPadded(sb, results.getString(i), colWidths[i - 1]);
                    sb.append(COL_SEPARATOR);
                }
                sb.append('\n');
                sendToStream(sb, os);
            }

            sendToStream(sbPad, os);
        } catch (SQLException sqlException) {
            LOG.error("Error reading from database: " + sqlException.toString());
        }
    }

}