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The AceQL Java Client JDBC Driver allows to wrap the AceQL HTTP APIs and eliminates the tedious works of handling communications errors and parsing JSON results. Android and Java Desktop application developers can access remote SQL databases and/or SQL databases in the cloud by simply including standard JDBC calls in their code, just like they would for a local database.

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/*
 * This file is part of AceQL JDBC Driver.
 * AceQL JDBC Driver: Remote JDBC access over HTTP with AceQL HTTP.
 * Copyright (c) 2023,  KawanSoft SAS
 * (http://www.kawansoft.com). All rights reserved.
 *
 * Licensed 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 com.aceql.jdbc.commons.main.util.framework;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Objects;

import org.apache.commons.lang3.StringUtils;

/**
 * A fast Result Set rows counter, does not use JSON parse...
 * @author Nicolas de Pomereu
 *
 */
public class FastRowCounter {

    public static boolean DEBUG = FrameworkDebug.isSet(FastRowCounter.class);
    
    /**
     * Returns the Result Set rows count without parsing the Json file.
     * @param file the Json Result Set file to counts the rows from
     * @return  the Json Result Set rows count
     * @throws IOException if any I/O Exception or file does not exist
     */
    public static int getRowCount(InputStream inputStream, long size) throws IOException {

	StringBuffer sb = new StringBuffer();

	//long size = file.length();

	try (InputStream is = new BufferedInputStream(inputStream)) {
	    byte[] c = new byte[1024];

	    int readChars = 0;
	    long cpt = 0;
	    while ((readChars = is.read(c)) != -1) {

		for (int i = 0; i < readChars; ++i) {
		    cpt++;
		    if (cpt > size - 40 && cpt < size - 1) {
			sb.append((char) c[i]);
		    }
		}
	    }

	} 

	String line = sb.toString();
	debug("!" + line + "!");
	line = StringUtils.substringAfter(line, ",");
	line = StringUtils.substringAfter(line, ":").trim();
	debug("!" + line + "!");
	return Integer.parseInt(line);
    }

    
    /**
     * Returns the Result Set rows count without parsing the Json file.
     * @param file the Json Result Set file to counts the rows from
     * @return  the Json Result Set rows count
     * @throws IOException if any I/O Exception or file does not exist
     */
    public static int getRowCount(File file) throws IOException {
	Objects.requireNonNull(file, "file cannot be null!");
	
	if (! file.exists()) {
	    throw new FileNotFoundException("file does not exist: " + file);
	}

	StringBuffer sb = new StringBuffer();

	long size = file.length();

	try (InputStream is = new BufferedInputStream(new FileInputStream(file))) {
	    byte[] c = new byte[1024];

	    int readChars = 0;
	    long cpt = 0;
	    while ((readChars = is.read(c)) != -1) {

		for (int i = 0; i < readChars; ++i) {
		    cpt++;
		    if (cpt > size - 40 && cpt < size - 1) {
			sb.append((char) c[i]);
		    }
		}
	    }

	} 

	String line = sb.toString();
	debug("!" + line + "!");
	line = StringUtils.substringAfter(line, ",");
	line = StringUtils.substringAfter(line, ":").trim();
	debug("!" + line + "!");
	return Integer.parseInt(line);
    }

    /**
     * https://stackoverflow.com/questions/453018/number-of-lines-in-a-file-in-java
     * Keep as model 
     * @param fileName
     * @return number of lines
     */
    public static long countLineFast(String fileName) {

	long lines = 0;

	try (InputStream is = new BufferedInputStream(new FileInputStream(fileName))) {
	    byte[] c = new byte[1024];
	    int count = 0;
	    int readChars = 0;
	    boolean endsWithoutNewLine = false;
	    while ((readChars = is.read(c)) != -1) {
		for (int i = 0; i < readChars; ++i) {
		    if (c[i] == '\n')
			++count;
		}
		endsWithoutNewLine = (c[readChars - 1] != '\n');
	    }
	    if (endsWithoutNewLine) {
		++count;
	    }
	    lines = count;
	} catch (IOException e) {
	    e.printStackTrace();
	}

	return lines;
    }
    
    /**
     * @param line
     */
    public static void debug(String line) {
	if (DEBUG) {
	    System.out.println(line);
	}

    }

}