source: main/trunk/greenstone3/src/java/org/greenstone/util/Misc.java@ 33043

 /*
 *    Misc.java
 *    Copyright (C) 2002 New Zealand Digital Library, http://www.nzdl.org
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

package org.greenstone.util;

import java.util.HashMap;
import java.util.Set;
import java.util.Map;
import java.util.Iterator;
import java.util.Properties;
import java.io.InputStream;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

/** contains miscellaneous functions */
public class Misc {

    // Can initialise static final vars on declaration or in static initialisation code block
    // http://stackoverflow.com/questions/2339932/java-can-final-variables-be-initialized-in-static-initialization-block
    // Initialise object member final vars on declaration or in constructors
    public static final String NEWLINE;
    
    // Before Java 7, no System.lineSeparator() or System.getProperty("line.separator")
    // And on local linux, am compiling with JDK 6, so need this.
    // http://stackoverflow.com/questions/207947/how-do-i-get-a-platform-dependent-new-line-character

    static {
    // http://stackoverflow.com/questions/2591083/getting-java-version-at-runtime
    // https://www.tutorialspoint.com/java/lang/package_getspecificationversion.htm
    
    double java_version = Double.parseDouble(System.getProperty("java.specification.version"));
    if(java_version >= 1.7) { // https://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html
        NEWLINE = System.getProperty("line.separator");
    } else {
        NEWLINE = isWindows() ? "\r\n" : "\n";
    }   
    }
    
    
    // Debugging function to print a string's non-basic chars in hex
    // Based on https://stackoverflow.com/questions/923863/converting-a-string-to-hexadecimal-in-java
    public static String stringToHex(String str) {
      String result = "";
      for(int i = 0; i < str.length(); i++) {
            int charCode = str.codePointAt(i); // unicode codepoint / ASCII code
            
            // ASCII table: https://cdn.sparkfun.com/assets/home_page_posts/2/1/2/1/ascii_table_black.png
            // If the unicode character code pt is less than the ASCII code for space and greater than for tilda, let's display the char in hex (x0000 format)
            if((charCode >= 20 && charCode <= 126) || charCode == 9 || charCode == 10 || charCode == 13) { // space to tilda, TAB, LF, CR are printable
                result += str.charAt(i);
            } else {
                result += "x" + String.format("%04x", charCode);
            }
      }
      
      return result;
    }
    
    
    public static void printHash(HashMap map) {
    Set entries = map.entrySet();
    Iterator i = entries.iterator();
    while (i.hasNext()) {
        Map.Entry m = (Map.Entry)i.next();
        String name = (String)m.getKey();
        String value = (String)m.getValue();
    }  
    }

    
    /** 
     * Handy function to display the list of calling functions by
     * printing out the stack trace even when you don't have an exception
     */
    static public void printStackTrace() {
    // https://stackoverflow.com/questions/1069066/get-current-stack-trace-in-java
    
    //Thread.dumpStack(); // looks too much like an exception, though the newlines separating each function call is handy
    //new Exception().printStackTrace(); // outputs in the format of an exception too   
    //System.err.println("\n@@@@ stacktrace:\n" + Arrays.toString(Thread.currentThread().getStackTrace()) + "\n"); // outputs all in one line
    
    System.err.println("\n@@@@ stacktrace:");
    StackTraceElement[] els = new Throwable().getStackTrace(); // starts at index 1, which is this function
    //StackTraceElement[] els = Thread.currentThread().getStackTrace(); starts at index 0, "java.lang.Thread.getStackTrace()"
    for(StackTraceElement ste : els) {
        System.err.println("   " + ste);
    }
    }
    
    /** 
     * Handy function to display the parent of the calling function
     * (the function that called the function that called printCaller())
     */
    static public void printCaller() {
    int parent = 1;
    // this function printCaller() itself adds another layer on the callstack since
    // it calls the overloaded method, so need to add 1 more to parent
    printCaller(parent++); 
    }
    
    /** 
     * Handy function to display the nth ancestor of the calling function
     * where ancestor=0 would be the calling function itself
     */
    static public void printCaller(int ancestor) {
    // https://stackoverflow.com/questions/1069066/get-current-stack-trace-in-java
    
    // Thread.currentThread().getStackTrace() starts at index 0: "java.lang.Thread.getStackTrace()"
    // index 1 will be this method (printCaller) and index 2 will be the calling function itself who wants
    // to know who called it. So need to at least start at index 3 to get informative caller information
    
    StackTraceElement[] callstack = Thread.currentThread().getStackTrace();
    StackTraceElement requestor = callstack[2]; // the calling function, the function that called this one
    StackTraceElement caller_requested = callstack[ancestor+3]; // the function requested
    System.err.println("@@@ Function " + requestor +  " called by:\n    "
               + caller_requested + " at " + ancestor + " ancestors back");
    }    
    
    
    /** Method to determine if the host system is Windows based.
     * @return a boolean which is true if the platform is Windows, 
     * false otherwise
     */
    public static boolean isWindows() {
    Properties props = System.getProperties();
    String os_name = props.getProperty("os.name","");
    if(os_name.startsWith("Windows")) {
        return true;
    }
    return false;
    }
    
    public static boolean isWindows9x() {
        Properties props = System.getProperties();
        String os_name = props.getProperty("os.name","");
        if(os_name.startsWith("Windows") && os_name.indexOf("9") != -1) {
            return true;
        }
        return false;
    }

    /** Method to determine if the host system is MacOS based.
     * @return a boolean which is true if the platform is MacOS, false otherwise
     */
    public static boolean isMac() {
        Properties props = System.getProperties();
        String os_name = props.getProperty("os.name","");
        if(os_name.startsWith("Mac OS")) {
            return true;
        }
        return false;
    }

    public static String getGsdlOS() {
        if (isWindows()) {
            return "windows";
        }
        if (isMac()) {
            return "darwin";
        }
        return "linux";
    }
    
    public static boolean isBigEndian() {

    if (System.getProperty("sun.cpu.endian").equals("big")) {
        return true;
    }
    return false;

    }

    public static BufferedReader makeHttpConnection(String url_string)
    throws java.net.MalformedURLException, java.io.IOException {
    BufferedReader reader = null;
    URL url = new URL(url_string);
    HttpURLConnection connection = (HttpURLConnection)url.openConnection();
    InputStream input = connection.getInputStream();
    reader = new BufferedReader(new InputStreamReader(input));  
    return reader;
    }

    public static void main(String [] args) {
    isBigEndian();
    }

}