Tilman
163 lines
4.1 KiB
Java
163 lines
4.1 KiB
Java
//Gruppe 01 (Übung 2)
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//Aufgabe 2-1
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package uebung02.aufgabe01;
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import java.io.BufferedInputStream;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import java.net.*;
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/**
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* Vergleicht zwei Ressourcen im Netz auf Übereinstimmung.
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* Zunächst werden die Inhalts-Header, danach die Ressourcen
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* selbst verglichen.
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*
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* @author Tilman Walther
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*/
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public class NetComparator {
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// Header, die auf Unterschiede im Inhalt schließen lassen
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private static String[] header = new String[] {
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"Content-Type",
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"Content-Length",
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"Content-Encoding",
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"Content-Language",
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"Last-Modified",
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"Expires" };
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/**
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* Compares two resources given as URLs.
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*
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* @param s1 The URL for the first resource
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* @param s2 The URL for the second resource
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* @return true, if the resources are equal, false otherwise
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* @throws IOException if an I/O Error occurs
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*/
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public static boolean compare(String s1, String s2) throws IOException {
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// Verbindungen für die Ressourcen erstellen
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URL url1 = new URL(s1);
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URLConnection connection1 = url1.openConnection();
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URL url2 = new URL(s2);
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URLConnection connection2 = url2.openConnection();
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// Header vergleichen
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String val1; // Header-Value Resource 1
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String val2; // Header-Value Resource 2
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long differences = 0; // Anz. festegestellter Unterschiede
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// relevante Header durchgehen
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for (int i = 0; i < header.length; i++) {
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val1 = connection1.getHeaderField(header[i]);
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val2 = connection2.getHeaderField(header[i]);
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if ((val1 != null) && (val2 != null)) {
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if (!val1.equals(val2)) {
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System.out.println("Header verschieden: "+header[i]+" "+val1+" / "+val2);
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differences++;
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}
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}
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}
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// Inhalt vergleichen
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BufferedInputStream input1 = new BufferedInputStream(connection1.getInputStream());
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BufferedInputStream input2 = new BufferedInputStream(connection2.getInputStream());
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long lengthRead = 0;
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long bytesDifferent = 0;
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long areasDifferent = 0;
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int length1 = 0;
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int length2 = 0;
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byte[] buffer1 = new byte[1024];
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byte[] buffer2 = new byte[1024];
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boolean differentArea = false;
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long marker = 0;
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// Inhalt vergleichen
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do {
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length1 = input1.read(buffer1);
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length2 = input2.read(buffer2);
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int in1 = Math.min(length1, length2);
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// Unterschiedliche Bereiche suchen
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for (int i = 0; i < in1; i++) {
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if ((buffer1[i] != buffer2[i])) {
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if (!differentArea) {
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differentArea = true;
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marker = lengthRead+i;
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}
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}
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else if (differentArea) {
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differentArea = false;
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bytesDifferent += (lengthRead + i - marker);
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System.out.println("Bereich von "+marker+" bis "+(lengthRead + i-1)+" unterschiedlich");
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areasDifferent++;
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differences++;
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}
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}
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lengthRead += length1;
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} while ((length1 > 0) && (length1 == length2));
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// Überprüfen, ob aus beiden Streams gleich viel gelesen wurde, bzw.
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// ob ein Stream noch nicht am Ende angelangt ist
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long diffLength = Math.abs(input1.available()+length1-input2.available()-length2);
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if (diffLength > 0) {
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System.out.println("Länge unterschiedlich ("+diffLength+" Byte)");
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differences++;
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}
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// Endergebnis ausgeben
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if (differences > 0) {
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System.out.println("Test beendet, "+differences+" Unterschiede festgestellt.\nDer Inhalt unterscheidet sich in "+bytesDifferent+" Bytes in "+areasDifferent+" Bereichen.");
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return false;
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}
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System.out.println("Test beendet, Ressourcen stimmen überein.");
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return true;
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}
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public static void main(String[] args) throws IOException {
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if (args.length == 2) {
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NetComparator.compare(args[0], args[1]);
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}
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else if (args.length == 0) {
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BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
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System.out.print("Please insert first URL: ");
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String s1 = in.readLine();
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System.out.print("Please insert second URL: ");
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String s2 = in.readLine();
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NetComparator.compare(s1, s2);
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}
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else {
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System.out.println("Aufruf: NetCompare [url1 url2]");
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}
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}
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}
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