first commit

2024-01-15 20:14:10 +00:00
commit 8c81ee28b7
3106 changed files with 474415 additions and 0 deletions
--- a/1/Java/examples/projects/chapter07/weblog-analyzer/LogfileReader.java
+++ b/1/Java/examples/projects/chapter07/weblog-analyzer/LogfileReader.java
@@ -0,0 +1,161 @@
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.Random;
+import java.util.Scanner;
+
+/**
+ * A class to read information from a file of web server accesses.
+ * Currently, the log file is assumed to contain simply
+ * date and time information in the format:
+ *
+ *    year month day hour minute
+ * Log entries are sorted into ascending order of date.
+ * 
+ * @author David J. Barnes and Michael Kölling.
+ * @version    2016.02.29
+ */
+public class LogfileReader implements Iterator<LogEntry>
+{
+    // The data format in the log file.
+    private String format;
+    // Where the file's contents are stored in the form
+    // of LogEntry objects.
+    private ArrayList<LogEntry> entries;
+    // An iterator over entries.
+    private Iterator<LogEntry> dataIterator;
+    
+    /**
+     * Create a LogfileReader to supply data from a default file.
+     */
+    public LogfileReader()
+    {
+        this("weblog.txt");
+    }
+    
+    /**
+     * Create a LogfileReader that will supply data
+     * from a particular log file. 
+     * @param filename The file of log data.
+     */
+    public LogfileReader(String filename)
+    {
+        // The format for the data.
+        format = "Year Month(1-12) Day Hour Minute";       
+        // Where to store the data.
+        entries = new ArrayList<>();
+        
+        // Attempt to read the complete set of data from file.
+        boolean dataRead;
+        try{
+            // Locate the file with respect to the current environment.
+            URL fileURL = getClass().getClassLoader().getResource(filename);
+            if(fileURL == null) {
+                throw new FileNotFoundException(filename);
+            }
+            Scanner logfile = new Scanner(new File(fileURL.toURI()));
+            // Read the data lines until the end of file.
+            while(logfile.hasNextLine()) {
+                String logline = logfile.nextLine();
+                // Break up the line and add it to the list of entries.
+                LogEntry entry = new LogEntry(logline);
+                entries.add(entry);
+            }
+            logfile.close();
+            dataRead = true;
+        }
+        catch(FileNotFoundException | URISyntaxException e) {
+            System.out.println("Problem encountered: " + e);
+            dataRead = false;
+        }
+        // If we couldn't read the log file, use simulated data.
+        if(!dataRead) {
+            System.out.println("Failed to read the data file: " + filename);
+            System.out.println("Using simulated data instead.");
+            createSimulatedData(entries);
+        }
+        // Sort the entries into ascending order.
+        Collections.sort(entries);
+        reset();
+    }
+    
+    /**
+     * Does the reader have more data to supply?
+     * @return true if there is more data available,
+     *         false otherwise.
+     */
+    public boolean hasNext()
+    {
+        return dataIterator.hasNext();
+    }
+    
+    /**
+     * Analyze the next line from the log file and
+     * make it available via a LogEntry object.
+     * 
+     * @return A LogEntry containing the data from the
+     *         next log line.
+     */
+    public LogEntry next()
+    {
+        return dataIterator.next();
+    }
+    
+    /**
+     * Remove an entry.
+     * This operation is not permitted.
+     */
+    public void remove()
+    {
+        System.err.println("It is not permitted to remove entries.");
+    }
+    
+    /**
+     * @return A string explaining the format of the data
+     *         in the log file.
+     */
+    public String getFormat()
+    {
+        return format;
+    }
+    
+    /**
+     * Set up a fresh iterator to provide access to the data.
+     * This allows a single file of data to be processed
+     * more than once.
+     */
+    public void reset()
+    {
+        dataIterator = entries.iterator();
+    }
+
+    /**
+     * Print the data.
+     */    
+    public void printData()
+    {
+        for(LogEntry entry : entries) {
+            System.out.println(entry);
+        }
+    }
+
+    /**
+     * Provide a sample of simulated data.
+     * NB: To simplify the creation of this data, no
+     * days after the 28th of a month are ever generated.
+     * @param data Where to store the simulated LogEntry objects.
+     */
+    private void createSimulatedData(ArrayList<LogEntry> data)
+    {
+        LogfileCreator creator = new LogfileCreator();
+        // How many simulated entries we want.
+        int numEntries = 100;
+        for(int i = 0; i < numEntries; i++) {
+            data.add(creator.createEntry());
+        }
+    }
+}