Create a class that implements ProfileListener and TweetListener.

	* Creates tweets.txt and profiles.txt when they don't exist.
	* Read these files to store a set of ids.
	* Consumes new tweets and profiles and writes if the ids are not found.

1 files changed, 130 insertions, 0 deletions

diff --git a/src/io/OutputStream.java b/src/io/OutputStream.java
new file mode 100644
index 0000000..5a92c59
--- /dev/null
+++ b/src/io/OutputStream.java
@@ -0,0 +1,130 @@
+package io;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.HashSet;
+import java.util.Scanner;
+import java.util.Set;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import org.json.JSONException;
+import org.json.JSONObject;
+import provider.ProfileListener;
+import provider.TweetListener;
+
+/**
+ * This class writes the output data into seperate files.
+ *
+ * @author Maurice Laveaux
+ */
+public class OutputStream implements ProfileListener, TweetListener {
+
+    /**
+     * The writer for the tweet stream.
+     */
+    private final FileWriter m_tweetWriter;
+
+    /**
+     * the writer for the profile stream.
+     */
+    private final FileWriter m_profileWriter;
+
+    /**
+     * the buffer of tweet ids that already exist.
+     */
+    private final Set<Long> m_tweetIdSet;
+
+    /**
+     * the buffer of profile ids that already exist.
+     */
+    private final Set<Long> m_profileIdSet;
+
+    private static final String profilesName = "profiles.txt";
+    private static final String tweetsName   = "tweets.txt";
+
+    /**
+     * Opens a stream to every single file that data will be streamed to.
+     */
+    public OutputStream() {
+        try {
+            m_profileIdSet = readIds(profilesName);
+            m_profileWriter = new FileWriter(profilesName, true);
+            
+            m_tweetIdSet = readIds(tweetsName);
+            m_tweetWriter = new FileWriter(tweetsName, true);
+        } catch (IOException ex) {
+            // This should not happen.
+            throw new RuntimeException(ex.getMessage());
+        }
+    }
+
+    @Override
+    public void profileGenerated(JSONObject obj) {
+        writeObject(obj, m_profileWriter, m_profileIdSet);
+    }
+
+    @Override
+    public void tweetGenerated(JSONObject obj) {
+        writeObject(obj, m_tweetWriter, m_tweetIdSet);
+    }
+
+    /**
+     * Read the current existing tweetName and profileName filenames and fill
+     * the existing id set.
+     *
+     * @param filename The file to parse
+     * @return The set of ids
+     */
+    private Set readIds(String filename) throws IOException {
+        try {
+            Scanner reader = new Scanner(new File(filename));
+            
+            // TODO: Read the file JSON objects and parse the ids.
+            Set idSet = new HashSet();
+            
+            // parse each line into a JSONObject, read the id and add it to
+            // the set of ids.
+            while(reader.hasNext()) {
+                JSONObject obj = new JSONObject(reader.nextLine());
+                long id = obj.getLong("id");
+                idSet.add(id);
+            }
+            
+            return idSet;
+        } catch (FileNotFoundException ex) {        
+            // File does not exist, so create one.
+            File file = new File(filename);
+            // Return value should always be true.
+            file.createNewFile();
+        } catch (JSONException ex) {
+            getLogger().log(Level.SEVERE, null, ex);
+        }
+        
+        // return the empty set.
+        return new HashSet();
+    }
+    
+    private void writeObject(JSONObject obj, FileWriter writer, Set idSet) {
+        try {
+            long id = obj.getLong("id");
+
+            if (!idSet.contains(id)) {
+                // Write a single profile into the profile file.
+                try {
+                    writer.write(obj.toString() + "\n");
+                    idSet.add(id);
+                } catch (IOException ex) {
+                    getLogger().log(Level.SEVERE, null, ex);
+                }
+            }
+        } catch (JSONException ex) {
+            getLogger().log(Level.SEVERE, null, ex);
+        }        
+    }
+
+    private Logger getLogger() {
+        return Logger.getLogger(OutputStream.class.getName());
+    }
+}