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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.ResultListener;
/**
* This class writes the output data into seperate files.
*
* @author Maurice Laveaux
*/
public class DataWriter implements ResultListener {
/**
* 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 DataWriter() {
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, it will create the file when it doesn't exist.
*
* @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();
}
/**
* Writes the JSONObject to a writer and update the idSet.
*
* @param obj The object to write.
* @param writer The writer object to append the object to.
* @param idSet The id set to add the obj id to.
*/
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(getClass().getName());
}
}
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