Get rid of DBConnection

That construct was hiding the Connection instance. Very bad abstraction
as I really need it to support transactions.

While at it, make the prepared statement objects final such that it is
detected when those are not properly initialized.

In Main, use try-with-resources, remove a noisy "exit succesfull" [sic]
message. Due to the extra try/catch for the db connection
(RuntimeException is not OK my friend!), the indentation had to be
changed.

4 files changed, 121 insertions, 105 deletions

diff --git a/src/database/ConnectionBuilder.java b/src/database/ConnectionBuilder.java
new file mode 100644
index 0000000..74e5c33
--- /dev/null
+++ b/src/database/ConnectionBuilder.java
@@ -0,0 +1,65 @@
+package database;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+
+/**
+ * Builder for connection.
+ *
+ * @author Peter Wu
+ */
+public class ConnectionBuilder {
+
+    private String dbms;
+    private String serverName;
+    private int port;
+    private String dbName;
+    private String username;
+    private String password;
+
+    /**
+     * Sets up a ConnectionBuilder for PostgreSQL and serverName localhost. The
+     * username, password and database name must still be supplied.
+     */
+    public ConnectionBuilder() {
+        dbms = "postgresql";
+        serverName = "localhost";
+        port = 5432;
+    }
+
+    public ConnectionBuilder setDbms(String dbms) {
+        this.dbms = dbms;
+        return this;
+    }
+
+    public ConnectionBuilder setServerName(String serverName) {
+        this.serverName = serverName;
+        return this;
+    }
+
+    public ConnectionBuilder setPort(int port) {
+        this.port = port;
+        return this;
+    }
+
+    public ConnectionBuilder setDbName(String dbName) {
+        this.dbName = dbName;
+        return this;
+    }
+
+    public ConnectionBuilder setUsername(String username) {
+        this.username = username;
+        return this;
+    }
+
+    public ConnectionBuilder setPassword(String password) {
+        this.password = password;
+        return this;
+    }
+
+    public Connection create() throws SQLException {
+        String url = "jdbc:" + dbms + "://" + serverName + ":" + port + "/" + dbName;
+        return DriverManager.getConnection(url, username, password);
+    }
+}
diff --git a/src/database/DBConnection.java b/src/database/DBConnection.java
deleted file mode 100644
index 330c2a5..0000000
--- a/src/database/DBConnection.java
+++ /dev/null
@@ -1,59 +0,0 @@
-package database;
-
-import java.sql.Connection;
-import java.sql.DriverManager;
-import java.sql.PreparedStatement;
-import java.sql.SQLException;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-/**
- * Create a persistent database connection.
- *
- * @author Maurice Laveaux
- */
-public class DBConnection {
-
-    /* The interface to the postgresql database connection. */
-    private Connection m_connection;
-
-    public DBConnection(final String hostaddress,
-            final String port,
-            final String databasename,
-            final String username,
-            final String password) {
-
-        String url = "jdbc:postgresql://" + hostaddress + ":" + port + "/" + databasename;
-
-        try {
-            m_connection = DriverManager.getConnection(url, username, password);
-        } catch (SQLException ex) {
-            //TODO: retry when db connection fails or something.
-            throw new RuntimeException("cannot connect to host: " + url);
-        }
-    }
-
-    /**
-     * prepares a statement.
-     *
-     * @param query The query to prepare.
-     * @return A prepared statement.
-     */
-    public PreparedStatement create(final String query) throws SQLException {
-        return m_connection.prepareStatement(query);
-    }
-
-    /**
-     * Closes the connection if it exists.
-     */
-    public void close() {
-        if (m_connection != null) {
-            try {
-                m_connection.close();
-            } catch (SQLException ex) {
-                /* TODO: what to do here else. */
-                Logger.getLogger(DBConnection.class.getName()).log(Level.SEVERE, null, ex);
-            }
-        }
-    }
-}
diff --git a/src/main/DataFiller.java b/src/main/DataFiller.java
index a65a032..6e1ba9d 100644
--- a/src/main/DataFiller.java
+++ b/src/main/DataFiller.java
@@ -1,8 +1,8 @@
 package main;
 
 import data.Tweet;
-import database.DBConnection;
 import database.QueryUtils;
+import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
 import java.util.ArrayList;
@@ -20,57 +20,57 @@ public class DataFiller {
     /**
      * The main database connection to fill.
      */
-    private final DBConnection m_connection;
+    private final Connection m_connection;
 
     /**
      * A single insert tweet that can be used.
      */
-    private PreparedStatement m_insertTweet;
+    private final PreparedStatement m_insertTweet;
 
     /**
      * A single insert profiles that can be used.
      */
-    private PreparedStatement m_insertProfile;
+    private final PreparedStatement m_insertProfile;
     /**
      * A single insert ispostedby that can be used.
      */
-    private PreparedStatement m_insertPosted;
+    private final PreparedStatement m_insertPosted;
 
     /**
      * A single insert brand that can be used.
      */
-    private PreparedStatement m_insertBrand;
+    private final PreparedStatement m_insertBrand;
 
     /**
      * A single insert hashtag that can be used.
      */
-    private PreparedStatement m_insertHash;
+    private final PreparedStatement m_insertHash;
 
     /**
      * A single insert url that can be used.
      */
-    private PreparedStatement m_insertUrl;
+    private final PreparedStatement m_insertUrl;
 
     /**
      * A single insert url that can be used.
      */
-    private PreparedStatement m_insertMentions;
+    private final PreparedStatement m_insertMentions;
 
     /**
      * Create the datafiller object.
      *
      * @param connection The database connection to use.
      */
-    public DataFiller(DBConnection connection) {
+    public DataFiller(Connection connection) {
         try {
             m_connection = connection;
-            m_insertTweet = m_connection.create(QueryUtils.insertTweet());
-            m_insertProfile = m_connection.create(QueryUtils.insertProfile());
-            m_insertPosted = m_connection.create(QueryUtils.insertPosted());
-            m_insertBrand = m_connection.create(QueryUtils.insertBrand());
-            m_insertHash = m_connection.create(QueryUtils.insertHash());
-            m_insertUrl = m_connection.create(QueryUtils.insertUrl());
-            m_insertMentions = m_connection.create(QueryUtils.insertMentions());
+            m_insertTweet = m_connection.prepareStatement(QueryUtils.insertTweet());
+            m_insertProfile = m_connection.prepareStatement(QueryUtils.insertProfile());
+            m_insertPosted = m_connection.prepareStatement(QueryUtils.insertPosted());
+            m_insertBrand = m_connection.prepareStatement(QueryUtils.insertBrand());
+            m_insertHash = m_connection.prepareStatement(QueryUtils.insertHash());
+            m_insertUrl = m_connection.prepareStatement(QueryUtils.insertUrl());
+            m_insertMentions = m_connection.prepareStatement(QueryUtils.insertMentions());
 
         } catch (SQLException ex) {
             throw new RuntimeException(ex.getMessage());
diff --git a/src/main/Main.java b/src/main/Main.java
index 5a8e137..ba59f8b 100644
--- a/src/main/Main.java
+++ b/src/main/Main.java
@@ -1,13 +1,16 @@
 package main;
 
-import com.google.gson.JsonIOException;
 import com.google.gson.JsonSyntaxException;
 import data.Tweet;
-import database.DBConnection;
+import database.ConnectionBuilder;
 import io.FileTweetReader;
 import io.ITweetReader;
 import io.TweetReader;
 import java.io.IOException;
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 /**
  * The main class.
@@ -40,35 +43,42 @@ public class Main {
             throw new IllegalArgumentException("Missing --dbhost to specify the hostaddress.");
         }
 
-        DBConnection connection = new DBConnection(m_hostaddress, "5432", "Twitter", "postgres", "2IOC02");
-        /* create the object that fills the database */
-        DataFiller filler = new DataFiller(connection);
-
-        ITweetReader reader = null;
-        try {
-            if (m_filename == null) {
-                reader = new TweetReader(System.in);
-            } else {
-                reader = new FileTweetReader(m_filename);
-            }
-
-            Tweet tweet;
-            while ((tweet = reader.getTweet()) != null) {
-                filler.processTweet(tweet);
-            }
-        } catch (JsonSyntaxException ex) {
-            System.err.println("Got an invalid tweet: " + ex);
-        } catch (IOException ex) {
-            System.err.println("Cannot open tweets: " + ex);
-        } finally {
-            if (reader != null) {
-                reader.close();
+        ConnectionBuilder cb = new ConnectionBuilder()
+                .setServerName(m_hostaddress)
+                .setUsername("postgres")
+                .setPassword("2IOC02")
+                .setDbName("Twitter");
+
+        try (Connection connection = cb.create()) {
+
+            /* create the object that fills the database */
+            DataFiller filler = new DataFiller(connection);
+
+            ITweetReader reader = null;
+            try {
+                if (m_filename == null) {
+                    reader = new TweetReader(System.in);
+                } else {
+                    reader = new FileTweetReader(m_filename);
+                }
+
+                Tweet tweet;
+                while ((tweet = reader.getTweet()) != null) {
+                    filler.processTweet(tweet);
+                }
+            } catch (JsonSyntaxException ex) {
+                System.err.println("Got an invalid tweet: " + ex);
+            } catch (IOException ex) {
+                System.err.println("Cannot open tweets: " + ex);
+            } finally {
+                if (reader != null) {
+                    reader.close();
+                }
             }
+        } catch (SQLException ex) {
+            Logger.getLogger(Main.class.getName()).log(Level.SEVERE,
+                    "Query error", ex);
         }
-
-        connection.close();
-
-        System.out.print("exit succesfull.");
     }
 
     private void parseGlobalOptions(String[] args) {