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* Copyright (C) 2011 Akiban Technologies Inc.
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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import java.io.BufferedReader;
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import java.io.InputStreamReader;
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import com.persistit.Exchange;
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import com.persistit.Key;
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import com.persistit.Persistit;
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* A very simple class to demonstrate basic operations of Persistit™
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* This class performs the following operations:
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* <li> Initializes {@link com.persistit.Persistit} using a Properties file.
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* <li> Creates a {@link com.persistit.Exchange} with which to store and fetch
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* data to and from a {@link com.persistit.Tree}.
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* <li> Reads some names from the console and stores records in the <tt>Tree</tt>
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* indexed by those names.
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* <li> Dispays the names in alphabetical order.
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* <li> Closes Persistic to ensure all records have been written to disk.
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public class SimpleDemo
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public static void main(String[] args)
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// Initializes buffer pool, loads Volume(s)
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// and sets up PrewriteJournal.
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System.out.println("Initializing Persistit");
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Persistit persistit = new Persistit();
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persistit.initialize();
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// A Exchange provides all the methods you use to
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// manipulate data. This constructs a Exchange in
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// volume "SimpleDemo" and either opens or creates
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// within that volume a Tree called "my_first_tree".
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Exchange exchange = new Exchange(persistit, "SimpleDemo", "my_first_tree", true);
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if (args.length > 0 && "-d".equals(args[0]))
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// Remove all elements.
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System.out.println("Please enter some names -");
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BufferedReader reader =
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new InputStreamReader(System.in));
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System.out.print("Name: ");
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String name = reader.readLine();
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if (name == null || name.length() == 0) break;
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// Set up the value to insert into the Tree.
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exchange.getValue().put("Name # " + (++count));
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// Set up the key and store the record. The to()
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// method replaces the final segment of the key with
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// the supplied value. If the key is empty then
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// it appends the segment.
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// Note that all key manipulation methods return the
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// Exchange so that you can chain calls like this:
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exchange.getKey().to(name);
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System.out.println();
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System.out.println("Here are the names you entered: ");
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// Set Exchange to an imaginary key that's to the left of all real
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// keys. This allows the next() operation to find the first key.
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exchange.getKey().to(Key.BEFORE);
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// The next() method advances to the next ascending key
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// segment (in this case, the next name). Returns false
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// if there is none. This method also atomically retrieves the
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// value associated with the key.
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while (exchange.next())
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// Recover the name from the Key.
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String name = exchange.getKey().decodeString();
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// Fetch the associated Value and decode it into
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String value = exchange.getValue().getString();
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System.out.println(name + " --> " + value);
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// Flushes everything nicely to disk and releases all resources.
added
removed
examples/SimpleDemo/SimpleDemo.java
