source: src/main/java/negotiator/boaframework/agent/Serializer.java

package negotiator.boaframework.agent;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;

import javax.xml.bind.DatatypeConverter;

/**
 * Series of methods to (un)serialize an object to a string to store it as a
 * file.
 * 
 * @author Tim Baarslag
 * @param <A>
 *            class of the object which is serialized.
 */
public class Serializer<A> {

        /** Path to the file in which the serialized class must be stored. */
        private final String fileName;
        /** If it should be reported if the file cannot be found. */
        private final boolean log;

        /**
         * Create an object to serialize a class. The filename specifies the path in
         * which the serialized class is stored. File not found exceptions are not
         * reported.
         * 
         * @param fileName
         *            path to file in which the serialized class is stored.
         */
        public Serializer(String fileName) {
                this(fileName, false);
        }

        /**
         * Create an object to serialize a class. The filename specifies the path in
         * which the serialized class is stored.
         * 
         * @param fileName
         *            path to file in which the serialized class is stored.
         * @param log
         *            specifies if file not found exceptions should be reported.
         */
        public Serializer(String fileName, boolean log) {
                super();
                this.fileName = fileName;
                this.log = log;
        }

        /**
         * Read a serialized object from a file and restore it.
         * 
         * @return unserialized object.
         */
        @SuppressWarnings("unchecked")
        public A readFromDisk() {
                InputStream is = null;
                ObjectInputStream ois = null;
                A obj = null;

                final String errorMsg = "Error opening (" + fileName + ").\n";
                try {
                        is = new BufferedInputStream(new FileInputStream(fileName), 50000 * 1024);

                        ois = new ObjectInputStream(is);

                        final Object readObject = ois.readObject();
                        ois.close();
                        is.close();
                        obj = (A) readObject;
                        return obj;
                } catch (FileNotFoundException e) {
                        if (log)
                                System.out.println(errorMsg + e);
                } catch (IOException e) {
                        System.out.println(errorMsg + e);

                } catch (ClassNotFoundException e) {
                        System.out.println(errorMsg + e);
                } catch (ClassCastException e) {
                        System.out.println(errorMsg + e);
                }
                System.out.println(fileName + " is old; It should be rebuilt.");
                return null;
        }

        /**
         * Serializes an object to the specified file.
         * 
         * @param a
         *            object to be serialized.
         */
        public void writeToDisk(A a) {
                OutputStream os = null;
                ObjectOutputStream oos = null;
                try {
                        os = new BufferedOutputStream(new FileOutputStream(fileName));

                        oos = new ObjectOutputStream(os);
                        oos.writeObject(a);
                        oos.close();
                        os.close();
                } catch (IOException ex) {
                        ex.printStackTrace();
                }
        }

        /**
         * Serializes an object to a string encoded by using Base64 to avoid
         * characterset problems.
         * 
         * @param a
         *            object to serialize.
         * @return serialized object.
         */
        public String writeToString(A a) {
                String out = null;
                if (a != null) {
                        try {
                                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                                ObjectOutputStream oos = new ObjectOutputStream(baos);
                                oos.writeObject(a);
                                out = DatatypeConverter.printBase64Binary(baos.toByteArray());
                        } catch (IOException e) {
                                e.printStackTrace();
                                return null;
                        }
                }
                return out;
        }

        /**
         * Converts a string back to an object.
         * 
         * @param str
         *            serialized object.
         * @return unserialized object.
         */
        @SuppressWarnings("unchecked")
        public A readStringToObject(String str) {
                Object out = null;
                if (str != null) {
                        try {
                                ByteArrayInputStream bios = new ByteArrayInputStream(DatatypeConverter.parseBase64Binary(str));
                                ObjectInputStream ois = new ObjectInputStream(bios);
                                out = ois.readObject();
                        } catch (IOException e) {
                                e.printStackTrace();
                                return null;
                        } catch (ClassNotFoundException e) {
                                e.printStackTrace();
                                return null;
                        }
                }
                return (A) out;
        }

        /**
         * @return filename in which the object should be/is serialized.
         */
        public String getFileName() {
                return fileName;
        }
}