serialization and deserialization

  One 、 Serialization and deserialization

After the object is serialized , It can be used for network transmission or disk storage .

The essence is , Serialization is to turn an object into byte[ ] form ; Deserialization Will be byte[ ] Become the object .

Object should be serialized , Class must implement Serializable Interface

ObjectInputStream and ObjectOutputStream

Direct read / write object , The premise is that the class implementation of the object Serializable Interface

public static void main(String[] args) {
    // Will a Person Object store to temp.txt in 
    Person p = new Person("tom",20);
    try {
        FileOutputStream fos = new FileOutputStream("D:\\Lession\\Java2113/temp.txt");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(p);
    } catch (FileNotFoundException e) {

        e.printStackTrace();
    } catch (IOException e) {

        e.printStackTrace();
    }
}

    // Read temp.txt Objects stored in the 
    try {
        FileInputStream fis = new FileInputStream("D:\\Lession\\Java2113/temp.txt");
        ObjectInputStream bis = new ObjectInputStream(fis);
        Person p = (Person)bis.readObject();
        System.out.println(p.getName()+","+p.getAge());
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }

Two 、 Object to serialize and deserialize

Get the object of byte[ ] And take byte[ ] Become the object ; Encapsulating two methods

Need to use ByteArrayInputStream and ByteArrayOutputStream , It's right byte[ ] Read / write stream of

public class Test {
    public static void main(String[] args) {
        Person p = new Person("tom",22);
        Person p2 = new Person("jack",21);
        Person p3 = new Person("smith",20);
        List<Person> list = new ArrayList<Person>();
        list.add(p);
        list.add(p2);
        list.add(p3);
        byte[] bytes = getBytes(list);
        List<Person> ps = (List<Person>)getObject(bytes);
        for(Person person:ps) {
            System.out.println(person.getName()+","+person.getAge());
        }
    }
    /**
    *  Sequence objects into byte[]
    * @param obj
    * @return
    */
    public static byte[] getBytes(Object obj) {
        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(baos);
            oos.writeObject(obj);
            return baos.toByteArray();
         } catch (IOException e) {

            e.printStackTrace();
    }
    return null;
}
    /**
    *  take byte[]  Anti serialization into objects 
    * @param bytes
    * @return
    */
    public static Object getObject(byte[] bytes) {
        try {
            ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
            ObjectInputStream ois = new ObjectInputStream(bais);
            return ois.readObject();
        } catch (ClassNotFoundException e) {

            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

3、 ... and 、Properties Tool class

For reading Properties The configuration file A tool class of ,Java The configuration file in includes .properties and .xml Configuration file in the form , properties Writing and reading configuration files is relatively simple , In order to key=value In the format of , But it can not represent the structure of data ; xml Formal Configuration file writing and reading relative replication , Represents the structure of data

Properties Inherited from Hashtable ,Properties The configuration information will be read to Hashtable in , adopt key get value Programming to read the configuration file

public class TestProperties {
    public static void main(String[] args) {
        Properties p = new Properties();
        try {
            // Read the contents of the configuration file into  Properties  Of Hashtable in 
            FileInputStream fis = new
    FileInputStream("D:\\MyWork\\MyWorkspaces\\eclipse0106\\pjt0211\\src\\test.properties");
            p.load(fis);
            System.out.println(p.getProperty("username"));
            System.out.println(p.getProperty("password"));
            // towards Hashtable Set content in 
            p.setProperty("sfz", "1001100");
            p.store(new
    FileOutputStream("D:\\MyWork\\MyWorkspaces\\eclipse0106\\pjt0211\\src\\test.properties"), " Is it a note ");
            System.out.println(p.getProperty("sfz"));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public static void main(String[] args) {
    // Class path  （classPath）
    ResourceBundle bundle = ResourceBundle.getBundle("test");
    System.out.println(bundle.getString("username"));
}