Examples of java.beans.PersistenceDelegate

java.beans.PersistenceDelegate
The PersistenceDelegate class takes the responsibility for expressing the state of an instance of a given class in terms of the methods in the class's public API. Instead of associating the responsibility of persistence with the class itself as is done, for example, by the readObject and writeObject methods used by the ObjectOutputStream, streams like the XMLEncoder which use this delegation model can have their behavior controlled independently of the classes themselves. Normally, the class is the best place to put such information and conventions can easily be expressed in this delegation scheme to do just that. Sometimes however, it is the case that a minor problem in a single class prevents an entire object graph from being written and this can leave the application developer with no recourse but to attempt to shadow the problematic classes locally or use alternative persistence techniques. In situations like these, the delegation model gives a relatively clean mechanism for the application developer to intervene in all parts of the serialization process without requiring that modifications be made to the implementation of classes which are not part of the application itself.
In addition to using a delegation model, this persistence scheme differs from traditional serialization schemes in requiring an analog of the writeObject method without a corresponding readObject method. The writeObject analog encodes each instance in terms of its public API and there is no need to define a readObject analog since the procedure for reading the serialized form is defined by the semantics of method invocation as laid out in the Java Language Specification. Breaking the dependency between writeObject and readObject implementations, which may change from version to version, is the key factor in making the archives produced by this technique immune to changes in the private implementations of the classes to which they refer.
A persistence delegate, may take control of all aspects of the persistence of an object including:
- Deciding whether or not an instance can be mutated into another instance of the same class.
- Instantiating the object, either by calling a public constructor or a public factory method.
- Performing the initialization of the object.
@see XMLEncoder @since 1.4 @version 1.12 11/17/05 @author Philip Milne

        }


        @SuppressWarnings("unchecked")
        @Override
        public PersistenceDelegate getPersistenceDelegate(Class type) {
            PersistenceDelegate result = super.getPersistenceDelegate(type);
            return result;
        }

View Full Code Here

    e.setPersistenceDelegate(Direction.class, new EnumDelegate());
  }


  public static void addAntlrPersistenceDelegates(XMLEncoder e)
  {
    e.setPersistenceDelegate(ASTNode.class, new PersistenceDelegate()
    {


      protected Expression instantiate(Object oldInstance, Encoder out)
      {
        return new Expression(oldInstance, oldInstance.getClass(),
            "new", new Object[]
            { ((ASTNode) oldInstance).getToken() });
      }
    });
    e.setPersistenceDelegate(CommonTree.class, new PersistenceDelegate()
    {
      protected Expression instantiate(Object oldInstance, Encoder out)
      {
        return new Expression(oldInstance, oldInstance.getClass(),
            "new", new Object[]
            { ((CommonTree) oldInstance).getToken() });
      }
    });
    e.setPersistenceDelegate(BaseTree.class, new PersistenceDelegate()
    {
      protected Expression instantiate(Object oldInstance, Encoder out)
      {
        return new Expression(oldInstance, oldInstance.getClass(),
            "new", new Object[]
            {});
      }


      @SuppressWarnings("rawtypes")
      protected void initialize(Class type, Object oldInstance,
          Object newInstance, Encoder out)
      {
        super.initialize(type, oldInstance, newInstance, out);


        BaseTree t = (BaseTree) oldInstance;


        for (int i = 0; i < t.getChildCount(); i++)
        {
          out.writeStatement(new Statement(oldInstance, "addChild",
              new Object[]
              { t.getChild(i) }));
        }
      }
    });
    e.setPersistenceDelegate(CommonToken.class, new PersistenceDelegate()
    {
      protected Expression instantiate(Object oldInstance, Encoder out)
      {
        return new Expression(oldInstance, oldInstance.getClass(),
            "new", new Object[]

View Full Code Here

  }


  public static void addHivePersistenceDelegates(XMLEncoder e)
  {
    e.setPersistenceDelegate(PrimitiveTypeInfo.class,
        new PersistenceDelegate()
        {
          protected Expression instantiate(Object oldInstance,
              Encoder out)
          {
            return new Expression(oldInstance,

View Full Code Here

        }


        @SuppressWarnings("unchecked")
        @Override
        public PersistenceDelegate getPersistenceDelegate(Class type) {
            PersistenceDelegate result = super.getPersistenceDelegate(type);
            return result;
        }

View Full Code Here

     */
    public void testProxyPD() throws Exception {
        MyInterface o = (MyInterface) Proxy.newProxyInstance(ClassLoader
                .getSystemClassLoader(), new Class[] { MyInterface.class },
                new MyHandler(1));
        PersistenceDelegate pd = new PersistenceDelegate() {


            @Override
            public Expression instantiate(Object o, Encoder e) {
                return new Expression(o, ClassLoader.class,
                        "getSystemClassLoader", null);

View Full Code Here

    e.setPersistenceDelegate(Direction.class, new EnumDelegate());
  }


  public static void addAntlrPersistenceDelegates(XMLEncoder e)
  {
    e.setPersistenceDelegate(ASTNode.class, new PersistenceDelegate()
    {


      @Override
      protected Expression instantiate(Object oldInstance, Encoder out)
      {
        return new Expression(oldInstance, oldInstance.getClass(),
            "new", new Object[]
            { ((ASTNode) oldInstance).getToken() });
      }
    });
    e.setPersistenceDelegate(CommonTree.class, new PersistenceDelegate()
    {
      @Override
      protected Expression instantiate(Object oldInstance, Encoder out)
      {
        return new Expression(oldInstance, oldInstance.getClass(),
            "new", new Object[]
            { ((CommonTree) oldInstance).getToken() });
      }
    });
    e.setPersistenceDelegate(BaseTree.class, new PersistenceDelegate()
    {
      @Override
      protected Expression instantiate(Object oldInstance, Encoder out)
      {
        return new Expression(oldInstance, oldInstance.getClass(),
            "new", new Object[]
            {});
      }


      @Override
      @SuppressWarnings("rawtypes")
      protected void initialize(Class type, Object oldInstance,
          Object newInstance, Encoder out)
      {
        super.initialize(type, oldInstance, newInstance, out);


        BaseTree t = (BaseTree) oldInstance;


        for (int i = 0; i < t.getChildCount(); i++)
        {
          out.writeStatement(new Statement(oldInstance, "addChild",
              new Object[]
              { t.getChild(i) }));
        }
      }
    });
    e.setPersistenceDelegate(CommonToken.class, new PersistenceDelegate()
    {
      @Override
      protected Expression instantiate(Object oldInstance, Encoder out)
      {
        return new Expression(oldInstance, oldInstance.getClass(),

View Full Code Here

  }


  public static void addHivePersistenceDelegates(XMLEncoder e)
  {
    e.setPersistenceDelegate(PrimitiveTypeInfo.class,
        new PersistenceDelegate()
        {
          @Override
          protected Expression instantiate(Object oldInstance,
              Encoder out)
          {

View Full Code Here

     * Tests array persistence delegate
     */
    public void testArrayPD_Normal() {
        Encoder enc = new MockEncoder();
        int[] ia = new int[] { 1 };
        PersistenceDelegate pd = enc.getPersistenceDelegate(ia.getClass());
        pd.writeObject(ia, enc);
    }

View Full Code Here

        lastIndex = index;
    }


    public void testGetPersistenceDelegate_Null() {
        Encoder enc = new Encoder();
        PersistenceDelegate pd = enc.getPersistenceDelegate(null);
        assertNotNull(pd);
    }

View Full Code Here

        assertNotNull(pd);
    }


    public void testGetPersistenceDelegate_ArrayClass() {
        Encoder enc = new Encoder();
        PersistenceDelegate pd = enc.getPersistenceDelegate(int[].class);
        assertFalse(pd instanceof DefaultPersistenceDelegate);
    }

View Full Code Here

0 1 2 3

TOP

Related Classes of java.beans.PersistenceDelegate

com.acelet.s.workflow.JGraphpad

com.sap.hadoop.windowing.query2.SerializationUtils

com.sun.beans.finder.PersistenceDelegateFinder

org.apache.hadoop.hive.ql.exec.PTFUtils

org.apache.harmony.beans.DefaultPersistenceDelegatesFactory

org.apache.harmony.beans.tests.java.beans.CustomizedPersistenceDelegateTest

org.apache.harmony.beans.tests.java.beans.DefaultPersistenceDelegateTest

org.apache.harmony.beans.tests.java.beans.EncoderTest

org.apache.harmony.beans.tests.java.beans.EncoderTest$VerboseEncoder

org.apache.harmony.beans.tests.java.beans.XMLEncoderTest$VerboseEncoder

All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.