Source Code : Soft Reference Object Pool Demo

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Soft Reference Object Pool Demo

import junit.framework.TestCase;
import junit.framework.TestSuite;

import org.apache.commons.pool.PoolableObjectFactory;
import org.apache.commons.pool.impl.SoftReferenceObjectPool;

import java.util.HashMap;
import java.lang.ref.SoftReference;

public class TestSoftRef extends TestCase {

  private SoftReferenceObjectPool pool;

  public static TestSuite suite() {
    return new TestSuite(TestSoftRef.class);
  }

  public static void main(String[] args) {
  String[] testClassName = { TestSoftRef.class.getName() };
    junit.textui.TestRunner.main(testClassName);
  }

  public TestSoftRef(String s) {
    super(s);
  }

public void testOutOfMemory() throws Exception {

  Object obj = pool.borrowObject();
  pool.returnObject(obj);
  obj = null;

  assertEquals(5, pool.getNumIdle());

  try {
    HashMap map = new HashMap();

    for(int i = 0; i < 1000000; i++) {
      map.put(new Integer(i), new String("Fred Flintstone" + i));
    }
  }catch(OutOfMemoryError ex) {
      pool.borrowObject();
      pool.borrowObject();
      pool.borrowObject();
      pool.borrowObject();
      pool.borrowObject();
     // assertEquals(0, pool.getNumIdle());
  }
}

  public void setUp() throws Exception {
    this.pool = new SoftReferenceObjectPool(new PoolableObjectFactory() {
       int counter;
       public Object makeObject()                   { return String.valueOf(counter++); }
       public void destroyObject( Object obj )      {}
       public boolean validateObject( Object obj )  { return true; }
       public void activateObject( Object obj )     {}
       public void passivateObject( Object obj )    {}
    }, 5);
  }
}


-------------------------------------------

import org.apache.commons.pool.BaseKeyedPoolableObjectFactory;

public class SkilledEmployeeFactory extends BaseKeyedPoolableObjectFactory {

  public Object makeObject(Object key) {
    if(key == null || !(key instanceof String) || ((String)key).length() == 0)
      throw new IllegalArgumentException("Invalid key specified");
    return new SkilledEmployee(key.toString());
  }

  /*public boolean validateObject(Object key, Object obj) {
    if(obj instanceof Employee) {
      if(((Employee)obj).getName() == null)
        return true;
    }
    return false;
  }

  public void passivateObject(Object obj) throws Exception {
    if(obj instanceof Employee) {
      ((Employee)obj).setName(null);
    } else throw new Exception("Unknown object");
  }*/
}

---------------------------------------

public class SkilledEmployee extends Employee {

  private String skill;

  public SkilledEmployee(String skill) {
    this.skill = skill;
  }

  public String getSkill() {
    return this.skill;
  }

  public String toString() {
    return getSkill() + " -- " + getName();
  }
}

----------------------------------

import org.apache.commons.pool.BasePoolableObjectFactory;

public class EmployeeFactory extends BasePoolableObjectFactory {

  public Object makeObject() {
    return new Employee();
  }

  public boolean validateObject(Object obj) {
    if(obj instanceof Employee) {
      if(((Employee)obj).getName() == null)
        return true;
    }
    return false;
  }

  public void passivateObject(Object obj) throws Exception {
    if(obj instanceof Employee) {
      ((Employee)obj).setName(null);
    } else throw new Exception("Unknown object");
  }
}

-------------------------------------

public class Employee {

  private static int base = 0;


  private int id;

  private String name;

  public Employee() {
    this.id = base++;
  }

  public int getId() {
    return this.id;
  }

  public String getName() {
    return this.name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public void doWork() {
    // does nothing
  }

  public String toString() {
    return ("Id: " + this.id + ", Name: " + this.name);
  }

  public void finalize() {
    System.err.println("Employee " + toString() + " made redundant");
  }
}
           
       

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