save progress

pom.xml

@@ -8,41 +8,56 @@
     <artifactId>java-snippets</artifactId>
     <version>1.0-SNAPSHOT</version>
 
+    <properties>
+        <dep.log4j.version>1.2.17</dep.log4j.version>
+        <dep.jackson-core.version>2.1.3</dep.jackson-core.version>
+        <dep.jackson-databind.version>2.1.3</dep.jackson-databind.version>
+        <dep.junit.version>4.11</dep.junit.version>
+        <dep.jetty.version>3.2.9.Final</dep.jetty.version>
+        <dep.jettison.version>1.3.3</dep.jettison.version>
+        <dep.jaxb-impl.version>2.2.6</dep.jaxb-impl.version>
+    </properties>
+
     <dependencies>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-core</artifactId>
-            <version>2.1.3</version>
+            <version>${dep.jackson-core.version}</version>
         </dependency>
         <!--<dependency>-->
-            <!--<groupId>com.fasterxml.jackson.core</groupId>-->
-            <!--<artifactId>jackson-annotations</artifactId>-->
-            <!--<version>2.1.3</version>-->
+        <!--<groupId>com.fasterxml.jackson.core</groupId>-->
+        <!--<artifactId>jackson-annotations</artifactId>-->
+        <!--<version>2.1.3</version>-->
         <!--</dependency>-->
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
-            <version>2.1.3</version>
+            <version>${dep.jackson-databind.version}</version>
         </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.11</version>
+            <version>${dep.junit.version}</version>
         </dependency>
         <dependency>
             <groupId>org.jboss.netty</groupId>
             <artifactId>netty</artifactId>
-            <version>3.2.9.Final</version>
+            <version>${dep.jetty.version}</version>
         </dependency>
         <dependency>
             <groupId>org.codehaus.jettison</groupId>
             <artifactId>jettison</artifactId>
-            <version>1.3.3</version>
+            <version>${dep.jettison.version}</version>
         </dependency>
         <dependency>
             <groupId>com.sun.xml.bind</groupId>
             <artifactId>jaxb-impl</artifactId>
-            <version>2.2.6</version>
+            <version>${dep.jaxb-impl.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${dep.log4j.version}</version>
         </dependency>
     </dependencies>
 </project>

src/main/java/net/bluedash/snippets/classloader/MultiThreadProductFactory.java

@@ -0,0 +1,49 @@
+package net.bluedash.snippets.classloader;
+
+import org.jboss.netty.handler.codec.serialization.WeakReferenceMap;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Proxy;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Created with IntelliJ IDEA.
+ * User: weli
+ * Date: 5/24/13
+ * Time: 7:28 PM
+ * To change this template use File | Settings | File Templates.
+ */
+public class MultiThreadProductFactory extends ProductFactory {
+    static protected WeakReferenceMap<Long, Proxy> productProxies; // in multi-thread environment, we need to store each threads' proxy independently.
+
+    public static Product newInstance() throws InstantiationException,
+            IllegalAccessException {
+        return newInstance(ProductImpl.class);// default implementation
+    }
+
+    public static Product newInstance(Class clazz) throws InstantiationException,
+            IllegalAccessException {
+        Product product = (Product) clazz.newInstance(); // default implementation
+        Product productProxy = ProductInvocationHandler.newInstance(product);
+        productProxies.put(Long.valueOf(Thread.currentThread().getId()), (Proxy) productProxy);
+        return productProxy;
+    }
+
+    public static void reload(String productClassPath) throws ClassNotFoundException,
+            InstantiationException, IllegalAccessException,
+            NoSuchMethodException, InvocationTargetException {
+        cl = new SimpleClassLoader(PREFIX + productClassPath);
+        String binaryName = productClassPath.replace('/', '.') + ".ProductImpl";
+        Class productImplClass = cl.loadClass(binaryName);
+
+        Proxy productProxy = productProxies.get(Thread.currentThread().getId());
+
+        if (productProxy != null) {
+            ProductInvocationHandler productInvocationHandler = (ProductInvocationHandler) Proxy.getInvocationHandler(productProxy);
+            Product replacement = (Product) productImplClass.newInstance();
+            productInvocationHandler.setProductInstance(replacement);
+        }
+    }
+
+}

src/main/java/net/bluedash/snippets/classloader/Product.java

@@ -1,5 +1,5 @@
 package net.bluedash.snippets.classloader;
 
 public interface Product {
-	public void show();
+	public String getName();
 }

src/main/java/net/bluedash/snippets/classloader/ProductFactory.java

@@ -1,46 +1,35 @@
 package net.bluedash.snippets.classloader;
 
-import java.lang.ref.WeakReference;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Proxy;
-import java.util.ArrayList;
-import java.util.List;
 
 public class ProductFactory {
-    static private ClassLoader cl = null;
-    static private Class implClass = ProductImpl.class; // default class
-    static private List instances = new ArrayList();
+    static protected ClassLoader cl = null;
+    static protected Object productProxy; // we store this because we want to get invocation handler from proxy later
 
     public static Product newInstance() throws InstantiationException,
             IllegalAccessException {
-        Product obj = (Product) implClass.newInstance();
-        Product anAProxy = (Product) ProductIH.newInstance(obj);
-        instances.add(new WeakReference(anAProxy));
-        return anAProxy;
+        Product product = ProductImpl.class.newInstance(); // default implementation
+        Product productProxy = ProductInvocationHandler.newInstance(product);
+        ProductFactory.productProxy = productProxy;
+        return productProxy;
     }
 
-    private static final String PREFIX = "target/classes/";
+    protected static final String PREFIX = "target/classes/";
 
-    public static void reload(String dir) throws ClassNotFoundException,
+    public static void reload(String productClassPath) throws ClassNotFoundException,
             InstantiationException, IllegalAccessException,
             NoSuchMethodException, InvocationTargetException {
-        cl = new SimpleClassLoader(PREFIX + dir);
-        String binaryName = dir.replace('/', '.') + ".ProductImpl";
-        implClass = cl.loadClass(binaryName);
-
-        List newInstances = new ArrayList();
-
-        for (int i = 0; i < instances.size(); i++) {
-            Proxy x = (Proxy) ((WeakReference) instances.get(i)).get();
-            if (x != null) {
-                ProductIH aih = (ProductIH) Proxy.getInvocationHandler(x);
-                Object oldObject = aih.getTarget();
-                Object replacement = implClass.newInstance();
-                aih.setTarget(replacement);
-                newInstances.add(new WeakReference(x));
-            }
+        cl = new SimpleClassLoader(PREFIX + productClassPath);
+        String binaryName = productClassPath.replace('/', '.') + ".ProductImpl";
+        Class productImplClass = cl.loadClass(binaryName);
+
+        Proxy productProxy = (Proxy) ProductFactory.productProxy;
+        if (productProxy != null) {
+            ProductInvocationHandler productInvocationHandler = (ProductInvocationHandler) Proxy.getInvocationHandler(productProxy);
+            Product replacement = (Product) productImplClass.newInstance();
+            productInvocationHandler.setProductInstance(replacement);
+            ProductFactory.productProxy = productProxy;
         }
-
-        instances = newInstances;
     }
 }

src/main/java/net/bluedash/snippets/classloader/ProductImpl.java

@@ -2,9 +2,7 @@
 
 public class ProductImpl implements Product {
 
-	public void show() {
-		System.out.println("ProductImpl");
-
-	}
-
+    public String getName() {
+        return "ProductImpl";
+    }
 }

src/main/java/net/bluedash/snippets/classloader/ProductInvocationHandler.java

@@ -0,0 +1,40 @@
+package net.bluedash.snippets.classloader;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
+class ProductInvocationHandler implements InvocationHandler {
+	private Object productInstance = null;
+	static private Class[] productInterface = { Product.class };
+
+	public static Product newInstance(Product productInstance) {
+		return (Product) Proxy.newProxyInstance(
+                productInstance.getClass().getClassLoader(), productInterface,
+                new ProductInvocationHandler(productInstance));
+	}
+
+	private ProductInvocationHandler(Object productInstance) {
+		this.productInstance = productInstance;
+	}
+
+	public void setProductInstance(Object productInstance) {
+		this.productInstance = productInstance;
+	}
+
+	public Object getProductInstance() {
+		return productInstance;
+	}
+
+	public Object invoke(Object t, Method m, Object[] args) throws Throwable {
+		Object result;
+		try {
+			Method _m = productInstance.getClass().getMethod(m.getName());
+			result = _m.invoke(productInstance);
+		} catch (InvocationTargetException e) {
+			throw e.getTargetException();
+		}
+		return result;
+	}
+}

src/main/java/net/bluedash/snippets/classloader/impl2/ProductImpl.java

@@ -4,8 +4,8 @@
 
 public class ProductImpl implements Product {
 
-	public void show() {
-		System.out.println("ProductImpl2");
+	public String getName() {
+		return "ProductImpl2";
 
 	}
 

src/main/java/net/bluedash/snippets/classloader/impl2/impl3/ProductImpl.java

@@ -0,0 +1,19 @@
+package net.bluedash.snippets.classloader.impl2.impl3;
+
+import net.bluedash.snippets.classloader.Product;
+
+/**
+ * Created with IntelliJ IDEA.
+ * User: weli
+ * Date: 5/24/13
+ * Time: 7:33 PM
+ * To change this template use File | Settings | File Templates.
+ */
+public class ProductImpl implements Product {
+
+    public String getName() {
+        return "ProductImpl3";
+
+    }
+
+}

src/main/java/net/bluedash/snippets/log4j/PlayWithLog4j.java

@@ -0,0 +1,11 @@
+package net.bluedash.snippets.log4j;
+
+/**
+ * Created with IntelliJ IDEA.
+ * User: weli
+ * Date: 5/24/13
+ * Time: 4:46 PM
+ * To change this template use File | Settings | File Templates.
+ */
+public class PlayWithLog4j {
+}

src/test/java/net/bluedash/snippets/classloader/ProductReloadTest.java

@@ -0,0 +1,19 @@
+package net.bluedash.snippets.classloader;
+
+
+import junit.framework.Assert;
+import org.junit.Test;
+
+public class ProductReloadTest {
+
+    @Test
+    public void testProductFactory() throws Exception {
+        Product product = ProductFactory.newInstance();
+        Assert.assertEquals("ProductImpl", product.getName());
+
+        ProductFactory.reload("net/bluedash/snippets/classloader/impl2");
+        /* the product is replaced by a new instance */
+        Assert.assertEquals("ProductImpl2", product.getName());
+    }
+
+}

src/test/java/net/bluedash/snippets/classloader/SimpleClassLoaderSmokeTest.java

@@ -1,5 +1,6 @@
 package net.bluedash.snippets.classloader;
 
+import junit.framework.Assert;
 import net.bluedash.snippets.classloader.SimpleClassLoader;
 import org.junit.Test;
 
@@ -31,7 +32,7 @@ public void testMultipleLevelClassLoading() throws ClassNotFoundException, NoSuc
         ClassLoader cl = new SimpleClassLoader("target/classes/net/bluedash/snippets/classloader/impl2");
         Class clazz = cl.loadClass("net.bluedash.snippets.classloader.impl2.ProductImpl");
         assertNotNull(clazz);
-        Method method = clazz.getMethod("show");
-		method.invoke(clazz.newInstance(), null);
+        Method method = clazz.getMethod("getName");
+        Assert.assertEquals("ProductImpl2", method.invoke(clazz.newInstance(), null));
     }
 }