From 432556fba6e015fe91d92692fc5e0ddb39bf1dc4 Mon Sep 17 00:00:00 2001
From: felmer <felmer>
Date: Tue, 7 Aug 2007 14:05:20 +0000
Subject: [PATCH] add general purpose create method (with test)
SVN: 1268
---
.../cisd/common/utilities/ClassUtils.java | 48 +++++++++++
.../cisd/common/utilities/ClassUtilsTest.java | 85 ++++++++++++++++++-
2 files changed, 131 insertions(+), 2 deletions(-)
diff --git a/common/source/java/ch/systemsx/cisd/common/utilities/ClassUtils.java b/common/source/java/ch/systemsx/cisd/common/utilities/ClassUtils.java
index 71670c9604b..625fde0bf8b 100644
--- a/common/source/java/ch/systemsx/cisd/common/utilities/ClassUtils.java
+++ b/common/source/java/ch/systemsx/cisd/common/utilities/ClassUtils.java
@@ -16,13 +16,17 @@
package ch.systemsx.cisd.common.utilities;
+import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
+import java.util.Properties;
import ch.systemsx.cisd.common.annotation.Mandatory;
import ch.systemsx.cisd.common.exceptions.CheckedExceptionTunnel;
+import ch.systemsx.cisd.common.exceptions.ConfigurationFailureException;
/**
* Operations on classes using reflection.
@@ -125,4 +129,48 @@ public final class ClassUtils
return null;
}
+ /**
+ * Creates a new instance of a class specified by its fully-qualified name.
+ *
+ * @param superClazz Super class <code>className</code> has to be implemented or extended.
+ * @param className Fully-qualified class name.
+ * @param properties Optional constructor argument. If not <code>null</code> an constructor with one single
+ * <code>Properties</code> argument is expected. Otherwise the default constructor will used.
+ * @return an instance of type <code>interfaze</code>.
+ */
+ public static <T> T create(Class<T> superClazz, String className, Properties properties)
+ {
+ assert superClazz != null : "Missing super class";
+ assert className != null : "Missing class name";
+
+ try
+ {
+ final Class<?> clazz = Class.forName(className);
+ assert clazz.isInterface() == false : clazz + " can not be instanciated";
+ assert superClazz.isAssignableFrom(clazz) : clazz + " does not implements/extends " + superClazz.getName();
+ if (properties == null)
+ {
+ return createInstance(clazz);
+ }
+ final Constructor<?> constructor = clazz.getConstructor(new Class[] {Properties.class});
+ return createInstance(constructor, properties);
+ } catch (Exception ex)
+ {
+ throw new ConfigurationFailureException("Cannot instanitate class " + className, ex);
+ }
+ }
+
+ @SuppressWarnings("unchecked")
+ private static <T> T createInstance(final Class<?> clazz) throws InstantiationException, IllegalAccessException
+ {
+ return (T) clazz.newInstance();
+ }
+
+ @SuppressWarnings("unchecked")
+ private static <T> T createInstance(final Constructor<?> constructor, Properties properties)
+ throws InstantiationException, IllegalAccessException, InvocationTargetException
+ {
+ return (T) constructor.newInstance(new Object[] {properties});
+ }
+
}
diff --git a/common/sourceTest/java/ch/systemsx/cisd/common/utilities/ClassUtilsTest.java b/common/sourceTest/java/ch/systemsx/cisd/common/utilities/ClassUtilsTest.java
index 8cfb894e4c0..50ac8d2142f 100644
--- a/common/sourceTest/java/ch/systemsx/cisd/common/utilities/ClassUtilsTest.java
+++ b/common/sourceTest/java/ch/systemsx/cisd/common/utilities/ClassUtilsTest.java
@@ -16,7 +16,14 @@
package ch.systemsx.cisd.common.utilities;
-import static org.testng.AssertJUnit.*;
+import static org.testng.AssertJUnit.assertEquals;
+import static org.testng.AssertJUnit.assertNull;
+import static org.testng.AssertJUnit.assertSame;
+import static org.testng.AssertJUnit.assertTrue;
+import static org.testng.AssertJUnit.fail;
+
+import java.io.IOException;
+import java.util.Properties;
import org.testng.annotations.Test;
@@ -71,4 +78,78 @@ public final class ClassUtilsTest
// we will have 'ch.systemsx.cisd.common.utilities.ClassUtilsTest.privateMethodOnStack()' here.
assertNull(ClassUtils.getMethodOnStack(1));
}
-}
\ No newline at end of file
+
+ @Test
+ public void testCreateWithDefaultConstructor()
+ {
+ CharSequence cs = ClassUtils.create(CharSequence.class, StringBuffer.class.getName(), null);
+ assertTrue(cs instanceof StringBuffer);
+ assertEquals(0, cs.length());
+ }
+
+ @Test
+ public void testCreateWithPropertiesConstructor()
+ {
+ Properties properties = new Properties();
+ Appendable appendable = ClassUtils.create(Appendable.class, MyClass.class.getName(), properties);
+ assertTrue(appendable instanceof MyClass);
+ assertSame(properties, ((MyClass) appendable).getProperties());
+ }
+
+ public static class MyClass implements Appendable
+ {
+ private final Properties properties;
+
+ public MyClass(Properties properties)
+ {
+ this.properties = properties;
+ }
+
+ public final Properties getProperties()
+ {
+ return properties;
+ }
+
+ public Appendable append(char c) throws IOException
+ {
+ return null;
+ }
+
+ public Appendable append(CharSequence csq, int start, int end) throws IOException
+ {
+ return null;
+ }
+
+ public Appendable append(CharSequence csq) throws IOException
+ {
+ return null;
+ }
+
+ }
+
+ @Test
+ public void testCreateWithIncompatibleSuperclass()
+ {
+ try
+ {
+ ClassUtils.create(Float.class, Integer.class.getName(), null);
+ fail("AssertionError expected.");
+ } catch (AssertionError e)
+ {
+ assertEquals("class java.lang.Integer does not implements/extends java.lang.Float", e.getMessage());
+ }
+ }
+
+ @Test
+ public void testCreateInstanceOfAnInterface()
+ {
+ try
+ {
+ ClassUtils.create(Float.class, CharSequence.class.getName(), null);
+ fail("AssertionError expected.");
+ } catch (AssertionError e)
+ {
+ assertEquals("interface java.lang.CharSequence can not be instanciated", e.getMessage());
+ }
+ }
+}
--
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