Add dynamic class compilation example

.gitignore

@@ -21,3 +21,5 @@
 
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
+
+target/

pom.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>fr.gasser</groupId>
+    <artifactId>java-cookbook</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>pom</packaging>
+    
+    <modules>
+        <module>reflection</module>
+    </modules>
+    
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+    
+</project>

reflection/pom.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>fr.gasser</groupId>
+        <artifactId>java-cookbook</artifactId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <artifactId>reflection</artifactId>
+    <packaging>jar</packaging>
+</project>

reflection/src/main/java/fr/gasser/reflection/dynamicload/DynamicLoadDemo.java

@@ -0,0 +1,75 @@
+package fr.gasser.reflection.dynamicload;
+
+import java.io.File;
+import java.io.IOException;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.Arrays;
+import javax.tools.JavaCompiler;
+import javax.tools.ToolProvider;
+
+public class DynamicLoadDemo {
+    
+    /**
+     * The source code to load dynamically
+     */
+    private static final String SOURCE = 
+            "package test;"
+            + "import static fr.gasser.reflection.dynamicload.DynamicLoadDemo.*;"
+            + "public class Test implements IDynamicLoad {"
+            + "     static { System.out.println(\"Test\"); }"
+            + "     @Override public String doSomething() {"
+            + "         return \"Hello world!\";"
+            + "     }"
+            + "     public String doSomethingReflection(String arg) {"
+            + "         return \"Hello reflection! \" + \"arg\";"
+            + "     }"
+            + "}";
+    
+    /**
+     * Represents the contract for the dynamically loaded class
+     */
+    public static interface IDynamicLoad {
+        public String doSomething();
+    }
+
+    /**
+     * @param args the command line arguments
+     * @throws java.io.IOException
+     * @throws java.lang.ReflectiveOperationException
+     */
+    public static void main(String[] args) throws IOException, ReflectiveOperationException {
+        
+        // Save source in .java file.
+        final File root = Files.createTempDirectory(null).toFile();
+        final File sourceFile = new File(root, "test/Test.java");
+        sourceFile.getParentFile().mkdirs();
+        Files.write(sourceFile.toPath(), SOURCE.getBytes(StandardCharsets.UTF_8));
+        
+        // Compile source file.
+        final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
+        compiler.run(null, null, null, sourceFile.getPath());
+        
+        // Load and instantiate compiled class.
+        final URLClassLoader classLoader = 
+                URLClassLoader.newInstance(new URL[] { root.toURI().toURL() });
+        final Class<?> cls = Class.forName("test.Test", true, classLoader);
+        IDynamicLoad instance = (IDynamicLoad) cls.newInstance();
+        System.out.format(
+                "Methods declared by the class : %s%n", 
+                Arrays.toString(cls.getDeclaredMethods())
+        );
+        
+        // Invoke methods of the contract IDynamicLoad
+        System.out.println(instance.doSomething());
+        
+        // Invoke methods using the reflection API
+	Method method = cls.getDeclaredMethod("doSomethingReflection", String.class);
+        String arg = "argument";
+        System.out.format("invoking %s.doSomethingReflection()%n", cls.getName());
+        System.out.println(method.invoke(instance, arg));
+    }
+}