This is a simple library which allows you to protect your java object with a interface. This can be helpful if you don't want to offer the full access to a object from outside. For example if you write a library and you wants to have all modifications under control to ensure that the library works as expected.
The following example shows how easy you can protect a list with a ast annotation.
class TestMethodAnnotation {
List<String> list = []
@Protect
Iterable getProtectedIterable() {
list
}
Iterable getIterable() {
list
}
}
class TestMethodAnnotationTest {
@Test
void testProtectedMethodAnnotation() {
TestMethodAnnotation testObject = new TestMethodAnnotation()
testObject.list << '1' << '2'
assertThat(testObject.list).isEqualTo(['1', '2'])
assertThat(testObject.getIterable()).isInstanceOf(List)
testObject.getIterable() << '3'
assertThat(testObject.list).isEqualTo(['1', '2', '3'])
assertThat(testObject.getProtectedIterable()).isNotInstanceOf(List)
assertThatThrownBy( { (List)testObject.getProtectedIterable() } ).isInstanceOf(ClassCastException)
assertThatThrownBy( { testObject.getProtectedIterable() << '4' } ).isInstanceOf(MissingMethodException)
}
It's possible to change modify the list with the not protected iterable. The object is still a List can all methods can be executed. The protected iterabel just offers the methods of a itrable. So it's not possible to modify the list.
The idea is that the object is wrapped by a proxy and we declare the method which will be delegated to the object by a interface.
public final class ProtectUtil {
public static <T> T protect(T t, Class<T> clazz) {
Set<Method> methodSet = new HashSet<>(Arrays.asList(clazz.getMethods()));
methodSet.addAll(Arrays.asList(Object.class.getMethods()));
return (T) Proxy.newProxyInstance(t.getClass().getClassLoader(), new Class[] { clazz },
(proxy, method, args) -> {
if (!methodSet.contains(method)) {
throw new NoSuchMethodException();
}
try {
return method.invoke(t, args);
}
catch (InvocationTargetException e) {
throw e.getCause();
}
});
}
}
This is done with the ProtectUtil class, which is available for java and groovy. The generated proxy also delegates the methods of the class Object. So mehtods like equals and toString should still work. The @Protect ast annotation can be used in groovy and can be defined on types and methods.
Groovy AST dependency gradle
implementation 'com.github.andycandy-de:protect-me-ast:1.2'
Groovy AST dependency maven
<dependency>
<groupId>com.github.andycandy-de</groupId>
<artifactId>protect-me-ast</artifactId>
<version>1.2</version>
</dependency>
Java util dependency gradle
implementation 'com.github.andycandy-de:protect-me-util:1.2'
Java util dependency maven
<dependency>
<groupId>com.github.andycandy-de</groupId>
<artifactId>protect-me-util</artifactId>
<version>1.2</version>
</dependency>
MIT License
Copyright (c) 2020 andycandy-de
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