61 lines
2.7 KiB
Java
61 lines
2.7 KiB
Java
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package com.baeldung.bytebuddy;
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import net.bytebuddy.ByteBuddy;
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import net.bytebuddy.agent.ByteBuddyAgent;
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import net.bytebuddy.dynamic.DynamicType;
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import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
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import net.bytebuddy.dynamic.loading.ClassReloadingStrategy;
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import net.bytebuddy.implementation.FixedValue;
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import net.bytebuddy.implementation.MethodDelegation;
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import net.bytebuddy.matcher.ElementMatchers;
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import org.junit.Test;
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import java.lang.reflect.Method;
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import java.lang.reflect.Modifier;
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import static net.bytebuddy.matcher.ElementMatchers.*;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertNotNull;
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public class ByteBuddyUnitTest {
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@Test
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public void givenObject_whenToString_thenReturnHelloWorldString() throws InstantiationException, IllegalAccessException {
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DynamicType.Unloaded unloadedType = new ByteBuddy().subclass(Object.class).method(ElementMatchers.isToString()).intercept(FixedValue.value("Hello World ByteBuddy!")).make();
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Class<?> dynamicType = unloadedType.load(getClass().getClassLoader()).getLoaded();
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assertEquals(dynamicType.newInstance().toString(), "Hello World ByteBuddy!");
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}
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@Test
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public void givenFoo_whenRedefined_thenReturnFooRedefined() throws Exception {
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ByteBuddyAgent.install();
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new ByteBuddy().redefine(Foo.class).method(named("sayHelloFoo")).intercept(FixedValue.value("Hello Foo Redefined")).make().load(Foo.class.getClassLoader(), ClassReloadingStrategy.fromInstalledAgent());
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Foo f = new Foo();
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assertEquals(f.sayHelloFoo(), "Hello Foo Redefined");
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}
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@Test
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public void givenSayHelloFoo_whenMethodDelegation_thenSayHelloBar() throws IllegalAccessException, InstantiationException {
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String r = new ByteBuddy().subclass(Foo.class).method(named("sayHelloFoo").and(isDeclaredBy(Foo.class).and(returns(String.class)))).intercept(MethodDelegation.to(Bar.class)).make().load(getClass().getClassLoader()).getLoaded().newInstance()
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.sayHelloFoo();
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assertEquals(r, Bar.sayHelloBar());
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}
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@Test
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public void givenMethodName_whenDefineMethod_thenCreateMethod() throws Exception {
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Class<?> type = new ByteBuddy().subclass(Object.class).name("MyClassName").defineMethod("custom", String.class, Modifier.PUBLIC).intercept(MethodDelegation.to(Bar.class)).defineField("x", String.class, Modifier.PUBLIC).make()
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.load(getClass().getClassLoader(), ClassLoadingStrategy.Default.WRAPPER).getLoaded();
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Method m = type.getDeclaredMethod("custom", null);
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assertEquals(m.invoke(type.newInstance()), Bar.sayHelloBar());
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assertNotNull(type.getDeclaredField("x"));
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}
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}
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