java.lang.invoke.LambdaMetafactory#metafactory ( )源码实例Demo

public static void main(String[] args) throws Throwable {
    l = MethodHandles.lookup();
    h = l.findVirtual(LambdaReceiver_A.class, "f", mt(int.class));
    MethodType X = mt(int.class, LambdaReceiver.class);
    MethodType A = mt(int.class, LambdaReceiver_A.class);
    MethodType mti = mt(IA.class);
    CallSite cs = LambdaMetafactory.metafactory(l, "m", mti,A,h,X);
    IA p = (IA)cs.dynamicInvoker().invoke();
    LambdaReceiver_A lra = new LambdaReceiver_A();
    try {
        p.m(lra);
    } catch (ClassCastException cce) {
        return;
    }
    throw new AssertionError("CCE expected");
}
 

public static void main(String[] args) throws Throwable {
    l = MethodHandles.lookup();
    h = l.findVirtual(LambdaReceiver_A.class, "f", mt(int.class));
    MethodType X = mt(int.class, LambdaReceiver.class);
    MethodType A = mt(int.class, LambdaReceiver_A.class);
    MethodType mti = mt(IA.class);
    CallSite cs = LambdaMetafactory.metafactory(l, "m", mti,A,h,X);
    IA p = (IA)cs.dynamicInvoker().invoke();
    LambdaReceiver_A lra = new LambdaReceiver_A();
    try {
        p.m(lra);
    } catch (ClassCastException cce) {
        return;
    }
    throw new AssertionError("CCE expected");
}
 

public static void main(String[] args) throws Throwable {
    l = MethodHandles.lookup();
    h = l.findVirtual(LambdaReceiver_A.class, "f", mt(int.class));
    MethodType X = mt(int.class, LambdaReceiver.class);
    MethodType A = mt(int.class, LambdaReceiver_A.class);
    MethodType mti = mt(IA.class);
    CallSite cs = LambdaMetafactory.metafactory(l, "m", mti,A,h,X);
    IA p = (IA)cs.dynamicInvoker().invoke();
    LambdaReceiver_A lra = new LambdaReceiver_A();
    try {
        p.m(lra);
    } catch (ClassCastException cce) {
        return;
    }
    throw new AssertionError("CCE expected");
}
 

public void testDirectStdNonser() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, non-serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(Predicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    Predicate<String> p = (Predicate<String>) cs.getTarget().invokeExact();
    assertNotSerial(p, fooAsserter);
}
 

public void testDirectStdSer() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(SerPredicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    assertNotSerial((SerPredicate<String>) cs.getTarget().invokeExact(), fooAsserter);
}
 

public void testDirectStdNonser() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, non-serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(Predicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    Predicate<String> p = (Predicate<String>) cs.getTarget().invokeExact();
    assertNotSerial(p, fooAsserter);
}
 

private static boolean mf(MethodType mti, MethodType mtf) {
    try {
        LambdaMetafactory.metafactory(l, "m", mti,mtf,h,mtf);
    } catch(LambdaConversionException e) {
        return true;
    }
    return false;
}
 

public void testDirectStdSer() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(SerPredicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    assertNotSerial((SerPredicate<String>) cs.getTarget().invokeExact(), fooAsserter);
}
 

public void testDirectStdSer() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(SerPredicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    assertNotSerial((SerPredicate<String>) cs.getTarget().invokeExact(), fooAsserter);
}
 

public void testDirectStdNonser() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, non-serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(Predicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    Predicate<String> p = (Predicate<String>) cs.getTarget().invokeExact();
    assertNotSerial(p, fooAsserter);
}
 

private static boolean mf(MethodHandles.Lookup l) {
    try {
        LambdaMetafactory.metafactory(l, "close",
            mt(Closeable.class),mt(void.class),h,mt(void.class));
    } catch(LambdaConversionException e) {
        return true;
    }
    return false;
}
 

private static boolean mf(MethodType mti, MethodType mtf) {
    try {
        LambdaMetafactory.metafactory(l, "m", mti,mtf,h,mtf);
    } catch(LambdaConversionException e) {
        return true;
    }
    return false;
}
 

public void testDirectStdNonser() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, non-serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(Predicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    Predicate<String> p = (Predicate<String>) cs.getTarget().invokeExact();
    assertNotSerial(p, fooAsserter);
}
 

public void testDirectStdSer() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(SerPredicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    assertNotSerial((SerPredicate<String>) cs.getTarget().invokeExact(), fooAsserter);
}
 

@SuppressWarnings("unchecked")
public static <T> T createLambda(Method instanceMethod, Class<?> functionalIntfCls) {
  if (Modifier.isNative(instanceMethod.getModifiers())) {
    // fix "Failed to create lambda from public final native java.lang.Class java.lang.Object.getClass()"
    return null;
  }
  try {
    Method intfMethod = findAbstractMethod(functionalIntfCls);
    MethodHandle methodHandle = LOOKUP.unreflect(instanceMethod);

    MethodType intfMethodType = MethodType.methodType(intfMethod.getReturnType(), intfMethod.getParameterTypes());

    // the return type of fluent setter is object instead of void, but we can assume the return type is void. it doesn't matter
    MethodType instanceMethodType = MethodType
        .methodType(intfMethod.getReturnType(), methodHandle.type().parameterList());
    CallSite callSite = LambdaMetafactory.metafactory(
        LOOKUP,
        intfMethod.getName(),
        MethodType.methodType(functionalIntfCls),
        intfMethodType,
        methodHandle,
        instanceMethodType);

    return (T) callSite.getTarget().invoke();
  } catch (Throwable e) {
    throw new IllegalStateException("Failed to create lambda from " + instanceMethod, e);
  }
}
 

private static boolean mf(Class<?> k) {
    try {
        LambdaMetafactory.metafactory(l, "m",
            mt(I.class),mt(k),h,mt(void.class));
    } catch(LambdaConversionException e) {
        return true;
    }
    return false;
}
 

public void testDirectStdSer() throws Throwable {
    MethodHandle fooMH = MethodHandles.lookup().findStatic(SerializedLambdaTest.class, "foo", predicateMT);

    // Standard metafactory, serializable target: not serializable
    CallSite cs = LambdaMetafactory.metafactory(MethodHandles.lookup(),
                                                "test", MethodType.methodType(SerPredicate.class),
                                                predicateMT, fooMH, stringPredicateMT);
    assertNotSerial((SerPredicate<String>) cs.getTarget().invokeExact(), fooAsserter);
}
 

private static boolean mf(MethodType mti, MethodType mtf) {
    try {
        LambdaMetafactory.metafactory(l, "m", mti,mtf,h,mtf);
    } catch(LambdaConversionException e) {
        return true;
    }
    return false;
}
 

private static boolean mf(MethodHandles.Lookup l) {
    try {
        LambdaMetafactory.metafactory(l, "close",
            mt(Closeable.class),mt(void.class),h,mt(void.class));
    } catch(LambdaConversionException e) {
        return true;
    }
    return false;
}
 

private static boolean mf(Class<?> k) {
    try {
        LambdaMetafactory.metafactory(l, "m",
            mt(I.class),mt(k),h,mt(void.class));
    } catch(LambdaConversionException e) {
        return true;
    }
    return false;
}