【TestRef.java】
public class TestRef {
 
    public static void main(String[] args) {
        try {
            Class<?> clazz = Class.forName("com.allen.commons.entity.CommonTestEntity");
            Object refTest = clazz.newInstance();
            Method method = clazz.getMethod("defaultMethod");
            //Method method1 = clazz.getDeclaredMethod("defaultMethod");
            method.invoke(refTest);
        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException e) {
            e.printStackTrace();
        }
 
    }
}
---------------------------------------------------------------------------------------
【CommonTestEntity.java】
public class CommonTestEntity {
 
    static {
        System.out.println("CommonTestEntity執(zhí)行類加載...");
    }
 
    public CommonTestEntity() {
        System.out.println(this.getClass() + " ｜ CommonTestEntity實例初始化 | " + this.getClass().getClassLoader());
    }
 
    public void defaultMethod() {
        System.out.println("執(zhí)行實例方法：defaultMethod");
    }
}

public Method getMethod(String name, Class<?>... parameterTypes)
        throws NoSuchMethodException, SecurityException {
        Objects.requireNonNull(name);
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            // 1. 檢查方法權限
            checkMemberAccess(sm, Member.PUBLIC, Reflection.getCallerClass(), true);
        }
        // 2. 獲取方法
        Method method = getMethod0(name, parameterTypes);
        if (method == null) {
            throw new NoSuchMethodException(methodToString(name, parameterTypes));
        }
        // 3. 返回方法
        return method;
    }
---------------------------------------------------------------------------------------
public Method getDeclaredMethod(String name, Class<?>... parameterTypes)
        throws NoSuchMethodException, SecurityException {
        Objects.requireNonNull(name);
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            // 1. 檢查方法是權限
            checkMemberAccess(sm, Member.DECLARED, Reflection.getCallerClass(), true);
        }
        // 2. 獲取方法
        Method method = searchMethods(privateGetDeclaredMethods(false), name, parameterTypes);
        if (method == null) {
            throw new NoSuchMethodException(methodToString(name, parameterTypes));
        }
        // 3. 返回方法
        return method;
}

// Returns an array of "root" methods. These Method objects must NOT
    // be propagated to the outside world, but must instead be copied
    // via ReflectionFactory.copyMethod.
    private Method[] privateGetDeclaredMethods(boolean publicOnly) {
        checkInitted();
        Method[] res;
        ReflectionData<T> rd = reflectionData();
        if (rd != null) {
            res = publicOnly ? rd.declaredPublicMethods : rd.declaredMethods;
            if (res != null) return res;
        }
        // No cached value available; request value from VM
        res = Reflection.filterMethods(this, getDeclaredMethods0(publicOnly));
        if (rd != null) {
            if (publicOnly) {
                rd.declaredPublicMethods = res;
            } else {
                rd.declaredMethods = res;
            }
        }
        return res;
    }

private Method getMethod0(String name, Class<?>[] parameterTypes, boolean includeStaticMethods) {
        MethodArray interfaceCandidates = new MethodArray(2);
        Method res =  privateGetMethodRecursive(name, parameterTypes, includeStaticMethods, interfaceCandidates);
        if (res != null)
            return res;
 
        // Not found on class or superclass directly
        interfaceCandidates.removeLessSpecifics();
        return interfaceCandidates.getFirst(); // may be null
    }

class Method {
    public Object invoke(Object obj, Object... args)
        throws IllegalAccessException, IllegalArgumentException,
           InvocationTargetException
    {
        if (!override) {
            Class<?> caller = Reflection.getCallerClass();
            // 1. 檢查權限
            checkAccess(caller, clazz,
                        Modifier.isStatic(modifiers) ? null : obj.getClass(),
                        modifiers);
        }
        // 2. 獲取 MethodAccessor
        MethodAccessor ma = methodAccessor;             // read volatile
        if (ma == null) {
            // 創(chuàng)建 MethodAccessor
            ma = acquireMethodAccessor();
        }
        // 3. 調用 MethodAccessor.invoke
        return ma.invoke(obj, args);
    }
}