根据java编译器规则在Class中搜索匹配指定参数类型表的泛型方法(GenericMethod)

public class TestGenericMethod {
    public void test(String a,String b,byte[] c){

    }
    public void test(Date a,URL b,byte[] c){

    }
    public <T>void test(int a,URL b,T c){

    }

    public <T1,T2,T3>void test(T1 a,T2 b,T3 c){

    }
}

    /**
     * @param clazz 要搜索的类
     * @param name 方法名
     * @param parameterTypes 希望匹配的参数类型数组
     * @return
     * @throws NoSuchMethodException
     */
    public static final java.lang.reflect.Method getGenericMethod(Class<?>clazz,String name,Class<?>... parameterTypes) throws NoSuchMethodException{
        List<java.lang.reflect.Method> methods=new ArrayList<java.lang.reflect.Method>();
        //查找同名且参数数目相同的所有方法
        for (java.lang.reflect.Method m : clazz.getMethods())
            if (m.getName().equals(name) && m.getParameterTypes().length == parameterTypes.length)
                methods.add(m);
        if (!methods.isEmpty()) {
            //过滤掉所有不能匹配的方法      
            for (int i = 0; i < parameterTypes.length; i++) {
                for (Iterator<java.lang.reflect.Method> it = methods.iterator(); it.hasNext();) {
                    if (!isConvert(it.next().getParameterTypes()[i], parameterTypes[i]))
                        it.remove();
                }
                if (methods.size() <= 1)
//找到唯一匹配的方法或没有匹配的方法就中止循环                
                    break;
            }
            if (methods.size() > 1) {
                //如果还有多个方法满足条件，再过滤掉不能直接赋值的方法
                for (int i = 0; i < parameterTypes.length; i++) {
                    for (Iterator<java.lang.reflect.Method> it = methods.iterator(); it.hasNext();) {
                        if (!isAssignable(it.next().getParameterTypes()[i], parameterTypes[i]))
                            it.remove();
                    }
                    if (methods.size() <= 1)
//找到唯一匹配的方法或没有匹配的方法就中止循环
                        break;
                }
            }
            if (methods.size() == 1)
                return methods.iterator().next();
            else if (methods.size() > 1){
                //如果还有多个方法满足条件，再过滤掉类型不相等的方法
                for (int i = 0; i < parameterTypes.length; i++) {
                    for (Iterator<java.lang.reflect.Method> it = methods.iterator(); it.hasNext();) {
                        if (it.next().getParameterTypes()[i]!= parameterTypes[i])
                            it.remove();
                    }
                    if (methods.size() <= 1)
//找到唯一匹配的方法或没有匹配的方法就中止循环
                        break;
                }
                if (methods.size() == 1)
                    return methods.iterator().next();
                else    if (methods.size() > 1)
                    throw new IllegalStateException("found more matched method");
            }

        }
        //没有找到匹配的方法就抛出异常
        throw new NoSuchMethodException();      
    }
    /**
     * from对象是否能转换成to
     * @param to
     * @param from
     * @return
     */
    public static final boolean isConvert(Class<?> to, Class<?> from) {
        if (!isAssignable(to, from)){
            if (to.isPrimitive() && PRIMITIVE_TYPE_MAP.get(to) == from) {
                return true;
            }
            return false;
        }
        return true;
    }
    /**
     * from对象能否则直接赋值给to
     * @param to
     * @param from
     * @return
     */
    public static final boolean isAssignable(Class<?> to,Class<?>from){
        if (from.isPrimitive()) {
            if (to != from && !to.isAssignableFrom(PRIMITIVE_TYPE_MAP.get(from)))
                return false;
        } else if (!to.isAssignableFrom(from))
            return false;
        return true;
    }
    //primitive类型与对应Object类的映射表
    private static final Map<Class<?>, Class<?>> PRIMITIVE_TYPE_MAP = new HashMap<Class<?>, Class<?>>() {
        private static final long serialVersionUID = 2638066380035384674L;
        {
            put(int.class, Integer.class);
            put(boolean.class, Boolean.class);
            put(byte.class, Byte.class);
            put(short.class, Short.class);
            put(char.class, Character.class);
            put(long.class, Long.class);
            put(float.class, Float.class);
            put(double.class, Double.class);
        }
    };