Question

我有以下代码：

private static void test() {
        try {
            TestWetterAdapter adap = new TestWetterAdapter();

            ClassParserUtil.executeMethod(adap.getClass().getName(), "getWeather", null);

        } catch(Exception e) {
            e.printStackTrace();
        }

        try {
            TestWetterAdapter adap = new TestWetterAdapter();

            Method methodToCall = ClassParserUtil.getMethod(adap.getClass(), "getWeather", null);
            System.out.println("Invoke Method " + methodToCall.getName()  + " (ParametersLen: " + methodToCall.getParameterTypes().length + ", Annotation: " + methodToCall.getAnnotations()[0] + ") with Class " + adap + " and null.");
            Object retObject = methodToCall.invoke(adap, null);
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

executeMethod的代码：

public static Object executeMethod(String className, String methodName, Object object) throws ExecuteFailedException {
    Object retObject = null;

    try {
        Class<?> klasse = Class.forName(className);
        Constructor<?> constructor = ClassParserUtil.getDefaultConstructor(klasse);
        Object classObject = constructor.newInstance();
        Method methodToCall = ClassParserUtil.getMethod(classObject.getClass(), methodName, object);
        System.out.println("Invoke Method " + methodToCall.getName() + " (ParametersLen: " + methodToCall.getParameterTypes().length + ", Annotation: " + methodToCall.getAnnotations()[0] + ") with Class " + classObject + " and " + object + ".");
        retObject = methodToCall.invoke(classObject, object);
    } catch(Exception e) {
        ExecuteFailedException efe = new ExecuteFailedException("Couldn't execute Method " + methodName + " in class " + className + ".");
        efe.initCause(e);
        throw(efe);
    }

    return retObject;
}

有趣的是，两个不同的调用会在调用它们时导致不同的输出。所以我的test（）的输出如下所示：

> Call getMethod(class at.wmfsoftware.cct.adapter.TestWetterAdapter, getWeather, null).
Invoke Method getWeather (ParametersLen: 0, Annotation: @at.wmfsoftware.cct.interfaces.AnnotationsInterface$ParseMethodGet()) with Class at.wmfsoftware.cct.adapter.TestWetterAdapter@7a1904 and null.
at.wmfsoftware.cct.exceptions.ExecuteFailedException: Couldn't execute Method getWeather in class at.wmfsoftware.cct.adapter.TestWetterAdapter.
    at at.wmfsoftware.cct.utils.parsers.ClassParserUtil.executeMethod(ClassParserUtil.java:301)
    at at.wmfsoftware.cct.test.TestMain.test(TestMain.java:92)
    at at.wmfsoftware.cct.test.TestMain.main(TestMain.java:78)
Caused by: java.lang.IllegalArgumentException: wrong number of arguments
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at at.wmfsoftware.cct.utils.parsers.ClassParserUtil.executeMethod(ClassParserUtil.java:299)
    ... 2 more
Call getMethod(class at.wmfsoftware.cct.adapter.TestWetterAdapter, getWeather, null).
Invoke Method getWeather (ParametersLen: 0, Annotation: @at.wmfsoftware.cct.interfaces.AnnotationsInterface$ParseMethodGet()) with Class at.wmfsoftware.cct.adapter.TestWetterAdapter@91a129 and null.
log4j:WARN No appenders could be found for logger (org.apache.http.client.protocol.RequestAddCookies).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
{"coord":{"lon":16.37,"lat":48.21},"sys":{"message":0.0348,"country":"AT","sunrise":1400986998,"sunset":1401043180},"weather":[{"id":800,"main":"Clear","description":"Sky is Clear","icon":"01d"}],"base":"cmc stations","main":{"temp":294.56,"humidity":56,"pressure":1016,"temp_min":293.15,"temp_max":296.35},"wind":{"speed":1.9,"gust":2.7,"deg":10},"rain":{"3h":0},"clouds":{"all":0},"dt":1401010263,"id":2761369,"name":"Vienna","cod":200}

所以有一次成功调用该方法，有一次我得到一个Exception。尽管它必须是相同的方法（我通过编写它的Name，Annotation和ParameterLength来确保这一点。）

有什么想法吗？

由于威利

Answer 1

当您将对象作为参数传递时，它将搜索堆中的相应存储，如果没有找到它，则会抛出异常。

所以总是更好地传递一个直接的null并保持安全。

调用Method返回两个不同的结果（1次异常）

1 个答案: