java 使用反射获取方法；找不到接口类型的方法参数
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原文地址: http://stackoverflow.com/questions/3602413/
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Using reflection to get a method; method parameters of interface types aren't found
提问by initialZero
Maybe I'm missing something simple here but how do I get a method whose parameter is an interface using reflection.
也许我在这里遗漏了一些简单的东西，但是我如何获得一个方法，其参数是使用反射的接口。
In the following case newValuewould be a List<String>called foo. So I would call addModelProperty("Bar", foo);But this only works for me if I don't use the interface and only use LinkedList<String> foo. How do I use an interface for newValueand get the method from modelthat has an interface as the parameter addBar(List<String> a0)?
在以下情况下newValue将是一个List<String>被调用的foo. 所以我会打电话，addModelProperty("Bar", foo);但这只对我有用，如果我不使用接口并且只使用LinkedList<String> foo. 如何使用接口newValue并从中获取model具有接口作为参数的方法addBar(List<String> a0)？
Here is a more detailed example. (based on: This example)
这里有一个更详细的例子。（基于：这个例子）
public class AbstractController {
public setModel(AbstractModel model) {
this.model = model;
}
protected void addModelProperty(String propertyName, Object newValue) {
try {
Method method = getMethod(model.getClass(), "add" + propertyName, newValue);
method.invoke(model, newValue);
} catch (NoSuchMethodException e) {
} catch (InvocationTargetException e) {
} catch (Exception e) {}
}
}
public class AbstractModel {
protected PropertyChangeSupport propertyChangeSupport;
protected void firePropertyChange(String propertyName, Object oldValue, Object newValue) {
propertyChangeSupport.firePropertyChange(propertyName, oldValue, newValue);
}
}
public class Model extends AbstractModel {
public void addList(List<String> list) {
this.list.addAll(list);
}
}
public class Controller extends AbstractController {
public void addList(List<String> list) {
addModelProperty(list);
}
}
public void example() {
Model model = new Model();
Controller controller = new Controller();
List<String> list = new LinkedList<String>();
list.add("example");
// addList in the model is only found if LinkedList is used everywhere instead of List
controller.addList(list);
}
回答by erickson
You'll actually have to search through all the methods in your model and find those that are compatible with the arguments you have. It is a bit messy, because, in general, there might be more that one.
您实际上必须搜索模型中的所有方法，并找到与您拥有的参数兼容的方法。这有点乱，因为一般来说，可能会有更多。
If you are interested in just public methods, the getMethods()method is the easiest to use, because it gives you all accessible methods without walking the class hierarchy.
如果您只对公共方法感兴趣，那么该getMethods()方法最容易使用，因为它为您提供了所有可访问的方法，而无需遍历类层次结构。
Collection<Method> candidates = new ArrayList<Method>();
String target = "add" + propertyName;
for (Method m : model.getClass().getMethods()) {
if (target.equals(m.getName())) {
Class<?>[] params = m.getParameterTypes();
if (params.length == 1) {
if (params[0].isInstance(newValue))
candidates.add(m);
}
}
}
/* Now see how many matches you have... if there's exactly one, use it. */
回答by Lodovik
If you don't mind adding a dependency to Apache Commons, you may use MethodUtils.getMatchingAccessibleMethod(Class clazz, String methodName, Class[] parameterTypes).
如果您不介意向 Apache Commons 添加依赖项，您可以使用MethodUtils.getMatchingAccessibleMethod(Class clazz, String methodName, Class[] parameterTypes).
If you mind adding this dependency, you may at least find it useful to take a look at how this method is implemented.
如果您介意添加此依赖项，那么您至少会发现查看此方法是如何实现的很有用。
