本文深入探讨了Java中`getMethod`和`getMethod0`两个方法的内部实现，包括如何查找指定名称和参数类型的公共方法。通过检查成员访问权限，遍历类及其超类和接口来寻找目标方法，对于找不到的方法抛出`NoSuchMethodException`。这个过程涉及到类的继承和多态性，是理解Java反射机制的关键部分。
javapublic Method getMethod(String name, Class>... parameterTypes)
throws NoSuchMethodException, SecurityException {
checkMemberAccess(Member.PUBLIC, Reflection.getCallerClass(), true);
Method method = getMethod0(name, parameterTypes);
if (method == null) {
throw new NoSuchMethodException(getName() + "." + name + argumentTypesToString(parameterTypes));
}
return method;
}
private Method getMethod0(String name, Class>[] parameterTypes) {
if ((res = searchMethods(privateGetDeclaredMethods(true),
name,
parameterTypes)) != null) {
return res;
}
if (!isInterface()) {
Class super T> c = getSuperclass();
if (c != null) {
if ((res = c.getMethod0(name, parameterTypes)) != null) {
return res;
}
}
}
Class>[] interfaces = getInterfaces();
for (int i = 0; i < interfaces.length; i++) {
Class> c = interfaces[i];
if ((res = c.getMethod0(name, parameterTypes)) != null) {
return res;
}
}
return null;
}
private static Method searchMethods(Method[] methods,
String name,
Class>[] parameterTypes)
{
Method res = null;
String internedName = name.intern();
for (int i = 0; i < methods.length; i++) {
Method m = methods[i];
if (m.getName() == internedName
&& arrayContentsEq(parameterTypes, m.getParameterTypes())
&& (res == null
|| res.getReturnType().isAssignableFrom(m.getReturnType())))
res = m;
}
return (res == null ? res : getReflectionFactory().copyMethod(res));
}
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