/**
* `使用反射机制调用方法`
*
* @param methodName Method name
* @param obj Object holder of the method
* @param paraType Array of parameter types
* @param paraValue Array of parameters
* @return Returned object of the method
*/
public static Object call(String methodName, Object obj, Class[] paraType, Object[] paraValue) {
try {
Class cls = obj.getClass();
Method method = cls.getDeclaredMethod(methodName, paraType);
// invoke() returns the object returned by the
// underlying method.
// It returns null, if the underlying method returns void.
return method.invoke(obj, paraValue);
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
/** Reflect operations demo */
public static void reflect(Object obj) {
// `cls用于描述对象所属的类`
Class cls = obj.getClass();
print("Class Name: " + cls.getCanonicalName());
// `fields包含对象的所有属性`
Field[] fields = cls.getDeclaredFields();
print("List of fields:");
for (Field f : fields) {
print(String.format("%30s %15s", f.getType(), f.getName()));
}
// `methods包含对象的所有方法`
Method[] methods = cls.getDeclaredMethods();
print("List of methods:");
for (Method m : methods)
print(
String.format(
"%30s %15s %30s",
m.getReturnType(), m.getName(), Arrays.toString(m.getParameterTypes())));
Constructor[] constructors = cls.getConstructors();
print("List of contructors:");
for (Constructor c : constructors)
print(String.format("%30s %15s", c.getName(), Arrays.toString(c.getParameterTypes())));
}