经过Class的getConstructors 能够取得类的全部构造函数定义。 java
[java] Class aClass = ...//obtain class object
Constructor[] constructors = aClass.getConstructors();
Class aClass = ...//obtain class object
Constructor[] constructors = aClass.getConstructors(); ide
若是知道构造函数的参数定义,能够直接取得对应的构造函数,如: 函数
[java]
Class aClass = ...//obtain class object
Constructor constructor =
aClass.getConstructor(new Class[]{String.class});
Class aClass = ...//obtain class object
Constructor constructor =
aClass.getConstructor(new Class[]{String.class}); ui
若是Reflection API找不到对应的构造函数,则抛出NoSuchMethodException异常。 get
1. 获取构造函数的参数定义 it
[java]
Class[] parameterTypes = constructor.getParameterTypes();
Class[] parameterTypes = constructor.getParameterTypes(); io
2. 使用构造函数定义建立实例 class
[java]
//get constructor that takes a String as argument
Constructor constructor = MyObject.class.getConstructor(String.class);
MyObject myObject = (MyObject)
constructor.newInstance("constructor-arg1");
//get constructor that takes a String as argument
Constructor constructor = MyObject.class.getConstructor(String.class);
MyObject myObject = (MyObject)
constructor.newInstance("constructor-arg1"); object
newInstance 的参数能够选,调用时参数个数必须和对应的Constructor 定义的参数个数一致。 sso
--Source---------------------------------------------------------------------------------
public T newInstance(Object ... initargs)
throws InstantiationException, IllegalAccessException,
IllegalArgumentException, InvocationTargetException
{
if (!override) {
if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
Class caller = Reflection.getCallerClass(2);
if (securityCheckCache != caller) {
Reflection.ensureMemberAccess(caller, clazz, null, modifiers);
securityCheckCache = caller;
}
}
}
if ((clazz.getModifiers() & Modifier.ENUM) != 0)
throw new IllegalArgumentException("Cannot reflectively create enum objects");
if (constructorAccessor == null) acquireConstructorAccessor();
return (T) constructorAccessor.newInstance(initargs);
}
adapter = (FileAdapterBase)clazz.getConstructor(types).newInstance(args);
--Source-----------------------------------------------------------------------------------