反射机制及使用说明,符代码.doc

反射使用反射经常要用到的类，位于java.lang.reflect包中。-Class类：代表一个类-Field类：代表类的成员变量-Method类：代表类的方法-Constructor类：代表类的构造方法-Array类：提供一个动态创建的数组，以及访问数组元素的静态方法。使用Method类public class RefletTestpublic static void main(String args) throws ExceptionClass classType = Class.forName(java.lang.String);/getDeclaredMethods获得对应类的所有方法，包括private的Method methods = classType.getDeclaredMethods();for(Method method : methods)System.out.println(method);使用反射进行方法的调用public class InvokeTesterpublic int add(int a,int b)return a + b;public void output(String msg)System.out.println(msg);public static void main(String args) throws Exception/取得自定义类的类型Class classType = InvokeTester.class;/创建自定义的一个实例Object invokeTester = classType.newInstance();/取得自定义类的一个方法Method addMethod = classType.getMethod(add, new Classint.class, int.class );/调用自定义类的实例的方法Object result = addMethod.invoke(invokeTester, new Object1, 2);System.out.println(result);Method outputMethod = classType.getMethod(output,new ClassString.class);outputMethod.invoke(invokeTester,new ObjectHello);System.out.println(Object.class);要使用反射，首先需要获得待处理类或对象所对应的Class对象。获取某个类或某个对象对应的Class对象的常用的3种方式：a.使用Class类的静态方法forName.如Class.forName(“java.lang.String”);b.使用类的.class语法：String.classc.使用对象的getClass()方法：Strings = “a”; Class clazz = s.getClass();public class ClassTestpublic static void main(String args)Class classType = Child.class;System.out.println(classType);classType = classType.getSuperclass();System.out.println(classType);classType = classType.getSuperclass();System.out.println(classType);classType = classType.getSuperclass();System.out.println(classType);class Parentclass Child extends ParentConstructor类的使用若想调用类的不带参数的构造方法来生成对象，我们有两种方法：a. 先获得Class对象，然后通过该Class对象的newInstance（）方法直接生成即可。Class clazz = String.class;Object object = clazz.newInstance();b. 先获得Class对象，然后通过该对象获得对应的Constructor对象，再通过该Constructor对象的newInstance方法生成：Class clazz = Customer.class;Constructor cons = clazz.getConstructor(new Class);Object obj = cons.newsInstance(new Object);若想调用类的带参数的构造方法，可以用如下方式：Class clazz = Customer.class;Constructor cons = clazz.getConstructor(new ClassString.class,int.class);Object obj = cons.newsInstance(new Object“jack”,23);public class Customerprivate long Id;private String name;private int age;public Customer()public Customer(String name, int age) = name ;this.age = age;public long getId()return Id;public void setId(long id)Id = id;public String getName()return name;public void setName(String name) = name;public int getAge()return age;public void setAge(int age)this.age = age;public class ConstructorTest/这个方法用于实现对object对象的拷贝操作public Object copy (Object object) throws Exception/*Class classType = object.getClass();/可以用于各种构造函数 Constructor cons = classType.getConstructor(new ClassString.class , int.class);Object obj = cons.newInstance(new ObjectJack, 30);/以上两行相当于下面的一行，但是下面这种用法，只能用于无参的构造函数。/Object obj1 = classType.newInstance();System.out.println(obj);*/Class classType = object.getClass();Object objCopy = classType.getConstructor(new Class).newInstance(new Object);Field fields = classType.getDeclaredFields();for(Field field : fields)String name = field.getName();String firstLetter = name.substring(0,1).toUpperCase();String getMethodName = get + firstLetter + name.substring(1);String setMethodName = set + firstLetter + name.substring(1);Method getMethod = classType.getMethod(getMethodName,new Class);Method setMethod = classType.getMethod(setMethodName,new Classfield.getType();Object value = getMethod.invoke(object, new Object);setMethod.invoke(objCopy, new Objectvalue);return objCopy;public static void main(String args) throws ExceptionCustomer customer = new Customer(Jack,30);customer.setId(1L);ConstructorTest test = new ConstructorTest();Customer customer2 = (Customer)test.copy(customer);System.out.println(customer2.getId()+ , + customer2.getName() + , + customer2.getAge();使用反射创建数组public class ArrayTest2public static void main(String args)int dims = new int5, 10, 15;Object array = Array.newInstance(Integer.TYPE, dims);Object arrObj = Array.get(array, 3);Class classType = arrObj.getClass().getComponentType();System.out.println(classType);arrObj = Array.get(arrObj , 5);Array.setInt(arrObj, 10, 35);int arrCast = (int)array;System.out.println(arrCast3510);public class ArrayTestpublic static void main(String args) throws ExceptionClass classType = Class.forName(java.lang.String);Object array = Array.newInstance(classType, 10);Array.set(array, 5, Jack);Object val = Array.get(array, 5);System.out.println(val);使用反射调用类里的私有方法：public class PrivateTestpublic static void main(String args) throws ExceptionPerson p = new Person();Class classType = p.getClass();Method method = classType.getDeclaredMethod(sayHello ,new ClassString.class);method.setAccessible(true);/压制java的类型检查Object val = method.invoke(p, new ObjectAlens);System.out.println(val);class Personprivate String sayHello(String name)return Hello, + name;public class PrivateTest2public static void main(String args) throws ExceptionPeople p = new People();Class classType = p.getClass();Field field = classType.getDeclaredField(name);field.setAccessible(true);field.set(p, Li