JAVA反射机制之Class类API实例介绍 - AJava

JAVA反射机制之Class类API实例介绍- AJavaJAVA反射机制之Class类API实例介绍核心提示：本文针对jdk6.0中ng.Class类的API进行了简单的实例应用，例子简单易懂，比较适合入门级阅读。

实例简介：/* *IncludeInnerClass类中包含了三种访问控制的内部类，并且以这三个内部类的引用对象和一个整型数作为属性，在外部类的方法中分别调用了内部本文针对jdk6.0中ng.Class类的API进行了简单的实例应用，例子简单易懂，比较适合入门级阅读。

实例简介：/**IncludeInnerClass类中包含了三种访问控制的内部类，并且以这三个内部类的引用对象和一个整型数作为属性，在外部类的方法中分别调用了内部类的方法*外部类有两个构造方法，一个默认构造方法，一个带一个整型参数的构造方法*Class类的API大家可以直接查阅jdk手册*getMethods()系列方法基本与getConstructors()系列方法类似，仅在后序文章中对getMethods()系列方法的一个特例做深入介绍，将涉及covariant return type 和bridge methods。

*/package classTest;import ng.reflect.Field;import ng.reflect.Modifier;import ng.reflect.Constructor;import ng.reflect.Method;class IncludeInnerClass implements Runnable{class DefaultInnerClass{int i;public DefaultInnerClass(){}DefaultInnerClass(int i){this.i = i;}void innerMethod(){System.out.println("I am DefaultInnerClass.");}}private class PrivateInnerClass{int i;PrivateInnerClass(){}PrivateInnerClass(int i){this.i = i;}void innerMethod(){System.out.println("I am PrivateInnerClass.");}}public class PublicInnerClass{int i;public PublicInnerClass(){}PublicInnerClass(int i){this.i = i;}void innerMethod(){System.out.println("I am PublicInnerClass.");}}DefaultInnerClass deic;private PrivateInnerClass pric;public PublicInnerClass puic;int i;public IncludeInnerClass(){deic = new DefaultInnerClass(1);pric = new PrivateInnerClass(2);puic = new PublicInnerClass(3);this.i=10;}private IncludeInnerClass(int i){deic = new DefaultInnerClass(1);pric = new PrivateInnerClass(2);puic = new PublicInnerClass(3);this.i=i;}public void method(){deic.innerMethod();pric.innerMethod();puic.innerMethod();}public void run(){method();}}public class GetInnerClassTest {public static void main(String[] args) throws SecurityException{//直接生成外部类的对象，并调用外部类的方法IncludeInnerClass iic = new IncludeInnerClass();System.out.println("regular use of outer class object.");iic.method();System.out.println("+++++++++++++++++++++++++++++ ++++++");//如何生成内部类对象：必须通过外部类实例IncludeInnerClass.DefaultInnerClass iicdic = iic.new DefaultInnerClass(2);System.out.println("regular use of inner class object.");System.out.println(iicdic.i);iicdic.innerMethod();System.out.println("+++++++++++++++++++++++++++++ ++++++");//动态加载外部类并通过getDeclaredClasses()得到其包含的内部类名称Class<?> clc = iic.getClass();Class<?>[] classArray =clc.getDeclaredClasses();System.out.println("print inner class name.");for(int i=0;i<classArray.length;i++){System.out.println(classArray[i].getName());}System.out.println("+++++++++++++++++++++++++++++++++++");//动态加载内部类，调用getDeclaringClass()得到其外部类Class<?> clac = iicdic.getClass();Class<?> outClass =clac.getDeclaringClass();System.out.println("print outer class name.");System.out.println(outClass.getName());//如果没有外部类则返回null，小心空指针异常System.out.println("+++++++++++++++++++++++++++++ ++++++");//得到所在的包Package pack;pack = clc.getPackage();System.out.println("print package name.");System.out.println(pack.getName());System.out.println(pack.equals(clac.getPackage()));//内部类和外部类的包名相同System.out.println("+++++++++++++++++++++++++++++ ++++++");//得到外部类继承的接口Class<?>[] interfaceArray =clc.getInterfaces();System.out.println("print interface name.");for(int i=0;i<interfaceArray.length;i++){System.out.println(interfaceArray[i].getName());}System.out.println("+++++++++++++++++++++++++++++ ++++++");//得到外部类的属性Field[] field = clc.getDeclaredFields();System.out.println("print outer class fields");for(int i=0;i<field.length;i++){System.out.println(Modifier.toString(field[i].getModifiers())+" "+field[i].getType().getName()+" "+field[i].getName());}System.out.println("+++++++++++++++++++++++++++++ ++++++");//得到外部类的指定属性Field f = null;try {f = clc.getDeclaredField("pric");} catch (NoSuchFieldException e) {System.out.println("no such Field.");}System.out.println("print the field we want.");System.out.println(Modifier.toString(f.getModifiers())+" "+f.getType().getName()+" "+f.getName());System.out.println("+++++++++++++++++++++++++++++ ++++++");//得到外部类的所有构造函数及其修饰符和参数：getDeclaredConstructors()得到所有的构造函数Constructor<?>[] allConArray =clc.getDeclaredConstructors();System.out.println("print all constructor of outer class.");for(int i=0;i<allConArray.length;i++){System.out.println("-----------------------------------");System.out.println("print modifier and name");System.out.println(Modifier.toString(allConArray[i].getModi fiers())+" "+allConArray[i].getName());System.out.println("print parameter type");Class<?>[] caparam =allConArray[i].getParameterTypes();for(int j=0;j<caparam.length;j++){System.out.println(caparam[j].getName());}}System.out.println("+++++++++++++++++++++++++++++ ++++++");//得到外部类所有public的构造函数：getConstructor()Constructor<?>[] publicCon =clc.getConstructors();System.out.println("print all public constructor of outer class.");for(int i=0;i<publicCon.length;i++){System.out.println(Modifier.toString(publicCon[i].getModifi ers())+" "+publicCon[i].getName());}System.out.println("+++++++++++++++++++++++++++++ ++++++");//得到指定的外部类构造函数getDeclaredConstructor(Class<?>[])，形参为指定构造函数的参数类型数组Class<?>[] parameterTypes = new Class[1];parameterTypes[0] = int.class;Constructor<?> con = null;try {con =clc.getDeclaredConstructor(parameterTypes);} catch (NoSuchMethodException e) {System.out.println("NO SUCH CONSTURCTOR!!!");}System.out.println("we want the constructor with one parameter.");System.out.println(Modifier.toString(con.getModifiers())+" "+con.getName());System.out.println(con.getParameterTypes()[0].getName() );System.out.println("+++++++++++++++++++++++++++++ ++++++");//Method类与Constructor基本一致，这里不做介绍。