Class Object的使用

 import  java.lang.reflect.Constructor;
 import  java.lang.reflect.Field;
 import  java.lang.reflect.Method;
 import  java.lang.reflect.Modifier;
 import  java.util.HashMap;

 public   class  TestRef   {

     public   static   void  main(String[] args)  throws  Exception  {
        TestRef testRef  =   new  TestRef();
        Class clazz  =  TestRef. class ;
        System.out.println( " getPackage() =  "   +  clazz.getPackage().getName());
        //  getModifiers()的返回值可以包含类的种类信息。比如是否为public,abstract,static 
        int  mod  =  clazz.getModifiers();
        System.out.println( " Modifier.isAbstract(mod) =  " + Modifier.isAbstract(mod));
        System.out.println( " getName() =  " + clazz.getName());
        System.out.println( " getSuperclass() =  " + clazz.getSuperclass().getName());
        System.out.println( " getInterfaces() =  " + clazz.getInterfaces()); // 实现了哪些Interface 
        System.out.println( " clazz.getDeclaredClasses() =  " + clazz.getDeclaredClasses()); // 包含哪些内部类 
        System.out.println( " getDeclaringClass() =  " + clazz.getDeclaringClass()); // 如果clazz是inner class 那么返回其outer class 
         
        System.out.println( " ---------- " );
        Constructor[] constructor  =  clazz.getDeclaredConstructors(); // 返回一组构造函数 Constructor[] 
           if  (constructor  !=   null )  {
             for  ( int  i  =   0 ; i  <  constructor.length; i ++ )   {
                System.out.println(constructor[i].getName());
            } 
        } 
        
        System.out.println( " ---------- " );
        Method[] method  =  clazz.getDeclaredMethods();  //  Method[] 
           if  (method  !=   null )  {
             for  ( int  i  =   0 ; i  <  method.length; i ++ )   {
                System.out.println(method[i].getName());
            } 
        } 
        
        System.out.println( " ---------- " );
        Field[] field  =  clazz.getDeclaredFields();  //  Field[] 
           if  (field  !=   null )  {
             for  ( int  i  =   0 ; i  <  field.length; i ++ )   {
                System.out.println(field[i].getName());
                System.out.println(field[i].getType().getName());
                System.out.println(field[i].get(testRef));
            } 
        } 
        
        //  动态生成instance(无参数) 
        Class clz  =  Class.forName( " reflection.TestRef " );
        Object obj  =  clz.newInstance();
        System.out.println(((TestRef)obj).getStr());
        
        //  动态生成instance(有参数) 
         Class[] params  =   new  Class[]  {String. class ,  int . class ,  double . class } ;
        Constructor construct  =  clz.getConstructor(params);
        //  JDK1.5的情况下可以直接用{"haha",999,100.01}作为参数         
         Object obj2  =  construct.newInstance( new  Object[]  { " haha " ,  new  Integer( 999 ),  new  Double( 100.01 )} ); 
        System.out.println(((TestRef)obj2).getStr());
        
        //  动态调用method(public method) 
         Class[] params2  =   new  Class[]  {String. class } ;
        Method methods  =  clz.getMethod( " setStr " , params2);
        methods.invoke(testRef,  new  Object[]  { " invoke method " } );
        System.out.println(testRef.getStr());
        
        //  动态改变field内容(public field) 
        Field fields  =  clz.getField( " str " );
        fields.set(testRef,  " set field's value " );
        System.out.println(testRef.getStr());
        
    } 
 
     public  TestRef()  {
        System.out.println( " --- complete TestRef() --- " );
    } 
    
    public  TestRef(String str,  int  i,  double  d)  {
         this .str  =  str;
         this .i  =  i;
         this .d  =  d;
        System.out.println( " --- complete TestRef(String str, int i, double d) --- " );
    } 
    
    public  String str  =   " I'm a string " ;

    int  i  =   1 ;

    double  d  =   3.14 ;

    HashMap map  =   new  HashMap();

     public   double  getD()   {
         return  d;
    } 
 
      public   void  setD( double  d)   {
         this .d  =  d;
    } 
 
      public   int  getI()   {
         return  i;
    } 
 
      public   void  setI( int  i)   {
         this .i  =  i;
    } 
 
      public  HashMap getMap()   {
         return  map;
    } 
 
      public   void  setMap(HashMap map)   {
         this .map  =  map;
    } 
 
      public  String getStr()   {
         return  str;
    } 
 
      public   void  setStr(String str)   {
         this .str  =  str;
    } 
}