学步园

package my;<br /> import java.lang.reflect.Constructor;<br /> import java.lang.reflect.Field;<br /> import java.lang.reflect.InvocationTargetException;<br /> import java.lang.reflect.Method;<br /> public class Start {<br /> public static void main(String[] args) {<br /> try {<br /> Class dataType = Class.forName("my.Data");<br /> // 访问私用的构造方法来创建对象实例<br /> Constructor constructor = dataType<br /> .getDeclaredConstructor(new Class[] { int.class,<br /> String.class });<br /> constructor.setAccessible(true);//访问私有成员方法，这句很关键<br /> Data data = (Data) constructor.newInstance(new Object[] {<br /> new Integer(50), new String("hello") });<br /> // 开始访问私有的静态方法showData来打印对象信息<br /> Method showDataMethod = dataType.getDeclaredMethod("showData",<br /> new Class[] {});<br /> showDataMethod.setAccessible(true);<br /> showDataMethod.invoke(null, new Object[] {});//output:Data is:50</p> <p> //开始访问私有方法showName来打印对象信息<br /> Method showNameMethod = dataType.getDeclaredMethod("showName",<br /> new Class[] {});<br /> showNameMethod.setAccessible(true);<br /> showNameMethod.invoke(data, new Object[] {});//output:Name is:hello<br /> // 开始访问的setData方法来更改对象信息<br /> Method setDataMethod = dataType.getDeclaredMethod("setData",<br /> new Class[] { int.class });<br /> setDataMethod.setAccessible(true);<br /> setDataMethod.invoke(data, new Object[]{new Integer(100)});//设置data域 为100</p> <p> //开始访问静态私有的成员变量<br /> Field dataField = dataType.getDeclaredField("data");<br /> dataField.setAccessible(true);<br /> System.out.println(dataField.getInt(data));//output:100<br /> dataField.setInt(null, 200);//再次修改私有成员data的值<br /> System.out.println(dataField.getInt(data));//output:200</p> <p> //开始访问私有成员变量<br /> Field nameField = dataType.getDeclaredField("name");<br /> nameField.setAccessible(true);<br /> nameField.set(data,new String("Fuck!"));//修改私有变量name的值<br /> showNameMethod.invoke(data, new Object[] {});//Name is:Fuck!</p> <p> } catch (ClassNotFoundException e) {<br /> e.printStackTrace();<br /> } catch (SecurityException e) {<br /> e.printStackTrace();<br /> } catch (NoSuchMethodException e) {<br /> e.printStackTrace();<br /> } catch (IllegalArgumentException e) {<br /> e.printStackTrace();<br /> } catch (InstantiationException e) {<br /> e.printStackTrace();<br /> } catch (IllegalAccessException e) {<br /> e.printStackTrace();<br /> } catch (InvocationTargetException e) {<br /> e.printStackTrace();<br /> } catch (NoSuchFieldException e) {<br /> e.printStackTrace();<br /> }<br /> }<br /> }<br /> package my;<br /> public class Data {<br /> private static int data;<br /> private String name;<br /> private Data(){</p> <p> }<br /> private Data(int data,String name){<br /> this.data = data;<br /> this.name = name;<br /> }<br /> private void showName(){<br /> System.out.println("Name is:"+name);<br /> }<br /> private static void showData(){<br /> System.out.println("Data is:"+getData());<br /> }<br /> private static int getData(){<br /> return data;<br /> }<br /> private void setData(int data){<br /> this.data = data;<br /> }<br /> private void setString(String name){<br /> this.name = name;<br /> }<br /> }