Java訪問類中private屬性和方法

建一個測試類A:

1. package com.shao.test;
3. public class A {
4. private String testStr="just for test";
5. private void get(int index,String value){
6. System.out.println(index+":"+value+" and testStr:"+testStr);
7. }
8. }

現在我們來訪問A中的testStr屬性和get方法：

1. package com.shao.test;
3. import java.lang.reflect.Field;
4. import java.lang.reflect.InvocationTargetException;
5. import java.lang.reflect.Method;
7. public class B {
8. public static void main(String[]args) throws ClassNotFoundException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException, NoSuchMethodException, InvocationTargetException{
9. Field field=Class.forName("com.shao.test.A").getDeclaredField("testStr");
10. field.setAccessible(true);
11. A a=new A();
12. System.out.println(field.getType().toString()); //print:class java.lang.String
13. System.out.println(field.getName()); //print:testStr
14. System.out.println(field.getModifiers()); //print:2
15. Object s=field.get(a);
16. System.out.println(s); //print:just for test
17. String x="Hello";
18. field.set(a, x);
19. System.out.println(field.get(a)); //print:Hello
20. Method method=Class.forName("com.shao.test.A").getDeclaredMethod("get", new Class[]{int.class,String.class});
21. method.setAccessible(true);
22. method.invoke(a, 3,"apples"); //print:3:apples and testStr:Hello
23. }
24. }