使用Java反射机制实现访问类中的私有变量或者方法

import java.lang.reflect.Field;
import java.lang.reflect.Method;

public class ReflectDemo {

    public static void main(String[] args) throws Exception {

        PrivateTest t = new PrivateTest();
        Field field = Class.forName("com.test.PrivateTest").getDeclaredField(
                "str");
        // 不让Java语言检查访问修饰符
        field.setAccessible(true);
        field.set(t, "world");
        t.getStr();

        Method method2 = Class.forName("com.test.PrivateTest")
                .getDeclaredMethod("method", new Class[] {});
        method2.setAccessible(true);
        method2.invoke(t, new Object[] {});

    }
}

class PrivateTest {
    private String str = "hello";

    public void getStr() {
        System.out
                .println("I'm str,I'm a private field,my old value is hello,now I am --->"
                        + str);
    }

    private void method() {
        System.out.println("I'm in a private method!");
    }
}

--------------结果---------------------
I'm str,I'm a private field,my old value is hello,now I am --->world
I'm in a private method!