ToBeReflact.java

package com.testcases.reflaction;

/**
 * Created by shiyanghuang on 16/3/2.
 */
public class ToBeReflact {
    private String name;

    ToBeReflact() { this.name = "Default"; }
    ToBeReflact(String name) {
        this.name = name;
    }

    private void setName(String name)
    {
        this.name = name;
    }

    private String getName() {
        return this.name;
    }
}

ReflactionClass.java

package com.testcases.reflaction;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * Created by shiyanghuang on 16/3/2.
 */
public class ReflactionClass {

    public static void main(String[] args) throws IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException {

        Class classtype = ToBeReflact.class;
        Object toBeReflact = classtype.newInstance();

        Method setNameMethod = classtype.getDeclaredMethod("setName", new Class[] {String.class});
        setNameMethod.setAccessible(true);
        Object invoke1 = setNameMethod.invoke(toBeReflact, "qwer");

        Method getNameMethod = classtype.getDeclaredMethod("getName", null);
        getNameMethod.setAccessible(true);
        Object invoke2 = getNameMethod.invoke(toBeReflact, null);
        System.out.print(invoke2);

    }
}

参考：
http://stackoverflow.com/questions/880365/any-way-to-invoke-a-private-method
http://blog.csdn.net/cuiran/article/details/5302074