Android中Java反射技术的使用示例

MainActivity如下::

package cn.testreflect;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import android.os.Bundle;
import android.app.Activity;
/**
 * Demo描述:
 * Android中Java反射技术的使用示例
 * 在Java中描述字节码文件(xxx.class)的类叫Class
 * 反射的过程可视为剖析Class的过程
 */
public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        init();
    }
    private void init(){
        try {
            /**
             * 1 反射出无参的构造方法并得到对象
             * 注意:
             *      1 在Class.forName()中应该传入含有包名的类全名
             *      2 newInstance()方法的本质是调用类的无参Public构造方法
             */
            String className1="cn.testreflect.Worker";
            Class clazz1=Class.forName(className1);
            Object object1=clazz1.newInstance();
            System.out.println("object1.toString()="+object1.toString());

            /**
             * 2 反射出带参数的构造方法并得到对象
             */
            String className2="cn.testreflect.Worker";
            Class clazz2=Class.forName(className2);
            Constructor constructor1=clazz2.getConstructor(int.class,String.class);
            Object object2=constructor1.newInstance(18,"小明");
            System.out.println("object2.toString()="+object2.toString());

            /**
             * 3 获取类的私有字段
             * 注意:
             *      获取共有字段应调用clazz3.getField(name)方法
             */
            String className3="cn.testreflect.Worker";
            Class clazz3=Class.forName(className3);
            Field ageField1=clazz3.getDeclaredField("age");
            System.out.println("ageField1="+ageField1);

            /**
             * 4 获取和更改某个对象的私有字段
             *   即模拟get()和set()方法
             */
            String className4="cn.testreflect.Worker";
            Class clazz4=Class.forName(className4);
            Field ageField2=clazz4.getDeclaredField("age");
            Object object4=constructor1.newInstance(18,"小明");
            //取消访问私有字段的合法性检查
            ageField2.setAccessible(true);
            //获取对象的私有字段
            Object ageObject4=ageField2.get(object4);
            System.out.println("ageObject4="+ageObject4);

            //再更改对象的私有字段的值
            ageField2.set(object4, 9527);
            //重新获得
            Object ageObject5=ageField2.get(object4);
            System.out.println("ageObject5="+ageObject5);

            /**
             * 5 调用对象的带参数的方法
             */
            String className5="cn.testreflect.Worker";
            Class clazz5=Class.forName(className5);
            Method method=clazz5.getMethod("printMessage", String.class,int.class,int.class);
            Object object5=clazz5.newInstance();
            method.invoke(object5, "周星星",50,9527);


        } catch (Exception e) {
            System.out.println(e.toString());
        }

    }

}

Worker.java:

package cn.testreflect;

public class Worker {
    private int age;
    private String name;
    public Worker() {
        super();
        System.out.println("---> public Worker(){ }");
    }
    public Worker(int age, String name) {
        super();
        this.age = age;
        this.name = name;
        System.out.println("---> public Worker(int age, String name){ }");
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "Worker [age=" + age + ", name=" + name + "]";
    }

    public void printMessage(String name,int age,int salary){
        System.out.println("name="+name+",age="+age+",salary="+salary);
    }

}