Android中Java反射技术的使用示例

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());  
        }  
      
    }

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);  
        }  
          
    }

main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
        xmlns:tools="http://schemas.android.com/tools"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        >  
      
        <TextView  
            android:layout_width="wrap_content"  
            android:layout_height="wrap_content"  
            android:text="Android中Java反射技术的使用"   
            android:layout_centerInParent="true"/>  
      
    </RelativeLayout>