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如下:

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);
	}
    
}

main.xml如下:

<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>