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>
