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 {@Overrideprotected 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;}@Overridepublic 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>

更多相关文章

随机推荐