Java 反射

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反射：java反射就是在运行时动态获取类的各个组成部分的信息，包括属性、方法、构造方法、注解、接口、父类等。
这里以ReflectClass类为例,以下是一个放射类的操作实例：
package util;import model.MethodInfo;import model.Test;import java.lang.annotation.Annotation;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;/** * 注：ReflectClass reflectClass = new ReflectClass();      reflectClass.initClass("model.App");      reflectClass.initConstructor();      reflectClass.initObject();      reflectClass.getAnnotationInfos(); */public class ReflectClass {    /**     * 即将要被反射的Class对象     */    private Class<?> mClazz;    /**     * 被放射对象的实例     */    private Object mObj;    /**     * 构造函数对象     */    private Constructor<?> constructor;    public ReflectClass(){}    /**     * 初始化反射类的Class对象，并实例化     * @param className     */    public void initClass(String className) throws Exception {        mClazz = Class.forName(className);    }    /**     * 获取构造函数对象     * @param paramTypes     * @throws Exception     */    public void initConstructor(Class<?>... paramTypes) throws Exception {        constructor = mClazz.getConstructor(paramTypes);    }    public void initObject(String... param) throws Exception {        mObj = constructor.newInstance(param);    }    public Object invoke(String methodName,Object... args) throws Exception {        Method method = mClazz.getDeclaredMethod(methodName);        return method.invoke(mObj,args);    }    /**     * 为属性设置值     * @param name     * @param grade     * @throws Exception     */    public void setField(String name,int grade) throws Exception {        Field field = mClazz.getDeclaredField("mGrade");        field.setAccessible(true);        field.set(mObj,grade);    }    /**     * 获取父类     */    public void getSuperClass(){        Class<?> superClass = mClazz.getSuperclass();        while(superClass !=null){            System.out.println(superClass.getName());            superClass = superClass.getSuperclass();        }    }    /**     * 获取接口     */    public void showInterface(){        Class<?>[] interfaces = mClazz.getInterfaces();        for(Class<?> i : interfaces){            System.out.println(i.getName());        }    }    public void getAnnotationInfos() throws Exception {        Method method = mClazz.getMethod("getAppName");        Annotation[] annotations = method.getAnnotations();        for(Annotation annotation : annotations){            if(method.isAnnotationPresent(MethodInfo.class)){                MethodInfo methodInfo = (MethodInfo) annotation;                System.out.println(methodInfo.author());                System.out.println(methodInfo.date());                System.out.println(methodInfo.version());            }        }    }    public void showFields(){        Field[] fields = mClazz.getFields();        //获取当前类以及父类的所有公有属性        for(Field f : fields){            System.out.println(f.getName());        }    }    public void setFieldFromAnnotation()throws Exception{        //获取私有的属性(包括private、protected),只能获取当前类        Field field = mClazz.getSuperclass().getDeclaredField("mName");        field.setAccessible(true);        Test test = field.getAnnotation(Test.class);//        Object obj = mClazz.getSuperclass().getConstructor().newInstance();        field.set(mObj,test.name());    }}
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