列举java语言中反射的常用方法

2019-08-16 10:51:45来源：博客园阅读 ()

列举java语言中反射的常用方法

package review;
/*12:43 2019/7/21*/

import model.AnotherClass;
import model.OneClassMore;
import model.SomeClass;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * 这个类列举了java语言中关于反射机制的常用的一些方法
 * @author zhangxingshuo
 */
public class AboutReflection {
    public static void main(String[] args) throws Exception {

    }

    /*获得Class对象的3种方式*/
    private static Class<?> getClazz0(String className) throws ClassNotFoundException {
        Class clazz=Class.forName(className);
        return clazz;
    }
    private static Class<?> getClazz1(Object object) {
        Class clazz=object.getClass();
        return clazz;
    }
    private static Class<?> getClazz2() {
        Class clazz=model.SomeClass.class;
        return clazz;
    }

    /*经常使用的Class对象的3个方法*/
    private static String useClazz0(Class clazz) {
        String fullyQualifiedName=clazz.getName();
        return fullyQualifiedName;
    }
    private static String useClazz1(Class clazz) {
        String className=clazz.getSimpleName();
        return className;
    }                                                   //ex:private            //ex:abstract
    private static Object useClazz2(Class clazz) throws IllegalAccessException, InstantiationException {
        Object object=clazz.newInstance();
        return object;
    }

    /*获得Constructor对象的3个方法*/
    private static Constructor<?>[] getConstructorObject0(Class clazz) {
        Constructor<?>[] constructors=clazz.getConstructors();
        return constructors;
    }
    private static Constructor<?>[] getConstructorObject1(Class clazz) {
        Constructor<?>[] constructors=clazz.getDeclaredConstructors();
        return constructors;
    }
    private static Constructor<?> getConstructorObject2(Class clazz) throws NoSuchMethodException {
        Constructor<?> constructor=clazz.getConstructor(SomeClass.class, AnotherClass.class, OneClassMore.class);
        return constructor;
    }
    private static Constructor<?> getConstructorObject3(Class clazz) throws NoSuchMethodException {
        Constructor<?> constructor=clazz.getDeclaredConstructor(SomeClass.class, AnotherClass.class, OneClassMore.class);
        return constructor;
    }

    /*经常使用的Constructor对象的2个方法*/
    private static Object useConstructorObject0(Constructor<?> constructor) throws IllegalAccessException, InvocationTargetException, InstantiationException {
                                //under here,if the variable override==true,jvm willl not check the accessible modifier
        Object object=constructor.newInstance(new SomeClass(),new AnotherClass(),new OneClassMore());
        return object;
    }
    private static void useConstructorObject1(Constructor<?> constructor) {
                                //under here changing "override" variable's value who is defined in AccessibleObject,the "super and super" Class of Constructor
        constructor.setAccessible(true);
    }
    /*还有一些*/
    private static Class<?> useConstructorObject2(Constructor<?> constructor) {
        Class clazz=constructor.getDeclaringClass();
        return clazz;
    }
    private static int useConstructorObject3(Constructor<?> constructor) {
        int modifiers=constructor.getModifiers();
        return modifiers;
    }
    private static String useConstructorObject4(Constructor<?> constructor) {
             //constructor name is same as the class name
        String constructorName = constructor.getName();
                                           //under here getDeclaringClass().getName();
        return constructorName;
    }

    /*获取Field对象的4个方法*/
    private static Field[] getFieldObject0(Class clazz){
        Field[] fields = clazz.getFields();
        return fields;
    }
    private static Field[] getFieldObject1(Class clazz){
        Field[] declaredFields = clazz.getDeclaredFields();
        return declaredFields;
    }
    private static Field getFieldObject2(Class clazz) throws NoSuchFieldException {
        Field field = clazz.getField("theFieldName");
        return field;
    }
    private static Field getField3(Class clazz) throws NoSuchFieldException {
        Field field = clazz.getDeclaredField("theFieldName");
        return field;
    }

    /*经常使用的Field对象的3个方法*/
    private static Object useFieldObject0(Field field,Object object) throws IllegalAccessException {
        Object fieldValue = field.get(object);
        return fieldValue;
    }
    private static void useFieldObject1(Field field,Object object) throws IllegalAccessException {
                       //an object as the field value
        field.set(object,new Object());
    }
    private static void useFieldObject2(Field field){
                          //same process
        field.setAccessible(true);
    }
    /*还有一些*/
    private static int useFieldObject3(Field field){
        int modifiers = field.getModifiers();
        return modifiers;
    }
    private static String useFieldObject4(Field field){
        String fieldName = field.getName();
        return fieldName;
    }

    /*获取Method对象的4个方法*/
    private static Method[] getMethodObject0(Class clazz){
        Method[] methods=clazz.getMethods();
        return methods;
    }
    private static Method[] getMethodObject1(Class clazz){
        Method[] methods=clazz.getDeclaredMethods();
        return methods;
    }
    private static Method getMethodObject2(Class clazz) throws NoSuchMethodException {
        Method method=clazz.getMethod("someMethodName",SomeClass.class,AnotherClass.class,OneClassMore.class);
        return method;
    }
    private static Method getMethodObject3(Class clazz) throws NoSuchMethodException {
        Method method=clazz.getDeclaredMethod("someMethodName",SomeClass.class,AnotherClass.class,OneClassMore.class);
        return method;
    }

    /*经常使用的Field对象的2个方法*/
    private static Object useMethodObject0(Method method,Object object) throws InvocationTargetException, IllegalAccessException {
        Object returnedobject=method.invoke(object,new SomeClass(),new AnotherClass(),new OneClassMore());
        return returnedobject;
    }
    private static void useMethodObject1(Method method){
        method.setAccessible(true);
    }
    /*还有一些*/
    private static int useMethodObject2(Method method){
        int modifiers = method.getModifiers();
        return modifiers;
    }
    private static String useMethodObject3(Method method){
        String methodName = method.getName();
        return methodName;
    }

    /*
    tips
    通过getMethods(),得到一个数组,里面是该类或接口独有的,和继承自它的所有父类与接口的public方法.
    通过getDeclaredMethods(),得到一个数组,里面是该类或接口独有的所有方法,(包括public和非public).
    */
    /*just as a empty template for convenience*/
    private static void m(){

    }
}