以下是我总结的一些简略的JAVA反射相干的小例子，非常简单，一看您就明确了，有什么问题您评论，我解答。
根底bean
public class Person { public int age; public 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; } public Person(String name,int age) { this.age = age; this.name = name; } public Person() { }}三种获取Class的形式
//第一种Class<?> helloClass = "hello".getClass();Class<? extends String> helloClassNew = "hello".getClass();Class<? extends Object> helloClassNew2 = "hello".getClass();//第二种Class<?> stringClass = String.class;//第三种String className ="java.lang.String";Class<?> stringClassNew = Class.forName(className);获取父类型以及实现的接口类型
Class<?> superClass = stringClass.getSuperclass();Class<?>[] interfaces = stringClass.getInterfaces();获取类的字段
Class<?> clss = Person.class;Field field = clss.getField("age");//获取该类也同时包含父类型的全副public字段Field[] declaredFields = clss.getDeclaredFields();//获取该类外部的全副字段，无论private还是publicField[] fields = clss.getFields();获取办法
Method method =clss.getMethod("setName", String.class);//获取该类也同时包含父类型的全副public办法Method[] declaredMethods = clss.getDeclaredMethods();//获取所有该类外部的method，无论private还是publicMethod[] methods = clss.getMethods();获取构造函数
Constructor<?> constructor = clss.getConstructor(Class<?> ..types);//获取该类外部的所有构造函数Constructor<?>[] declaredConstructor = clss.getDeclaredConstructors();//获取该类外部的所有public构造函数Constructor<?>[] constructors = clss.getConstructors();获取润饰
int modifiers = constructor.getModifiers();boolean isPublic = Modifier.isPublic(modifiers);设置字段为public的值，字段age为publicPerson person = new Person();Class<?> o = person.getClass();Field field = o.getDeclaredField("age");field.set(person,"d");System.out.println(person.getAge());//输入d设置字段为private的值，字段name为private，须要减少setAccessible为true，如果不设置为true则会报IllegalAccessException
Person person = new Person();Class<?> o = person.getClass();Field field = o.getDeclaredField("name");field.setAccessible(true);field.set(person,"d");System.out.println(person.getName());通过获取字段的注解，做操作。
Person person = new Person();Class<?> o = person.getClass();Field[] fields = o.getDeclaredFields();for(Field field:fields){ if(field.getAnnotatedType(PrimaryKey.class) !=null){ //this is the primary key } if(field.getAnnotatedType(Column.class) !=null){ //this is an elment to read / write }}通过MethodHandles获取类
MethodHandles.Lookup lookup = MethodHandles.lookup();Class<?> personClass = MethodHandles.lookup().findClass(Person.class.getName()); 创立四种method
//getter办法MethodType getterType = MethodType.methodType(String.class);MethodHandle getterHandle = lookup.findVirtual(Person.class,"getName",getterType);//setter办法MethodType setterType = MethodType.methodType(void.class,String.class);MethodHandle setterHandle = lookup.findVirtual(Person.class,"setName",setterType);//构造方法MethodType constructorType = MethodType.methodType(void.class,String.class,int.class);MethodHandle constructorHandle = lookup.findConstructor(Person.class, constructorType);//空构造方法MethodType emptyConstructorType = MethodType.methodType(void.class);MethodHandle emptyConstructorHandle = lookup.findConstructor(Person.class,emptyConstructorType);通过invoke创立bean
MethodType constructorType = MethodType.methodType(void.class,String.class,int.class);MethodHandle constructorHandle = lookup.findConstructor(Person.class, constructorType);Person p = (Person)constructorHandle.invoke("Xuesong",33);System.out.println(p);//输入Person{age=33, name='Xuesong'}MethodType emptyConstructorType = MethodType.methodType(void.class);MethodHandle emptyConstructorHandle = lookup.findConstructor(Person.class,emptyConstructorType);Person p2 = (Person)emptyConstructorHandle.invoke();System.out.println(p2);//输入Person{age=0, name='null'}通过invoke调用getter和setter
MethodHandle nameReader = lookup.findGetter(Person.class, "name", String.class);MethodHandle nameWriter = lookup.findSetter(Person.class,"name",String.class);Person person = new Person("Xuesong",33);String name = (String) nameReader.invoke(person);//或者//String name = (String) getterHandle.invoke(person);System.out.println(name);//输入XuesongnameWriter.invoke(person,"John");//或者//setterHandle.invoke(person,"John");System.out.println(person.getName());//输入John针对private的字段须要非凡解决
Field nameField = Person.class.getDeclaredField("name");nameField.setAccessible(true);MethodHandle privateNameReader = lookup.unreflectGetter(nameField);String name = (String) privateNameReader.invoke(person);System.out.println(name);MethodHandle privateNameWriter = lookup.unreflectSetter(nameField);privateNameWriter.invoke(person,"John");System.out.println(person.getName());//JDK9当前的形式Lookup privateLookup = MethodHandles.privateLookupIn(Person.class, lookup);MethodHandle privateNameWriter = privateLookup.findSetter(Person.class,"name",String.class);privateNameWriter.invoke(person, "John");JDK9当前减少了线程平安的一种VarHandle，也能够解决
VarHandle nameVarHandle = MethodHandles.privateLookupIn(Person.class,lookup) .findVarHandle(Person.class,"name",String.class);String name = (String) nameVarHandle.get(person);String name = (String) nameVarHandle.getVolatile(person);