创建型模式
:对象的创建(6)
结构型模式
:对象的组成(结构)(7)
行为型模式
:对象的行为(10)
静态工厂方法模式
,它定义一个具体的工厂类负责创建一些类的实例public class AnimalDemo {
public static void main(String[] args) {
// 具体类调用
Dog d = new Dog();
d.eat();
Cat c = new Cat();
c.eat();
System.out.println("------------");
// 工厂有了后,通过工厂给造
// Dog dd = AnimalFactory.createDog();
// Cat cc = AnimalFactory.createCat();
// dd.eat();
// cc.eat();
// System.out.println("------------");
// 工厂改进后
Animal a = AnimalFactory.createAnimal("dog");
a.eat();
a = AnimalFactory.createAnimal("cat");
a.eat();
// NullPointerException
a = AnimalFactory.createAnimal("pig");
if (a != null) {
a.eat();
} else {
System.out.println("对不起,暂时不提供这种动物");
}
}
}
public abstract class Animal {
public abstract void eat();
}
public class Cat extends Animal {
@Override
public void eat() {
System.out.println("猫吃鱼");
}
}
public class Dog extends Animal {
@Override
public void eat() {
System.out.println("狗吃肉");
}
}
public class AnimalFactory {
private AnimalFactory() {
}
// public static Dog createDog() {
// return new Dog();
// }
//
// public static Cat createCat() {
// return new Cat();
// }
public static Animal createAnimal(String type) {
if ("dog".equals(type)) {
return new Dog();
} else if ("cat".equals(type)) {
return new Cat();
} else {
return null;
}
}
}
工厂方法模式中抽象工厂类
负责定义创建对象的接口,具体对象的创建工作由继承抽象工厂的具体类实现。
优点
缺点
public class AnimalDemo {
public static void main(String[] args) {
// 需求:我要买只狗
Factory f = new DogFactory();
Animal a = f.createAnimal();
a.eat();
System.out.println("-------");
//需求:我要买只猫
f = new CatFactory();
a = f.createAnimal();
a.eat();
}
}
public abstract class Animal {
public abstract void eat();
}
public interface Factory {
public abstract Animal createAnimal();
}
public class Dog extends Animal {
@Override
public void eat() {
System.out.println("狗吃肉");
}
}
public class DogFactory implements Factory {
@Override
public Animal createAnimal() {
return new Dog();
}
}
public class Cat extends Animal {
@Override
public void eat() {
System.out.println("猫吃鱼");
}
}
public class CatFactory implements Factory {
@Override
public Animal createAnimal() {
return new Cat();
}
}
单例模式就是要确保类在内存中只有一个对象,该实例必须自动创建,并且对外提供。
优点
缺点
如何保证类在内存中只有一个对象呢?
public class StudentDemo {
public static void main(String[] args) {
// Student s1 = new Student();
// Student s2 = new Student();
// System.out.println(s1 == s2); // false
// 通过单例如何得到对象呢?
// Student.s = null;
Student s1 = Student.getStudent();
Student s2 = Student.getStudent();
System.out.println(s1 == s2);
System.out.println(s1); // null,cn.itcast_03.Student@175078b
System.out.println(s2);// null,cn.itcast_03.Student@175078b
}
}
public class Student {
// 构造私有,不让外界构造对象。
private Student() {
}
// 自己造一个
// 静态方法只能访问静态成员变量,加静态
// 为了不让外界直接访问修改这个值,加private
private static Student s = new Student();
// 提供公共的访问方式
// 为了保证外界能够直接使用该方法,加静态
public static Student getStudent() {
return s;
}
}
public class TeacherDemo {
public static void main(String[] args) {
Teacher t1 = Teacher.getTeacher();
Teacher t2 = Teacher.getTeacher();
System.out.println(t1 == t2);
System.out.println(t1); // cn.itcast_03.Teacher@175078b
System.out.println(t2);// cn.itcast_03.Teacher@175078b
}
}
public class Teacher {
private Teacher() {
}
private static Teacher t = null;
public synchronized static Teacher getTeacher() {
// t1,t2,t3
if (t == null) {
//t1,t2,t3
t = new Teacher();
}
return t;
}
}
1,什么是代理模式?
代理模式的作用是:为其他对象提供一种代理以控制对这个对象的访问。
2,代理模式有什么好处?
在某些情况下,一个客户不想或者不能直接引用另一个对象,而代理对象可以在客户端和目标对象之间起到中介的作用。
3,代理模式一般涉及到的角色有:
public abstract class AbstractObject {
//操作
public abstract void operation();
}
public class RealObject extends AbstractObject {
@Override
public void operation() {
//一些操作
System.out.println("一些操作");
}
}
public class ProxyObject extends AbstractObject{
RealObject realObject = new RealObject();
@Override
public void operation() {
//调用目标对象之前可以做相关操作
System.out.println("before");
realObject.operation();
//调用目标对象之后可以做相关操作
System.out.println("after");
}
}
public class Client {
public static void main(String[] args) {
// TODO Auto-generated method stub
AbstractObject obj = new ProxyObject();
obj.operation();
}
}
public class ForDemo extends GetTime {
@Override
public void code() {
for (int x = 0; x < 100000; x++) {
System.out.println(x);
}
}
}
public abstract class GetTime {
// 需求:请给我计算出一段代码的运行时间
public long getTime() {
long start = System.currentTimeMillis();
code();
long end = System.currentTimeMillis();
return end - start;
}
public abstract void code();
}
public class GetTimeDemo {
public static void main(String[] args) {
// GetTime gt = new GetTime();
// System.out.println(gt.getTime() + "毫秒");
GetTime gt = new ForDemo();
System.out.println(gt.getTime() + "毫秒");
gt = new IODemo();
System.out.println(gt.getTime() + "毫秒");
}
}
public class IODemo extends GetTime{
@Override
public void code() {
try {
BufferedInputStream bis = new BufferedInputStream(
new FileInputStream("a.avi"));
BufferedOutputStream bos = new BufferedOutputStream(
new FileOutputStream("b.avi"));
byte[] bys = new byte[1024];
int len = 0;
while ((len = bis.read(bys)) != -1) {
bos.write(bys, 0, len);
}
bos.close();
bis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public interface Phone {
public abstract void call();
}
public class IPhone implements Phone {
@Override
public void call() {
System.out.println("手机可以打电话了");
}
}
public class MusicPhoneDecorate extends PhoneDecorate {
public MusicPhoneDecorate(Phone p) {
super(p);
}
@Override
public void call() {
super.call();
System.out.println("手机可以听音乐");
}
}
public class RingPhoneDecorate extends PhoneDecorate {
public RingPhoneDecorate(Phone p) {
super(p);
}
@Override
public void call() {
System.out.println("手机可以听彩铃");
super.call();
}
}
public abstract class PhoneDecorate implements Phone {
private Phone p;
public PhoneDecorate(Phone p) {
this.p = p;
}
@Override
public void call() {
this.p.call();
}
}
public class PhoneDemo {
public static void main(String[] args) {
Phone p = new IPhone();
p.call();
System.out.println("------------");
// 需求:我想在接电话前,听彩铃
PhoneDecorate pd = new RingPhoneDecorate(p);
pd.call();
System.out.println("------------");
// 需求:我想在接电话后,听音乐
pd = new MusicPhoneDecorate(p);
pd.call();
System.out.println("------------");
// 需求:我要想手机在接前听彩铃,接后听音乐
// 自己提供装饰类,在打电话前听彩铃,打电话后听音乐
pd = new RingPhoneDecorate(new MusicPhoneDecorate(p));
pd.call();
System.out.println("----------");
// 想想我们在IO流中的使用
// InputStream is = System.in;
// InputStreamReader isr = new InputStreamReader(is);
// BufferedReader br = new BufferedReader(isr);
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter bw = new BufferedWriter((new OutputStreamWriter(
System.out)));
Scanner sc = new Scanner(System.in);
}
}
/*
* 问题:
* 接口(方法比较多) -- 实现类(仅仅使用一个,也得把其他的实现给提供了,哪怕是空实现)
* 太麻烦了。
* 解决方案:
* 接口(方法比较多) -- 适配器类(实现接口,仅仅空实现) -- 实现类(用哪个重写哪个)
*/
public class UserDaoDemo {
public static void main(String[] args) {
UserDao ud = new UserDaoImpl();
ud.add();
// 我没有说我们需要四种功能都实现啊。
UserDao ud2 = new UserDaoImpl2();
ud2.add();
}
}
public abstract class UserAdapter implements UserDao {
@Override
public void add() {
}
@Override
public void delete() {
}
@Override
public void update() {
}
@Override
public void find() {
}
}
public class UserDaoImpl2 extends UserAdapter {
@Override
public void add() {
System.out.println("添加功能");
}
}