十、代理模式 Proxy

• 静态代理
• 动态代理
• Sping AOP
  

import java.util.Random;

/**
 * 问题：我想记录坦克的移动时间
 * 最简单的办法：修改代码，记录时间
 * 问题2：如果无法改变方法源码呢？
 * 用继承？
 * v05:使用代理
 */
public class Tank implements Movable {

    /**
     * 模拟坦克移动了一段儿时间
     */
    @Override
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        new TankTimeProxy(new Tank()).move();
    }
}

class TankTimeProxy implements Movable {

    Tank tank;

    public TankTimeProxy(Tank tank) {
        this.tank = tank;
    }

    @Override
    public void move() {
        long start = System.currentTimeMillis();
        tank.move();
        long end = System.currentTimeMillis();
        System.out.println(end - start);
    }
}

interface Movable {
    void move();
}

import java.util.Random;

/**
 * 问题：我想记录坦克的移动时间
 * 最简单的办法：修改代码，记录时间
 * 问题2：如果无法改变方法源码呢？
 * 用继承？
 * v05:使用代理
 * v06:代理有各种类型
 * 问题：如何实现代理的各种组合？继承？Decorator?
 */
public class Tank implements Movable {

    /**
     * 模拟坦克移动了一段儿时间
     */
    @Override
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        new TankTimeProxy().move();
    }
}

class TankTimeProxy implements Movable {
    Tank tank;
    @Override
    public void move() {
        long start = System.currentTimeMillis();
        tank.move();
        long end = System.currentTimeMillis();
        System.out.println(end - start);
    }
}

//日志代理
class TankLogProxy implements Movable {
    Tank tank;
    @Override
    public void move() {
        System.out.println("start moving...");
        tank.move();
        System.out.println("stopped!");
    }
}

interface Movable {
    void move();
}

• 静态代理

import java.util.Random;

/**
 * 问题：我想记录坦克的移动时间
 * 最简单的办法：修改代码，记录时间
 * 问题2：如果无法改变方法源码呢？
 * 用继承？
 * v05:使用代理
 * v06:代理有各种类型
 * 问题：如何实现代理的各种组合？继承？Decorator?
 * v07:代理的对象改成Movable类型-越来越像decorator了
 *
 */
public class Tank implements Movable {

    /**
     * 模拟坦克移动了一段儿时间
     */
    @Override
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {

        Tank t = new Tank();
        TankTimeProxy ttp = new TankTimeProxy(t);
        TankLogProxy tlp = new TankLogProxy(ttp);
        tlp.move();

//        new TankLogProxy(
//                new TankTimeProxy(
//                        new Tank()
//                )
//        ).move();
    }
}

class TankTimeProxy implements Movable {
    Movable m;

    public TankTimeProxy(Movable m) {
        this.m = m;
    }

    @Override
    public void move() {
        long start = System.currentTimeMillis();
        m.move();
        long end = System.currentTimeMillis();
        System.out.println(end - start);
    }
}

class TankLogProxy implements Movable {
    Movable m;

    public TankLogProxy(Movable m) {
        this.m = m;
    }

    @Override
    public void move() {
        System.out.println("start moving...");
        m.move();
        long end = System.currentTimeMillis();
        System.out.println("stopped!");
    }
}

interface Movable {
    void move();
}

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Random;

/**
 * 问题：我想记录坦克的移动时间
 * 最简单的办法：修改代码，记录时间
 * 问题2：如果无法改变方法源码呢？
 * 用继承？
 * v05:使用代理
 * v06:代理有各种类型
 * 问题：如何实现代理的各种组合？继承？Decorator?
 * v07:代理的对象改成Movable类型-越来越像decorator了
 * v08:如果有stop方法需要代理...
 * 如果想让LogProxy可以重用，不仅可以代理Tank，还可以代理任何其他可以代理的类型 Object
 * （毕竟日志记录，时间计算是很多方法都需要的东西），这时该怎么做呢？
 * 分离代理行为与被代理对象
 * 使用jdk的动态代理
 */
public class Tank implements Movable {

    /**
     * 模拟坦克移动了一段儿时间
     */
    @Override
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Tank tank = new Tank();

        //reflection 通过二进制字节码分析类的属性和方法
        //反射
        Movable m = (Movable)Proxy.newProxyInstance(Tank.class.getClassLoader(),
                new Class[]{Movable.class}, //tank.class.getInterfaces()
                new LogHander(tank)
        );

        m.move();
    }
}

class LogHander implements InvocationHandler {

    Tank tank;

    public LogHander(Tank tank) {
        this.tank = tank;
    }
    //getClass.getMethods[]
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("method " + method.getName() + " start..");
        Object o = method.invoke(tank, args);
        System.out.println("method " + method.getName() + " end!");
        return o;
    }
}



interface Movable {
    void move();
}

• jdk实现动态代理，底层是ASM

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Random;

/**
 * 问题：我想记录坦克的移动时间
 * 最简单的办法：修改代码，记录时间
 * 问题2：如果无法改变方法源码呢？
 * 用继承？
 * v05:使用代理
 * v06:代理有各种类型
 * 问题：如何实现代理的各种组合？继承？Decorator?
 * v07:代理的对象改成Movable类型-越来越像decorator了
 * v08:如果有stop方法需要代理...
 * 如果想让LogProxy可以重用，不仅可以代理Tank，还可以代理任何其他可以代理的类型
 * （毕竟日志记录，时间计算是很多方法都需要的东西），这时该怎么做呢？
 * 分离代理行为与被代理对象
 * 使用jdk的动态代理
 *
 * v09: 横切代码与业务逻辑代码分离 AOP
 */
public class Tank implements Movable {

    /**
     * 模拟坦克移动了一段儿时间
     */
    @Override
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Tank tank = new Tank();

        Movable m = (Movable)Proxy.newProxyInstance(Tank.class.getClassLoader(),
                new Class[]{Movable.class}, //tank.class.getInterfaces()
                new TimeProxy(tank)
        );

        m.move();

    }
}

class TimeProxy implements InvocationHandler {
    Movable m;

    public TimeProxy(Movable m) {
        this.m = m;
    }

    public void before() {
        System.out.println("method start..");
    }

    public void after() {
        System.out.println("method stop..");
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        before();
        Object o = method.invoke(m, args);
        after();
        return o;
    }

}

interface Movable {
    void move();
}

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.Random;

/**
 * 问题：我想记录坦克的移动时间
 * 最简单的办法：修改代码，记录时间
 * 问题2：如果无法改变方法源码呢？
 * 用继承？
 * v05:使用代理
 * v06:代理有各种类型
 * 问题：如何实现代理的各种组合？继承？Decorator?
 * v07:代理的对象改成Movable类型-越来越像decorator了
 * v08:如果有stop方法需要代理...
 * 如果想让LogProxy可以重用，不仅可以代理Tank，还可以代理任何其他可以代理的类型
 * （毕竟日志记录，时间计算是很多方法都需要的东西），这时该怎么做呢？
 * 分离代理行为与被代理对象
 * 使用jdk的动态代理
 *
 * v09: 横切代码与业务逻辑代码分离 AOP
 * v10: 通过反射观察生成的代理对象
 * jdk反射生成代理必须面向接口，这是由Proxy的内部实现决定的
 */
public class Tank implements Movable {

    /**
     * 模拟坦克移动了一段儿时间
     */
    @Override
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Tank tank = new Tank();

        System.getProperties().put("jdk.proxy.ProxyGenerator.saveGeneratedFiles","true");

        Movable m = (Movable)Proxy.newProxyInstance(Tank.class.getClassLoader(),
                new Class[]{Movable.class}, //tank.class.getInterfaces()
                new TimeProxy(tank)
        );

        m.move();

    }
}

class TimeProxy implements InvocationHandler {
    Movable m;

    public TimeProxy(Movable m) {
        this.m = m;
    }

    public void before() {
        System.out.println("method start..");
    }

    public void after() {
        System.out.println("method stop..");
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        //Arrays.stream(proxy.getClass().getMethods()).map(Method::getName).forEach(System.out::println);

        before();
        Object o = method.invoke(m, args);
        after();
        return o;
    }

}

interface Movable {
    void move();
}

jdk动态代理

Cglib实现：

• 注意：maven要加cglib依赖
• 原理：生成被代理类的一个子类，不能代理final类；但是ASM可以，因为ASM是直接操作二级制码；cglib的底层原理也是ASM

/**
 * CGLIB实现动态代理不需要接口
 */
public class Main {
    public static void main(String[] args) {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(Tank.class);
        enhancer.setCallback(new TimeMethodInterceptor());
        Tank tank = (Tank)enhancer.create();
        tank.move();
    }
}

class TimeMethodInterceptor implements MethodInterceptor {

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {

        System.out.println(o.getClass().getSuperclass().getName());
        System.out.println("before");
        Object result = null;
        result = methodProxy.invokeSuper(o, objects);
        System.out.println("after");
        return result;
    }
}

class Tank {
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

spring AOP

    <bean id="tank" class="com.mashibing.dp.spring.v1.Tank"/>
    <bean id="timeProxy" class="com.mashibing.dp.spring.v1.TimeProxy"/>

    <aop:config>
        <aop:aspect id="time" ref="timeProxy">
            <aop:pointcut id="onmove" expression="execution(void com.mashibing.dp.spring.v1.Tank.move())"/>
            <aop:before method="before" pointcut-ref="onmove"/>
            <aop:after method="after" pointcut-ref="onmove"/>
        </aop:aspect>
    </aop:config>

/**
 * spring aop test
 */

public class Main {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("app.xml");
        Tank t = (Tank)context.getBean("tank");
        t.move();
    }
}

import java.util.Random;

/**
 *
 */
public class Tank {

    /**
     * 模拟坦克移动了一段儿时间
     */
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public class TimeProxy {

    public void before() {
        System.out.println("method start.." + System.currentTimeMillis());
    }

    public void after() {
        System.out.println("method stop.." + System.currentTimeMillis());
    }
}

• 注解

/**
 * spring aop test
 */

public class Main {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("app_auto.xml");
        Tank t = (Tank)context.getBean("tank");
        t.move();
    }
}

import java.util.Random;

/**
 *
 */
public class Tank {

    /**
     * 模拟坦克移动了一段儿时间
     */
    public void move() {
        System.out.println("Tank moving claclacla...");
        try {
            Thread.sleep(new Random().nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;

@Aspect
public class TimeProxy {

    @Before("execution (void com.mashibing.dp.spring.v2.Tank.move())")
    public void before() {
        System.out.println("method start.." + System.currentTimeMillis());
    }

    @After("execution (void com.mashibing.dp.spring.v2.Tank.move())")
    public void after() {
        System.out.println("method stop.." + System.currentTimeMillis());
    }

}

十一、迭代器模式 Iterator

容器与容器遍历

• 数组实现

/**
 * 构建一个容器，可以添加对象
 */

public class Main {
    public static void main(String[] args) {
        ArrayList_ list = new ArrayList_();
        for(int i=0; i<15; i++) {
            list.add(new String("s" + i));
        }
        System.out.println(list.size());
    }
}


/**
 * 相比数组，这个容器不用考虑边界问题，可以动态扩展
 */
class ArrayList_ {
    Object[] objects = new Object[10];
    //objects中下一个空的位置在哪儿,或者说，目前容器中有多少个元素
    private int index = 0;
    public void add(Object o) {
        if(index == objects.length) {
            Object[] newObjects = new Object[objects.length*2];
            System.arraycopy(objects, 0, newObjects, 0, objects.length);
            objects = newObjects;
        }

        objects[index] = o;
        index ++;
    }

    public int size() {
        return index;
    }
}

-链表实现

/**
 * v1:构建一个容器，可以添加对象
 * v2:用链表来实现一个容器
 */

public class Main {
    public static void main(String[] args) {
        LinkedList_ list = new LinkedList_();
        for(int i=0; i<15; i++) {
            list.add(new String("s" + i));
        }
        System.out.println(list.size());
    }
}


/**
 * 相比数组，这个容器不用考虑边界问题，可以动态扩展
 */
class LinkedList_ {
    Node head = null;
    Node tail = null;
    //目前容器中有多少个元素
    private int size = 0;

    public void add(Object o) {
        Node n = new Node(o);
        n.next = null;

        if(head == null) {
            head = n;
            tail = n;
        }

        tail.next = n;
        tail = n;
        size++;
    }

    private class Node {
        private Object o;
        Node next;

        public Node(Object o) {
            this.o = o;
        }
    }

    public int size() {
        return size;
    }
}

• Iterator_ 接口

public interface Iterator_ {
    boolean hasNext();

    Object next();
}

public interface Collection_ {
    void add(Object o);
    int size();

    Iterator_ iterator();
}


/**
 * 相比数组，这个容器不用考虑边界问题，可以动态扩展
 */
class ArrayList_ implements Collection_ {
    Object[] objects = new Object[10];
    //objects中下一个空的位置在哪儿,或者说，目前容器中有多少个元素
    private int index = 0;
    public void add(Object o) {
        if(index == objects.length) {
            Object[] newObjects = new Object[objects.length*2];
            System.arraycopy(objects, 0, newObjects, 0, objects.length);
            objects = newObjects;
        }

        objects[index] = o;
        index ++;
    }

    @Override
    public int size() {
        return index;
    }

    @Override
    public Iterator_ iterator() {
        return new ArrayListIterator();
    }

    private class ArrayListIterator implements Iterator_{

        private int currentIndex = 0;

        @Override
        public boolean hasNext() {
            if(currentIndex >= index) return false;
            return true;
        }

        @Override
        public Object next() {
            Object o = objects[currentIndex];
            currentIndex ++;
            return o;
        }
    }
}

• JDK的容器的Iterator

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

/**
 * v1:构建一个容器，可以添加对象
 * v2:用链表来实现一个容器
 * v3:添加容器的共同接口，实现容器的替换
 * v4:如何对容器遍历呢？
 * v4:用一种统一的遍历方式，要求每一个容器都要提供Iterator的实现类
 *    作业：实现LinkedList的Iterator
 * v6:JDK的容器的Iterator
 */

public class Main {
    public static void main(String[] args) {
        Collection c = new ArrayList();
        for(int i=0; i<15; i++) {
            c.add(new String("s" + i));
        }

        Iterator it = c.iterator();
        while(it.hasNext()) {
            System.out.println(it.next());
        }
    }
}

• 终版

/**
 * 相比数组，这个容器不用考虑边界问题，可以动态扩展
 */
class ArrayList_<E> implements Collection_<E> {
    E[] objects = (E[])new Object[10];
    //objects中下一个空的位置在哪儿,或者说，目前容器中有多少个元素
    private int index = 0;
    public void add(E o) {
        if(index == objects.length) {
            E[] newObjects = (E[])new Object[objects.length*2];
            System.arraycopy(objects, 0, newObjects, 0, objects.length);
            objects = newObjects;
        }

        objects[index] = o;
        index ++;
    }

    public int size() {
        return index;
    }

    @Override
    public Iterator_<E> iterator() {
        return new ArrayListIterator();
    }

    private class ArrayListIterator<E> implements Iterator_<E> {

        private int currentIndex = 0;

        @Override
        public boolean hasNext() {
            if(currentIndex >= index) return false;
            return true;
        }

        @Override
        public E next() {
            E o = (E)objects[currentIndex];
            currentIndex ++;
            return o;
        }
    }
}

public interface Collection_<E> {
    void add(E o);
    int size();

    Iterator_ iterator();
}

public interface Iterator_<E> { //Element //Type //K //Value V Tank
    boolean hasNext();

    E next(); //Tank next() Iterator_<Tank> it = ... Tank t = it.next();
}


/**
 * 相比数组，这个容器不用考虑边界问题，可以动态扩展
 */
class LinkedList_ implements Collection_ {
    Node head = null;
    Node tail = null;
    //目前容器中有多少个元素
    private int size = 0;

    public void add(Object o) {
        Node n = new Node(o);
        n.next = null;

        if(head == null) {
            head = n;
            tail = n;
        }

        tail.next = n;
        tail = n;
        size++;
    }

    private class Node {
        private Object o;
        Node next;

        public Node(Object o) {
            this.o = o;
        }
    }

    public int size() {
        return size;
    }

    @Override
    public Iterator_ iterator() {
        return null;
    }
}

/**
 * 相比数组，这个容器不用考虑边界问题，可以动态扩展
 */
class ArrayList_<E> implements Collection_<E> {
    E[] objects = (E[])new Object[10];
    //objects中下一个空的位置在哪儿,或者说，目前容器中有多少个元素
    private int index = 0;
    public void add(E o) {
        if(index == objects.length) {
            E[] newObjects = (E[])new Object[objects.length*2];
            System.arraycopy(objects, 0, newObjects, 0, objects.length);
            objects = newObjects;
        }

        objects[index] = o;
        index ++;
    }

    public int size() {
        return index;
    }

    @Override
    public Iterator_<E> iterator() {
        return new ArrayListIterator();
    }

    private class ArrayListIterator<E> implements Iterator_<E> {

        private int currentIndex = 0;

        @Override
        public boolean hasNext() {
            if(currentIndex >= index) return false;
            return true;
        }

        @Override
        public E next() {
            E o = (E)objects[currentIndex];
            currentIndex ++;
            return o;
        }
    }

}

/**
 * v1:构建一个容器，可以添加对象
 * v2:用链表来实现一个容器
 * v3:添加容器的共同接口，实现容器的替换
 * v4:如何对容器遍历呢？
 * v4:用一种统一的遍历方式，要求每一个容器都要提供Iterator的实现类
 *    作业：实现LinkedList的Iterator
 * v6:JDK的容器实现
 * v7:实现泛型版本
 */

public class Main {
    public static void main(String[] args) {
        Collection_<String> list = new ArrayList_<>();
        for(int i=0; i<15; i++) {
            list.add(new String("s" + i));
        }
        System.out.println(list.size());

        //这个接口的调用方式：
        Iterator_<String> it = list.iterator();
        while(it.hasNext()) {
            String o = it.next();
            System.out.println(o);
        }
    }
}

十二、访问者模式 Visitor

在结构不变的情况下，动态改变对于内部元素的动作

public class Computer {
    ComputerPart cpu = new CPU();
    ComputerPart memory = new Memory();
    ComputerPart board = new Board();

    public void acccept(Visitor v) {
        this.cpu.accept(v);
        this.memory.accept(v);
        this.board.accept(v);
    }

    public static void main(String[] args) {
        PersonelVisitor p = new PersonelVisitor();
        new Computer().acccept(p);
        System.out.println(p.totalPrice);
    }
}

abstract class ComputerPart {
    abstract void accept(Visitor v);
    //some other operations eg:getName getBrand
    abstract double getPrice();
}

class CPU extends ComputerPart {

    @Override
    void accept(Visitor v) {
        v.visitCpu(this);
    }

    @Override
    double getPrice() {
        return 500;
    }
}

class Memory extends ComputerPart {

    @Override
    void accept(Visitor v) {
        v.visitMemory(this);
    }

    @Override
    double getPrice() {
        return 300;
    }
}

class Board extends ComputerPart {

    @Override
    void accept(Visitor v) {
        v.visitBoard(this);
    }

    @Override
    double getPrice() {
        return 200;
    }
}

interface Visitor {
    void visitCpu(CPU cpu);
    void visitMemory(Memory memory);
    void visitBoard(Board board);
}

class PersonelVisitor implements Visitor {
    double totalPrice = 0.0;

    @Override
    public void visitCpu(CPU cpu) {
        totalPrice += cpu.getPrice()*0.9;
    }

    @Override
    public void visitMemory(Memory memory) {
        totalPrice += memory.getPrice()*0.85;
    }

    @Override
    public void visitBoard(Board board) {
        totalPrice += board.getPrice()*0.95;
    }
}

class CorpVisitor implements Visitor {
    double totalPrice = 0.0;

    @Override
    public void visitCpu(CPU cpu) {
        totalPrice += cpu.getPrice()*0.6;
    }

    @Override
    public void visitMemory(Memory memory) {
        totalPrice += memory.getPrice()*0.75;
    }

    @Override
    public void visitBoard(Board board) {
        totalPrice += board.getPrice()*0.75;
    }
}

十三、建造者模式 Builder

构建复杂对象

• 分离复杂对象的构建和表示
• 同样的构建过程可以创建不同的表示
• 无需记忆，自然使用

public class Terrain {
    Wall w;
    Fort f;
    Mine m;
}

class Wall {
    int x, y, w, h;

    public Wall(int x, int y, int w, int h) {
        this.x = x;
        this.y = y;
        this.w = w;
        this.h = h;
    }
}

class Fort {
    int x, y, w, h;

    public Fort(int x, int y, int w, int h) {
        this.x = x;
        this.y = y;
        this.w = w;
        this.h = h;
    }

}

class Mine {
    int x, y, w, h;

    public Mine(int x, int y, int w, int h) {
        this.x = x;
        this.y = y;
        this.w = w;
        this.h = h;
    }
}

public interface TerrainBuilder {
    TerrainBuilder buildWall();
    TerrainBuilder buildFort();
    TerrainBuilder buildMine();
    Terrain build();
}

public class ComplexTerrainBuilder implements TerrainBuilder {
    Terrain terrain = new Terrain();

    @Override
    public TerrainBuilder buildWall() {
        terrain.w = new Wall(10, 10, 50, 50);
        return this;
    }

    @Override
    public TerrainBuilder buildFort() {
        terrain.f = new Fort(10, 10, 50, 50);
        return this;
    }

    @Override
    public TerrainBuilder buildMine() {
        terrain.m = new Mine(10, 10, 50, 50);
        return this;
    }

    @Override
    public Terrain build() {
        return terrain;
    }
}

public class Main {
    public static void main(String[] args) {
        TerrainBuilder builder = new ComplexTerrainBuilder();
        Terrain t = builder.buildFort().buildMine().buildWall().build();
        //new Terrain(Wall w, Fort f, Mine m)
        //Effective Java

        Person p = new Person.PersonBuilder()
                .basicInfo(1, "zhangsan", 18)
                //.score(20)
                .weight(200)
                //.loc("bj", "23")
                .build();
    }
}

public class Person {
    int id;
    String name;
    int age;
    double weight;
    int score;
    Location loc;

    private Person() {}

    public static class PersonBuilder {
        Person p = new Person();

        public PersonBuilder basicInfo(int id, String name, int age) {
            p.id = id;
            p.name = name;
            p.age = age;
            return this;
        }

        public PersonBuilder weight(double weight) {
            p.weight = weight;
            return this;
        }

        public PersonBuilder score(int score) {
            p.score = score;
            return this;
        }

        public PersonBuilder loc(String street, String roomNo) {
            p.loc = new Location(street, roomNo);
            return this;
        }

        public Person build() {
            return p;
        }
    }
}

class Location {
    String street;
    String roomNo;

    public Location(String street, String roomNo) {
        this.street = street;
        this.roomNo = roomNo;
    }
}

十四、适配器模式 Adapter(Wrapper)

• java.io
• jdbc-odbc bridge(不是桥接模式)
• ASM transformer

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;


public class Main {
    public static void main(String[] args) throws Exception {
        FileInputStream fis = new FileInputStream("c:/test.text");
        InputStreamReader isr = new InputStreamReader(fis);
        //字节流不能直接读String, 中间使用InputSteam进行适配
        BufferedReader br = new BufferedReader(isr);
        String line = br.readLine();
        while (line != null && !line.equals("")) {
            System.out.println(line);
        }
        br.close();
    }
}

• 误区：
  • 常见的Adapter类反而不是Adapter
  • windowAdpter（一个抽象类写了很多空方法，只需要重写自己想要的那个类即可，啥模式都不是）
  • KeyAdapetyter