java 枚举高级应用_Java 枚举高级应用之责任链模式

悠悠 2022-11-03 04:05 258阅读 0赞

看 thinking in java 枚举那一段，看到这个例子还挺有意思的，所以记录了下来。

这是用枚举+责任链模式 模拟邮件发信步骤的例子。(PS:遍历枚举时顺序是按照定义时的顺序)

废话少说，贴代码。效果把代码拷回去run一下就知道了。

package enums;

import java.util.Random;

//获取枚举中随机属性

public class Enums \{

public static > T random(Class ec)\{

return random(ec.getEnumConstants());

public static T random(T\[\] values)\{

//每次调用new一个新random，标识要不一样，要不然每次运行的结果都一样。

return values\[new Random(System.nanoTime()).nextInt(values.length)\];

package enums;

import java.util.Iterator;

class Mail \{

enum GeneralDelivery \{

NO, OK1, OK2, OK3, OK4, OK5

\};

enum Scannability \{

// 信件无法扫描

UNSCANNABLE, YES1, YES2, YES3, YES4

\};

enum Readablility \{

// 字迹模糊不清

ILLEGIBLE, YES1, YES2, YES3, YES4

\};

enum Address \{

// 寄件地址错误

INCORRECT, OK1, OK2, OK3, OK4, OK5, OK6

\};

enum ReturnAddress \{

// 返件地址模糊不清

MISSING, OK1, OK2, OK3, OK4, OK5

\};

// 取邮件

GeneralDelivery generalDelivery;

// 扫描邮件

Scannability scannability;

// 信件可读性

Readablility readablility;

// 地址

Address address;

// 退件地址

ReturnAddress returnAddress;

// 信件计数

static long counter = 0;

// 信件ID

long id = counter++;

public String toString() \{

return "Mail" + id;

public String details() \{

return toString() + ",General Delivery: " + generalDelivery

\+ ",Address Scanability: " + scannability

\+ ",Address Readablility: " + readablility

\+ ",Address address: " + address + ",Return address: "

\+ returnAddress;

// 创建一封信件

public static Mail randomMail() \{

Mail m = new Mail();

m.generalDelivery = Enums.random(GeneralDelivery.class);

m.scannability = Enums.random(Scannability.class);

m.readablility = Enums.random(Readablility.class);

m.address = Enums.random(Address.class);

m.returnAddress = Enums.random(ReturnAddress.class);

return m;

// 创建count个邮件迭代集合

public static Iterable generator(final int count) \{

return new Iterable() \{

int n = count;

@Override

public Iterator iterator() \{

return new Iterator() \{

@Override

public boolean hasNext() \{

return n-- > 0;

@Override

public Mail next() \{

return randomMail();

@Override

public void remove() \{

throw new UnsupportedOperationException();

\};

class PostOffice \{

enum MailHandler \{

GENERAL\_DELIVERY \{

@Override

public boolean handle(Mail m) \{

switch (m.generalDelivery) \{

case NO:

System.out.println("揽收邮件(" + m + ")失败！");

return false;

default:

System.out.println("揽收邮件(" + m + ")成功！");

return true;

\},

MACHINE\_SCAN \{

@Override

public boolean handle(Mail m) \{

switch (m.scannability) \{

case UNSCANNABLE:

System.out.println("机器扫描邮件寄件地址(" + m + ")失败！");

return false;

default:

System.out.println("机器扫描邮件寄件地址(" + m+ ")成功！");

switch (m.address) \{

case INCORRECT:

System.out.println("邮件(" + m + ")寄件地址错误！");

return false;

default:

System.out.println("邮件(" + m+ ")寄件地址正确！");

return true;

\},

VISUAL\_INSPECTION \{

@Override

public boolean handle(Mail m) \{

switch (m.readablility) \{

case ILLEGIBLE:

System.out.println("人工核查邮件(" + m + ")寄件地址发现错误！");

return false;

default:

System.out.println("人工核查邮件(" + m + ")寄件地址正常！");

return true;

\},

RETURN\_TO\_SEND \{

@Override

public boolean handle(Mail m) \{

switch (m.returnAddress) \{

case MISSING:

System.out.println("核查邮件(" + m + ")返件地址发现字迹模糊不清！");

return false;

default:

System.out.println("核查邮件(" + m + ")返件地址结果正常！");

return true;

\}\};

abstract boolean handle(Mail m);

//模拟发邮件

static void handle(Mail m)\{

for(MailHandler handler : MailHandler.values())\{

if(!handler.handle(m))\{

System.out.println("邮件"+m+" 是一封死信！");

return;

\}else continue;

System.out.println("邮件"+m+" 被正常发送！");

public static void main(String\[\] args)\{

for(Mail mail : Mail.generator(10))\{

//System.out.println(mail.details());

handle(mail);

System.out.println("\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*");

java 枚举高级应用_Java 枚举高级应用之责任链模式

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