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在上篇《Java是如何快速煮成C#的?》(一):相似的方法》中,我们开启了C#与Java中的话题之一:相似的方法。本节我们再举例说明,到底有多相似。
我们用一个简单的工厂模式的例子说明,顺便复习下设计模式,呵呵。
首先邀月得补充一下:
1、语言对比:Java的文件名必须与类名匹配。在Java中,文件名必须遵循类的名称。在C#中,虽然通常如此,但不是必需的。在C#中,可以有两个class在一个文件中,并且从C#2.0开始,可能有一个Class跨越多个文件。
2、简单工厂(Simple Factory)模式
Simple Factory模式根据提供给它的数据,返回几个可能类中的一个类的实例。通常它返回的类都有一个公共的父类和公共的方法。
好了,我们看一个C#/Java的类图
就类图本身而言,除了String与string的大小写之外,并无区别。两个图均用Powerdesigner所画,只是依据模板分别为c#2.0和Java。
基类:Namer
派生类:FirstFirst和LastFirst均继承Namer
NameFactory实现了Namer的Create方法,在本例中为getName()。
代码对比如下:
Namer(C#):
- using System;
- namespace NameFactory
- {
- /// <summary>
- /// Summary description for Namer.
- /// </summary>
- //Base class for getting split names
- public class Namer
- {
- //parts stored here
- protected string frName, lName;
- //return first name
- public string getFrname()
- {
- return frName;
- }
- //return last name
- public string getLname()
- {
- return lName;
- }
- }
- }
Namer(Java):
- package com.factory.SimpleFactory;
- public class Namer {
- protected String frName, lName;
- //return first name
- public String getFrname()
- {
- return frName;
- }
- //return last name
- public String getLname()
- {
- return lName;
- }
- }
FirstFirst(C#):
- using System;
- namespace NameFactory
- {
- /// <summary>
- /// Summary description for FirstFirst.
- /// </summary>
- public class FirstFirst : Namer
- {
- public FirstFirst(string name)
- {
- int i = name.IndexOf(" ");
- if (i > 0)
- {
- frName = name.Substring(0, i).Trim();
- lName = name.Substring(i + 1).Trim();
- }
- else
- {
- lName = name;
- frName = "";
- }
- }
- }
- }
FirstFirst(Java):
- package com.factory.SimpleFactory;
- public class FirstFirst extends Namer {
- public FirstFirst(String name) {
- int i = name.indexOf(" ");
- if (i > 0) {
- frName = name.substring(0, i).trim();
- lName = name.substring(i + 1).trim();
- } else {
- lName = name;
- frName = "";
- }
- }
- }
LastFirst(C#):
- using System;
- namespace NameFactory
- {
- /// <summary>
- /// Summary description for LastFirst.
- /// </summary>
- public class LastFirst : Namer
- {
- public LastFirst(string name)
- {
- int i = name.IndexOf(",");
- if (i > 0)
- {
- lName = name.Substring(0, i);
- frName = name.Substring(i + 1).Trim();
- }
- else
- {
- lName = name;
- frName = "";
- }
- }
- }
- }
LastFirst(Java):
- package com.factory.SimpleFactory;
- public class LastFirst extends Namer {
- public LastFirst(String name) {
- int i = name.indexOf(",");
- if (i > 0) {
- lName = name.substring(0, i);
- frName = name.substring(i + 1).trim();
- } else {
- lName = name;
- frName = "";
- }
- }
- }
NameFactory(C#):
- using System;
- namespace NameFactory
- {
- /// <summary>
- /// Summary description for NameFactory.
- /// </summary>
- public class NameFactory
- {
- public NameFactory() { }
- public Namer getName(string name)
- {
- int i = name.IndexOf(",");
- if (i > 0)
- return new LastFirst(name);
- else
- return new FirstFirst(name);
- }
- }
- }
NameFactory(Java):
- package com.factory.SimpleFactory;
- public class NameFactory {
- public NameFactory() {
- }
- public Namer getName(String name) {
- int i = name.indexOf(",");
- if (i > 0)
- return new LastFirst(name);
- else
- return new FirstFirst(name);
- }
- }
测试方法:(C#):
- using System;
- using System.Text;
- namespace NameFactory
- {
- class Program
- {
- static string s;
- private static NameFactory nameFact;
- static void Main(string[] args)
- {
- System.Console.WriteLine("please enter a string:");
- s = Console.ReadLine();
- //s="zhang,tony";
- ShowFactoryName(s);
- Console.ReadKey();
- }
- static void ShowFactoryName(String input)
- {
- System.Console.WriteLine("input:" + input);
- nameFact = new NameFactory();
- Namer nm = nameFact.getName(input);//此处可以用反射,类似于getClass方法
- System.Console.WriteLine("FirstName:" + nm.getFrname());
- System.Console.WriteLine("LastName:" + nm.getLname());
- }
- }
- }
(Java):
- package com.factory.SimpleFactory;
- import java.io.BufferedReader;
- import java.io.IOException;
- import java.io.InputStreamReader;
- public class SimpleFactoryDemo1 {
- private static NameFactory nameFact;
- static String s;
- /**
- * @param args
- */
- /**
- * @param args
- */
- public static void main(String[] args) {
- System.out.println("please enter a string:");
- try {
- BufferedReader in = new BufferedReader(new InputStreamReader(
- System.in));
- s = in.readLine();
- } catch (IOException e) {
- }
- // s="zhang,tony";
- ShowFactoryName(s);
- }
- static void ShowFactoryName(String input) {
- System.out.println("input:" + input);
- nameFact = new NameFactory();
- Namer nm = nameFact.getName(input);// 此处可以用反射,类似于getClass方法
- System.out.println("FirstName:" + nm.getFrname());
- System.out.println("LastName:" + nm.getLname());
- }
- }
正常情况下,分别得出如下结果:
小结:从代码的比较中,大多数情况下,改下大小写,代码就可以通用,只是命名空间可能有较大差异。如果你熟悉c#所有的类,Java是否也感觉很容易呢?
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