]]>
栈，利用单向链表实现Q?br />
public abstract class AbstractStack
{
public abstract Object Pop();
public abstract void Push(Object obj);
public abstract bool IsEmpty();
public abstract Object Top();
public abstract void Clear();
}
public class Stack : AbstractStack
{
private SList list;
public Stack()
{
list = new SList();
}
public override bool IsEmpty()
{
return list.IsEmpty();
}
public override void Push(Object obj)
{
list.Push(obj);
}
public override object Pop()
{
return list.Pop();
}
public override object Top()
{
return list.getTail();
}
public override void Clear()
{
list.Clear();
}
}
{
public abstract Object Pop();
public abstract void Push(Object obj);
public abstract bool IsEmpty();
public abstract Object Top();
public abstract void Clear();
}
public class Stack : AbstractStack
{
private SList list;
public Stack()
{
list = new SList();
}
public override bool IsEmpty()
{
return list.IsEmpty();
}
public override void Push(Object obj)
{
list.Push(obj);
}
public override object Pop()
{
return list.Pop();
}
public override object Top()
{
return list.getTail();
}
public override void Clear()
{
list.Clear();
}
}
队列的实玎ͼ通过双向链表实现Q对于环形数l的实现请参考?a href="/killme2008/archive/2007/02/20/100239.html">数组l构之栈与链?/a>》：
public interface Queue
{
bool IsEmpty();
void Enqueue(Object obj);
Object Dequeue();
Object First();
}
public class ListQueue:Queue
{
private LinkedList list;
public ListQueue()
{
list = new LinkedList();
}
public bool IsEmpty()
{
return list.IsEmpty();
}
public void Enqueue(Object obj)
{
list.Push(obj);
}
public Object Dequeue()
{
return list.Shift();
}
public Object First()
{
return list.getHead();
}
}
{
bool IsEmpty();
void Enqueue(Object obj);
Object Dequeue();
Object First();
}
public class ListQueue:Queue
{
private LinkedList list;
public ListQueue()
{
list = new LinkedList();
}
public bool IsEmpty()
{
return list.IsEmpty();
}
public void Enqueue(Object obj)
{
list.Push(obj);
}
public Object Dequeue()
{
return list.Shift();
}
public Object First()
{
return list.getHead();
}
}
]]>
]]>
- POST: 创徏
- GET: d
- PUT: 更新
- DELETE: 删除
l过q样的一番扩展，我们对一个资源的 CRUD 操作可以通过同一?URI 完成了。需要注意的是REST的核心就是资源（resourcesQ这个概c我们所说的webservice是一U徏立在http协议上的q程调用Q而REST是把远E调用抽象成对远E资源的CRUD的操作，正好可以用HTTP的PUT GET POST DELETE来对应，而不是重新发明一个协议（比如soapQ简单对象访问协议）。REST与AJAX的流行，甚至q至设计模式的兴P都充分说明一个现象，在成熟的应用的基上创新而非扩展出复杂所谓“创新性”架构在软g行业是更为可靠?/p>
实战体验REST可以从IBM Developer的这文章开始?a >跨越边界QRest On Rails》。这文章是在Rails1.2发布之前出来的，有些地方已经可以修改的更l，我把我的l习q程记录下，q添加了C#调用REST风格web service的例子?/p>
首先Q你的机器上需要安装rails1.2Qƈ且假设你对rails有基本的了解Q徏立一个应用叫service,命o行执行：
rails service
rails自动帮你生成应用的基本结构和基础代码Q然后编辑config下面的database.yml讄数据库，q徏立数据service_developmentQ我用的是mysql数据库?/p>
利用rails1.2新的scaffold命oQ?/p>
ruby script/generate scaffold_resource person
q个命o自动生成ActiveRecord,Controller以及ViewQ在\app\models下可以发现自动生成的Model——person.rb。打开service\db\migrate下面?01_create_people.rbQ编辑如下：
class CreatePeople < ActiveRecord::Migration
def self.up
create_table :people do |t|
t.column :first_name, :string, :limit => 40
t.column :last_name, :string, :limit => 40
t.column :email, :string, :limit => 40
t.column :phone, :string, :limit => 15
end
end
def self.down
drop_table :people
end
end
def self.up
create_table :people do |t|
t.column :first_name, :string, :limit => 40
t.column :last_name, :string, :limit => 40
t.column :email, :string, :limit => 40
t.column :phone, :string, :limit => 15
end
end
def self.down
drop_table :people
end
end
利用rake命o自动Q执?
rake db:migrate
rails默认表明是Model的复数Ş式，也就是这里将自动建立一张名叫people的表?br />OKQ一切就l，启动WEBricQ访问http://localhost:3000/peopleQ显C：
scaffold已经帮我们自动生成了一个对person资源的crud操作Q增删改查似乎跟传统的rails没有什么不同嘛。如果你认真观察在操作过E中URL的变化情况就会发现在操作q程中URL的变化很，而且与传lrails的URL路由相比Q省Maction名称。出现的变化?people?people/1?people/1;edit?people/newq几个之中。在/people的URL中隐藏这可能是http的POST或者GET的方法，前者用于create操作Q而GET用于show操作Q具体你可以查看app/controllers/目录下的PeopleControllerc，每个action的前面都注释了它们将对应哪个HTTPҎ。?people/1中的1指的是资源的标志W，比如q里person的idQ通过q个ID来进行资源的操作Q也许是PUTҎQ更斎ͼQ也许是DELETEҎQ删除）。rails实现PUT和Delete是通过隐藏字段来实现的Q查看编辑页面生成的html源代码，你将发现一个_method的隐藏字D，gؓPUT。而另外两个URLQ?people/1;edit?people/newQ这两个q严格意义上的RESTful URLQ它们只是ؓ了显C用Q显Cform表单用于新徏和编辑。关于RESTful风格的URL的详l讨见《RESTfull Rails Development》文?br />
如果rails只是q样的威力，那就有点提大做了，看看PeopleController的show actionQ它对应于http的GEThQ返回people列表Q?br />
# GET /people/1
# GET /people/1.xml
def show
@person = Person.find(params[:id])
respond_to do |format|
format.html # show.rhtml
format.xml { render :xml => @person.to_xml }
end
end
# GET /people/1.xml
def show
@person = Person.find(params[:id])
respond_to do |format|
format.html # show.rhtml
format.xml { render :xml => @person.to_xml }
end
end
奇的地方在respond_toҎ中，Ҏh文gcdQhttp Header的ContentTypeQ，昄html格式Q或者xml格式Q还有其他支持，比如json、RSS、Atom{等Q。比如你d了一个person,通过http://localhost:3000/people/1讉KQ可以看到这个h员的具体信息Q?br />
我们再通过http://localhost:3000/people/3.xml讉K看到的却是一个xml文gQ?br />
不仅如此Q我们也可以通过其他语言~写客户端来调用http://localhost:3000/people/1q个urlQ慢着Q这不正是web serviceq程调用吗？没错QREST风格的web service相比于wsdl、soap定义的web service单了太多太多Q也更加实用。我们来~写一个javac调用http://localhost:3000/people获得所有的人员列表Q?br />
package example;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
public class RESTDemo {
/**
* @param args
*/
public static void main(String[] args) {
RESTDemo restDemo = new RESTDemo();
restDemo.get();
}
void get() {
try {
URL url = new URL("http://localhost:3000/people");
URLConnection urlConnection = url.openConnection();
urlConnection.setRequestProperty("accept", "text/xml");
BufferedReader in = new BufferedReader(new InputStreamReader(
urlConnection.getInputStream()));
String str;
while ((str = in.readLine()) != null) {
System.out.println(str);
}
in.close();
} catch (Exception e) {
System.out.println(e);
}
}
}
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
public class RESTDemo {
/**
* @param args
*/
public static void main(String[] args) {
RESTDemo restDemo = new RESTDemo();
restDemo.get();
}
void get() {
try {
URL url = new URL("http://localhost:3000/people");
URLConnection urlConnection = url.openConnection();
urlConnection.setRequestProperty("accept", "text/xml");
BufferedReader in = new BufferedReader(new InputStreamReader(
urlConnection.getInputStream()));
String str;
while ((str = in.readLine()) != null) {
System.out.println(str);
}
in.close();
} catch (Exception e) {
System.out.println(e);
}
}
}
我们没有什么服务端接口classQ我们也不用生成什么stubQ我们调用的最常见最常见的http协议Q发送的是默认的GEThQrails自动该h转发lshow action。注意，我们q里?span style="color: rgb(0, 0, 0);">accept讄为text/xmlQshowҎҎ此格式返回一个xml文Q下面是输出Q?br />
<?xml version="1.0" encoding="UTF-8"?>
<people>
<person>
<email>killme2008@gmail.com</email>
<first-name>dennis</first-name>
<id type="integer">1</id>
<last-name>zane</last-name>
<phone>1355XXXXXXX</phone>
</person>
</people>
<people>
<person>
<email>killme2008@gmail.com</email>
<first-name>dennis</first-name>
<id type="integer">1</id>
<last-name>zane</last-name>
<phone>1355XXXXXXX</phone>
</person>
</people>
如果仅仅是GETh是不够的Q我们说q，把远E调用抽象成对远E资源的CRUD操作Q那么如何create、delete和updateq程资源呢？同样很简单，比如我们通过C#q程调用Q创Z个新personQ还记的我说q吗Q?people可以是POSThQ他调用PeopleController的createҎQ?br />
using System;
using System.Net;
using System.IO;
using System.Text;
namespace demo
{
class RESTDemo
{
static void Main(string[] args)
{
string xmlText = "<person> " + "<first-name>jordan</first-name>"
+ "<last-name>jordan</last-name>"
+ "<email>maggie@tate.com</email>"
+ "<phone>010-XXXXXXXX</phone>" + "</person>";
Uri address = new Uri("http://localhost:3000/people");
// 创徏webh
HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;
// 讄hcd为POSTQ调用create action
request.Method = "POST";
request.ContentType = "application/xml";
byte[] xmlBytes = Encoding.ASCII.GetBytes(xmlText);
using (Stream reqStream = request.GetRequestStream())
{
reqStream.Write(xmlBytes, 0, xmlBytes.Length);
}
using (WebResponse wr = request.GetResponse())
{
wr.
//打印q回的http?/span>
Console.WriteLine(wr.Headers.ToString());
}
}
}
}
using System.Net;
using System.IO;
using System.Text;
namespace demo
{
class RESTDemo
{
static void Main(string[] args)
{
string xmlText = "<person> " + "<first-name>jordan</first-name>"
+ "<last-name>jordan</last-name>"
+ "<email>maggie@tate.com</email>"
+ "<phone>010-XXXXXXXX</phone>" + "</person>";
Uri address = new Uri("http://localhost:3000/people");
// 创徏webh
HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;
// 讄hcd为POSTQ调用create action
request.Method = "POST";
request.ContentType = "application/xml";
byte[] xmlBytes = Encoding.ASCII.GetBytes(xmlText);
using (Stream reqStream = request.GetRequestStream())
{
reqStream.Write(xmlBytes, 0, xmlBytes.Length);
}
using (WebResponse wr = request.GetResponse())
{
wr.
//打印q回的http?/span>
Console.WriteLine(wr.Headers.ToString());
}
}
}
}
执行此程序，hhttp://localhost:3000/peopleQ可以看到新Z一个h员如?br />
好极了，GET和POST都有了，那么PUT对应的更新和DELETE对应的删除又该怎么做呢Q唯一的区别就是设|请求类型不同而已Qjava调用如下Q?br />
void put() {
try {
String xmlText = "<person> " + "<first-name>test</first-name>"
+ "<last-name>test</last-name>"
+ "<email>maggie@tate.com</email>"
+ "<phone>010-XXXXXXXX</phone>" + "</person>";
URL url = new URL("http://localhost:3000/people/1");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
//讄h为PUT
conn.setRequestMethod("PUT");
conn.setRequestProperty("Content-Type", "text/xml");
OutputStreamWriter wr = new OutputStreamWriter(conn
.getOutputStream());
wr.write(xmlText);
wr.flush();
wr.close();
} catch (Exception e) {
System.out.println("Error" + e);
}
}
void delete() {
try {
URL url = new URL("http://localhost:3000/people/2");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
//讄h为DELETE
conn.setRequestMethod("DELETE");
conn.setRequestProperty("Content-Type", "text/xml");
if(conn.getResponseCode()==200)
System.out.println("删除成功Q?/span>");
}catch (Exception e) {
System.out.println("Error" + e);
}
}
try {
String xmlText = "<person> " + "<first-name>test</first-name>"
+ "<last-name>test</last-name>"
+ "<email>maggie@tate.com</email>"
+ "<phone>010-XXXXXXXX</phone>" + "</person>";
URL url = new URL("http://localhost:3000/people/1");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
//讄h为PUT
conn.setRequestMethod("PUT");
conn.setRequestProperty("Content-Type", "text/xml");
OutputStreamWriter wr = new OutputStreamWriter(conn
.getOutputStream());
wr.write(xmlText);
wr.flush();
wr.close();
} catch (Exception e) {
System.out.println("Error" + e);
}
}
void delete() {
try {
URL url = new URL("http://localhost:3000/people/2");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
//讄h为DELETE
conn.setRequestMethod("DELETE");
conn.setRequestProperty("Content-Type", "text/xml");
if(conn.getResponseCode()==200)
System.out.println("删除成功Q?/span>");
}catch (Exception e) {
System.out.println("Error" + e);
}
}
q里的putҎ第一个h员的名字改了Q而deleteҎq脆刚才C#d的h员删除掉。异构系l的q程调用变的如此单很LQ把什么EJB、CORBA、SOAPl统忘掉吧。想象这L场景Q所有的|站都提供REST风格的APIQ这个世界将是什么模P
REST带来的不仅仅是web service的改变，对MVC架构同样h很重要的意义Q过L们的复用通常在MODEL层，我们一直希望复用业务逻辑层，却没有想q是否能复用Controller甚至View呢？REST为我们提供了可能Q比如以一个很l常被提到的例子来说Q用户加入某个圈子这个操作跟圈子的管理员用户加入圈子的操作是一P但是操作成功后的跌{昄的页面也怸同，q去也许我们是通过写两个不同的Action来实玎ͼ而现在，同一个ActionQ加入圈子这个操作）只负责发送数据（XML格式的文）Q而页面的展示留l客L去选择Q从而复用了ControllerQ减了Action和View层的代码量。进一步，请你惌QREST与AJAX的技术结合生多么有的画面?b>REST仅用于提供数?/b>Q展现更多的交给了客L?br />
本文仅仅是我接触RESTq两天的学习ȝQ对于REST的应用才刚刚hQ需要更多的探讨和实c其实java实现REST也是相当单的Qservlet本n是很好的模型，恐怕没有多人注意到HttpServletcM的doPut和doDeleteҎQ我们过dGET和POSTQ反而忽视了PUT和DELETE可能带来的改变。java开源世界中已经有了REST风格的框Ӟ比如cetia4Q?/a>q是一个servlet-base的REST框架Q值的x?br />
]]>
]]>
C#中的using除了作ؓ命名I间指示W?using System)Q类型的别名指示W?using Dos=System.Console)Q还有资源管理的语句功能Q?br /> using (R r1 = new R ()) {
r1.F();
}
在C#中被译为：
R r1 = new R();
try {
r1.F();
}
finally {
if (r1 != null) ((IDisposable)r1).Dispose();
}
try {
r1.F();
}
finally {
if (r1 != null) ((IDisposable)r1).Dispose();
}
r1当然要支持Dispose()Ҏ?br />
再来一个例子：
# MyObject.cs
using System;
namespace MyProjects
{
public class MyObject : IDisposable
{
public MyObject()
{
}
public void Dispose ( )
{
// Dispose
Console.WriteLine ( " Disposed " ) ;
//
}
}
}
# Class1.cs
using System;
namespace MyProjects
{
public class Class1
{
public Class1()
{
}
public static void Main ( string [] args )
{
using ( MyObject myObject = new MyObject ( ) )
{
Console.WriteLine ( " quit " ) ;
}
}
}
}
using System;
namespace MyProjects
{
public class MyObject : IDisposable
{
public MyObject()
{
}
public void Dispose ( )
{
// Dispose
Console.WriteLine ( " Disposed " ) ;
//
}
}
}
# Class1.cs
using System;
namespace MyProjects
{
public class Class1
{
public Class1()
{
}
public static void Main ( string [] args )
{
using ( MyObject myObject = new MyObject ( ) )
{
Console.WriteLine ( " quit " ) ;
}
}
}
}
使用using会自动调?span lang="EN-US">MyObject?span lang="EN-US">DisposeҎ.
]]>
using System;
public class HelloWorld
{
public static void Main()
{
Console.WriteLine("Hello World");
}
}
public class HelloWorld
{
public static void Main()
{
Console.WriteLine("Hello World");
}
}
存ؓhello.cs。配|好环境变量Q在命o行运?csc hello.cs。在目录下会生成一个hello.exe,直接q行hello。打华ͼ
Hello World
看v来跟java实没什么不同，除了字母的大写Q和java默认引入java.lang包，而这里需要using System;
E微复杂点的例子Q我们写一个库文gstack.dllQ或者说一个程序集Qjava中包的概念）Q?br />
using System;
namespace Acme.Collections
{
public class Stack
{
Entry top;
public void push(object data)
{
top = new Entry(top, data);
}
public object pop()
{
if (top == null) throw new InvalidOperationException();
object result = top.data;
top = top.next;
return result;
}
public Stack()
{
}
class Entry
{
public Entry next;
public object data;
public Entry(Entry next, object data)
{
this.next = next;
this.data = data;
}
}
}
}
namespace Acme.Collections
{
public class Stack
{
Entry top;
public void push(object data)
{
top = new Entry(top, data);
}
public object pop()
{
if (top == null) throw new InvalidOperationException();
object result = top.data;
top = top.next;
return result;
}
public Stack()
{
}
class Entry
{
public Entry next;
public object data;
public Entry(Entry next, object data)
{
this.next = next;
this.data = data;
}
}
}
}
代码很明显，一个简单的栈结构，我们把StackcL在命名空?span style="color: rgb(0, 0, 0);">Acme.Collections中?/span>q行Qcsc /t:library stack.csQ在应用目录下生成一个stack.dll。我们怎么调用q个链接库呢Q写个测试类Q?br />
using System;
using Acme.Collections;
public class Test
{
public static void Main()
{
Stack stack = new Stack();
stack.push(1);
stack.push(10);
stack.push(100);
Console.WriteLine(stack.pop());
Console.WriteLine(stack.pop());
Console.WriteLine(stack.pop());
}
}
using Acme.Collections;
public class Test
{
public static void Main()
{
Stack stack = new Stack();
stack.push(1);
stack.push(10);
stack.push(100);
Console.WriteLine(stack.pop());
Console.WriteLine(stack.pop());
Console.WriteLine(stack.pop());
}
}
很明显，只是把java的import换成了usingQ而且不需要通配W。编译test.cs:csc /r:stack.dll test.cs?br /> C#和ruby是?7q主要的学习计划Q另外就是J2EE深入技术方面的掌握和理?特别是模式、工作流和Portal斚w?br />
]]>