free vector pattern design

derivation, the creation of the instance has more free control;Third, Other:Database connection can you do singleton?If a connection object is simply sealed in a singleton object, this is wrong, so there are multiple links in the connection pool can be used, if the use of Singleton, that in the Web Access, you can only use a database link, it is not dead miserable?However, the link pool can use a singleton mode, initialize the time to create such as

Reprint Please specify source: http://blog.csdn.net/lhy_ycu/article/details/40028509Visitor Mode (Visitor): The data structure and the action on the structure are decoupled, so that the operation set can evolve relatively freely. The visitor pattern is suitable for systems with relatively stable data structures and easy to change algorithms. The advantage of the visitor pattern is that it is easy to increas

thread-safe by a virtual machine.The advantage of this pattern is that the getinstance () method is not synchronized and only performs a domain access, so deferred initialization does not add any access costs.Singleton and enumerationSingle-element enumeration types have become the best way to implement Singleton. It is very simple to use enumerations to implement a singleton, just to write an enumeration type that contains a single element. package

singletonholder.instance; }}When the GetInstance method is called for the first time, It first reads singletonholder.instance, causing the Singletonholder class to be initialized, and when the class is loaded and initialized, it initializes its static domain to create an instance of singleton, because it is a static domain, so only when the virtual machine loads the class Initialized once and is guaranteed to be thread-safe by a virtual machine.The advantage of this

template method pattern:1, good package 2, good reuse, 3, shielding details 4, easy to maintainAs for the disadvantage, it is the inheritance problem, in Java can only inherit a parent class.Process: Analyze scenes---step----Refactor code--important, complex algorithms, core algorithms designed as templatesNote the point:Template method needs to be declared as public finalThe private method is the basic logicProtect abstract method is an extensible m

visit (elementb element ){System. Out. println ("visitorb is a hard worker ....");Element. operationb ();System. Out. println ("I want to do some extra work on B ....");} Public void visit (elementc element ){System. Out. println ("visitorb is a hard worker ....");Element. operationc ();System. Out. println ("I want to do some extra work on C ....");}} Modify main to demonstrate: Main. Java Public class main {Public static void main (string [] ARGs ){Ielement [

Builder mode: Separates the construction of a complex object from its representation so that the same build process can create different representations. Pattern implementation: [Code]class builder;//Product class product{public:void Addpart (const char *info) {m_partinfovec.push_back (info); } void Showproduct () {for (std::vector Client: [Code]int Main () { Builder *builderobj = new ConcreteBuilder

IntentionDefines a one-to-many dependency between objects, and when an object's state changes, all objects that depend on it are notified and automatically updated.Public interface Observer {public void update (); 　　public class Observer1 implements Observer { @Override public Void Update () { System.out.println (" Observer1 has received! "); } 　　Public interface Subject { /* Add Observer * /public void Add (Observer Observer); /* Notif

Design Pattern 17: Singleton) Singleton mode: Make sure that a class has only one instantiated object and provides a method to access this object. UML diagram: It mainly includes: Singleton (LoadBalancer): defines a method to operate on a unique object; creates and operates on this unique object. In C ++, the singleton mode is implemented through static member variables and static methods. # Include

Visitor definition: An action that acts on each object in a group of objects. It allows you to define new actions that work on these objects without changing the objects themselves. In Java, the visitor pattern is actually a separation of elements in the collection structure and the act of manipulating those elements. Why Use visitor modeJava collection (including Vector and Hashtable) is the technology w

composition Pattern definition: Combines objects into a tree structure to represent a "partial-whole" hierarchy, which makes the user consistent with the use of individual objects and composite objects.Advantages:1, high-level module call simple.2, the node is free to add.Disadvantages:The use of leaves and branches is an implementation class that violates the concept of interface-oriented programming and c

I am preparing to write a design pattern Practice Guide recently. It is relatively easy to use non-teaching materials, popular books, and texts. It is intended for front-line developers and model scholars, about 300 pages (with a price of less than 40), we are currently collecting some comments and suggestions from xdjm: 1.Programming Language? C #, Java or C ++. If it is completely irrelevant to the lang

Visitor definition Actions that act on objects in an object group. It allows you to define new actions that work on these objects without changing the objects themselves. In Java, the visitor pattern is actually a separation of elements in the collection structure and the act of manipulating those elements. Why use visitor? Java collection (including Vector and Hashtable) is the technology we use most o

(Milk. GetDescription () +": $"+ Milk. Cost ()); Beverage Mochamilk =NewMilk (Mocha); Console.WriteLine (mochamilk.getdescription () +": $"+ Mochamilk.cost ()); Console.readkey (); } }Run resultsEffect1. More flexible than static inheritance2. Avoid having too many features in a class at the top level of the hierarchy3. The adorner is not the same as the object it decorates, and cannot be relied upon for object representation4. Many small objects are producedReference

The policy mode supports the selection of the appropriate algorithm by the user at run time, and the user does not care about the specific matters behind it, and the consumer automatically chooses the appropriate algorithm from the list of existing algorithms to handle the current task, based on the context and configuration of the current program execution.1. The problem to be resolved2. How to Achieve3. Use in open source frameworks and class libraries4. SummaryThe problem to be solvedThe poli

-safe creation instances synchronized(Singleton.class) { //Check again if the instance exists, and if it does not exist, actually create the instance if(Instance = =NULL) {instance=NewSingleton (); } } } returninstance; }}Lazy Loading Internal implementations:Features: Delayed load and thread safety are implemented PackageSingleton; Public classSingleton {PrivateSingleton () {}/*** Class and the inner class, that is, the static me

mode, one part is the component construction and the product assembly, the other part is the overall built algorithm . It is important to recognize this because in the construction model, the emphasis is on fixing the overall built algorithm, while flexibly extending and switching the specific construction of the part and the way the product is assembled.To put it bluntly, the focus of the construction model is to separate the construction algorithm and the concrete construction implementation,

changes, C needs to know about these changes, so how can we let C know about m changes? Notifications (Notification) and KVO are good ways to solve problems. That's how they work, and when something in M changes, they send a notice to C, "Hey, man, watch out, I've changed," or they'll send a pointer to change to C, or something. In short, their mode of work is like this.Summarize:C to M:apiC to V:outletV to C:target-action, Delegate,datasourceM to C:notification,kvoOriginal source: http://blog.

(The second layer of the decorator, equivalent to the decorator_first above)Package decorator; public class Chilli extends condiment { Humburger humburger; Public chilli (Humburger humburger) { This.humburger = Humburger; } @Override public String getName () { return humburger.getname () + "add Pepper"; } @Override public Double GetPrice () { return humburger.getpr

1. Overview Abstract Factory mode provides a unified creation interface for a product family. When a series of this product family is needed, the corresponding series can be selected from the abstract factory to create a specific factory category. 2. The role in the abstract factory model 2.1 Abstract Factory (Abstractfactory): This role is the core of the factory method model, which is unrelated to the business logic of the application system. 2.2 Specific Factory (Concretefactory): This ro