CN100373332C - Method for constructing coupling system - Google Patents

Abstract

The present invention discloses a method for constructing a coupling system, which comprises the following steps: setting relevant interfaces according to functions; setting specific types for realizing different functions; correlating relevant interfaces with specific types. When a coupling system is constructed, the technical scheme of the present invention permits a developer to dispense with the determination that which subjects serve as a topic design when starting design; after subsequent development, even submitting software, when revisions are made as the demands and variations, only a new code is required to be added so that the specific topic subject is determined, a publishing point is customized and a topic issue behavior is added without any revision of the original sections in normal work.

Description

Make up the method for coupled system

Technical field

The present invention relates to make up the method for coupled system.

Background technology

Existing Observer Pattern is the related a kind of effective mode of complex logic between the resolution system model.Briefly, Observer Pattern has defined the dependence of an one-to-many, allows one or more observers supervise a subject.Variation on the subject state can be notified all those observers that depend on this object like this, and these observers can be upgraded automatically.Theme here and observer are the model Is of system, logically depend on model as theme as observer's model, be according to the state variation of theme and change self accordingly.

Topmost behavior is the notice behavior of theme to the observer in the Observer Pattern.Theme is kept at quoting of all observers in the tabulation, and each theme can have the observer of any amount.Observer's definition has also realized renewal (Update) method.When the content of theme changes, will travel through observer's tabulation that it is preserved successively, call their update method.For making things convenient for description, claiming the theme state to change and need notify observer's point is publishing point, specific in the system program often in a concrete function code segment; Claim to call successively the issue behavior that is the theme of all observer's method for updating.In the realization of conventional view person's pattern, theme issue behavior is carried out at publishing point by subject, and purpose is to notify its state of observer to change.

In existing a kind of application, subject (Subject) has defined increase (attach), has removed (detach) observer's (Observer) method; Also defined the method for notifying all observers, i.e. theme issue behavior.The realization of theme issue behavior is to travel through all observers that are registered on this theme successively, calls their update method.Generally speaking, when the theme state changes, and this variation just need add the code that behavior issued in theme need notify corresponding observer the time in corresponding code snippet (being publishing point).

For example, suppose that the foo method of a certain theme has changed the theme state, need carry out the active issue, the foo method is a publishing point here, calls theme issue behavior and carries out the theme issue exactly.

Observer Pattern has solved the directly related property of complicated association preferably, helps to make up the complication system of loose coupling.But as from the foregoing, the main cause that Observer Pattern is proved effective is when the theme state changes, and is initiatively issued by theme, promptly at the publishing point place that causes that the theme state changes, has carried out the theme issue, promptly needs relevant code and exists.Under the prerequisite clear and definite at system requirements, that variation is little, be satisfiable.But because the complicacy of system, indeterminate usually on the related surface between each model, the initial period that is difficult in the design or the system of realization changes and need supervise with regard to the state of determining which theme fully, and some model all is not taken as the subject that will supervise at the beginning.And along with the evolution of system, the refinement of each functional module, the state that the model that need supervise and needing is paid close attention to is just progressively clear and definite.Need change into subject this moment with common object; Need in subject, add new publishing point.According to the realization requirement of Observer Pattern, just need add as the required additional code information of subject (as the tabulation of preserving observer's object reference etc.) common object; At emerging publishing point, add theme issue behavior.

Bertrand Meyer proposed famous opening-sealing principle (The Open-ClosedPrinciple is called for short the OCP principle) in 1988.This principle is pointed out: the software systems entity (as, class, module, function or the like) should expand, but can not revise.Follow the module that opening-sealing principle designs and have two main features, they are: 1, " is open for expansion " 2, " sealing for change ".When promptly revising software systems, should only need to add new code, and needn't change the code that has normally moved.

The realization of conventional view person's pattern requires theme to have the ability of initiatively issuing its state variation.Therefore, the model that is taken as theme also needs to add theme issue behavior except needs are realized the service logic of self.Along with the exploitation and the maintenance of system, because the change of incidence relation between model will cause the normally modification of operation code, thereby cause carrying out again work such as test to this part code, increased software cost.Should be realized that,, and cause that the variation of system requirements is physical presence because of user's the requirement variation or the variation of software systems applying environment, and along with software systems use increasingly extensive and more frequent.Fast-response changes the corresponding software systems that modify more, and its vitality is strong more.The OCP principle is exactly the basis that guarantees the good adaptability to changes of software systems.

Summary of the invention

Technical matters to be solved by this invention is in the coupled system that overcomes existing employing Observer Pattern, must pre-define publishing point, adding is called theme issue behavior, object as theme need add extraneous information (as preserving observer's object reference tabulation etc.) simultaneously, realize theme issue behavior, can not satisfy the technical matters of " opening-sealing principle ".

The technical scheme that realizes technical matters to be solved by this invention and take is as follows,

According to function, set corresponding interface;

Set the specific implementation class, realize different functions;

Adopt the mode of dynamic proxy corresponding interface and specific implementation class to be associated by the instrument class;

When needs are changed subject and publishing point, determine publishing point earlier, and write issue behavior class, utilize the instrument class to be inserted in the determined interface method then, wherein, subject is the interface that sets, publishing point is the interface method in this interface.

Further, the method for described structure coupled system is further comprising the steps of:

When publishing point was called, the standard method of the issue behavior class that is associated was performed, and carries out the issue of theme state variation.

Further, the method for described structure coupled system adopts the corresponding relation of binary picture group shape data structure type table record interface and specific implementation class in the step that corresponding interface and specific implementation class are associated.Further, the described dynamic proxy of the method for described structure coupled system is a special defects of dynamically realizing one group of specified interface in the coupled system runtime.

Further, the method for described structure coupled system is further comprising the steps of:

Determine to have the interface class of setting interface method, and by retrieval＜interface, specific implementation class object binary picture group shape data structure type table, associated specific implementation class obtained;

＜interface method, issue behavior class〉whether exist issue behavior class in the binary picture group shape data structure type table in requisition for the calling interface method, if exist, then call the call method of issue behavior class, carry out the theme issue;

Call the interface method that described specific implementation class is realized.

Adopt technical solution of the present invention, when the structure coupled system, allow the developer when beginning to design, need not to determine that painstakingly which object designs as theme; And after subsequent development even software submission, when making amendment, only need to add fresh code because of changes in demand, just energy designated key object customizes publishing point, adds theme to issue behavior, and need not to revise original part of operate as normal.

Adopt the coupled system of technical solution of the present invention structure,, all be used as potential possible publishing point the method for each interface, when needed, utilize dynamic proxy mechanism, before the specific implementation class methods that realize special interface were by actual calling, issued the calling of behavior to theme dynamic the adding.Application the present invention adds calling of behavior of theme issue and need not to revise the functional based method that is designated as publishing point, has therefore well met " opening-sealing " principle.Subject also needn't add the data structures such as tabulation of preserving observer's object reference in advance.In fact, use the present invention, subject and general object are without any difference.This is because the method for each interface all can be taken as publishing point.Actual publishing point and accordingly can be along with the evolution of system to calling of behavior of theme issue, the variation of demand and dynamically add or remove, this makes software systems have the ability of quick response change.

Simultaneously, adopt technical scheme of the present invention, determine publishing point, add the theme release code, can not influence the interface and relevant specific implementation class that have defined fully.Can determine publishing point dynamically and add the theme issuing function flexibly according to demand, need not to add theme issue behavior at default publishing point in advance, even need not to pre-determine the model that will be designed to topic style.Can in the process of system evolved, progressively increase publishing point and theme issue behavior.Improve the ability of software systems response change, helped to make up large complicated system.

Description of drawings

Fig. 1 shows and the invention provides the process flow diagram that makes up coupled system;

Fig. 2 shows dynamic proxy and calls synoptic diagram;

Fig. 3 shows specific implementation class methods provided by the invention and is called synoptic diagram by the issue behavior class before calling out;

Fig. 4 shows agency provided by the invention and helps inner invoke (calling the standard Chinese) the method flowchart that realizes calling supvr's class (InvocationHandler) interface class of class (ProxyHelper).

Embodiment

Below in conjunction with accompanying drawing, illustrate the specific embodiment of the present invention.

The present invention is governing principle with OCP, and its realization is based upon on the language manufacturing basis of " at interface programming, but not realizing " this object based programming governing principle and dynamic proxy, and its step that comprises is as follows:

The first step: determine each model function of software systems, according to the functional definition interface.Interface in this step is primarily aimed at the service logic of system.Be convenient narration, the program language of a preferred realization system of the present invention is a Java language.In Java, this notion of interface (Interface) is expressed by key word " interface ".During defining interface, should avoid realization angle, but consider from the functional perspective that each module will provide from system.Interface should be able to be expressed the function collection of module complete, clearly.

Second step: write the specific implementation class, realize the interface that defines in the first step.Here should note, specific implementation class and interface might not be to concern one to one, actual conditions according to system's realization, may realize the part of a certain interface by a plurality of classes respectively, then by inheriting, modes such as combination correspond to this interface, also may be finished the function of several interfaces by a class.After the specific implementation class realizes finishing, can the specific implementation class be got up with corresponding interface conjunctionn, can be mapped to calling to calling finally of abstraction interface like this these specific implementation class methods by the instrument class hereinafter described in detail.

The 3rd step:, determine subject and the publishing point that to supervise according to system requirements.This step and subsequent step may be carried out repeatedly, till system satisfies customer requirements.The subject here is the interface of determining in the first step, and publishing point is exactly the interface method in these interfaces.In Observer Pattern, theme issue behavior is embedded in the subject, and the present invention's behavior of will issuing is peeled off from subject, becomes independent entity.The class that has claimed to realize the issue behavior is an issue behavior class.Issue behavior class all has a standard method, and this method will be performed before associated publishing point (being specific interface method) operation.Need realize issue behavior class at concrete theme interface, just realize operation content concrete in the standard method of issue behavior class.Instrument class by hereinafter describing in detail is issued behavior class and the publishing point of determining with this then, and promptly a definite interface method associates.Consequently system's operation, particular interface methods (publishing point) is when being called, and the standard method of the issue behavior class that is associated is performed, and carries out the issue of theme state variation.

The 4th step: after aforementioned three steps were finished, the coupled system that can move was fabricated, and can try system this moment out, and whether the subject and the publishing point that detect in the 3rd step be suitable.Change subject and publishing point as needs, then came back to for the 3rd step, make amendment, and try out once more.Such cyclic process, according to the complexity of system, the complexity difference can be carried out several times, and system will settle out gradually.Because subject is separated with the issue behavior, the loop modification cost is less like this, can comparatively faster systems stabilisation.

The 5th step: constructed coupled system tends towards stability, and pays the user and uses.After this system maintenance stage, if because the model interaction relation changes, and cause when system is revised, still can get back to third step, carry out the realization again that redefines and issue behavior of subject and publishing point once more, that is, determine publishing point, and write issue behavior class, the instrument class of utilization is inserted in the determined interface method (being publishing point).

Below in conjunction with Fig. 1, describe the embodiment among each the present invention in detail:

At the above-mentioned first step of the present invention, further embodiment is:

Each model function of define system, defining interface, and write the specific implementation class and realize interface.Adopting the governing principle of " at interface programming " this moment, go out some function set for each model abstract definition, specific to Java language, is exactly common Interface, i.e. interface.By these interfaces, the service logic of system is expressed more clearly.Introduce the governing principle of ", but not realizing " below at interface programming:

Interface is simply said, has defined the set of one group of function exactly, if a certain object is supported this interface, it has just necessarily realized the function set of this interface definition so.As, two big object oriented language (i.e. 00 language) language of current popular: but C++ and java applet language this notion of supporting interface all.The C++ program language is expressed with the abstract class of all forming with pure virtual function usually, and for example following generation describes:

class?intf{

public：

void?fool()＝0；

void?foo2()＝0；

}；

Java applet then just has this notion of interface on grammatical levels, with key word " interface " (being Interface) expression, and form that can only define method in interface: as, the title of method, parameter, return type, but define method main body not.Class can realize one or several interfaces, and class can be expressed with " implements ".In for example following generation, describe:

Interface?intf{

public?void?foo()；

}

Class?cls?implements?intf{

public?void?foo(){

The realization of //foo

}

}

The OCP principle of " at interface programming, but not realize " makes: object can be implemented at an easy rate same-interface another object replace.Connection between object needn't be tied on the object of a specific implementation class firmly, has therefore increased dirigibility.It has expressed such theory: separate the realization of the behavior of object and object.Be exactly, then when the describing mode of design entity behavior, should reach such target specifically: when using entity, need not the implementation of detail knowledge entity behavior if an entity can have multiple implementation.

In fact, increasing software systems framework is all very emphasized the definition of interface, realizes details increasing system flexibility in the hope of shielding better.Commercial Java assembly (EJB-Enterprise Java Bean) as Java2 enterprise version (J2EE-Java 2 Enterprise Edition).

At above-mentioned second step of the present invention, further embodiment is:

Write the specific implementation class of interface, and it is related with corresponding interface, its technical foundation is a dynamic proxy mechanism, and the program language of a preferred realization system of the present invention is a Java language, is described below in conjunction with Fig. 2:

In Design Mode, the essence of agency's (Proxy) pattern is not direct invocation target object, but by the invocation target object that agent object is indirect.In this way, agent object can increase extra function in the front and back of invocation target object.It is transparent fully that agent object will be done, so it must realize same interface with destination object.The close-coupled that agent object and destination object need keep same-interface to bring makes the application proxy pattern to pay a high price.Dynamic proxy is then more flexible.In this proxy mode, agent object needn't keep identical interface with the destination object acted on behalf of, even can be with dynamic proxy object broker several destination objects.Dynamic proxy generally is to realize that by the reflex mechanism in the programming language for example the dynamic proxy mechanism among the Java is like this.

For Java, dynamic proxy can be regarded as one and realizes the special defects of one group of specified interface in the runtime, and it has two characteristics

● the runtime dynamically generates

● realize one group of specified interface, can directly be formed into the object of appointment

It dynamically is the proxy class that a group interface produces type safety that dynamic proxy can be used for.Method call to dynamic proxy institute exposed interface will be converted into a kind of unified method of calling, adjust back calling of it then and handle on the class (InvocationHandler), finish concrete processing by calling processing class (InvocationHandler).

An agency (Proxy) class that provides in the java.lang.reflect bag of dynamic proxy by Java language development kit (being JDK-Java Development Kit) on the specific implementation produces, it comprises one and creates the used static method of dynamic proxy, for example following code description:

newProxyInstance()

public?static?Object?newProxyInstance(ClassLoader?loader，

Class[]interfaces，

Invocat?ionHandler?h)

throws?IllegalArgumentException

This method is returned an example with proxy class of specified interface, and the method that this proxy example will call its interface is mapped to calling on the processor (invocation handler), as shown in Figure 4 of appointment.

Parameter:

Loader:proxy place Classloader

Interfaces: one group of interface that needs proxy class to realize

H: call processor, be used for the method call of the Treatment on Dynamic agency interface of realizing.

In the process of creating dynamic proxy, what need that specified response calls calls processor (invocationhandler), this is a centralized control point of method call, all all can be converted into calling calling of (invoke) method among the InvocationHandler calling of interface that dynamic proxy provides, InvocationHandler is an interface below the java.lang.reflect bag among the JDK, have only method of invoke in this interface, in for example following generation, describe:

public?Object?invoke(Object?proxy，Method?method，Object[]args)

Here JDK will be responsible for finishing the conversion that dynamic proxy is called, invoke method by readjustment InvocationHandler is converted to unified form with various calling, can see that from interface function method name and the parameter array called are to be delivered to the invoke method as method parameter, the invoke method will be handled all calling dynamic proxy.

To sum up, dynamic proxy can be realized specified interface at the dynamic binding of runtime, and it can regard dynamic proxy as a common JAVA object of having realized one group of specified interface for caller, calls just the same to calling of dynamic proxy and commonsense method.Dynamic proxy will be bound calling of interface to it and all pass to a unified processing class InvocationHandler in addition, can finish concentrated control and processing on InvocationHandler.

At above-mentioned second step of the present invention, further embodiment is:

With specific implementation class and interface conjunctionn, this is by realizing an instrument class---ProxyHelper (agency helps class) finishes.The corresponding relation of this instrument class record interface and concrete class, consider the situation of the corresponding a plurality of specific implementation classes of an interface, can adopt with figure shape data structure type (being map) data structure records corresponding relation, to such＜interface, specific implementation class object〉two tuple Map table, be referred to as interface-realization Map table.ProxyHelper also outwards provides the method for creating the special interface object.This method just is to use and creates instance of agent (is newProxyInstance, be the canonical function among the JDK-Java Development Kit) the function creation agent object, and import the inner InvocationHandler that realizes of ProxyHelper into as the processing class object in the parameter.

The InvocationHandler that ProxyHelper is realized inside handles class, its invoke method is carried out flow process: calling the class that obtains the method place (is Method.GetDeclaringClass, be the canonical function among the JDK-JavaDevelopment Kit) obtain having the interface class of this interface method, and by Retrieval Interface-realization Map table, obtain associated specific implementation class, after calling through the follow-up issue behavior class of mentioning again, finally call the interface method that the specific implementation class is realized to existing.

Publishing point is exactly an interface method among the present invention.

At above-mentioned the 3rd step of the present invention, further embodiment is:

The theme interface object that selection need be supervised from the interface of system, and further select the publishing point of one or several interface methods of this interface as the needs supervision.Theme issue behavior class is to realize the specific implementation class of standard interface blocker (Interceptor).

For example following code description:

The Interceptor interface definition is as follows:

public?interface?Interceptor?{

public?Object?invoke(Invocation?invocetion)；

}

As shown in Figure 3, the invoke method of Interceptor is standard method noted earlier, and it will be called at publishing point.

Use the present invention and will realize this interface, in invoke, write the action that carry out when the subject state changes, corresponding conventional view person's pattern, invoke just is equivalent to renewal (Update) method of observer (Observer).Wherein, the invocetion object has been preserved the contextual information that may use among the invoke.

Utilize Java reflex mechanism (as Class.getMethod) to obtain representing the Java object (Method) of interface method, this has just specified the interface method as publishing point.Theme issue behavior and this publishing point that to realize Interceptor then associate.This is realized by ProxyHelper that also promptly ProxyHelper is responsible for writing down the incidence relation of such publishing point-theme issue behavior class.Similar with the front, ProxyHelper claims such＜interface method, issue behavior class with this corresponding relation of Map type data structure records〉two tuple Map table shows for method-issue Map.In fact, ProxyHelper also just replaces will preserving observer's tabulation as subject in conventional view person's pattern, and the function of carrying out the theme issue.

The ProxyHelper inner classes realizes calling processor interface, specifically to the realization of this interface method of the publicObject invoke of InvocationHandler (Object proxy, Method method, Object[] args), as shown in Figure 4, its entire flow is as follows:

The first step is called the interface class that Method.GetDeclaringClass obtains having this interface method, and by Retrieval Interface-realization Map table, obtains associated specific implementation class.

Whether second step existed in the search method-issue Map table issue behavior class (Interceptor) that should time calling interface method (Methodmethod), as existing, then called the invoke method of issue behavior class, carried out theme and issued.

In the 3rd step, call the interface method (Method.invoke) that the specific implementation class is realized.Promptly import the specific implementation class object of record in interface-realization tabulation into, carry out the interface method that the specific implementation class realizes.

To sum up, the function of aid class ProxyHelper and realization details are as follows:

ProxyHelper is responsible for: 1, this interface specific implementation class object example of registration interface and realization.2, the specific pairing issue behavior of interface method of record, in concrete the enforcement, theme issue behavior generally all is the specific implementation of interface Interceptor.3, collect the interface of all registrations, create the dynamic proxy object.4, realized that the needed response of establishment dynamic proxy object calls device (InvocationHandler), in the realization of its invoke method, the theme release code of finishing publishing point calls.

Write down two two tuple Map tables among the ProxyHelper:

One,＜and interface, specific implementation class object〉two tuple Map table: be called interface-realizations Map and show; The corresponding relation that is used for record interface and this interface specific implementation class object example of realization.

ProxyHelper collects the interface of all registrations according to the tabulation of interface-realization, and with inner classes for calling processor, call the Proxy class static function newProxyInstance establishment dynamic proxy object in the Java reflection bag.

Two,＜and interface method, theme release code〉two tuple Map table: be called method-issue Map and show; Be used to write down the pairing issue behavior of specific interface method class.

Claims (5)

1. make up the method for coupled system, it is characterized in that may further comprise the steps:

According to function, set corresponding interface;

Set the specific implementation class, realize different functions;

Adopt the mode of dynamic proxy corresponding interface and specific implementation class to be associated by the instrument class;

When needs are changed subject and publishing point, determine publishing point earlier, and write issue behavior class, utilize the instrument class to be inserted in the determined interface method then, wherein, subject is the interface that sets, publishing point is the interface method in this interface.

2. method according to claim 1 is characterized in that, and is further comprising the steps of:

When publishing point was called, the standard method of the issue behavior class that is associated was performed, and carries out the issue of theme state variation.

3. method according to claim 1 and 2 is characterized in that, in the step that corresponding interface and specific implementation class are associated, adopts the corresponding relation of binary picture group shape data structure type table record interface and specific implementation class.

4. method according to claim 1 is characterized in that described dynamic proxy is a special defects of dynamically realizing one group of specified interface in the coupled system runtime.

5. method according to claim 3 is characterized in that, and is further comprising the steps of:

Determine to have the interface class of setting interface method, and, obtain associated specific implementation class by the binary picture group shape data structure type table that retrieval is made up of interface and specific implementation class object;

Whether exist issue behavior class in the binary picture group shape data structure type table of forming by interface method and issue behavior class,, then call the call method of issue behavior class, carry out theme and issue if exist in requisition for the calling interface method;

Call the interface method that described specific implementation class is realized.

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