Design and implementation of Java shopping system

This example shares the design and implementation code of Java shopping system for your reference. The specific contents are as follows

1. Demand analysis and class division of shopping system

The shopping system itself is a very complex system. There are many details that will be more complex if you study deeply. Moreover, the general shopping system is of web page type and needs a friendly interface. However, as a simple project, this project is only to introduce the basic idea of development to java beginners and how to design the framework and implementation process when object-oriented, Therefore, it is only a simple project based on eclipse development, without the participation of GUI, and many details are taken as follow-up research. The overall design is relatively simple, but it is enough to explain a lot of design ideas and design ideas. Then the basic requirements are analyzed below.

As a simple shopping system, at least the following functions are required (these functions are distributed in menus at different levels):

(1) The user login function and the user account and password modification function do not provide the registration function temporarily; (2) after the user successfully logs in, it needs to have the customer information management function, shopping settlement function and some lottery activities; (3) under the customer information management function, there are many functions, such as query, modification, addition, etc; (4) Under the shopping settlement function, many functions can be divided, such as commodity purchase, payment, bill, etc.; (5) under the lottery activity, a variety of lottery forms can be designed, which can be further divided into many new functional modules. (6) The function of exiting the system shall be provided in the first level menu, the function of logging off and login shall be provided in the second level menu, and all other level menus shall be able to return to the previous level menu.

The above functions are some basic functions. If they are designed according to the process oriented idea, they will be divided into many functional modules, and then go step by step according to the process. But now we use the object-oriented idea to design, so how should we consider the design framework? The main idea of object-oriented is to abstract some requirements into many classes, and then establish the relationship between these classes. All functions can be realized through the cooperation between different classes. Therefore, the main task now is how to reasonably Abstract these classes, what functions these classes want to achieve, and what is the relationship between classes? This process is analyzed through the structure of this design.

(1) Startsms class: used for system startup. Our system definitely needs a startup class. This class contains the main method to start the system. This class is the top level, so it can't involve too many bottom-level details. It only needs to implement some top-level basic processes, mainly calling some methods of other bottom-level classes to realize functions.

(2) Data class: it is used to store all our data information. This design mainly stores some pre stored commodity information available for purchase and registered member information. Why do you need this class? Let's think about it. In object-oriented design, we have a lot of data, so we can't define and modify it everywhere, which will make the system more complex The aggregation degree of is too low, prone to many errors, and it is difficult to carry out later function expansion and error modification. Therefore, we need to classify some public data used, put them in a class, and provide methods to operate these data in this class.

(3) Menu class: used to display and process menus at all levels. Since we are designing a shopping system, even if it is simple, we need a basic menu to interact with users. Because there are many menus and menus at all levels are connected layer by layer, we need to manage the menus uniformly, so the menu class appears. Note that the dishes here Just some top-level menu displays and basic function calls, the specific underlying algorithms still need to be implemented by more underlying classes.

(4) Manager class: it is used to store the user's account and password. Since we need the user to log in, we certainly need a separate class to manage the user's account and password, so as to make the system more independent. The user in this design has only one account and password. Only the account and password can be modified, but registration is not allowed.

(5) Verifyequal class: used to verify login information. This class is equivalent to abstracting the login function into a class. In fact, this implementation is not very necessary, but in order to make the system function division clearer, this class is designed to verify login information and existing accounts and passwords, so as to give verification results.

(6) Custmanagement class: used for customer information management. This class implements some underlying functions, such as query, modification, addition, etc. when we enter the menu of customer information management, we must carry out many operations on customer information. In order to facilitate these operations and consider the subsequent scalability, all functions of customer information management are included here Can be abstracted and placed in this class. The upper menu realizes the management of customer information by calling the methods in this class.

(7) Pay class: it is used to handle shopping and settlement operations. The principle of this class is basically the same as that of the above classes. When customers choose to shop, there must be many operations, such as what to buy, how much, payment, change, etc. these functions are fragmented, so we manage them centrally, so we abstract this class and control the menu options of shopping and settlement The underlying algorithm is implemented. The upper menu realizes the shopping and settlement functions by calling this class of methods, and can return to the upper menu.

(8) Giftmanagement class: it is used to process lottery activities. The reason for the existence of this class is basically the same as that of the classes in (6) and (7). This class uniformly manages lottery activities. The upper menu can realize the lottery function only by calling the methods of this class.

(9) Gift class: used to manage gifts. Since the lucky draw is designed, gifts must be needed. What kind of gifts will we give? We can't list every gift in detail. It's very redundant and troublesome, so we simply abstract a gift class and save some attributes of the gift: gift name and price as the components of this class Member variable, and then you can easily manage this class. You can directly create a new gift object for what kind of gift you need, and then modify and manage the properties of the object. This implementation is similar to an interface, but it is completely different from the interface and has few functions.

In short, the above classes are abstracted after some functional modules are divided, and some places are not necessarily reasonable. We mainly need to see the requirements and formulate different schemes according to different requirements. here I want to "gift" class "More importantly, the design of this class is very consistent with the object-oriented idea. For example, if the shopping system needs many gifts, such as mobile phones, computers, mobile power supplies, etc., if we write these gifts one by one, the system code will be very redundant. Because the properties of the gifts are basically the same, we can abstract them into a class, so that we can When we need a gift, we only need to define an object and give it certain attributes. For example, if we need a mobile phone or a computer, we only need to create a new gift object, and then set its attribute to the mobile phone when we need a mobile phone, and set its attribute to the computer when we need a computer. We can set what we need, This simplifies our code and makes the structure clearer. In more complex systems, it is more reasonable to use the interface to realize gifts, so that different gift classes can be realized according to the interface, so as to meet different needs, which is similar to the USB interface on our computer. Only this interface is needed, we can plug in a lot of various peripheral devices. The reason is almost the same.

2. Relationship and process between classes of shopping system (represented by graphical method)

The following figure shows the relationship between these 9 classes I drew with Microsoft Office Visio 2003 drawing tool.

The relationship between various types can be clearly seen from the above figure. The general relationship and process are as follows:

(1) The startsms class is a startup class, containing the main method. This class defines the objects of verifyequal class and data class to store data and authentication information. At the same time, the data class contains the manager class to store the pre stored user account information. Then, through certain logic in the main method, call the showloginmenu() method in the menu class, Used to process the first level menu - login modification process;

(2) If the login is successful, call the showmainmenu() method in the menu class to process the secondary menu - the main process of the shopping system. If the login fails 3 times, directly exit the system;

(3) In the showmainmenu() method of the menu class, select different secondary menu options to call the showcustmmenu() method of the menu class to handle the customer information management process, or call the showsendmenu() method of the menu class to handle the lottery activity process, or call the calcprice() method of the pay class to handle the shopping settlement process;

(4) If the customer information management option in the secondary menu is selected, the showcustmmenu() method in the menu class will be called. This method will call various methods in the custmanagement class to handle different operations of customer information management;

(5) If the shopping settlement option in the secondary menu is selected, the calcprice() method in the pay class will be called to process the shopping settlement process. Note that the getdiscount() method in the pay class is used to calculate the discount rate according to the customer member information;

(6) If you select the truth feedback option in the secondary menu, that is, the lottery activity, you will call the showsendmenu() method in the menu class, which will call various methods in the giftmanagement class to handle different operations of the lottery activity;

Notice that there is a returnlastmenu () method in custmanagement class and giftmanagement class, which is used to return the previous menu.

3. Code implementation

It should be noted that these codes should be placed on CN Itcast package.

3.1 startsms class

3.2 data class

3.3 manager class

3.4 verifyequal class

3.5 menu class

3.6 custmanagement class

3.7 pay class

3.8 giftmanagement class

3.9 gift class

3.10 code summary

From the codes of the above 9 classes, there are some points to pay attention to:

(1) In many classes, basically the same member variables as those in data are defined, but there is no manager object. This is to save and transfer data layer by layer. This method is implemented through the SetData () method, but this method is not very good. In general, the member variables should be set to private. This design is for convenient operation, Make the system simpler and less secure.

(2) Note that the StringBuilder class in Java is used in all places where string splicing is required. This is to efficiently handle string splicing and prevent splicing data redundancy caused by string class.

(3) The processes in these designs are not very reasonable. You can modify them according to your own needs.

(4) The code basically does not consider the handling of exceptions, so when there are errors in input, ordinary errors can be re input, but if there are mismatches and other errors, exceptions will appear directly and exit the system. These are also the defects of this design, which can be improved by regular expressions.

In short, the code given is for reference only. You can modify it as needed. These codes are verified and can be run directly.

4. Summary

This design is only to explain some basic design ideas and design concepts, as well as the problems to be considered in the design process, mainly to explain how to use object-oriented ideas to solve problems in real life, so the design is relatively simple, but I hope you can understand these basic ideas through this design, So as to help you realize the basic idea of object-oriented.

In short, language is just a tool to solve problems. You can use C + +, c# and other languages to realize this system, as long as you have good design ideas and design ideas. Again, this design is for reference only. You are welcome to participate in the discussion. If there are mistakes, you are welcome to correct them. Thank you.