[Abstract] Because the automobile market in our country is rising at a steady pace, the second-hand car market has also moved to a rapid development. According to the buying and selling situation in the automobile market in recent years, more and more people tend to buy used cars

[Abstract] Because the automobile market in our country is rising at a steady pace, the second-hand car market has also moved to the road of rapid development. According to the buying and selling situation in the automobile market in recent years, more and more people tend to buy used cars because it saves money and is practical. However, the transactions of used cars still lack certain safety, order and rationality. Using modern computer technology, establishing a second-hand car transaction management system can bring convenience to used car transactions and make used car transactions more. The functions of this system are divided into administrator module and user module. These two modules mainly implement the system administrator's functional operations on used cars and other information, while the functions implemented by users are various inquiries on used cars and suppliers and other information. The system uses the java language to use J2EE as the technical platform architecture and develops on the MyEclipse platform, uses Mysql5.5 as the backend database and the unified software development process as the development method, and uses Rational Rose 2003 as the modeling tool.

[Keywords] Used Cars; Information Management; UML; MySQL; J2EE

Abstract: Because the car market in our country is rising at a steady speed, and it also makes the market for the second-hand car market develop rapidly. According to the sales situation of the car market in recent years, more and more people tend to buy used cars, because it saves money and is practical, but the transaction of used cars is still lack of security, order and rationality. Using modern computer technology, the establishment of a second-hand car transaction management system is able to facilitate the transaction of second-hand cars and make used car transactions more. The function of this system is divided into the administrator module and the user module. The two modules mainly realize the function operation of the system administrators to the second-hand car and other information, and the function of the user is the various inquiries about the information of the second-hand car and the supplier. The system uses the Java language as the J2EE technology platform architecture, develops on the MyEclipse platform, uses the MYSQL5.5 as the background database and the unified software development process as the development method, and uses the Rational Rose 2003 as the modeling tool.

Key words: Used cars; information management; UML; MySQL; J2EE

1 Introduction on

1.1 Project background and significance

Over the years, our country's rapid development and rapid improvement in economy and status have made our country's automobile market irreplaceable importance in the world. Due to the rapid development of the automotive industry and the continuous purchase of new cars by people, used cars have gradually appeared in the public's vision. While second-hand cars appear in the public's vision at a high frequency, we need to build a management system of used cars, just like the transaction management system of new cars. Therefore, it has become a very important thing to establish a safe used car transaction management system. In recent years, network technology has also developed rapidly, making used car transaction management systems very common in various car dealers. Before our used car transaction management system was established, the transaction processing problems of used cars were solved by acquaintances or storing cars sold on behalf of others in the car dealer for buying and selling. For such private transactions, such as waiting for buyers to watch, this is unreasonable and unsafe. Compared with the previous method, the used car transaction management system has many advantages. It can provide comprehensive and rich information about used cars, and view faster and more accurate and has no geographical restrictions. Through relevant surveys, we can know that in developed Western countries, online second-hand car transactions are very common, and our country's current second-hand car trading market will look like it step by step according to the changes in our country's unique market economy .However, due to the type, model and quantity of vehicles, under the current trend, the second-hand car transaction management system should be continuously established. This topic is a management system designed to facilitate the management of used car transactions.

1.2 Current status and development trends of domestic and foreign applications in related fields

Under the leadership of outstanding leaders and scientific policies, our country's living standards are unimaginably fast. One aspect is that more and more individuals and families want to buy a car as a tool for daily life. In recent years, due to the large number of people buying cars, the production of vehicles has continued to increase, so more and more used cars have been generated. However, there has not been much change in the used car market. Therefore, under this negative market environment and under the continuous increase and squeeze of used cars, the pressure on issues such as how to trade used cars in a newly generated market is becoming increasingly greater. Under the conditions of high intensity and short-term conditions, such a huge amount of information makes it increasingly difficult to ensure security. To solve this problem, most car dealers choose to establish an information-based second-hand car transaction management system to alleviate the increasing pressure brought by car purchase. However, because at present, the established second-hand car transaction management system is almost in its infancy, many problems are still urgently needed to be improved after the incident. Taking the vehicle transaction management system as an example, each system is independent of each other, and it is impossible to share a large amount of used car information, which will greatly reduce the sales rate of used cars. At present, the management method of traditional used car transaction management systems is obviously difficult to bear the work needs brought by the growing large number of new cars. In order to facilitate the management of sales work, the work is divided on a scale. Therefore, modern used car transaction management and sales of used cars are necessary. From this we can see that the goal of the used car transaction management system we are going to design is exactly consistent with the demand of the current vehicle market. In order to show the unique characteristics of the car dealer, most car dealers urgently need to try their best to meet the needs of the car dealer, which has the characteristics of the car dealer, to ensure that the internal database system of the car dealer can promptly accept the second-hand car sales data of the car dealer, so as to ensure the normal operation of the second-hand car management and trading system. Under the current circumstances, the used car transaction management system in the market generally includes a management subsystem and a service subsystem. Each subsystem has independent functions, and independent work meets different needs. However, it is also necessary to cooperate with each other to complete the overall function of used car sales information management. During the system construction process, since the modules need to cooperate with each other relative to different functions, there will be some external and internal problems:

(1) At present, many car behaviors provide hardware conditions provided by the used car information transaction management system are not very complete. Although some car dealers nominally have established their own used car transaction management system and claim to the outside world that second-hand car transaction management is carried out through second-hand car information system, many places are just staying at the stage of promoting used car transaction management, and have not realized the functions of data information processing and data sharing of used cars entering inventory and out of stock. The modules of the car dealer's second-hand car transaction management system are independent of each other, which has caused extreme dissynchronization of used car transaction information. Some trading information or registration information of the system cannot be obtained by vehicle managers in a timely manner, resulting in the administrator receiving delayed information. Therefore, the car dealer cannot synchronize the latest data to the website, and the real-time information management function cannot be realized. This will seriously affect the number of used car dealers' sales.

(2) The types, colors and sizes of the cars of the car are of various types, colors and sizes, and the corresponding vehicle numbers are also very chaotic. As people continue to purchase new cars, this situation also occurs at the same time that second-hand cars are increasing rapidly. This produces a large number of used cars that are not single, but like new cars, there are many types that buyers can choose from.

(3) With the rapid development of science and technology, the software updates and replacement are developing rapidly at a speed that surprised us. The software settings in the used car transaction management systems of various car companies have become relatively backward. In addition, there are no unified standards. The software environment and hardware environments between different departments are very different, and the components of the system software are also diverse, so we can see that the system environments between employees in the same department are also very different. Among them, the processing of databases is particularly obvious. Given that there are too many different types of databases, and they all have their own advantages and shortcomings, each car dealer has different choices for databases. The various similarities and differences between each car dealer has caused the resources between each car dealer to be unable to be shared in real time, which seriously affects work efficiency. In addition, due to the inconsistency of the database, many redundant data and missing situations occur simultaneously, which will be a serious vulnerability in the entire system. The continuous development of

technology has promoted major changes in the trading methods of used cars in the car industry, and many new information technologies have played a huge role in the used car transaction management system. In order to adapt to the era of rapid development, various car dealers increasingly need a complete set of used car transaction management systems with their own characteristics, so as to achieve the modern and integrated management level of vehicle market transaction work, which will bring great convenience to the transaction work and other related work in the entire used car market.

1.3 Main work

This system development hopes to meet the following requirements:

(1) Management of used car information: administrators manage information query, add, modify and delete functions such as second-hand vehicles, such as checking the model and price of the vehicle. Ordinary users need to enter the system to browse vehicle information, select vehicles, submit orders to the system, and complete the vehicle transaction process. Then the backend can query, add, delete and modify the vehicle sales information through the sales management function of the vehicle.

(2) System administrator login: The system administrator logs in by entering the correct information. When logging in, he enters the system as an administrator, and he can have administrative permissions.

(3) System administrator management: System administrators can add, delete, modify second-hand car information, vehicle evaluation, inventory, procurement, sales and statistics and other functions.

(4) Password management: System administrators can have the function of changing their passwords, mainly to prevent passwords from being discovered and causing unnecessary trouble.

(5) Data security: In order to improve the security of the entire used car transaction management system, this system adopts a timed backup function and a restore function. If there is a problem, data can be restored in time in the shortest time.

1.4 Development Environment

This used car transaction management system design mainly uses two technologies: Java project development and Mysql's database operation. Our design this time uses the B/S architecture, which is divided into the system's backend management. The backend management uses Java for development; and the system's frontend display, while the frontend uses JSP technology (a dynamic page technology) for implementation.

1.4.1 Introduction to the hardware environment

processor: Intel Core I5-2430M.

memory: more than 1GB.

Hard disk space: more than 100G of available storage space.

graphics card: NVIDIA GeForce GT 550M + Intel GMA HD.

Network configuration: broadband network.

1.4.2 Introduction to the software environment

operating system: Windows98 and above;

application server: Tomcat6.0 or above;

JDK version: 1.6 or above;

database: MYSQL

2 System analysis

2.1 System function requirements

The mode used in the design issue of this used car transaction management system is the browser/server mode. In this basic , in order to achieve different compatibility between systems and sharing of data about the system, JSP technology is also used, which improves the compatibility and operability between systems, repeatability issues, and has good scalability in the development technology. This also allows the stability of the system to be better not to shorten the system life due to problems caused by operation and other errors. We analyze the system functions based on completing the overall task of system development. The total task we want to complete mainly includes a series of operations such as adding user information, such as adding and retrieving user information, also has functions such as adding and retrieving supplier management, product management, addition and retrieving, addition and retrieving, warehousing management, adding and retrieving, inventory management, adding and retrieving, outbound management, adding and retrieving, statistical management query, second-hand car evaluation, and other functions. In terms of design, this system conforms to the principles of standardized design and standardized design, and conforms to the software development method. While giving this system independence, the system also provides a higher level of development efficiency. Regarding this system, we also adopt a modular approach, separating the various functions of the module to make it more convenient in program maintenance and expansion, and thus ensuring the reusability of the program.

2.2 System development function

Used car transaction management system design and implement used car transaction management website. The main research direction of the system is the allocation and sharing of used car information data resources based on the B/S model, and uses JSP technology, combined with MySQL database with good compatibility. Based on the rapid economic development and automobiles have become an indispensable tool for transportation in the current society and the support of various policies, the basic conditions for users to purchase a practical car have been met. Therefore, each car dealer can use these existing conditions to deploy a used car transaction management system, so that users can more conveniently and timely grasp the latest developments in the used car market, so that the sales volume of used cars can greatly increase while also increasing the demand for vehicle liquidity in the used car market.

2.3 System feasibility analysis

2.3.1 Economic feasibility

With the rapid development of the economy and the rapid development of the Internet, the system written in this project will open a new window for the efficiency of used car transaction management. Compared with the system to be written with the previous used car transaction management, the used car transaction management system has great advantages in all aspects. Once this system is put into use, it will reduce the working pressure of staff on a large scale. The operation of this system can reduce a lot of unnecessary manpower, thereby saving some resources for other purposes. At the same time, this system can also count a large amount of data and sort each database. This is mainly considered for the security and uniformity of data. So overall, this system is economically feasible and optimistic.

2.3.2 Technical feasibility

The user range of used car transaction management systems is very large, for example, users who want to purchase a car, users who want to change a car, etc., so issues such as stability, accuracy and safety are very important to this system. Therefore, the design of the used car transaction management system is developed based on the B/S model. The front desk database of this system uses MySQL database. This database system has absolute advantages over other databases in terms of stability, accuracy, security and operation speed. At the same time, it processes data information in a particularly large amount and high efficiency.The backend of this system uses MyEclipse 8.5 from Microsoft Corporation as the main development platform. MyEclipse 8.5 provides us with rich data types, very complete instruction control statements, and support for classes and objects. While the development system is guaranteed by high performance, the modular requirements of the code are guaranteed, which facilitates future system modification problems and future system expansion problems.

To sum up, this system is feasible whether it is technically or in terms of equipment.

2.3.3 Operation feasibility

Although previous car dealers adopted many methods and methods to manage used cars transactions to achieve the desired effect, this has many disadvantages compared to traditional methods and methods. This method and method requires a lot of time and a lot of manpower, which is not only inefficient, but also affects the normal business of users due to problems caused by some human errors.

The used car transaction management system is developed in combination with the needs of daily work. The hardware and software requirements are very common and can solve many problems in the current used car transaction testing work. Therefore, this project is very consistent with the daily work of related industries such as car dealers. It has a solid and solid customer base. Therefore, from the analysis described above, we can see that the technical operation of this system has become increasingly mature and perfect, and the possibility of operationalization of technical implementation issues is extremely high. After the development of this system, the administrator only needs to use a browser to log in to use this system. Therefore, this system is feasible in terms of operationality.

3 Overall design

3.1 Function module division

(1) System administrator function module

System administrator only enters the system after entering the correct information on the login interface, and manages the system with permissions as an administrator. At the same time, pay attention to logging in as an administrator when logging in. The main functions of the system administrator are the management of users, suppliers, second-hand cars, vehicle inlet management and vehicle out-of-warehouse management, vehicle inventory management and second-hand car evaluation management. System administrators can also change their passwords, mainly to prevent passwords from being discovered and causing unnecessary trouble.

(2) Ordinary user module

Ordinary users also log in as an ordinary user when logging in. The main functions of ordinary users are querying user information, querying supplier information, querying used car information, management of sales, management of vehicle inventory, etc.

3.2 module functions

used car transaction management system includes system administrator module and ordinary users' modules. In this module of the system administrator, the system administrator can have permissions to manage user information, manage suppliers, manage used car information, manage vehicle evaluation, manage inventory information, manage procurement information and manage sales, etc. After entering the system by entering the user name and password, the system administrator can add, delete and modify information to the system users, etc. after clicking User Management. After clicking on Vendor Management, the system administrator can add, modify and delete the supplier name, contact number and contact address. In the management of used car information, the system administrator can query, delete, and change the vehicle name, color, model, purchase time, and number of kilometers of used cars. In vehicle evaluation management, the system administrator can query, modify and delete the evaluation information of used cars, and can also add the brake performance, stability, appearance conditions and engine performance of used cars to conduct a series of evaluation operations. In inventory management, administrators can query the inventory of used cars. Then in procurement management , you can query the used cars based on the order number and vehicle type, and you can also add information about purchasing second-hand vehicles, such as vehicle name, quantity and notes (can not be filled in). As shown in Figure 3.1.

Figure 3.1 System Administrator Use Case Diagram

3.2.1 Supply Management Functions

After the system administrator logs into the system by entering the account and password, he comes to the system operation interface. Users can click Supplier Management under Supplier Management in the menu on the left menu to enter the supplier management interface. In the supplier management interface, the administrator can execute supplier information query, delete supplier information, and modify a certain information of existing suppliers. Its function is shown in Figure 3.2.

Figure 3.2 Functional design diagram of supplier management

3.2.2 Functional management

Inventory management is a statistical management of used car records in the car shop. In inventory management, administrators can clearly know whether the existing vehicles in the car shop are enough for the next period of sales, so that inventory can be replenished in time. Inventory management is also something that the system administrator can operate after logging in to the system. Similarly, users can find the inventory management options in the menu bar on the left. After clicking, they enter the inventory management interface and perform operations to query the relevant information of used cars.

3.2.3 Functions of vehicle evaluation management

The role of vehicle evaluation is very important for used cars, because we need to conduct professional and accurate evaluation of used cars before we can set a price for used cars that is suitable and reasonable for buyers. Vehicle evaluation management is also a functional operation of the administrator after logging into the system. After selecting Vehicle Assessment Management in the menu bar, if you want to view the evaluated used cars or modify the evaluated used cars, you can click the hyperlink of the vehicle evaluation list under the vehicle evaluation management bar to view it; if you want to evaluate a used car, you can click the hyperlink of the vehicle evaluation to perform a series of evaluation operations on the used cars.

3.3 System module design diagram

Figure 3.3 System module design diagram

3.4 System flow diagram

After the system administrator enters the correct user name and password in the login interface to enter the used car transaction management system, he can perform management of users in the system, query, modify and delete the supplier's name, contact number and contact address; add and query, delete information such as the vehicle number and number of kilometers of used cars; evaluate and manage the evaluation and management of used cars, which is reflected in the professional judgment of whether the vehicle has collided, the stability of the vehicle and the brake performance of the vehicle, and similar operations; there are also specific management of the sales information of used cars, such as the addition, deletion and modification of information such as the price and quantity of vehicles.

Figure 3.4 System Administrator Flowchart

Users need to enter the user's own relevant information in the system. After entering the user's own relevant information according to the prompt box, if the input is correct, you can directly enter the system's operation interface. If the prompt box shows that the information input is incorrect, you need to re-enter and enter the operation interface. After entering the operation interface, users can query the user's own relevant information, supplier's relevant information, second-hand car related information, and inventory, etc. within the system.

Figure 3.5 User flow chart

4 Detailed design of

4.1 System data model

The data model of the system database is the core part and the most basic part of a program's database. A good database data model can help users determine application results in time when configuring the database or building a database, and can play their own advantages in different database systems. The relational model of this topic also has many advantages. For example, its concept is single and its access path is transparent to the user.

The relational data model of this topic is designed as follows:

l User table (t_user): ID, note, product name, product number, supplier number.

l Supplier table (t_gongyingshang): ID, supplier name, contact address, contact number.

l Used car table (t_shangpin): ID, user name, etc.

l Inventory Table (t_kucun): ID, inventory quantity, product number.

l Purchase form (t_ruku): ID, note, order number, price, inventory time, quantity, product number.

l Sales table (t_chuku): ID, notes, outbound number, outbound time, price, quantity, product number.

4.1.1 Create the structure of the database table

(1) User table

Table name: t_user, The user's private information is saved in this table, and the user information entity attribute diagram is shown in Figure 4.1.

Figure 4.1 User information entity attribute diagram

data table structure is shown in Table 4.1.

Table 4.1 User information table

(2)Supply table

Table name: t_gongyingshang, This table mainly stores the supplier's number, supplier name, contact address and contact number. The supplier information entity attribute diagram is shown in Figure 4.2.

Figure 4.2 Supplier information entity attribute diagram

Its data structure is shown in Table 4.2.

Table 4.2 Supplier information table

(3) Used car table

Table name: t_shangpin. This table stores information about used cars, such as number, product name, product number, notes, etc. The physical attribute diagram of used car information is shown in Figure 4.3.

Figure 4.3 Used car information entity attribute diagram

Its data structure is shown in Table 4.3.

Table 4.3 Used car information table

9

Supplier number

(4)Inventory table

Table name: t_kucun, This table saves information on the inventory quantity and number of used cars. The inventory information entity attribute diagram is shown in Figure 4.4.

Figure 4.4 Inventory information entity attribute diagram

Its data structure is shown in Table 4.4.

Table 4.4 Inventory information table

(5)Purchase table

Table name: t_ruku, This table contains detailed information on the purchase price, order number, etc. of used cars. The physical attribute diagram of the procurement information is shown in Figure 4.5.

Figure 4.5 Procurement information entity attribute diagram

Its data structure is shown in Table 4.5.

Table 4.5 Purchase information table

(6)Sales table

Table name: t_chuku, The detailed information about selling used cars is stored in this table, including price, notes, outbound number and other information. The physical attribute diagram of the sales information is shown in Figure 4.6.

Figure 4.6 Sales Information Entity Attributes Diagram

Its data structure is shown in Table 4.6.

Table 4.6 Sales Information Table

number

is

4.1.2 Reasons for choosing a database

MySQL is a relational database management system (RDBMS) open to source code. It is different from the Sql Server developed by Microsoft itself. Anyone can download and modify it when allowed. That is to say, when we use it, we can delete unnecessary functions according to our own situation. Although it is slightly weaker than Sql Server in terms of security due to open source and other reasons, MySql has great advantages in terms of speed, reliability and adaptability. MySql will not charge at all, and its server functions are also very comprehensive, so this is one of the reasons why many people give up the database made by Microsoft and choose this. Although MySql has some disadvantages compared with Sql Server databases and other databases. For example, its security is not as strong as Sql Server and it does not have a stored procedure language, the advantages mentioned above have already attracted me to choose MySql.