Java subject notes ~ Program example environment construction of Spring affairs

  Example: Purchase a trans_sale item

 

This example is to realize the purchase of goods, simulate the user to place an order, add sales records to the order table, and reduce inventory from the product table.

Implementation steps:

Step0: Create database tables

Create two database tables sale, goods

sale sales table:

 goods table:

 Goods table data:

 Step1: maven depends on pom.xml

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.3.26</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
        <version>5.3.26</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>5.3.26</version>
    </dependency>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.11</version>
    </dependency>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis-spring</artifactId>
        <version>2.1.0</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.29</version>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.2.8</version>
    </dependency>
</dependencies>	
 <!--插件：-->
<build>
    <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
    </resources>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.11.0</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
    </plugins>
</build>

Step2: Create entity classes

Create entity classes Sale and Goods

 Step3: Define the dao interface

Define two dao interfaces SaleDao and GoodsDao

SaleDao:

  GoodsDao ：

Step4: Define the sql mapping file corresponding to the dao interface

SaleDao.xml

 

 GoodsDao.xml

 

Step5: Define the exception class

Define the exception class NotEnoughException that may be thrown by the service layer

 

Step6: Define the Service interface

Define the Service interface BuyGoodsService

 

Step7: Define the implementation class of service

Define the implementation class BuyGoodsServiceImpl of the service layer interface

1) Class definition

 

2) Dao attribute

 

3) Buy method

 

 

Step8: Modify the content of the Spring configuration file

Declare the Mybatis object

  Declare business layer objects

 

Step9: Define the test class

Define the test class MyTest. It is now ready to run without a transactional proxy

 

Run the program and view the database:

 Test code can be of three types:

① Normal purchase [id and amount match]

② There is no such product【there is no id in the library】

③ Insufficient inventory [amount is greater than the original amount]