Use Properties to Modify Database Configuration

Introduction

In this project, you will learn how to use properties to modify the database configuration in a MyBatis-based application. MyBatis is a popular Java persistence framework that simplifies the interaction between Java applications and databases.

👀 Preview

-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running org.labex.test.MyBatisTest
Data deleted successfully
Data inserted successfully
[course number：1 course name：Data Structures teacher：John Smith, course number：2 course name：Java teacher：Mary Johnson, course number：3 course name：Python teacher：David Brown, course number：4 course name：C++ teacher：Jennifer Davis, course number：6 course name：C teacher：Michael Wilson, course number：8 course name：Artificial Intelligence teacher：Emily Thompson]
Data updated successfully
Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.1 sec

🎯 Tasks

In this project, you will learn:

• How to move the database configuration from the mybatis-config.xml file to the db.properties file.
• How to modify the mybatis-config.xml file to use the properties defined in the db.properties file to configure the database connection.
• How to verify the application's functionality by running the provided test cases.

🏆 Achievements

After completing this project, you will be able to:

• Separate the database configuration from the MyBatis configuration file.
• Use properties to configure the database connection in a MyBatis-based application.
• Import and use property values in the MyBatis configuration file.
• Ensure the application's functionality by running test cases.

Skills Graph

Move the Database Configuration to the db.properties File

In this step, you will learn how to move the database configuration from the mybatis-config.xml file to the db.properties file.

1. Open the db.properties file located in the MyBatisPropertiesProject/src/main/resources directory.
2. Add the following properties to the db.properties file:

## Database Configuration
## Database driver class name
driver=com.mysql.cj.jdbc.Driver
## Database connection URL
url=jdbc:mysql://localhost:3306/MyBatisDemo?characterEncoding=utf-8
## Database username
username=root
## Database password
password=
## Mapper Configuration
## Package containing MyBatis mapper interfaces
mapper.package=org.labex.mapper

These properties define the database driver, connection URL, username, and password, as well as the package containing the MyBatis mapper interfaces.

Modify the mybatis-config.xml File to Use the Properties

In this step, you will learn how to modify the mybatis-config.xml file to use the properties defined in the db.properties file.

1. Open the mybatis-config.xml file located in the MyBatisPropertiesProject/src/main/resources directory.
2. Add the following line at the beginning of the file to import the properties from the db.properties file:

<properties resource="db.properties"/>

3. Update the database connection configuration in the <dataSource> element to use the imported properties:

<dataSource type="POOLED">
    <property name="driver" value="${driver}"/>
    <property name="url" value="${url}"/>
    <property name="username" value="${username}"/>
    <property name="password" value="${password}"/>
</dataSource>

4. Update the <mappers> element to use the mapper.package property:

<mappers>
    <package name="${mapper.package}"/>
</mappers>

The complete mybatis-config.xml file should now look like this:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!-- Import properties from db.properties file -->
    <properties resource="db.properties"/>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <!-- Configure database connection using imported properties -->
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>

    <!-- Register SQL mapping files -->
    <mappers>
        <package name="${mapper.package}"/>
    </mappers>
</configuration>

Now, the database configuration is stored in the db.properties file, and the mybatis-config.xml file uses the properties defined in db.properties to configure the database connection.

Run the Test Case

To run the test case, follow these steps:

1. In your terminal, navigate to the MyBatisPropertiesProject project directory using the following command:

cd ~/project/MyBatisPropertiesProject/

2. Run the following command to execute the test case:

mvn test

The output should be similar to the following:

-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running org.labex.test.MyBatisTest
Data deleted successfully
Data inserted successfully
[course number：1 course name：Data Structures teacher：John Smith, course number：2 course name：Java teacher：Mary Johnson, course number：3 course name：Python teacher：David Brown, course number：4 course name：C++ teacher：Jennifer Davis, course number：6 course name：C teacher：Michael Wilson, course number：8 course name：Artificial Intelligence teacher：Emily Thompson]
Data updated successfully
Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.1 sec

This shows that the test class uses MyBatis to perform CRUD operations on a database table named Course, including select, insert, update, and delete operations.

Summary

Congratulations! You have completed this project. You can practice more labs in LabEx to improve your skills.