Solve common problems when configuring database connection in MyBatis

MyBatis is a popular Java persistence framework that can easily map Java objects to database tables. In the process of using MyBatis to configure database connections, we often encounter some problems. This article will introduce several common problems and provide solutions and specific code examples.

Problem 1: Database connection configuration error
Solution: Check whether the database connection string, user name and password are correct; confirm whether the database server is started and running normally.

Sample code:

<environment id="development">
   <transactionManager type="JDBC"></transactionManager>
   <dataSource type="POOLED">
       <property name="driver" value="com.mysql.jdbc.Driver"/>
       <property name="url" value="jdbc:mysql://localhost:3306/myDatabase"/>
       <property name="username" value="root"/>
       <property name="password" value="123456"/>
   </dataSource>
</environment>

Problem 2: The database driver is not introduced
Solution: Introduce the jar package of the database driver into the project.

Sample code:

<dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>8.0.13</version>
</dependency>

Problem 3: Database connection pool configuration error
Solution: Check whether the database connection pool configuration is correct, including the maximum number of connections, the minimum number of connections, and idle connection timeout Time etc.

Sample code:

<dataSource type="POOLED">
   <property name="driver" value="com.mysql.jdbc.Driver"/>
   <property name="url" value="jdbc:mysql://localhost:3306/myDatabase"/>
   <property name="username" value="root"/>
   <property name="password" value="123456"/>
   <property name="poolMaximumActiveConnections" value="50"/>
   <property name="poolMaximumIdleConnections" value="10"/>
   <property name="poolMaximumCheckoutTime" value="20000"/>
   <property name="poolPingEnabled" value="true"/>
   <property name="poolPingQuery" value="SELECT 1"/>
</dataSource>

Problem 4: Connection timeout
Solution: Increase the connection timeout, or increase the maximum number of connections in the database connection pool.

Sample code:

<dataSource type="POOLED">
   <property name="driver" value="com.mysql.jdbc.Driver"/>
   <property name="url" value="jdbc:mysql://localhost:3306/myDatabase?connectTimeout=5000"/>
   <property name="username" value="root"/>
   <property name="password" value="123456"/>
   <property name="poolMaximumActiveConnections" value="100"/>
</dataSource>

Problem 5: Error in mapping between database fields and Java object properties
Solution: Confirm whether the field names of the database table are consistent with the Java object property names, or use MyBatis Mapping configuration for manual mapping.

Sample code:

<resultMap id="userMap" type="User">
   <result property="userId" column="id"/>
   <result property="userName" column="name"/>
</resultMap>

Through the above solutions and code examples, we can solve common problems in the MyBatis configuration database connection process. Of course, other problems may be encountered in actual applications, which need to be adjusted and solved according to specific circumstances. I hope this article can provide some help to everyone when using MyBatis to configure database connections.

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