- Properties
Define attributes and read attribute files
- Define properties file
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/development
jdbc.username=root
jdbc.password=123456
- Import the properties file into the sqlMappingConfig file
<?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> <!--use resource Import external property profile--> <properties resource="db.properties"> <!--stay properties Internal use property Define properties--> <!--If the external configuration file has this attribute, the internally defined attribute will be overwritten by the external attribute--> <property name="jdbc.username" value="root"/> <property name="jdbc.password" value="1234"/> </properties> <environments default="development"> <environment id="development"> <!--use jdbc transaction management--> <transactionManager type="JDBC"/> <!--Configure database connection pool--> <dataSource type="POOLED"> <property name="driver" value="$"/> <property name="url" value="$"/> <property name="username" value="$"/> <property name="password" value="$"/> </dataSource> </environment> </environments> <!--Load mapping file--> <mappers> <!--<mapper resource="demo1/Mapping"/>--> <mapper resource="demo2/Mapping"/> </mappers> </configuration>
After using properties configuration
- Settings
This is a very important adjustment setting in Mybatis. They will change the runtime behavior of Mybatis
<!-- Used to configure settings in Mybatis -- >
<settings>
<!-- Enable hump mapping to serve customized SQL statements -- >
<!-- Set the hump naming attribute that enables the mapping of database field underscores to java objects. The defau lt is false -- >
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
The sqlMappingConfig file is as follows
<?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> <!--use resource Import external property profile--> <properties resource="db.properties"> <!--stay properties Internal use property Define properties--> <!--If the external configuration file has this attribute, the internally defined attribute will be overwritten by the external attribute--> <property name="jdbc.username" value="root"/> <property name="jdbc.password" value="1234"/> </properties> <!--Used to configure Mybatis Settings in--> <settings> <!--Turn on hump mapping, which is user-defined SQL Statement service--> <!--Set enable database field underline mapping to java Hump naming attribute of the object. The default is false--> <setting name="mapUnderscoreToCamelCase" value="true"/> </settings> <environments default="development"> <environment id="development"> <!--use jdbc transaction management--> <transactionManager type="JDBC"/> <!--Configure database connection pool--> <dataSource type="POOLED"> <property name="driver" value="$"/> <property name="url" value="$"/> <property name="username" value="$"/> <property name="password" value="$"/> </dataSource> </environment> </environments> <!--Load mapping file--> <mappers> <!--<mapper resource="demo1/Mapping"/>--> <mapper resource="demo2/Mapping"/> </mappers> </configuration>
- typeAliases
The function of type alias is to set a short name for Java type for our subsequent writing
<typeAliases>
<!-- Single alias definition -- >
<typeAlias alias="Customer" type="demo2.Customer"/>
<!-- Batch alias definition, scan the classes under the whole package, and the alias is the class name (case insensitive) - >
<!-- Note: if the current package class and the sub package class have the same name, an exception will be reported. We can use the annotation @ Alias ("Alias") -- > on the class
<package name="demo2"/>
</typeAliases>
After the alias is defined, the alias can be used in Mapping
- typeHandlers
Whether Mybatis sets a parameter in the PreparedStatement or takes a value from the result set, it will use the type processor to convert the obtained value into Java type in an appropriate way. Before Mybatis 3.4, we need to register these processors manually, but in later versions, the processors are registered automatically. Just need to know
- Plugins
Plug in is a very powerful mechanism provided by Mybatis, which allows us to modify some core behaviors of Mybatis through plug-ins
- Environments
Mybatis can configure a variety of environments, such as development environment, test environment and production environment. Each environment needs different configurations, so we can configure each environment with an environment tag and specify a unique identifier id. Quickly switch environments by specifying an environment identifier through the default attribute in the environments tab
Environment sublabel description
1. Transaction manager transaction management
The value of type (JDBC/MANAGED / user defined) has the following differences:
JDBC: use the commit and rollback settings of JDBC to manage the transaction scope depending on the connection from the data source
MANAGED: do not commit or roll back a connection, let the container manage the whole life cycle of the transaction, ManagedTransactionFactory
Custom: implement TransactionFactory interface. At this time, type = full class name / alias
2. dataSource datasource
type has the following values
UNPOOLED: do not use connection pool UnpooledDataSourceFactory
POOLED: PooledDataSourceFactory using connection pool
JNDI: find the specified data source in containers such as EJB or application server
Custom: implement the DataSourceFactory interface and define the data source acquisition method
During actual development, we will use Spring to manage data sources and configure transaction control to override the configuration of the above data sources
- databaseIDProvider
Mybatis can execute different sql statements according to different database manufacturers. Therefore, we can set different vendors through the databaseIDProvider tag
<!-- Configuring databases from different vendors -- >
<databaseIdProvider type="DB_VENDOR">
<property name="MYSQL" value="mysql"/>
<property name="DB2" value="db2"/>
<property name="Oracle" value="oracle"/>
<property name="SQL Server" value="sqlserver"/>
</databaseIdProvider>
- Mappers
- <mapper resource=" ">
Use resources relative to classpath
- <mapper>
When using the mapper interface class path, the mapper interface name and mapper mapping file name should be the same and placed in the same directory
- <package name=" ">
Specify all mapper interfaces under the package. The mapper interface name and mapper mapping file name shall be the same and placed in the same directory
