Configuration of Bean for 6.Spring series 3

One, two ways to configure beans using the XML configuration Bean

1. Introduction of external Properties file in IOC container

In an IOC container, when a bean is configured, it is sometimes necessary to introduce information about the system deployment in the bean's configuration (e.g., file path, data source configuration information, etc.), and these deployment details actually need to be separated from the bean configuration, and Spring provides a The Beanfactory Propertyplaceholderconfigurer processor, which allows partial configuration of the bean to be transferred to the properties file, can be used in the IOC container as a variable of ${var}. Propertyplaceholderconfigurer dependent files are loaded with attributes, and using these attributes to replace variables, Spring also allows the use of ${propname} in the property file to implement mutual references between attributes.

Note: With spring iterations, the release of the 2.5 version introduces an external properties file that simplifies the introduction of external properties files through the <context:property-placeholder> element:

First, we introduce the C3P0 and MySQL driver jar packages:

C3p0-0.9.1.2.jar, Mysql-connector-java-5.1.7-bin.jar

Next, create the Db.properties configuration file, which is configured with MySQL connection information:

jdbc.user=xxxjdbc.password=123456jdbc.driverclass=com.mysql.jdbc.Driverjdbc.jdbcUrl =jdbc:mysql://xxx:3306/spring

Next, introduce the external properties file in the IOC container and configure the database connection information:

<?XML version= "1.0" encoding= "UTF-8"?><Beansxmlns= "Http://www.springframework.org/schema/beans"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"Xmlns:context= "Http://www.springframework.org/schema/context"xsi:schemalocation= "Http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd Http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd ">        <!--introducing external resource files -    <Context:property-placeholder Location= "Classpath:db.properties"/>        <!--Configure database connection information using the C3P0 connection pool -    <BeanID= "DataSource"class= "Com.mchange.v2.c3p0.ComboPooledDataSource">        < Propertyname= "User"value= "${jdbc.user}"></ Property>        < Propertyname= "Password"value= "${jdbc.password}"></ Property>        < Propertyname= "Jdbcurl"value= "${jdbc.jdbcurl}"></ Property>        < Propertyname= "Driverclass"value= "${jdbc.driverclass}"></ Property>    </Bean></Beans>

Finally, start the test program:

 Public classMain {@SuppressWarnings ("Resource")     Public Static voidMain (string[] args)throwsSQLException {applicationcontext ctx=NewClasspathxmlapplicationcontext ("Applicationcontext.xml"); //test whether the database can be connectedDataSource DataSource = (DataSource) ctx.getbean ("DataSource");        System.out.println (Datasource.getconnection ()); //post-run output: [email protected]//represents a successful connection    }}

The life cycle of a bean in a 2..IOC container

Configuration of Bean for 6.Spring series 3