初学，求教关于Mybatis 外部配置properties的问题

daniu8726 2016-06-12 05:11:13

db.properties 文件

driver=org.postgresql.Driver

url=jdbc:postgresql://127.0.0.1:5432/enmia

username=test

password=test

Configuration.xml 配置



<configuration>

	

	<properties resource="db.properties"></properties>

	

    <typeAliases>

        <typeAlias alias="Step" type="com.test.obj.Step"/>

    </typeAliases>





    <environments default="enmia">

        <environment id="enmia">

        	<transactionManager type="JDBC"/>

            	<dataSource type="POOLED">

            		<property name="url" value="${url}" />

            		<property name="username" value="${username}"/>

            		<property name="password" value="${password}"/>

            		<property name="driver" value="${driver}"/>

            	</dataSource>

        	</environment>

    </environments>

   

    <mappers>

        <mapper resource="com/test/obj/Step.xml"/>

    </mappers>

</configuration>

测试



public class ServiceTest {

	

	private static SqlSessionFactory sqlSessionFactory;

    private static Reader reader;



    static{

        try{

            reader    = Resources.getResourceAsReader("Configuration.xml");

            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);

        }catch(Exception e){

            e.printStackTrace();

        }

    }



	public static void main(String[] args) {

		SqlSession session = sqlSessionFactory.openSession();

		try {

			StepService stepservice = session.getMapper(StepService.class);

			List<Step> steps = stepservice.selectStepByStatus(0);

			for(Step step:steps){

				System.out.println(step.getId());

				System.out.println(step.getStatus());

			}

		} finally {

			session.close();

		}

	}

运行后报出如下错误：Cause: java.lang.ClassNotFoundException: Cannot find class: ${driver}
看了下sqlSessionFactory那个实例，里面的确已经读取了properties文件的内容。
但是，原来的字符串${driver} ${url}等等都没有被替换掉。
这是什么原因呢？

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