今天在看同事程式碼的時候看到了這樣的寫法：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.26</version>
    <scope>runtime</scope>
</dependency>

There are 6 scopes available:

• compile 
  This is the default scope, used if none is specified. Compile dependencies are available in all classpaths of a project. Furthermore, those dependencies are propagated to dependent projects.
• provided 
  This is much like compile , but indicates you expect the JDK or a container to provide the dependency at runtime. For example, when building a web application for the Java Enterprise Edition, you would set the dependency on the Servlet API and related Java EE APIs to scope provided 
  because the web container provides those classes. This scope is only available on the compilation and test classpath, and is not transitive.
• runtime 
  This scope indicates that the dependency is not required for compilation, but is for execution. It is in the runtime and test classpaths, but not the compile classpath.
• test 
  This scope indicates that the dependency is not required for normal use of the application, and is only available for the test compilation and execution phases.
• system 
  This scope is similar to provided except that you have to provide the JAR which contains it explicitly. The artifact is always available and is not looked up in a repository.
• import (only available in Maven 2.0.9 or later) 
  This scope is only used on a dependency of type pom in the <dependencyManagement> section. It indicates that the specified POM should be replaced with the dependencies in that POM's <dependencyManagement>section. Since they are replaced, dependencies with a scope of import do not actually participate in limiting the transitivity of a dependency.

這是在xml中的配置

<bean id="jade.dataSource.worldcup" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://10.3.20.118:3306/worldcup"></property>
        <property name="username" value="worldcup"></property>
        <property name="password" value="geed2014"></property>
</bean>

<scope>runtime</scope>

如果不加，我試驗過了。雖然加了這個依賴，但是由於編譯的時候沒有用到，那麼生成的target下的lib中是沒有對應的jar包的。