maven scope runtime

今天在看同事代码的时候看到了这样的写法：

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

不明白<scope>runtime</scope>的意思，查了一下

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.

这是在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>

由于还在测试别的功能的阶段，还没有编写mysql，所以编译的时候不会用到这个包。但是生成Context上下文的时候会用到。

也就是说这个包mysql包编译的时候是用不到的，但是在运行的时候会用到。所以如果我们在package的时候没有将其打包到target中，运行时就会出错。所以要加上

<scope>runtime</scope>

如果不加，我试验过了。虽然加了这个依赖，但是由于编译的时候没有用到，那么生成的target下的lib中是没有对应的jar包的。