Spring AOP加载时编织是否需要JVM参数？

Question

For a standalone Java application using Spring AOP, is it necessary to require JVM arguments such as -javaagent:pathto/aspectjweaver.jar to "turn on" AOP support? When would you want or need to do so?

To be clear, "standalone" means a Maven-built, excecutable .jar; that will be invoked across a variety of platforms.

Answer 1

It depends. If you are using Spring AOP to do only coarse-grained interception (meaning you'd like to intercept only outer calls to a bean, but not calls inside a bean), you need no JVM arguments at all. Just use code like:

<bean id="myInterceptor" class="com.company.interceptors.MyInterceptor"></bean>

<aop:config>
    <aop:pointcut id="myPointcut"
        expression="execution(* com.company.services..MyService.*(..))" />

    <aop:advisor pointcut-ref="myPointcut"
        advice-ref="myInterceptor" />
</aop:config>

If this is not enough and you need load-time weaving to advise intra-bean calls for example, then You'd need to add a JVM argument as described in the Spring 3.0 docs:

Generic Java applications

You may enable Spring's support for LTW in any Java application (standalone as well as application server based) through the use of the Spring-provided instrumentation agent. To do so, start the VM by by specifying the -javaagent:path/to/spring-agent.jar option. Note that this requires modification of the VM launch script which may prevent you from using this in application server environments (depending on your operation policies).

See here http://static.springsource.org/spring/docs/3.0.0.RC2/reference/html/ch07s08.html#aop-aj-ltw-environments

Answer 2

Consider using compile time weaving via maven:

<properties>
    <aspectj.version>1.6.12</aspectj.version>
</properties>

        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>aspectj-maven-plugin</artifactId>
            <version>1.4</version>
            <dependencies>
                <dependency>
                    <groupId>org.aspectj</groupId>
                    <artifactId>aspectjtools</artifactId>
                    <version>${aspectj.version}</version>
                </dependency>
            </dependencies>
            <configuration>
                <source>1.7</source>
                <target>1.7</target>
                <complianceLevel>1.7</complianceLevel>
                <aspectLibraries>
                    <aspectLibrary>
                        <groupId>org.springframework</groupId>
                        <artifactId>spring-aspects</artifactId>
                    </aspectLibrary>
                </aspectLibraries>
            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>compile</goal>
                        <goal>test-compile</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

Doing so covers all the crazy Spring AOP cases, even private transactional methods.

Answer 3

Check more doc here http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/aop.html#aop-aj-ltw . It depends.

Answer 4

通常，仅在类路径中包含weaver jar就足够了。