解析SpringBoot中使用LoadTimeWeaving技术实现AOP功能

byte[]
transform(  ClassLoader         loader,
            String              className,
            Class<?>            classBeingRedefined,
            ProtectionDomain    protectionDomain,
            byte[]              classfileBuffer)
    throws IllegalClassFormatException;

void
addTransformer(ClassFileTransformer transformer);

* Defines the contract for adding one or more
* {@link ClassFileTransformer ClassFileTransformers} to a {@link ClassLoader}.
*
public interface LoadTimeWeaver {

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <configuration>
                <argLine>
                    -javaagent:"${settings.localRepository}/org/aspectj/aspectjweaver/${aspectj.version}/aspectjweaver-${aspectj.version}.jar"
                    -javaagent:"${settings.localRepository}/org/springframework/spring-instrument/${spring.version}/spring-instrument-${spring.version}.jar"
                    <!-- -Dspring.profiles.active=test-->
                </argLine>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <agent>
                    ${settings.localRepository}/org/aspectj/aspectjweaver/${aspectj.version}/aspectjweaver-${aspectj.version}.jar
                </agent>
                <agent>
                    ${settings.localRepository}/org/springframework/spring-instrument/${spring.version}/spring-instrument-${spring.version}.jar
                </agent>
            </configuration>
        </plugin>
    </plugins>

</build>

@Component
public class LtwBean {
    public void test(){
        System.out.println("process.......");
    }
}

@Aspect
public class LogMethodInvokeAspect {

    @Pointcut("execution(public * com.takumiCX.ltw.*.*(..))")
    public void pointCut(){

    }
    @Around("pointCut()")
    public void advise(ProceedingJoinPoint pjp) throws Throwable {


        Signature signature = pjp.getSignature();
        System.out.println(signature+" start..... ");
        pjp.proceed();
        System.out.println(signature+" end......");
    }
}

@Configuration
@ComponentScan("com.takumiCX.ltw")
@EnableLoadTimeWeaving(aspectjWeaving=AUTODETECT)
public class CustomLtwConfig{
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE aspectj PUBLIC "-//AspectJ//DTD//EN" "Http://www.eclipse.org/aspectj/dtd/aspectj.dtd">
<aspectj>

    <!--要织入切面的目标类-->
    <weaver>
        <include within="com.takumiCX.ltw..*" />
    </weaver>
    <!--切面类-->
    <aspects>
        <aspect name="com.takumiCX.ltw.aspect.LogMethodInvokeAspect" />
    </aspects>
</aspectj>

@RunWith(SpringRunner.class)
@SpringBootTest(classes ={CustomLtwConfig.class})
public class LTWTest {
    @Autowired
    private LtwBean ltwBean;
    @Test
    public void testLTW() throws InterruptedException {

        ltwBean.test();

    }
}

@Aspect
@Component
public class LogMethodInvokeAspect {

@Configuration
@ComponentScan("com.takumiCX.ltw")
@EnableAspectJAutoProxy
@EnableLoadTimeWeaving(aspectjWeaving=AUTODETECT)
public class CustomLtwConfig{
}