blog/article
2
1
Fork 0
Code Pull Requests Activity

使用LTW(LoadTimeWeaving)技术实现AOP功能

Browse Source
This commit is contained in:
xking
2022-08-28 14:02:13 +08:00
parent 84be98ac74
commit 7824d19c0f
1 changed files with 245 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

245
java/使用LoadTimeWeaving技术实现AOP功能.md Normal file
View File

@@ -0,0 +1,245 @@
## 使用LTW(LoadTimeWeaving)技术实现AOP功能
### aop增强分类
###### 编译时：
使用特殊的编译器在编译期将切面织入目标类,这种比较少见,因为需要特殊的编译器的支持。例如，AspectJ编译 器，很少有到，目前我还没有用到。
###### 加载时：
通过字节码编辑技术在类加载期将切面织入目标类中,它的核心思想是：在目标类的class文件被JVM加 载前,通过自定义类加载器或者类文件转换器将横切逻辑织入到目标类的class文件中，然后将修改后class文件交给JVM加载 这种织入方式可以简称为LTW(LoadTimeWeaving)，AspectJ的LoadTimeWeaving (LTW)
###### 运行时：
运行期通过为目标类生成动态代理的方式实现AOP就属于运行期织入，这也是Spring AOP中的默认实现,并且提供了两种创建动态代理的方式：JDK自带的针对接口的动态代理和使用CGLib动态创建子类的方式创建动态代理。
### 优劣势
编译时：需要特殊的编译器
加载时：需要特殊的类加载器
运行时：功能有限
### 使用LTW 切面第三方JAR 包（普通maven项目）
#### 配置文件
##### pom 文件
```xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>cn.x47.blog</groupId>
<artifactId>LoadTimeWeaving-demo</artifactId>
<version>1.0</version>
</parent>
<artifactId>java-aspectj-agent</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>cn.x47.ltw.Main</mainClass><!--这里改成自己的主类位置-->
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
```
##### aop.xml
放在`META-INF/aop.xml`
```
<!DOCTYPE aspectj PUBLIC "-//AspectJ//DTD//EN" "https://www.eclipse.org/aspectj/dtd/aspectj.dtd">
<aspectj>
<weaver>
<!-- 注意 目标类 和使用目标类方法的类都要配置 -->
<include within="cn.x47.ltw..*"/>
<include within="com.alibaba.fastjson.*"/>
</weaver>
<aspects>
<!-- 切面 -->
<aspect name="cn.x47.ltw.ProfilingAspect"/>
</aspects>
</aspectj>
```
### 目录结构
![image-20220828130642183](http://pic.61dz.com/pic/image-20220828130642183.png)
### 执行方法
##### 开发环境
可以通过添加jvm参数的方式来启动
![image-20220828123756596](http://pic.61dz.com/pic/image-20220828123756596.png)
### springboot 使用 LTW切面第三方JAR包
#### 配置文件
##### pom配置
```
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>cn.x47.blog</groupId>
<artifactId>LoadTimeWeaving-demo</artifactId>
<version>1.0</version>
</parent>
<artifactId>springboot-aspectj-agent</artifactId>
<version>1.0</version>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>2.0.12</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.9</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
```
##### oop配置
```
<?xml version="1.0" encoding="UTF-8" ?>
<aspectj>
<weaver options="-XnoInline -Xset:weaveJavaxPackages=true -Xlint:ignore -verbose -XmessageHandlerClass:org.springframework.aop.aspectj.AspectJWeaverMessageHandler">
<!--在编织时导入切面类和需要被切入的目标类-->
<include within="cn.x47.ltw..*"/>
<include within="com.alibaba.fastjson..*"/>
</weaver>
<aspects>
<!--指定切面类-->
<aspect name="cn.x47.ltw.springboot.aop.TestAspect"/>
</aspects>
</aspectj>
```
#### 目录结构
![image-20220828135835641](http://pic.61dz.com/pic/image-20220828135835641.png)
### 源码地址
https://git.dr1997.com/chenkuangwei/LoadTimeWeaving-demo