AOP （Aspect Oriented Programming）
将非功能性需求从功能性需求中剥离出来，解耦并且解决代码复用的问题，比如说权限控制，事务控制，记录操作日志，全局捕获异常等
@Aspect 切面
@PointCut 描述在哪些类哪些方法织入代码
@Advice 在方法的什么执行时机（之前或者之后）去执行
Advice分为5种
@Before,前置通知
@After(finally) 后置通知，方法执行完后
@AfterReturning,返回通知，方法成功执行之后
@AfterThrowing,异常通知，发生异常之后
@Around,环绕通知
AOP实现的方式有静态代理和动态代理
动态代理实现分为两种：基于接口和基于继承
基于接口的是JDK代理，基于继承的是Gglib代理
Spring中的代理可以使用配置项指定采用哪一种
添加AOP依赖后，编写切面
@Aspect @Component public class AdviceAspectConfig { /** * 每种通配符表示的含义: | *表示任意字符 | ..表示本包和子包 或者是任意参数 | * 切入点：修饰符是public ,返回值任意类型， service包和他的子包，以Service结尾的类，任意的方法 */ @Pointcut("execution(public * com.irish.service..*Service.*(..))") public void matchServiceMethod(){} /** * 可以在方法执行的前后添加非功能性的代码 */ @Around("matchServiceMethod()") public java.lang.Object after(ProceedingJoinPoint joinPoint){ System.out.println("###before"); java.lang.Object result = null; try{ System.out.println("方法参数:"); java.lang.Object[] args = joinPoint.getArgs(); System.out.println("被代理的对象"+joinPoint.getTarget()); result = joinPoint.proceed(joinPoint.getArgs()); System.out.println("###after returning"); }catch (Throwable e){ System.out.println("###after throwing"); e.printStackTrace(); }finally { System.out.println("###finally"); } return result; } }
（1）编程式事务，手动开启事务，提交事务，回滚事务
@Service public class UserServiceImpl implements UserService { @Autowired private UserDao userDao; @Autowired private TransactionUtils transactionUtils; public void add() { TransactionStatus transactionStatus = null; try { // 开启事务 transactionStatus = transactionUtils.begin(); userDao.add(20, "password001","test001"); //System.out.println("开始报错啦!@!!"); //int i = 1 / 0; System.out.println("################"); userDao.add(21, "password002","test002"); // 提交事务 if (transactionStatus != null) transactionUtils.commit(transactionStatus); } catch (Exception e) { System.out.println(e.getMessage()); // 回滚事务 if (transactionStatus != null) transactionUtils.rollback(transactionStatus); } } }
项目结构：
（2）记录操作日志
对dao包的所有以save开头和以delete开头的方法，进行拦截处理，生成操作日志，记录在mongodb中
1 引入依赖jar包
<?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> <groupId>com.irish.aop</groupId> <artifactId>datalog</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>datalog</name> <description>datalog</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.2.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <!-- mysql --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-mongodb</artifactId> </dependency> <dependency> <groupId>commons-beanutils</groupId> <artifactId>commons-beanutils</artifactId> <version>1.9.3</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.28</version> </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>
2 编写切面
@Aspect @Component public class DatalogAspect { private static final Logger logger = LoggerFactory.getLogger(DatalogAspect.class); @Autowired ActionDao actionDao; @Pointcut("execution(public * com.irish.aop.dao.*.save*(..))") public void save(){ } @Pointcut("execution(public * com.irish.aop.dao.*.delete*(..))") public void delete(){ } /** * 1判断是什么类型的操作,增加删除还是更新 * 增加/更新 save(Product),通过id区分是增加还是更新 * 删除delete(id) * 2获取changeitem * (1)新增操作,before直接获取,after记录下新增之后的id * (2)更新操作,before获取操作之前的记录,after获取操作之后的记录,然后diff * (3)删除操作,before根据id取记录 * 3保存操作记录 * actionType * objectId * objectClass * @param pjp * @return * @throws Throwable */ @Around("save() || delete()") public Object addOperateLog(ProceedingJoinPoint pjp) throws Throwable { Object returnObj = null; //TODO BEFORE OPERATION init action String method = pjp.getSignature().getName(); ActionType actionType = null; Action action = new Action(); Long id = null; Object oldObj = null; try{ if("save".equals(method)){ //insert or update Object obj = pjp.getArgs()[0]; try{ id = Long.valueOf(PropertyUtils.getProperty(obj,"id").toString()); }catch (Exception e){ //ignore } if(id == null){ actionType = ActionType.INSERT; List<ChangeItem> changeItems = DiffUtil.getInsertChangeItems(obj); action.getChanges().addAll(changeItems); action.setObjectClass(obj.getClass().getName()); }else{ actionType = ActionType.UPDATE; action.setObjectId(id); //pjp.getTarget()被代理的对象，即ProductDao oldObj = DiffUtil.getObjectById(pjp.getTarget(),id); action.setObjectClass(oldObj.getClass().getName()); } }else if("delete".equals(method)){ id = Long.valueOf(pjp.getArgs()[0].toString()); actionType = ActionType.DELETE; oldObj = DiffUtil.getObjectById(pjp.getTarget(),id); ChangeItem changeItem = DiffUtil.getDeleteChangeItem(oldObj); action.getChanges().add(changeItem); action.setObjectId(Long.valueOf(pjp.getArgs()[0].toString())); action.setObjectClass(oldObj.getClass().getName()); } returnObj = pjp.proceed(pjp.getArgs()); //TODO AFTER OPERATION save action action.setActionType(actionType); if(ActionType.INSERT == actionType){ //new id Object newId = PropertyUtils.getProperty(returnObj,"id"); action.setObjectId(Long.valueOf(newId.toString())); }else if(ActionType.UPDATE == actionType){ //pjp.getTarget()获取的是被代理的对象 【目标对象(target object)：被代理对象】 //在保存方法之后，所以这时候获取的是新值 Object newObj = DiffUtil.getObjectById(pjp.getTarget(),id); List<ChangeItem> changeItems = DiffUtil.getChangeItems(oldObj,newObj); action.getChanges().addAll(changeItems); } action.setOperator("admin"); //dynamic get from threadlocal/session action.setOperateTime(new Date()); actionDao.save(action); }catch (Exception e){ logger.error(e.getMessage(),e); } return returnObj; } }
项目结构
（3）在springboot项目中使用注解事务
spring集成的事务只是对事务的管理，真正实现事务的是持久层框架，如jdbcTemplate ,hibernate等
测试时候注意mysql的版本要是5.5以上，数据库引擎是InnoDB
在一张表中设置一个字段是唯一约束，插入相同数据时，这时候要么两张表都插入失败，保证了事务的原子性
项目结构
1 @Transactional只能被应用到public方法上,对于其它非public的方法,如果标记了@Transactional也不会报错,但方法没有事务功能
@Transactional annotations only work on public methods. If you have a private or protected method with this annotation there’s no (easy) way for Spring AOP to see the annotation. It doesn’t go crazy trying to find them so make sure all of your annotated methods are public.
2 默认情况下,一个有事务的方法 遇到RuntimeException 时会回滚 . 但是遇到检查异常 是不会回滚的，要想所有异常都回滚,要加上 @Transactional( rollbackFor={Exception.class,其它异常})
（4）自定义注解实现事务
思路：注解版本的事务其实是AOP+编程式事务，
1定义注解 @interface ExtTransaction
2在AOP切入点中配置要扫描的类及方法
3在Around通知中，判断方法是否有自定义注解，有就开启事务，方法执行完提交事务，发生异常回滚事务
@Aspect @Component public class AopExtTransaction { // 一个事务实例子 针对一个事务 @Autowired private TransactionUtils transactionUtils; // 环绕通知 在方法之前和之后处理事情 @Around("execution( * com.irish.service.*.*.*(..))") public Object around(ProceedingJoinPoint pjp) throws Throwable { Object result = null; try { // 1.获取该方法上是否加上注解 ExtTransaction extTransaction = getMethodExtTransaction(pjp); TransactionStatus transactionStatus = begin(extTransaction); // 2.调用目标代理对象方法 result = pjp.proceed(); // 3.判断该方法上是否就上注解 commit(transactionStatus); }catch(Exception e) { //4发生异常回滚 transactionUtils.rollback(); } return result; } private TransactionStatus begin(ExtTransaction extTransaction) { if (extTransaction == null) { return null; } // 2.如果存在事务注解,开启事务 return transactionUtils.begin(); } private void commit(TransactionStatus transactionStatus) { if (transactionStatus != null) { // 5.如果存在注解,提交事务 transactionUtils.commit(transactionStatus); } } // 获取方法上是否存在事务注解 private ExtTransaction getMethodExtTransaction(ProceedingJoinPoint pjp) throws NoSuchMethodException, SecurityException { String methodName = pjp.getSignature().getName(); // 获取目标对象 Class<?> classTarget = pjp.getTarget().getClass(); // 获取目标对象类型 Class<?>[] par = ((MethodSignature) pjp.getSignature()).getParameterTypes(); // 获取目标对象方法 Method objMethod = classTarget.getMethod(methodName, par); ExtTransaction extTransaction = objMethod.getDeclaredAnnotation(ExtTransaction.class); return extTransaction; } }
项目结构：
github地址：https://github.com/jake1263/AOP