簡介

在項目實際開發(fā)過程中，需要統(tǒng)計部分函數(shù)的調(diào)用耗時，用于協(xié)助查找性能問題，并指導部分系統(tǒng)參數(shù)配置。

本文通過實現(xiàn)一個這樣的示例功能，來展示AOP+SpEL結(jié)合帶來的巨大好處，同時加深對Spring Expression Language了解

設(shè)計目標

只需要通過添加注解的方式，就能快速統(tǒng)計函數(shù)調(diào)用耗時，同時還能輸出更豐富的函數(shù)調(diào)用上下文信息，使結(jié)果具有更大的分析價值。

函數(shù)調(diào)用上下文包含：

• 函數(shù)所屬類實例
• 函數(shù)入?yún)⒘斜?/li>
• 函數(shù)調(diào)用結(jié)果

可以自行添加更多的上下文信息

實現(xiàn)步驟

1. 實現(xiàn)自定義注解
2. 實現(xiàn)SpEL計算接口
3. 實現(xiàn)自定義切面攔截器
4. 為函數(shù)添加自定義注解

代碼Review

自定義注解

/**
 * @author wurenhai
 * @since 2019/1/11 9:00
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TimeMeasure {

    /**
     * expression: target=#{#target}, a0=#{#a0}, result=#{#result}
     */
    String value() default "";

}

實現(xiàn)SpEL計算接口

/**
 * @author wurenhai
 * @since 2019/1/11 9:44
 */
public class AspectExpressContext {

    private final EvaluationContext context;
    private final ExpressionParser parser;
    private final ParserContext parserContext;

    private AspectExpressContext() {
        this(null);
    }

    private AspectExpressContext(ApplicationContext applicationContext) {
        StandardEvaluationContext context = new StandardEvaluationContext();
        if (applicationContext != null) {
            context.setBeanResolver(new BeanFactoryResolver(applicationContext));
        }
        SpelParserConfiguration config = new SpelParserConfiguration(true, true);
        this.context = context;
        this.parser = new SpelExpressionParser(config);
        this.parserContext = new TemplateParserContext();
    }

    public AspectExpressContext(Object target, Object[] args, Object result) {
        this();
        context.setVariable("target", target);
        context.setVariable("result", result);
        for (int i = 0; i < args.length; i++) {
            context.setVariable("a" + i, args[i]);
        }
    }

    public String getValue(String express) {
        Expression expression = parser.parseExpression(express, parserContext);
        return expression.getValue(context, String.class);
    }

}

自定義切面攔截器

/**
 * @author wurenhai
 * @since 2019/1/11 9:00
 */
@Aspect
@Component
public class TimeMeasureInterceptor {

    private static final Logger logger = LoggerFactory.getLogger(TimeMeasureInterceptor.class);

    @Around("@annotation(TimeMeasure)")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        StopWatch sw = new StopWatch();
        sw.start();
        Object result = null;
        try {
            result = point.proceed();
            return result;
        } finally {
            sw.stop();
            output(point, result, sw.getLastTaskTimeMillis());
        }
    }

    private void output(ProceedingJoinPoint point, Object result, long timeInMs) {
        String taskName = point.getSignature().getDeclaringType().getSimpleName()
                + "." + point.getSignature().getName() + "()";
        MethodSignature signature = (MethodSignature)point.getSignature();
        TimeMeasure annotation = signature.getMethod().getAnnotation(TimeMeasure.class);
        String expression = annotation.value();

        String text = expression;
        if (StringUtils.hasLength(expression)) {
            AspectExpressContext context = new AspectExpressContext(point.getTarget(), point.getArgs(), result);
            try {
                text = context.getValue(expression);
            } catch (ParseException e) {
                logger.warn("{} parse[{}] error: {}", taskName, expression, e.getMessage());
            } catch (EvaluationException e) {
                logger.warn("{} eval[{}] error: {}", taskName, expression, e.getMessage());
            }
        }

        logger.info("{} cost {}(ms): {}", taskName, timeInMs, text);
    }

}

為函數(shù)添加自定義注解

    @SuppressWarnings("MVCPathVariableInspection")
    @TimeMeasure("text1=#{#a0}, text2=#{#a1}, result=#{#result}")
    @GetMapping("/demo/echo")
    @ResponseBody
    public String echo(String text1, String text2) {
        return "ECHO: " + text1 + "," + text2;
    }

參考文檔

Spring Expression Language
Aspect Oriented Programming with Spring