Watch Spring context invoke method field

[WangJi92]

Watch Spring Context Invoke Method Field 命令

右键选择需要调用的spring bean 的方法或者 字段的信息

获取命令

没有错，这个和 Static spring context invoke method field 一样的，只是这里的获取spring context的路径不一样，这里通过watch 去获取spring context ** watch 必须要被触发一次才能进行调用哦**

watch -x 3 -n 3  org.springframework.web.servlet.DispatcherServlet doDispatch '@org.springframework.web.context.support.WebApplicationContextUtils@getWebApplicationContext(params[0].getServletContext()).getBean("controllerTest").test()'

触发调用一下这个接口,必须要触发一下接口的调用，任意接口都可以，由于这里watch的是org.springframework.web.servlet.DispatcherServlet doDispatch 因此都可以


效果如下

help watch

the content you want to watch, written by ognl. 由于这里是被ognl 处理的，所以可以支持ognl的表达式去处理哦。

[arthas@21289]$ help watch
 USAGE:
   watch [-b] [-e] [-x <value>] [-f] [-h] [-n <value>] [-E] [-M <value>] [-s] class-pattern method-pattern
 express [condition-express]

 SUMMARY:
   Display the input/output parameter, return object, and thrown exception of specified method invocation
   The express may be one of the following expression (evaluated dynamically):
           target : the object
            clazz : the object's class
           method : the constructor or method
           params : the parameters array of method
     params[0..n] : the element of parameters array
        returnObj : the returned object of method
         throwExp : the throw exception of method
         isReturn : the method ended by return
          isThrow : the method ended by throwing exception
            #cost : the execution time in ms of method invocation
 Examples:
   watch -b org.apache.commons.lang.StringUtils isBlank params
   watch -f org.apache.commons.lang.StringUtils isBlank returnObj
   watch org.apache.commons.lang.StringUtils isBlank '{params, target, returnObj}' -x 2
   watch -bf *StringUtils isBlank params
   watch *StringUtils isBlank params[0]
   watch *StringUtils isBlank params[0] params[0].length==1
   watch *StringUtils isBlank params '#cost>100'
   watch -E -b org\.apache\.commons\.lang\.StringUtils isBlank params[0]

 WIKI:
   https://alibaba.github.io/arthas/watch

 OPTIONS:
 -b, --before                        Watch before invocation
 -e, --exception                     Watch after throw exception
 -x, --expand <value>                Expand level of object (1 by default)
 -f, --finish                        Watch after invocation, enable by default
 -h, --help                          this help
 -n, --limits <value>                Threshold of execution times
 -E, --regex                         Enable regular expression to match (wildcard matching by default)
 -M, --sizeLimit <value>             Upper size limit in bytes for the result (10 * 1024 * 1024 by default)
 -s, --success                       Watch after successful invocation
 <class-pattern>                     The full qualified class name you want to watch
 <method-pattern>                    The method name you want to watch
 <express>                           the content you want to watch, written by ognl.
                                     Examples:
                                       params
                                       params[0]
                                       'params[0]+params[1]'
                                       '{params[0], target, returnObj}'
                                       returnObj
                                       throwExp
                                       target
                                       clazz
                                       method

 <condition-express>                 Conditional expression in ognl style, for example:
                                       TRUE  : 1==1
                                       TRUE  : true
                                       FALSE : false
                                       TRUE  : 'params.length>=0'
                                       FALSE : 1==2

可以参考学习的网址

ognl 官方
ognl 特殊用法
ognl 最佳实践

other

这里watch的是接口的分发的入口类，一般只要watch 执行 ognl的spring context 表达式都会成功的，调用方法要注意安全哦。

[WangJi92]

watch 可以直接调用ognl 表达式，当前就是利用了 通过获取静态的方法获取到spring 的application context 的值而已 获取分布式跟踪的 traceId 这个也是通过利用这个特性来获取值的。

watch com.test.pandora.eagleeye.HomeController home '@com.taobao.eagleeye.EagleEye@getTraceId()'