arthas/tutorials/katacoda/command-vmtool-en/vmtool-spring.md

Next, use the vmtool command to find objects in spring.

Find spring context

vmtool --action getInstances --className org.springframework.context.ApplicationContext {{execute T2}}

$ vmtool --action getInstances --className org.springframework.context.ApplicationContext
@ApplicationContext[][
    @AnnotationConfigEmbeddedWebApplicationContext[org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@12028586: startup date [Thu May 13 16:08:38 UTC 2021]; root of context hierarchy],
]

Specify the number of expanded layers of returned results

The return result of the getInstances action is bound to the instances variable, which is an array.

The expansion level of the result can be specified by the -x/--expand parameter, the default value is 1.

vmtool --action getInstances --className org.springframework.context.ApplicationContext -x 2{{execute T2}}

Execute expression

The return result of the getInstances action is bound to the instances variable, which is an array. The specified expression can be executed through the --express parameter.

Find the names of all spring beans:

vmtool --action getInstances --className org.springframework.context.ApplicationContext --express 'instances[0].getBeanDefinitionNames()'{{execute T2}}

Call the userController.findUserById(1) method:

vmtool --action getInstances --className org.springframework.context.ApplicationContext --express 'instances[0].getBean("userController").findUserById(1)'{{execute T2}}

$ vmtool --action getInstances --className org.springframework.context.ApplicationContext --express'instances[0].getBean("userController").findUserById(1)'
@User[
    id=@Integer[1],
    name=@String[name1],
]

Find all spring mapping objects

vmtool --action getInstances --className org.springframework.web.servlet.HandlerMapping{{execute T2}}

$ vmtool --action getInstances --className org.springframework.web.servlet.HandlerMapping
@HandlerMapping[][
    @SimpleUrlHandlerMapping[org.springframework.web.servlet.handler.SimpleUrlHandlerMapping@5d3819c8],
    @EmptyHandlerMapping[org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport$EmptyHandlerMapping@11d509ba],
    @RequestMappingHandlerMapping[org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping@56a5f2e3],
    @WelcomePageHandlerMapping[org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WelcomePageHandlerMapping@4c0a4ed3],
    @EmptyHandlerMapping[org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport$EmptyHandlerMapping@51e1f8c3],
    @BeanNameUrlHandlerMapping[org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping@68c0a39c],
    @SimpleUrlHandlerMapping[org.springframework.web.servlet.handler.SimpleUrlHandlerMapping@110b768d],
]