Arthas' dynamic load class (retransform)

One 、 demand

There is an interface on the line as follows . Because of business needs , Can't shut down , Modify the interface to return to all uppercase + Time stamp ;

http://192.168.1.4:5656/hi

@RestController
public class HelloController {
    @GetMapping("/hi")
    public String getMessage(String msg) {

        return msg.toLowerCase()+System.currentTimeMillis();
    }
}

  Two 、 Dynamic replacement jvm Load class

1、 Modify the code

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {
    public HelloController() {
    }

    @GetMapping({"/hi"})
    public String getMessage(String msg) {
        return msg.toUpperCase() + System.currentTimeMillis();
    }
}

2、 Compiled into class file

3、 Upload to the specified directory of the service

4、 Use  Arthas Replace

start-up arthas, Select replacement items , perform

retransform /usr/local/jar/HelloController.class

 

5、 test