Using Lombok @ slf4j annotation to simplify the introduction of log function

出于代码复用和简洁的考量，我们建议使用lombok 的注解@Slf4j

读者可以对比下文的传统写法。

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In the development process , Printing the necessary logs is an essential part , And print the log , In the related class, it is necessary to introduce log related attributes , Traditionally , Usually by LoggerFactory.getLogger To achieve the :

package net.xiaogd.demo.mybatis.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class LogDemoController {

    //  Self declaration 
    private static final Logger log = LoggerFactory.getLogger((LogDemoController.class));

    //...
}

Although it's already very simple , But if there are a large number of classes to do similar operations , It's a little repetitive , from The angle of Repetitive management , How can we minimize this duplication of boilerplate [ˈbɔɪlərˌpleɪt]n.（可供模仿的）样板文件 code ?

The answer is to use lombok Of @Slf4j annotation .

 

Use lombok @Slf4j The premise of annotation

natural , You need to introduce... In your project first lombok, maven Add related dependence in , IDE It also needs to be adjusted , Install related plug-ins.

Besides , Related log dependency also needs to have , If you have enabled logging in the old way , Dependent dependencies usually contain.

 

lombok @Slf4j The specific usage of annotations

With lombok after , It is very simple to introduce the logging function into the class , Just add... To the class @Slf4j Annotations can be :

package com.demo.controller;

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

import lombok.extern.slf4j.Slf4j;

@Slf4j
@RestController
public class DemoController {
    // ...
}

After this , lombok It will inject us with a name by log Log properties of , Use it directly in the code :

package net.xiaogd.demo.mybatis.controller;

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

import lombok.extern.slf4j.Slf4j;

@Slf4j
@RestController
public class DemoController {

    @GetMapping("/hello")
    public String hello() {
        log.info("enter hello...");
        return "hello rest";
    }
}

Be careful : The default variable name is injection log.

Of course , The name can also be used by lombok.log.fieldName Configuration to adjust , Reference resources lombok About the official website : https://projectlombok.org/features/configuration as well as https://projectlombok.org/features/log

It is generally not recommended to adjust , After all log This name is the most concise , It's easy to knock .

If your existing code uses the traditional way , And it's not for use log The name , Now I want to adjust to use @Slf4j The way , So you can use it first restructure (refactor)-- rename (rename) How to change the name , And then introduce .

It's like saying this to yourself Logger log like that :

@RestController
public class LogDemoController {

    //  Self declaration 
    private static final Logger log = LoggerFactory.getLogger((LogDemoController.class));

    @GetMapping("/hello1")
    public String hello() {
        log.info("enter hello...");
        return "hello rest";
    }
}

If you declare yourself , There are some problems :

1. The statement is cumbersome and lengthy , It may be hard for you to remember .
2. Different classes need to adjust the name of the current class Value , If you copy carelessly and forget to change, there may be some potential problems ;
3. The mistake introduces Logger and LoggerFactory Interfaces can also lead to some potential problems .

It's much easier to use annotations , You don't have to worry about the above problems at all .

Constantly eliminating all kinds of duplication , Improving efficiency is a pursuit in our coding process.