lombok插件/slf4j中字符串格式化

Posted 2022-10-06

大家在编写springboot项目的过程中可能会接触到​​lombok​​这个插件，这个插件可以在编译时帮我生成很多代码。

1、@Data生成Getter和Setter代码，用于类名注释

2、@Getter 生成字段对应的getXXX方法

3、@Setter生成字段对应的setXXX(xxx yyy)方法

4、@Builder构造器设计模式生成个字段的设置属性方法，该字段一般用于一些类参数可以选，可单选，可多选的环境中

5、@Slf4j使用Slf4j中门面模式，适配底层日志框架，slf4j和底层日志框架协调记录日志

6、@NoArgsConstructor生成类的默认构造函数

7、@AllArgsConstructor生成类所有字段的构造函数，常常和@Builder同时出现

8、@ToString，笔者不常用这个

9、var 兼容ECMA规范，可以编译时自动推断数类型的注解

代码如下

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.ToString;
import lombok.extern.slf4j.Slf4j;
import lombok.var;

@Data
@Getter
@Setter
@Slf4j
@NoArgsConstructor
@AllArgsConstructor
@Builder
@ToString
public class LombokClass 
    @Setter
    private Integer id;

    @Setter
    @Getter
    private String name;


    public void test()
    
        var t ="s";
    

 生成代码：

 

 

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LombokClass

    private static final Logger log;
    private Integer id;
    private String name;
    
    public void test() 
        final String t = "s";
    
    
    public static LombokClassBuilder builder() 
        return new LombokClassBuilder();
    
    
    @Override
    public boolean equals(final Object o) 
        if (o == this) 
            return true;
        
        if (!(o instanceof LombokClass)) 
            return false;
        
        final LombokClass other = (LombokClass)o;
        if (!other.canEqual(this)) 
            return false;
        
        final Object this$id = this.getId();
        final Object other$id = other.getId();
        Label_0065: 
            if (this$id == null) 
                if (other$id == null) 
                    break Label_0065;
                
            
            else if (this$id.equals(other$id)) 
                break Label_0065;
            
            return false;
        
        final Object this$name = this.getName();
        final Object other$name = other.getName();
        if (this$name == null) 
            if (other$name == null) 
                return true;
            
        
        else if (this$name.equals(other$name)) 
            return true;
        
        return false;
    
    
    protected boolean canEqual(final Object other) 
        return other instanceof LombokClass;
    
    
    @Override
    public int hashCode() 
        final int PRIME = 59;
        int result = 1;
        final Object $id = this.getId();
        result = result * 59 + (($id == null) ? 43 : $id.hashCode());
        final Object $name = this.getName();
        result = result * 59 + (($name == null) ? 43 : $name.hashCode());
        return result;
    
    
    public Integer getId() 
        return this.id;
    
    
    public LombokClass() 
    
    
    public LombokClass(final Integer id, final String name) 
        this.id = id;
        this.name = name;
    
    
    @Override
    public String toString() 
        return "LombokClass(id=" + this.getId() + ", name=" + this.getName() + ")";
    
    
    public void setId(final Integer id) 
        this.id = id;
    
    
    public void setName(final String name) 
        this.name = name;
    
    
    public String getName() 
        return this.name;
    
    
    static 
        log = LoggerFactory.getLogger((Class)LombokClass.class);
    
    
    public static class LombokClassBuilder
    
        private Integer id;
        private String name;
        
        LombokClassBuilder() 
        
        
        public LombokClassBuilder id(final Integer id) 
            this.id = id;
            return this;
        
        
        public LombokClassBuilder name(final String name) 
            this.name = name;
            return this;
        
        
        public LombokClass build() 
            return new LombokClass(this.id, this.name);
        
        
        @Override
        public String toString() 
            return "LombokClass.LombokClassBuilder(id=" + this.id + ", name=" + this.name + ")";
        
    

 

 

本文要讲解的重点是@Slf4j相关的使用，使用该注解默认生成代码如下

import org.slf4j.Logger;


private static final Logger log = org.slf4j.LoggerFactory.getLogger(当前类名.class);

log有以下几个方法info,trace,debug,error,warn及对应的重载方法。

追踪了一下代码，内部会使用StringBuilder这个线程安全类处理，StringBuilder比String速度比较快，他不会创建多个String对象。

 

 

 以上几个方法常用格式化代码如下（使用作为占位符）：

来自：​​https://examples.javacodegeeks.com/enterprise-java/slf4j/slf4j-format-string-example/​​

package com.javacodegeeks.slf4.formatting;
 
import java.lang.invoke.MethodHandles;
import java.text.MessageFormat;
import java.util.Calendar;
 
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
 
/**
 * Substituting Parameters!
 *
 */
public class Slf4jSusbstitutionExample 

    private static final Logger LOGGER = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
     
    public static void main( String[] args )
    
        String user = "john";
        String application = "gateway";
         
        // Crafting a message without substitution.
        // Not a good idea as the String concatenation and eval（"Bad experience for user " + user + " at time " + Calendar.getInstance().getTime());
         
        // Substitution with one formatting anchor and one argument
        LOGGER.info("Bad experience for user ", user);
         
        // If you happen to forget to provide a substituting object
        LOGGER.info("Bad experience for user ");
         
        // Substitution with two formatting anchors and two arguments
        LOGGER.info("Bad experience for user  at time ", user, Calendar.getInstance().getTime());
         
        // Substitution with three formatting anchors and three arguments
        LOGGER.info("Bad experience for user  at time  while accessing ", user, Calendar.getInstance().getTime(), application);
         
        // Escaping formatting anchor
        LOGGER.info("ERROR CODE \\\\; Bad experience for user  at time ", user, Calendar.getInstance().getTime());
         
        // Formatting anchor with data inside; no problem
        LOGGER.info("ERROR CODE 22; Bad experience for user  at time ", user, Calendar.getInstance().getTime());
         
        // Crafting a message with Javas own MessageFormatter.
        // Not a good idea as per SLF4Js documentation.
        // 1. SLF4Js implementation is 10 times faster than that of MessageFormat.
        // 2. Moreover to make sure that the eval（LOGGER.isInfoEnabled()) 
            String message = MessageFormat.format("Bad experience for user 0 at time 1 while accessing 2", user, Calendar.getInstance().getTime(), application);
            LOGGER.info(message);
        
    

输出结果：

2017-04-20 20:25:42 INFO  Slf4jSusbstitutionExample - Bad experience for user john at time Thu Apr 20 20:25:42 IST 2017
2017-04-20 20:25:42 INFO  Slf4jSusbstitutionExample - Bad experience for user john
2017-04-20 20:25:42 INFO  Slf4jSusbstitutionExample - Bad experience for user 
2017-04-20 20:25:42 INFO  Slf4jSusbstitutionExample - Bad experience for user john at time Thu Apr 20 20:25:42 IST 2017
2017-04-20 20:25:42 INFO  Slf4jSusbstitutionExample - Bad experience for user john at time Thu Apr 20 20:25:42 IST 2017 while accessing gateway
2017-04-20 20:25:42 INFO  Slf4jSusbstitutionExample - ERROR CODE ; Bad experience for user john at time Thu Apr 20 20:25:42 IST 2017
2017-04-20 20:25:42 INFO  Slf4jSusbstitutionExample - ERROR CODE 22; Bad experience for user john at time Thu Apr 20 20:25:42 IST 2017
2017-04-20 20:25:42 INFO  Slf4jSusbstitutionExample - Bad experience for user john at time 4/20/17 8:25 PM while

 

本博客lombok其他文章:

idea中Lombok的Buider构造器模式，getter/setter正确使用方法

 lombok编译时注解@Slf4j的使用及相关依赖包

Lombok子类与父类的@Builder注解冲突