Rust日志学习（三）——simple_logger

simple_logger——A rust logger that prints all messages with a readable output format.

simple_logger的Github链接：https://github.com/borntyping/rust-simple_logger

下面是simple_logger的简单示例：

示例1：

最简单用法

#[macro_use]extern crate log;extern crate simple_logger;fn main() {    simple_logger_fn();}#[warn(dead_code)]fn simple_logger_fn(){    simple_logger::init().unwrap();    warn!("This is an example message.");}

编译、运行结果如下：

示例2：

初始化时改变默认日志level等级：

#[macro_use]extern crate log;extern crate simple_logger;fn main() {    simple_logger_level();}#[warn(dead_code)]fn simple_logger_level(){    simple_logger::init_with_level(log::LogLevel::Warn).unwrap();    warn!("This will be logged.");    info!("This will NOT be logged.");//过滤掉了}

编译、运行结果如下：

源代码分析

因为这个源代码较少，所以就把所有源代码都列出来了：

//! A logger that prints all messages with a readable output format.#[macro_use]extern crate log;extern crate time;use log::{Log,LogLevel,LogMetadata,LogRecord,SetLoggerError};struct SimpleLogger {    log_level: LogLevel,}//实现Log特性impl Log for SimpleLogger {    fn enabled(&self, metadata: &LogMetadata) -> bool {        metadata.level() <= self.log_level    }    fn log(&self, record: &LogRecord) {        if self.enabled(record.metadata()) {            println!(                "{} {:<5} [{}] {}",                time::strftime("%Y-%m-%d %H:%M:%S", &time::now()).unwrap(),                record.level().to_string(),                record.location().module_path(),                record.args());        }    }}//2种初始化logger的方式：/// Initializes the global logger with a SimpleLogger instance with/// `max_log_level` set to a specific log level.pub fn init_with_level(log_level: LogLevel) -> Result<(), SetLoggerError> {    log::set_logger(|max_log_level| {        max_log_level.set(log_level.to_log_level_filter());//设置日志level        return Box::new(SimpleLogger { log_level: log_level });    })}/// Initializes the global logger with a SimpleLogger instance with/// `max_log_level` set to `LogLevel::Trace`.pub fn init() -> Result<(), SetLoggerError> {    init_with_level(LogLevel::Trace)//默认等级为Trace}

果然是simple logger，代码很simple，功能很simple。