ionic3日志组件

背景

我们在开发时都很喜欢使用console.*来打印出日志信息以方便我们调试代码，但是在上线时肯定是需要去除所有的console；但是大多数情况下开发者都会忘记移除console输出，这会带来生产日志风险。

编写

1. 新增一个日志组件：logger

ionic g provier logger

2. 修改logger.ts的内容如下：

import {Injectable} from '@angular/core';
import {Constants} from "../Constants";

@Injectable()
export class Logger {

  constructor() {

  }

  /**
   * Logs messages or objects  with the debug level.
   * Works the same as console.log().
   */
  public log(...objects: any[]) {
    this.log_real(console.log, LogLevel.Debug, objects);
  }

  /**
   * Logs messages or objects  with the debug level.
   * Works the same as console.debug().
   */
  public debug(...objects: any[]) {
    this.log_real(console.log, LogLevel.Debug, objects);
  }

  /**
   * Logs messages or objects  with the info level.
   * Works the same as console.info().
   */
  public info(...objects: any[]) {
    this.log_real(console.info, LogLevel.Info, objects);
  }

  /**
   * Logs messages or objects  with the warning level.
   * Works the same as console.warn().
   */
  public warn(...objects: any[]) {
    this.log_real(console.warn, LogLevel.Warning, objects);
  }

  /**
   * Logs messages or objects  with the error level.
   * Works the same as console.error().
   */
  public error(...objects: any[]) {
    this.log_real(console.error, LogLevel.Error, objects);
  }

  protected async log_real(func: Function, level: LogLevel, objects: any[]) {
    const env = Constants.ENVIRONMENT || 'development';
    if (env !== 'production') {
      func.apply(console, objects);
    }
  }
}

export enum LogLevel {
  Error,
  Warning,
  Info,
  Debug,
}

3. 在app.module.ts中引入Logger组件：

import {Logger} from "../common/logger/logger";
......
  providers: [
    Logger, 
]
......

使用:

1. 在Constants中新增一个变量：

export const Constants = {
  ENVIRONMENT: 'development',//app环境，开发时为development，正式发布时需求注掉或者改为production
}

2. 在需要打印日志的地方引用

import {Injectable} from "@angular/core";
import {RequestPreviewHandler} from "../RequestPreviewHandler";
import {HttpRequest} from "@angular/common/http";
import {Logger} from "../../../../common/logger/logger";

@Injectable()
export class DefaultRequestPreviewHandler extends RequestPreviewHandler {
  constructor(private logger: Logger) {
    super();
  }


  handle(request: HttpRequest): HttpRequest {
    this.logger.warn("未注入自定义请求前置处理类，使用默认前置处理");
    return request;
  }
}

效果与使用console一致,如下：

logger.png

3. 生产发版
   只需要将Constants中ENVIRONMENT的值为production即可去除所有日志输出

export const Constants = {
  ENVIRONMENT: 'production',//app环境，开发时为development，正式发布时需求注掉或者改为production
}
;

避免了还需要手动删除console相关代码的问题。