A brief discussion on how to use Nodejs to create access logging middleware

This article will share with you how to use node.js to implement the interface access logging function. I hope it will be helpful to everyone!

Middleware-Access Log

Target

Use middleware technology to write a middleware for recording access logs

Middleware

middleware, middleware is A special url address processing function , which is used as a parameter of app.use (middleware function) or used in a routing processing function.

• Middleware is the biggest feature of express and the most important design. Express is a web development framework with minimalist functions. It is completely composed of routing and middleware: in essence, an Express application is calling various middleware. [Recommended learning: "nodejs tutorial"]
• An express application is completed by many middlewares.

Basic use of middleware

// 具名函数格式：
const handler1 = (req, res, next) => {
  console.log(Date.now());
  next();
}
app.use(handler1);

// 匿名函数格式：
app.use((req, res, next) => {
  console.log(Date.now());
  next();
});

Description: Middleware function There are three basic parameters in it, req, res, next

• req is the request-related object, which is related to the next middleware function The req object is an object

• res which is the response-related object. It is the same object as the res object in the next middleware function

• next It is a function. Calling it will jump out of the current middleware function and execute subsequent middleware; if next is not called or res.end is not executed, the entire request will be stuck in the current middleware.

Ideas

##Apply middleware technology to record each request
Create a
• .json file to store records
Read the data and put it into the
• .json file

js implementation code

const express = require("express");
const app = express();
const fs = require("fs");
// 获取ip的函数
function getClientIp(req) {
  return (
    req.headers["x-forwarded-for"] ||
    req.connection.remoteAddress ||
    req.socket.remoteAddress ||
    req.connection.socket.remoteAddress
  );
}
// 中间件
app.use((req, res, next) => {
  console.log("时间", new Date());
  console.log("访问地址", req.url);
  console.log("f访问ip", getClientIp(req));
  /**
   * 建立一个.json的文件 []
   * 获取文件内容'[]'==>[]
   * let obj = {time:xxx,url:xxx,ip:xxx}
   * [].push(obj)
   * [].push(obj)覆盖写入.json的文件
   */
  fs.readFile("hhhh.json", "utf8", (err, data) => {
    if (err) {
      console.log("文件读取错误", err);
      return;
    }
    let arr = JSON.parse(data);
    //console.log(arr);
    let obj = {};
    obj.time = new Date();
    obj.url = req.url;
    obj.ip = getClientIp(req);
    arr.push(obj);
    console.log(arr);
    let newArr = JSON.stringify(arr);
    fs.writeFile("hhhh.json", newArr, (err) => {
      if (err) {
        console.log("写入错误", err);
      }
    });
  });
  next();
});
// 监听接口
app.listen(8080, () => {
  console.log("成功，接口是8080");
});

Console screenshot

Original address: https://juejin.cn/post/7008510822578126862

Author: Not cowardly

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