浅谈express 中间件机制及实现原理

let items = req.headers.split('rn');
let header = {}
for(let i in items) {
let item = items[i].split(':');
let key = item[0];
let value = item[1];
header[key] = value;
}
req.header = header;
next(); //执行下一个中间件
}

function bodyParser(req, res, next) {
let bodyStr = req.requestBody;
let body = {};
let items = bodyStr.split('&');
for(let i in items) {
let item = items[i].split('=');
let key = item[0];
let value = item[1];
body[key] = value;
}
req.body = body;
next(); //执行下一个中间件
}

function middleware3(req, res, next) {
console.log('url: '+req.url);
console.log('methond: '+req.methond);
console.log('version: '+req.version);
console.log(req.body);
console.log(req.header);
next(); //执行下一个中间件
}
let app = App();
app.use(lineParser);
app.use(headersParser);
app.use(bodyParser);
app.use(middleware3);
app.next();

运行结果

将以上整体代码运行后将打印以下信息

url: /iven_
methond: POST
version: HTTP/1.1
{key1: "value1", key2: "value2", key3: "value3"}
{Host: "www.baidu.com", Cookie: "BAIDUID=E063E9B2690116090FE24E01ACDDF4AD"}