nodejs 中间件

1:全集中间件

//导入模块
const express = require('express');
//创建应用
const app = express();function logger(req, resp, next) { console.log(`${req.method} ${req.path} "${req.headers['user-agent']}"`);next();
}
app.use(logger); //注冊中間件
app.get('/',(req,resp)=>{//输出响应console.log('request coming.............');resp.send("hello world");
});app.listen(8080,()=>{console.log('listening on 8080');
});

执行结果:
GET / “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36”
request coming…
GET /.well-known/appspecific/com.chrome.devtools.json “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36”

路由中间件:

//导入模块
const express = require('express');
//创建应用
const app = express();function logger(req, resp, next) { console.log(`${req.method} ${req.path} "${req.headers['user-agent']}"`);next();
}app.get('/',logger,(req,resp)=>{ //注册到路由上//输出响应console.log('request coming.............');resp.send("hello world");
});app.listen(8080,()=>{console.log('listening on 8080');
});``
可配置中间件:

//导入模块
const express = require(‘express’);
//创建应用
const app = express();

function logger(options) {
return function (req, resp, next) {
const logs = [];
if (options.method) {
logs.push(req.method);
}
if (options.path) {
logs.push(req.path);
}
if (options[‘user-agent’]) {
logs.push(req.headers[‘user-agent’]);
}
console.log(logs.join(’ '));
next();
};
}

app.use(logger({ method: true, path: true }));
app.get(‘/’,(req,resp)=>{
//输出响应
console.log(‘request coming…’);
resp.send(“hello world”);
});

app.get(‘/user’,(req,resp)=>{
//输出响应
console.log(‘request coming…’);
resp.send(“hello user”);
});

app.listen(8080,()=>{
console.log(‘listening on 8080’);
});

**响应时长中间件**

//导入模块
const express = require(‘express’);
//创建应用
const app = express();
function responseTime(req,resp,next) {
const start = Date.now();
resp.once(‘finish’, function () {
console.log(‘处理时长’,Date.now() - start);
});
next();
}
app.use(responseTime);
app.get(‘/’,(req,resp)=>{
//输出响应
setTimeout(() => {
console.log(‘request coming…’);
resp.send(“hello world”);
},1000);

});

app.listen(8080,()=>{
console.log(‘listening on 8080’);
});

**静态资源中间件**
express.static(root,[options])

//导入模块
const express = require(‘express’);
//创建应用
const app = express();

app.use(‘/public’,express.static(‘./public’));

app.listen(8080,()=>{
console.log(‘listening on 8080’);
});