【笔记】Koa学习笔记

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前言

Expressive HTTP middleware framework for node.js to make web applications and APIs more enjoyable to write.（Github）

下载依赖

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npm install koa

引入依赖

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const Koa = require("koa");

创建Web服务器

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const app = new Koa();
app.use(function (context, next) {
  context.body = "";
});
app.listen(8080);
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const app = new Koa();
app.use(function (context, next) {
  context.body = "";
});
app.listen(8080, function () {
  console.log(`http://127.0.0.1:8080`);
});
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const app = new Koa();
app.use(function (context, next) {
  context.body = "";
});
app.listen(8080, "0.0.0.0", function () {
  console.log(`http://127.0.0.1:8080`);
});

中间件

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app.use(function (context, next) {
  ...
});

继续下一个中间件

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next();

处理请求

获取Nodejs请求对象

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const request = context.req;

获取Koa请求对象

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const request = context.request;

获取请求行

获取请求URL

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const path = context.request.path;
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const path = context.path;

获取请求方法

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const method = context.request.method;
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const method = context.method;

处理响应

获取Nodejs响应对象

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const response = context.res;

获取Koa响应对象

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const response = context.response;

设置响应体并返回响应

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context.body = "";

路由

下载依赖

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npm install @koa/router

引入依赖

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const KoaRouter = require("@koa/router");

定义路由

  • 如果没有注册router.allowedMethods()，则访问没有匹配的路由时会返回Not Found
  • 如果注册了router.allowedMethods()，则访问没有匹配的路由时会返回Method Not Allowed
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const router = new KoaRouter({ prefix: "/api" });

router.get("/", function (context, next) {
  ...
});

app.use(router.routes());
app.use(router.allowedMethods());

处理请求

获取请求参数

query
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router.get("/", function (context, next) {
  const query = context.query;
});
path
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router.get("/:id", function (context, next) {
  const id = context.params.id;
});

解析Form请求体和JSON请求体

下载依赖

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npm install koa-bodyparser

解析Form请求参数和JSON请求参数

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const bodyParser = require("koa-bodyparser");

app.use(bodyParser());

app.use(function (context, next) {
  const body = context.request.body;
});

解析FormData请求参数

下载依赖

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npm install @koa/multer multer

解析FormData请求参数

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const multer = require("@koa/multer");

const formParser = multer();

app.use(formParser.any(), function (context, next) {
  const body = context.request.body;
});

解析单个文件上传请求参数

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const multer = require("@koa/multer");

const upload = multer({ dest: "./uploads" });

app.use(upload.single("key"), function (context, next) {
  const file = context.request.file;
});
  • 自定义文件名
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const multer = require("@koa/multer");

const upload = multer({
  storage: multer.diskStorage({
    destination: function (request, file, callback) {
      callback(null, "./uploads");
    },
    filename: function (request, file, callback) {
      callback(null, file.originalname);
    }
  })
});

app.use(upload.single("key"), function (context, next) {
  const file = context.request.file;
});

解析多个文件上传请求参数

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const multer = require("@koa/multer");

const upload = multer({ dest: "./uploads" });

app.post("/", upload.array("key"), function (context, next) {
  const files = context.request.files;
});

完成