1. parse 反序列化（将url字符串解析成对象）

语法：url.resolve (url字符串，query参数是否进行querystring反序列化解析，可省略)

const url = require("url");
const url_str = "http://localhost:8080/api/canda/user?username=青龙&password=123456&code=10086";
const result1 = url.parse(url_str)
console.log('result1: ', result1);
const result2 = url.parse(url_str,true)
console.log('result2: ', result2);

结果如下，query参数在第二个参数为true的情况下会被反序列化成对象

result1:  Url {
  protocol: 'http:',
  slashes: true,
  auth: null,
  host: 'localhost:8080',
  port: '8080',
  hostname: 'localhost',
  hash: null,
  search: '?username=青龙&password=123456&code=10086',
  query: 'username=青龙&password=123456&code=10086',  
  pathname: '/api/canda/user',
  path: '/api/canda/user?username=青龙&password=123456&code=10086',
  href: 'http://localhost:8080/api/canda/user?username=青龙&password=123456&code=10086'
}
result2:  Url {
  protocol: 'http:',
  slashes: true,
  auth: null,
  host: 'localhost:8080',
  port: '8080',
  hostname: 'localhost',
  hash: null,
  search: '?username=青龙&password=123456&code=10086',
  query: [Object: null prototype] {
    username: '青龙',
    password: '123456',
    code: '10086'
  },
  pathname: '/api/canda/user',
  path: '/api/canda/user?username=青龙&password=123456&code=10086',
  href: 'http://localhost:8080/api/canda/user?username=青龙&password=123456&code=10086'
}

2. format 序列化（将url对象解析成url字符串）

语法：url.resolve (url对象)

const url = require("url");
const url_obj = {
    protocol: 'http:',
    slashes: true,
    auth: null,
    host: 'localhost:8080',
    port: '8080',
    hostname: 'localhost',
    hash: null,
    search: '?username=青龙&password=123456&code=10086',
    query:  {
      username: '青龙',
      password: '123456',
      code: '10086'
    },
    pathname: '/api/canda/user',
    path: '/api/canda/user?username=青龙&password=123456&code=10086',
    href: 'http://localhost:8080/api/canda/user?username=青龙&password=123456&code=10086'
  }
const result = url.format(url_obj)
console.log(result); // 结果： http://localhost:8080?username=青龙&password=123456&code=10086

3. resolve url路径拼接（路由切换）

语法：url.resolve (基础路径 , 拼接路径)

const url = require("url");
const a = 'localhost:8080/';
const b = 'api/scan/user'
const c = 'api/scan/roles'
const result1 = url.resolve(a,b)
const result2 = url.resolve(a,c)
console.log(result1); // 结果： localhost:8080/api/scan/user
console.log(result2); // 结果： localhost:8080/api/scan/roles