我们目前正在开发一个新项目,定期更新,我们的客户每天都会使用这些更新。该项目正在使用角度2开发,我们面临缓存问题,即我们的客户没有看到他们的机器上的最新变化。
主要是js文件的html / css文件似乎得到了正确的更新而没有给出太多麻烦。
angular-cli通过为--output-hashing
命令提供build标志来解决这个问题。用法示例:
ng build --aot --output-hashing=all
Bundling & Tree-Shaking提供了一些细节和背景。运行ng help build
,记录标志:
--output-hashing=none|all|media|bundles (String) Define the output filename cache-busting hashing mode.
aliases: -oh <value>, --outputHashing <value>
虽然这仅适用于angular-cli的用户,但它的工作非常出色,不需要任何代码更改或其他工具。
找到了一种方法,只需添加一个查询字符串来加载组件,如下所示:
@Component({
selector: 'some-component',
templateUrl: `./app/component/stuff/component.html?v=${new Date().getTime()}`,
styleUrls: [`./app/component/stuff/component.css?v=${new Date().getTime()}`]
})
这应该强制客户端加载服务器的模板副本而不是浏览器的副本。如果您希望仅在一段时间后刷新它,则可以使用此ISOString:
new Date().toISOString() //2016-09-24T00:43:21.584Z
并对一些字符进行子字符串处理,以便它只会在一小时后更改,例如:
new Date().toISOString().substr(0,13) //2016-09-24T00
希望这可以帮助
在每个html模板中,我只在顶部添加以下元标记:
<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate">
<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Expires" content="0">
根据我的理解,每个模板都是独立的,因此它不会继承index.html文件中的元无缓存规则设置。
我有类似的问题,因为index.html被浏览器缓存,或者中间cdn /代理比较棘手(F5不会帮助你)。
我找了一个解决方案,100%验证客户端有最新的index.html版本,幸运的是我找到了Henrik Peinar的这个解决方案:
https://blog.nodeswat.com/automagic-reload-for-clients-after-deploy-with-angular-4-8440c9fdd96c
该解决方案还解决了客户端在浏览器中保持打开数天的情况,客户端会按时间间隔检查更新,并在较新的版本deployd时重新加载。
解决方案有点棘手,但就像一个魅力:
ng cli -- prod
生成散列文件的事实,其中一个称为main。[hash] .js由于Henrik Peinar解决方案是针对角度4的,所以有一些细微的变化,我在这里也放置了固定的脚本:
VersionCheckService:
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
@Injectable()
export class VersionCheckService {
// this will be replaced by actual hash post-build.js
private currentHash = '{{POST_BUILD_ENTERS_HASH_HERE}}';
constructor(private http: HttpClient) {}
/**
* Checks in every set frequency the version of frontend application
* @param url
* @param {number} frequency - in milliseconds, defaults to 30 minutes
*/
public initVersionCheck(url, frequency = 1000 * 60 * 30) {
//check for first time
this.checkVersion(url);
setInterval(() => {
this.checkVersion(url);
}, frequency);
}
/**
* Will do the call and check if the hash has changed or not
* @param url
*/
private checkVersion(url) {
// timestamp these requests to invalidate caches
this.http.get(url + '?t=' + new Date().getTime())
.subscribe(
(response: any) => {
const hash = response.hash;
const hashChanged = this.hasHashChanged(this.currentHash, hash);
// If new version, do something
if (hashChanged) {
// ENTER YOUR CODE TO DO SOMETHING UPON VERSION CHANGE
// for an example: location.reload();
// or to ensure cdn miss: window.location.replace(window.location.href + '?rand=' + Math.random());
}
// store the new hash so we wouldn't trigger versionChange again
// only necessary in case you did not force refresh
this.currentHash = hash;
},
(err) => {
console.error(err, 'Could not get version');
}
);
}
/**
* Checks if hash has changed.
* This file has the JS hash, if it is a different one than in the version.json
* we are dealing with version change
* @param currentHash
* @param newHash
* @returns {boolean}
*/
private hasHashChanged(currentHash, newHash) {
if (!currentHash || currentHash === '{{POST_BUILD_ENTERS_HASH_HERE}}') {
return false;
}
return currentHash !== newHash;
}
}
更改为主AppComponent:
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
constructor(private versionCheckService: VersionCheckService) {
}
ngOnInit() {
console.log('AppComponent.ngOnInit() environment.versionCheckUrl=' + environment.versionCheckUrl);
if (environment.versionCheckUrl) {
this.versionCheckService.initVersionCheck(environment.versionCheckUrl);
}
}
}
后构建脚本,使魔术,后build.js:
const path = require('path');
const fs = require('fs');
const util = require('util');
// get application version from package.json
const appVersion = require('../package.json').version;
// promisify core API's
const readDir = util.promisify(fs.readdir);
const writeFile = util.promisify(fs.writeFile);
const readFile = util.promisify(fs.readFile);
console.log('\nRunning post-build tasks');
// our version.json will be in the dist folder
const versionFilePath = path.join(__dirname + '/../dist/version.json');
let mainHash = '';
let mainBundleFile = '';
// RegExp to find main.bundle.js, even if it doesn't include a hash in it's name (dev build)
let mainBundleRegexp = /^main.?([a-z0-9]*)?.js$/;
// read the dist folder files and find the one we're looking for
readDir(path.join(__dirname, '../dist/'))
.then(files => {
mainBundleFile = files.find(f => mainBundleRegexp.test(f));
if (mainBundleFile) {
let matchHash = mainBundleFile.match(mainBundleRegexp);
// if it has a hash in it's name, mark it down
if (matchHash.length > 1 && !!matchHash[1]) {
mainHash = matchHash[1];
}
}
console.log(`Writing version and hash to ${versionFilePath}`);
// write current version and hash into the version.json file
const src = `{"version": "${appVersion}", "hash": "${mainHash}"}`;
return writeFile(versionFilePath, src);
}).then(() => {
// main bundle file not found, dev build?
if (!mainBundleFile) {
return;
}
console.log(`Replacing hash in the ${mainBundleFile}`);
// replace hash placeholder in our main.js file so the code knows it's current hash
const mainFilepath = path.join(__dirname, '../dist/', mainBundleFile);
return readFile(mainFilepath, 'utf8')
.then(mainFileData => {
const replacedFile = mainFileData.replace('{{POST_BUILD_ENTERS_HASH_HERE}}', mainHash);
return writeFile(mainFilepath, replacedFile);
});
}).catch(err => {
console.log('Error with post build:', err);
});
只需将脚本置于(新)构建文件夹中,使用node ./build/post-build.js
构建dist文件夹后使用ng build --prod
运行脚本
您可以使用HTTP标头控制客户端缓存。这适用于任何Web框架。
您可以设置这些标头的指令,以便对启用和禁用缓存的方式和时间进行细粒度控制:
Cache-Control
Surrogate-Control
Expires
ETag
(非常好)Pragma
(如果你想支持旧的浏览器)在所有计算机系统中,良好的缓存都很好,但非常复杂。有关更多信息,请查看https://helmetjs.github.io/docs/nocache/#the-headers。