问题描述

我要使用ASP.NET Web表单创建一个PWA。我无法了解如何注册服务工作者以及如何使Web应用程序可供联机使用。

推荐答案

对您的问题的简短回答是"是"。

我已在我的Web Forms ASP.NET站点上启动并运行它。

使用Microsoft PWA Builder。这非常简单，而且会为你节省一些时间。 https://www.pwabuilder.com/

我确实必须将pwaBuilder-sw.js移到根目录才能使其工作。 很抱歉，这里的回答很简短，是一步一步来的。请阅读代码中的注释。

它最终将如下所示：

{
  "name": "Longer Answer",
  "short_name": "Not a short answer",
  "start_url": ".",
  "display": "standalone",
  "background_color": "#fff",
  "description": "A simply readable Longer Answer News app.",
  "icons": [{
    "src": "images/touch/homescreen48.png",
    "sizes": "48x48",
    "type": "image/png"
  }, {
    "src": "images/touch/homescreen72.png",
    "sizes": "72x72",
    "type": "image/png"
  }, {
    "src": "images/touch/homescreen96.png",
    "sizes": "96x96",
    "type": "image/png"
  }, {
    "src": "images/touch/homescreen144.png",
    "sizes": "144x144",
    "type": "image/png"
  }, {
    "src": "images/touch/homescreen168.png",
    "sizes": "168x168",
    "type": "image/png"
  }, {
    "src": "images/touch/homescreen192.png",
    "sizes": "192x192",
    "type": "image/png"
  }]      
}

文件名：Register-sw.js

// This is the "Offline page" service worker

// Add this below content to your HTML page, or add the js file to your page at the very top to register service worker

// Check compatibility for the browser we're running this in
if ("serviceWorker" in navigator) {
  if (navigator.serviceWorker.controller) {
    console.log("[PWA Builder] active service worker found, no need to register");
  } else {
    // Register the service worker
    navigator.serviceWorker
      .register("pwabuilder-sw.js", {
        scope: "./"
      })
      .then(function (reg) {
        console.log("[PWA Builder] Service worker has been registered for scope: " + reg.scope);
      });
  }
}

文件名：pwa-sw.js

//This is the service worker with the Advanced caching

const CACHE = "pwabuilder-adv-cache";
const precacheFiles = [
  /* Add an array of files to precache for your app */
];

// TODO: replace the following with the correct offline fallback page i.e.: const offlineFallbackPage = "offline.html";
const offlineFallbackPage = "ToDo-replace-this-name.html";

const networkFirstPaths = [
  /* Add an array of regex of paths that should go network first */
  // Example: //api/.*/
];

const avoidCachingPaths = [
  /* Add an array of regex of paths that shouldn't be cached */
  // Example: //api/.*/
];

function pathComparer(requestUrl, pathRegEx) {
  return requestUrl.match(new RegExp(pathRegEx));
}

function comparePaths(requestUrl, pathsArray) {
  if (requestUrl) {
    for (let index = 0; index < pathsArray.length; index++) {
      const pathRegEx = pathsArray[index];
      if (pathComparer(requestUrl, pathRegEx)) {
        return true;
      }
    }
  }

  return false;
}

self.addEventListener("install", function (event) {
  console.log("[PWA] Install Event processing");

  console.log("[PWA] Skip waiting on install");
  self.skipWaiting();

  event.waitUntil(
    caches.open(CACHE).then(function (cache) {
      console.log("[PWA] Caching pages during install");

      return cache.addAll(precacheFiles).then(function () {
        if (offlineFallbackPage === "ToDo-replace-this-name.html") {
          return cache.add(new Response("TODO: Update the value of the offlineFallbackPage constant in the serviceworker."));
        }

        return cache.add(offlineFallbackPage);
      });
    })
  );
});

// Allow sw to control of current page
self.addEventListener("activate", function (event) {
  console.log("[PWA] Claiming clients for current page");
  event.waitUntil(self.clients.claim());
});

// If any fetch fails, it will look for the request in the cache and serve it from there first
self.addEventListener("fetch", function (event) {
  if (event.request.method !== "GET") return;

  if (comparePaths(event.request.url, networkFirstPaths)) {
    networkFirstFetch(event);
  } else {
    cacheFirstFetch(event);
  }
});

function cacheFirstFetch(event) {
  event.respondWith(
    fromCache(event.request).then(
      function (response) {
        // The response was found in the cache so we responde with it and update the entry

        // This is where we call the server to get the newest version of the
        // file to use the next time we show view
        event.waitUntil(
          fetch(event.request).then(function (response) {
            return updateCache(event.request, response);
          })
        );

        return response;
      },
      function () {
        // The response was not found in the cache so we look for it on the server
        return fetch(event.request)
          .then(function (response) {
            // If request was success, add or update it in the cache
            event.waitUntil(updateCache(event.request, response.clone()));

            return response;
          })
          .catch(function (error) {
            // The following validates that the request was for a navigation to a new document
            if (event.request.destination !== "document" || event.request.mode !== "navigate") {
              return;
            }

            console.log("[PWA] Network request failed and no cache." + error);
            // Use the precached offline page as fallback
            return caches.open(CACHE).then(function (cache) {
              cache.match(offlineFallbackPage);
            });
          });
      }
    )
  );
}

function networkFirstFetch(event) {
  event.respondWith(
    fetch(event.request)
      .then(function (response) {
        // If request was success, add or update it in the cache
        event.waitUntil(updateCache(event.request, response.clone()));
        return response;
      })
      .catch(function (error) {
        console.log("[PWA ] Network request Failed. Serving content from cache: " + error);
        return fromCache(event.request);
      })
  );
}

function fromCache(request) {
  // Check to see if you have it in the cache
  // Return response
  // If not in the cache, then return error page
  return caches.open(CACHE).then(function (cache) {
    return cache.match(request).then(function (matching) {
      if (!matching || matching.status === 404) {
        return Promise.reject("no-match");
      }

      return matching;
    });
  });
}

function updateCache(request, response) {
  if (!comparePaths(request.url, avoidCachingPaths)) {
    return caches.open(CACHE).then(function (cache) {
      return cache.put(request, response);
    });
  }

  return Promise.resolve();
}

我知道有两种方法可以测试您的pwa配置：

1. 打开Google开发工具并转到应用程序选项卡。然后在左侧点击Service Worker。接下来，勾选顶部的"重新加载时更新"框。之后，重新加载页面并查看结果。

2. 使用灯塔审核网站。您可以在"审计"选项卡下的"Google开发人员工具"中找到它。

如果您有任何问题，请告诉我。

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