缓存方案流程图
网上看了很多的WebView缓存的文章，做了个H5缓存的方案，提高H5体验，提升H5加载 速度。主要部分为缓存和文件差异对比。
- 缓存：SP+文件存储，SP 保存文件名和存储路径
- 文件差异对比：文件MD5对比，不同则需要删除更新，相同则可以直接使用，保证用户看到的是最新的页面
PS: 文件对比方案可以服务端给客户端返回缓存文件对应的MD5配置表，然后每次取缓存文件时对比MD5值。
工具类
实现WebViewClient shouldInterceptRequest 方法，此方法做具体逻辑操作,代码如下：
public class XWebViewClient extends WebViewClient {
@Override
public WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request) {
return XWebInterceptor.shouldInterceptRequest(view, request);
}
@Override
public WebResourceResponse shouldInterceptRequest(WebView view, String url) {
return XWebInterceptor.shouldInterceptRequest(view, url);
}
}
public class XWebInterceptor {
public static final String TAG = "====XWebInterceptor====";
private static Map<String, String> interceptMap = new HashMap<>();
static {
interceptMap.put(".js", "application/javascript");
interceptMap.put(".html", "text/html");
interceptMap.put(".htm", "text/html");
interceptMap.put(".css", "text/css");
interceptMap.put(".png", "image/png");
interceptMap.put(".jpg", "image/jpeg");
interceptMap.put(".jpeg", "image/jpeg");
interceptMap.put(".gif", "image/gif");
interceptMap.put(".ico", "image/x-icon");
interceptMap.put(".mp3", "audio/mp3");
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public static WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request) {
return shouldInterceptRequest(view.getContext(), request.getUrl());
}
public static WebResourceResponse shouldInterceptRequest(WebView view, String url) {
return shouldInterceptRequest(view.getContext(), Uri.parse(url));
}
private static WebResourceResponse shouldInterceptRequest(final Context context, Uri requestUri) {
final String remoteUrl = requestUri.toString();
Log.d(TAG, "拦截时间:" + System.currentTimeMillis() + "\t拦截地址:" + remoteUrl);
if (isInterceptor(remoteUrl)) {
Log.d(TAG, "符合拦截条件，开始拦截");
String filePath = SPUtil.getString(context, remoteUrl);
File localFile = null;
if (TextUtils.isEmpty(filePath)) {
localFile = download(context, remoteUrl);
}
if(localFile == null){
localFile = new File(filePath);
if (!localFile.exists()) {
localFile = download(context, remoteUrl);
}
}
try {
FileInputStream fis = new FileInputStream(localFile);
//本地文件MD5
String localFileMd5 = FileUtil.getFileMD5(fis);
//获取远端返回MD5
String remoteFileMd5 = SPUtil.getString(context, remoteUrl.substring(remoteUrl.lastIndexOf("/") + 1));
if (!localFileMd5.equals(remoteFileMd5)) {
//校验本地文件MD5,不一致则删除本地文件再次下载
localFile.delete();
localFile = download(context, remoteUrl);
}
return new WebResourceResponse(getMimeType(remoteUrl), "UTF-8", new FileInputStream(localFile));
} catch (FileNotFoundException e) {
e.printStackTrace();
Log.d(TAG, "存在缓存文件，发生异常");
} catch (NullPointerException e) {
e.printStackTrace();
}
}
return null;
}
@SuppressLint("CheckResult")
private static File download(final Context context, final String remoteUrl) {
Log.d(TAG, "无现有缓存可用，开始下载:" + remoteUrl);
File localFile = null;
OkHttpClient okHttpClient = new OkHttpClient();
Request request = new Request.Builder()
.url(remoteUrl)
.build();
try {
String path = context.getCacheDir().getPath() + File.separator + "h5Cache" + File.separator;
FileUtil.createFolder(path);
String name = remoteUrl.substring(remoteUrl.lastIndexOf("/") + 1);
Response response = okHttpClient.newCall(request).execute();
InputStream is = response.body().byteStream();
localFile = FileUtil.createFile(path + name, is);
SPUtil.putString(context, remoteUrl, path + name);
Log.d(TAG, "下载完成，缓存文件保存路径" + localFile.getPath());
} catch (IOException e) {
Log.d(TAG, "IO 异常，下载失败：" + remoteUrl + "\t" + e.getMessage());
} catch (Exception e) {
Log.d(TAG, "其他异常，下载失败：" + remoteUrl + "\t" + e.getMessage());
}
return localFile;
}
private static boolean isInterceptor(String remoteUrl) {
if (!remoteUrl.contains(".")) {
return false;
}
String suffixName = remoteUrl.substring(remoteUrl.lastIndexOf("."));
return interceptMap.containsKey(suffixName);
}
/**
* @see <a href=" http://tool.oschina.net/commons">Http Content-type 对照表</a>
*/
private static String getMimeType(String remoteUrl) {
if (TextUtils.isEmpty(remoteUrl) || !remoteUrl.contains(".")) {
return null;
}
String suffixName = remoteUrl.substring(remoteUrl.lastIndexOf("."));
if (interceptMap.containsKey(suffixName)) {
return interceptMap.get(suffixName);
}
return URLConnection.guessContentTypeFromName(remoteUrl);
}
}
参考资料
