Android獲取清單檔案中的meta-data,解決碰到數值為null的問題
阿新 • • 發佈:2020-03-25
1.meta-data是什麼?如何獲取meta-data?
在AndroidManifest.xml中,元素可以作為子元素,被包在activity、application 、service、或者receiver元素中,不同的父元素,在應用時讀取的方法也不同。
在activity中:
ActivityInfo info = null; try { info = this.getPackageManager().getActivityInfo(getComponentName(),PackageManager.GET_META_DATA); } catch (PackageManager.NameNotFoundException e) { e.printStackTrace(); } info.metaData.getString("meta_name");
在application中:
ApplicationInfo appInfo = null; try { appInfo = this.getPackageManager().getApplicationInfo(getPackageName(),PackageManager.GET_META_DATA); } catch (PackageManager.NameNotFoundException e) { e.printStackTrace(); } appInfo.metaData.getString("meta_name");
在service中:
ComponentName cn = new ComponentName(this,XXXXService.class); ServiceInfo info = null; try { info = this.getPackageManager().getServiceInfo(cn,PackageManager.GET_META_DATA); } catch (PackageManager.NameNotFoundException e) { e.printStackTrace(); } info.metaData.getString("meta_name");
在receiver中:
ComponentName cn = new ComponentName(getApplicationContext(),XXXXXReceiver.class); ActivityInfo info = null; try { info = getApplicationContext().getPackageManager().getReceiverInfo(cn,PackageManager.GET_META_DATA); } catch (PackageManager.NameNotFoundException e) { e.printStackTrace(); } info.metaData.getString("meta_name");
2.遇到的問題:獲取到值為null
之前在application中獲取一直key值,但是一直獲取到的都是null,後來人大神說:讀取字串的數值要用info.metaData.getInt,嘗試了一下,彎的佛,成功拿到,如果是數值型別的,獲取值的時候,可以採用:
info.metaData.getInt("meta_name"));
替代
info.metaData.getString("meta_name");
補充知識:android webview攔截替換本地資源,提升載入效能,節省流量
現在許多遊戲都是直接提供一個訪問地址,然後由webview去訪問載入,載入速度的快慢取決於網速,當然也耗流量,這個時候,為了提高產品競爭力,產品經理就會提出需求了,web前端的同學也就會把資源給到Android前端,接下來就是要做的處理了,程式碼不多,用作記錄:
package com.dxgame.demo; import android.net.Uri; import android.os.Build; import android.os.Bundle; import android.support.annotation.RequiresApi; import android.support.v7.app.AppCompatActivity; import android.text.TextUtils; import android.util.Log; import android.webkit.MimeTypeMap; import android.webkit.WebResourceRequest; import android.webkit.WebResourceResponse; import android.webkit.WebView; import android.webkit.WebViewClient; import java.io.InputStream; import java.util.HashMap; public class CheckLocal extends AppCompatActivity { private WebView webView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.check_local); webView.setWebViewClient(webViewClient); } //WebViewClient主要幫助WebView處理各種通知、請求事件 private WebViewClient webViewClient = new WebViewClient() { @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) public WebResourceResponse shouldInterceptRequest(WebView view,WebResourceRequest request) { Uri uri = request.getUrl(); WebResourceResponse response = checkLocalWebResourceResponse(uri); if (response != null) { return response; } return super.shouldInterceptRequest(view,request); } @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) public WebResourceResponse shouldInterceptRequest(WebView view,String url) { Uri uri = Uri.parse(url); WebResourceResponse response = checkLocalWebResourceResponse(uri); if (response != null) { return response; } return super.shouldInterceptRequest(view,url); } }; @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) private WebResourceResponse checkLocalWebResourceResponse(Uri uri) { WebResourceResponse resourceResponse = null; String urlStr = uri.toString(); Log.i("checkUrl",urlStr); String path = uri.getPath(); if (!TextUtils.isEmpty(path)) { path = path.substring(1); } try { InputStream input = getAssets().open(path); if (input != null) { Log.i("assetsPath",path); String mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(path.substring(path.lastIndexOf(".") + 1)); HashMap<String,String> header = new HashMap<>(); header.put("Access-Control-Allow-Origin","*"); header.put("Access-Control-Allow-Headers","Content-Type"); resourceResponse = new WebResourceResponse(mimeType,"",200,"ok",header,input); } } catch (Exception e) { e.printStackTrace(); } } return resourceResponse; }
還可以進一步優化,利用webview的快取機制,將資料快取到本地,方法就不列出來了,網上有很多,自行百度
以上這篇Android獲取清單檔案中的meta-data,解決碰到數值為null的問題就是小編分享給大家的全部內容了,希望能給大家一個參考,也希望大家多多支援我們。