Android 是怎么判断某个APK文件是否已经安装

目前Android有两种主流的判断方式，第一种是根据程序包的名称（packageName）来判断。另外一种就是根据intent来判断，具体代码如下：

1. 根据包名判断,以下为判断代码：
   public boolean checkApkExist(Context context, String packageName) {
   if (packageName == null || “”.equals(packageName))
   return false;
   try {
   ApplicationInfo info = context.getPackageManager()
   .getApplicationInfo(packageName,
   PackageManager.GET_UNINSTALLED_PACKAGES);
   return true;
   } catch (NameNotFoundException e) {
   return false;
   }
   }
   
   2. 根据Intent判断，以下为判断代码：
   public boolean checkApkExist(Context context, Intent intent) {
   List list = context.getPackageManager().queryIntentActivities(intent, 0);
   if(list.size() > 0){
   return true;
   }
   return false;
   }
   public boolean checkApkExist(Context context, String packageName) {
   if (packageName == null || “”.equals(packageName)) return false;
   try {
   ApplicationInfo info = context.getPackageManager() .getApplicationInfo(packageName, PackageManager.GET_UNINSTALLED_PACKAGES); return true;
   } catch (NameNotFoundException e) { return false; }
   } 
   public boolean checkApkExist(Context context, Intent intent) {
   List list = context.getPackageManager()
   .queryIntentActivities(intent, 0);
   if (list.size() > 0) {
   return true;
   }
   return false;
   }

   以上代码只是基于安卓系统来判断，对于ios系统无效。

判断某个APK文件是否已经安装
privateboolean isAppInstalled(String uri) {
PackageManager pm = getPackageManager();
boolean installed =false;
try {
pm.getPackageInfo(uri,PackageManager.GET_ACTIVITIES);
installed =true;
} catch(PackageManager.NameNotFoundException e) {
installed =false;
}
return installed;
}

if(isAppInstalled("com.yourpackage.package")) {
//app installed
} else {
//app not installed
}

PackageManager