android检查是否安装

A. Android 是怎么判断某个APK文件是否已经安装

Android系统中，判断应用有无安装有两种方式：

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<ResolveInfo> 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<ResolveInfo> list = context.getPackageManager()
.queryIntentActivities(intent, 0);
if (list.size() > 0) {
return true;
}
return false;
}