【Android】判断某个AP是否在系统中存在（PackageManager与PackageInfo）

 【0】我们可以使用 getPackageManager() 方法来查询安装在系统上的AP.

public abstract class

PackageManager

extends Object

java.lang.Object   ↳android.content.pm.PackageManagerKnown Direct Subclasses

MockPackageManager

Class for retrieving various kinds of information related to the application packages that are currently installed on the device. You can find this class through getPackageManager().

【1】使用从Manifest.xml文件中获得到的PackageInfo来取得AP的信息.

public class

PackageInfo

extends Object
implements Parcelable

java.lang.Object   ↳android.content.pm.PackageInfo

Overall information about the contents of a package. This corresponds to all of the information collected from AndroidManifest.xml.

public static final Creator<PackageInfo> CREATOR

Since: API Level 1

public ActivityInfo[] activities

Since: API Level 1

Array of all <activity> tags included under <application>, or null if there were none. This is only filled in if the flag GET_ACTIVITIES was set.

public ApplicationInfo applicationInfo

Since: API Level 1

Information collected from the <application> tag, or null if there was none.

public ConfigurationInfo[] configPreferences

Since: API Level 3

Application specified preferred configuration <uses-configuration> tags included under <manifest>, or null if there were none. This is only filled in if the flag GET_CONFIGURATIONSwas set.

public long firstInstallTime

Since: API Level 9

The time at which the app was first installed. Units are as per currentTimeMillis().

public int[] gids

Since: API Level 1

All kernel group-IDs that have been assigned to this package. This is only filled in if the flag GET_GIDS was set.

public InstrumentationInfo[] instrumentation

Since: API Level 1

Array of all <instrumentation> tags included under <manifest>, or null if there were none. This is only filled in if the flag GET_INSTRUMENTATION was set.

public long lastUpdateTime

Since: API Level 9

The time at which the app was last updated. Units are as per currentTimeMillis().

public String packageName

Since: API Level 1

The name of this package. From the <manifest> tag's "name" attribute.

public PermissionInfo[] permissions

Since: API Level 1

Array of all <permission> tags included under <manifest>, or null if there were none. This is only filled in if the flag GET_PERMISSIONS was set.

public ProviderInfo[] providers

Since: API Level 1

Array of all <provider> tags included under <application>, or null if there were none. This is only filled in if the flag GET_PROVIDERS was set.

public ActivityInfo[] receivers

Since: API Level 1

Array of all <receiver> tags included under <application>, or null if there were none. This is only filled in if the flag GET_RECEIVERS was set.

public FeatureInfo[] reqFeatures

Since: API Level 5

The features that this application has said it requires.

public String[] requestedPermissions

Since: API Level 1

Array of all <uses-permission> tags included under <manifest>, or null if there were none. This is only filled in if the flag GET_PERMISSIONS was set. This list includes all permissions requested, even those that were not granted or known by the system at install time.

public ServiceInfo[] services

Since: API Level 1

Array of all <service> tags included under <application>, or null if there were none. This is only filled in if the flag GET_SERVICES was set.

public String sharedUserId

Since: API Level 3

The shared user ID name of this package, as specified by the <manifest> tag's sharedUserId attribute.

public int sharedUserLabel

Since: API Level 3

The shared user ID label of this package, as specified by the <manifest> tag's sharedUserLabel attribute.

public Signature[] signatures

Since: API Level 1

Array of all signatures read from the package file. This is only filled in if the flag GET_SIGNATURES was set.

public int versionCode

Since: API Level 1

The version number of this package, as specified by the <manifest> tag's versionCode attribute.

public String versionName

Since: API Level 1

The version name of this package, as specified by the <manifest> tag's versionName attribute.

【2】使用上面两个类来实现一个判断某个AP是否安装在系统中的工具类

/** * Whether the AP was installed * @param context:the Context * @param packageName:the ap packageName * @return */public static boolean isAppInstalled(Context context, String packageName){//获取到一个PackageManager的instancefinal PackageManager packageManager = context.getPackageManager();//PERMISSION_GRANTED = 0List<PackageInfo> mPackageInfo = packageManager.getInstalledPackages(0);boolean flag = false;if(mPackageInfo != null){String tempName = null;for(int i = 0; i < mPackageInfo.size(); i++){//获取到AP包名tempName = mPackageInfo.get(i).packageName;if(tempName != null && tempName.equals(packageName)){MyLogger.kLog().i("Package[" + packageName + "]:is installed.");flag = true;break;}}}return flag;}

public abstract List<PackageInfo> getInstalledPackages (int flags)

Since: API Level 1

Return a List of all packages that are installed on the device.

Parameters

flagsAdditional option flags. Use any combination of GET_ACTIVITIES, GET_GIDS, GET_CONFIGURATIONS, GET_INSTRUMENTATION, GET_PERMISSIONS,GET_PROVIDERS, GET_RECEIVERS, GET_SERVICES, GET_SIGNATURES, GET_UNINSTALLED_PACKAGES to modify the data returned.

Returns

• A List of PackageInfo objects, one for each package that is installed on the device. In the unlikely case of there being no installed packages, an empty list is returned. If flag GET_UNINSTALLED_PACKAGES is set, a list of all applications including those deleted with DONT_DELETE_DATA (partially installed apps with data directory) will be returned.

谢谢！