Android源码分析-PackageManagerService（PMS）源码分析（三）- queryIntentActivities函数来查找activity

快来打我* 2023-10-16 18:38 15阅读 0赞

#### queryIntentActivities函数的作用： ####

在Android应用程序开发中，用startActivity可以开启另外一个Activity或应用。startActivity函数必须包含Intent参数，这个参数用来指定具体要打开的组件。

例如，

>   
> startActivity(new Intent(this,MyActivity.class));

那么，Android系统是如何进行Intent的匹配的呢？答案主要在PackageManagerService（PMS）的queryIntentActivities函数中。本节来分析queryIntentActivities相关源代码。

#### queryIntentActivities源码分析： ####

在启动一个activity时，会通过调用queryIntentActivities来获取activity，例如：

List<ResolveInfo> results = queryIntentActivities(intent, resolvedType, flags
                    | PackageManager.GET_RESOLVED_FILTER, userId);

相关的数据结构：

>     ActivityInfo mResolveActivity： 保存Activity相关的信息。例如启动模式，权限......等；
>     
>     ApplicationInfo mAndroidApplication： 应用程序信息；
>     
>     final ResolveInfo mResolveInfo = new ResolveInfo();
>     
>     ComponentName mResolveComponentName： Component组件
>     
>     PackageParser.Package mPlatformPackage; package

#### queryIntentActivities函数的源代码： ####

queryIntentActivities函数的代码位置：

> frameworks/base/services/java/com/android/server/pm/

#### 源代码： ####

@Override
        public List<ResolveInfo> queryIntentActivities(Intent intent,
                String resolvedType, int flags, int userId) {
            if (!sUserManager.exists(userId)) return null;
            ComponentName comp = intent.getComponent();
            if (comp == null) {
                if (intent.getSelector() != null) {
                    intent = intent.getSelector(); 
                    comp = intent.getComponent();
                }
            }
    
            if (comp != null) {
                final List<ResolveInfo> list = new ArrayList<ResolveInfo>(1);
                final ActivityInfo ai = getActivityInfo(comp, flags, userId);
                if (ai != null) {
                    final ResolveInfo ri = new ResolveInfo();
                    ri.activityInfo = ai;
                    list.add(ri);
                }
                return list;
            }
    
            // reader
            synchronized (mPackages) {
                final String pkgName = intent.getPackage();
                if (pkgName == null) {
                    return mActivities.queryIntent(intent, resolvedType, flags, userId);
                }
                final PackageParser.Package pkg = mPackages.get(pkgName);
                if (pkg != null) {
                    return mActivities.queryIntentForPackage(intent, resolvedType, flags,
                            pkg.activities, userId);
                }
                return new ArrayList<ResolveInfo>();
            }
        }

**分析：**

> 1. 获取Component组件实例；
> 
> 2. comp！=null: 即intent精确匹配，这种情况下，会跳转到具体的activity；
> 
> 3. 通过调用getActivityInfo来获取ActivityInfo实例；
> 
> 在getActivityInfo中，再通过调用mActivitys数据成员来获取component对应的activity，代码如下：
> 
>     @Override
>         public ActivityInfo getActivityInfo(ComponentName component, int flags, int userId) {
>             if (!sUserManager.exists(userId)) return null;
>             synchronized (mPackages) {
>                 PackageParser.Activity a = mActivities.mActivities.get(component);
>     
>                 if (DEBUG_PACKAGE_INFO) Log.v(TAG, "getActivityInfo " + component + ": " + a);
>                 if (a != null && mSettings.isEnabledLPr(a.info, flags, userId)) {
>                     PackageSetting ps = mSettings.mPackages.get(component.getPackageName());
>                     if (ps == null) return null;
>                     return PackageParser.generateActivityInfo(a, flags, ps.getStopped(userId),
>                             ps.getEnabled(userId), userId);
>                 }
>                 if (mResolveComponentName.equals(component)) {
>                     return mResolveActivity;
>                 }
>             }
>             return null;
>         }

另外，还可以参考如下博文：

[Android源码分析-PackageManagerService（PMS）源码分析（一）PMS的初始化以及PackageManager的使用][Android_-PackageManagerService_PMS_PMS_PackageManager]

[Android源码分析-PackageManagerService（PMS）源码分析（二）- 利用PackageParser进行package的解析][Android_-PackageManagerService_PMS_- _PackageParser_package]

[Android_-PackageManagerService_PMS_PMS_PackageManager]: https://blog.csdn.net/liranke/article/details/13295141
[Android_-PackageManagerService_PMS_- _PackageParser_package]: https://blog.csdn.net/liranke/article/details/13510821