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ClipboardService

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1.复制数据到剪切板

public void copyDataToClipBoard(){    ClipBoardManager mgr =  (ClipboardManager)getSystemService(CLIPBOARD_SERVICE);    myClipboard.setPrimaryClip(ClipData.newUri(getContentResolver(),"Note", noteUri);}

ClipData对象可以采取三种形式用于创建数据：

1. Text

newPlainText(label, text)

返回ClipData对象，其单个ClipData.Item对象包含一个文本字符串
2. URI

newUri(resolver, label, URI)

返回ClipData对象，其单ClipData.Item对象包含一个URI
3. Intent

newIntent(label, intent)

返回ClipData对象，其单ClipData.Item对象包含意图

    // 用于获取剪切板制定的数据类型    static public ClipData newUri(ContentResolver resolver, CharSequence label,            Uri uri) {        Item item = new Item(uri);        String[] mimeTypes = null;        // 获取这个Uri所代表的数据类型，先尝试利用ContentResolver 查询，如果查询不到，将mimeTypes设置为        //ClipDescription.MIMETYPE_TEXT_URILIST        if ("content".equals(uri.getScheme())) {            String realType = resolver.getType(uri);            mimeTypes = resolver.getStreamTypes(uri, "*/*");            if (mimeTypes == null) {                if (realType != null) {                    mimeTypes = new String[] { realType, ClipDescription.MIMETYPE_TEXT_URILIST };                }            } else {                String[] tmp = new String[mimeTypes.length + (realType != null ? 2 : 1)];                int i = 0;                if (realType != null) {                    tmp[0] = realType;                    i++;                }                System.arraycopy(mimeTypes, 0, tmp, i, mimeTypes.length);                tmp[i + mimeTypes.length] = ClipDescription.MIMETYPE_TEXT_URILIST;                mimeTypes = tmp;            }        }        if (mimeTypes == null) {            mimeTypes = MIMETYPES_TEXT_URILIST;        }        return new ClipData(label, mimeTypes, item);    }

将数据传递到 ClipManagerService(–>ClipboardManager.java::setPrimaryClip)

    /**     * Sets the current primary clip on the clipboard.  This is the clip that     * is involved in normal cut and paste operations.     *     * @param clip The clipped data item to set.     */    public void setPrimaryClip(ClipData clip) {        try {            if (clip != null) {                clip.prepareToLeaveProcess();            }            getService().setPrimaryClip(clip, mContext.getOpPackageName());        } catch (RemoteException e) {        }    }

ClipboardManagerService 完成实际的功能

public void setPrimaryClip(ClipData clip, String callingPackage) {        synchronized (this) {            // ...            // todo 权限检查，稍后分析            checkDataOwnerLocked(clip, callingUid);            final int userId = UserHandle.getUserId(callingUid);            PerUserClipboard clipboard = getClipboard(userId);            revokeUris(clipboard);            // 保存新的clipData 到 mprimaryClip中，同时向监控剪切板的客户端发送通知            setPrimaryClipInternal(clipboard, clip);        }    }

/** 保存新的clipData 到 mprimaryClip中，同时向监控剪切板的客户端发送通知* 客户端通过addPrimaryClipChanageedListener函数注册回调*/void setPrimaryClipInternal(PerUserClipboard clipboard, ClipData clip) {        clipboard.activePermissionOwners.clear();        if (clip == null && clipboard.primaryClip == null) {            return;        }        clipboard.primaryClip = clip;        final long ident = Binder.clearCallingIdentity();        final int n = clipboard.primaryClipListeners.beginBroadcast();        try {            for (int i = 0; i < n; i++) {                try {                    ListenerInfo li = (ListenerInfo)                            clipboard.primaryClipListeners.getBroadcastCookie(i);                    if (mAppOps.checkOpNoThrow(AppOpsManager.OP_READ_CLIPBOARD, li.mUid,                            li.mPackageName) == AppOpsManager.MODE_ALLOWED) {                        clipboard.primaryClipListeners.getBroadcastItem(i)                                .dispatchPrimaryClipChanged();                    }                } catch (RemoteException e) {                    // The RemoteCallbackList will take care of removing                    // the dead object for us.                }            }        } finally {            clipboard.primaryClipListeners.finishBroadcast();            Binder.restoreCallingIdentity(ident);        }    }

2.从剪切板粘贴数据

public void parseDataFromClipboard(Context context){    ClipBoardManager mgr =  (ClipboardManager)context.getSystemService(CLIPBOARD_SERVICE);    // 这个方法是通过ClipboardManagerService 的getPrimaryClip()方法获取剪切板数据    ClipData clip = clipboard.getPrimaryClip();    ContentResolover cr = getContentResolover();    if(clip != null){        String text = null;        ClipData.Item item = abc.getItemAt(0);        Uri uri = item.getUri();        Cursor orig = cr.query(uri, PROJECTION, null, null, null);        // ... 查询数据库并获取信息        orig.close();        if(text == null){            // 如果paste方不了解clipData中的数据类型，可调用该方法强制得到文本型数据            text = item.coerceToText(context).toString();        }    }}

–> ClipboardManagerService.java::getPrimaryClip()

public ClipData getPrimaryClip(String pkg) {        synchronized (this) {            if (mAppOps.noteOp(AppOpsManager.OP_READ_CLIPBOARD, Binder.getCallingUid(),                    pkg) != AppOpsManager.MODE_ALLOWED) {                return null;            }            // todo 赋予该包相应的权限，稍后分析            addActiveOwnerLocked(Binder.getCallingUid(), pkg);            return getClipboard().primaryClip;        }    }

–> ClipData.java::coerceToText()

 public CharSequence coerceToText(Context context) {            // 如果该item已经有mText，则直接返回            CharSequence text = getText();            if (text != null) {                return text;            }            // 如果是Uri类型数据            Uri uri = getUri();            if (uri != null) {                // ContentProvider 需要实现 openTypedAssetFileDescriptor函数，                // 以返回制定MIME类型的数据源                //                FileInputStream stream = null;                try {                    // Ask for a stream of the desired type.                    AssetFileDescriptor descr = context.getContentResolver()                            .openTypedAssetFileDescriptor(uri, "text/*", null);                    //创建一个输入流                    stream = descr.createInputStream();                    //创建一个InputStreamReader，读出来的数据转换成UTF8的文本                    InputStreamReader reader = new InputStreamReader(stream, "UTF-8");                    // Got it...  copy the stream into a local string and return it.                    StringBuilder builder = new StringBuilder(128);                    char[] buffer = new char[8192];                    int len;                    //从ContentProvider那读取数据，然后转化成utf-8字符串                    while ((len=reader.read(buffer)) > 0) {                        builder.append(buffer, 0, len);                    }                    return builder.toString();                } catch (FileNotFoundException e) {                    // Unable to open content URI as text...  not really an                    // error, just something to ignore.                } catch (IOException e) {                    // Something bad has happened.                    Log.w("ClippedData", "Failure loading text", e);                    return e.toString();                } finally {                    if (stream != null) {                        try {                            stream.close();                        } catch (IOException e) {                        }                    }                }                // If we couldn't open the URI as a stream, then the URI itself                // probably serves fairly well as a textual representation.                return uri.toString();            }            // Finally, if all we have is an Intent, then we can just turn that            // into text.  Not the most user-friendly thing, but it's something.            Intent intent = getIntent();            if (intent != null) {                return intent.toUri(Intent.URI_INTENT_SCHEME);            }            // Shouldn't get here, but just in case...            return "";        }

3.权限检查

Android 系统的权限管理是专门针对URI的，例如我们在应用开发的时候需要往sdcard读写数据，我们需要在AndroidMainfest.xml文件中申请对应的权限，当我们实际进行读取数据时，系统会判断我们是否拥有权限，如果没有则会抛出异常.下面分析一下我们之前没有分析的权限检查.

1. 复制数据时，权限检查函数:

为每一个Item调用checkItemOwnerLocked

–> ClipboardSrvice.java::checkDataOwnerLocked

–> ClipboardSrvice.java::checkItemOwnerLocked

private final void checkItemOwnerLocked(ClipData.Item item, int uid) {        if (item.getUri() != null) {            checkUriOwnerLocked(item.getUri(), uid);        }        Intent intent = item.getIntent();        if (intent != null && intent.getData() != null) {            checkUriOwnerLocked(intent.getData(), uid);        }    }

private final void checkUriOwnerLocked(Uri uri, int uid) {        if (!"content".equals(uri.getScheme())) {            return;        }        long ident = Binder.clearCallingIdentity();        try {            // 调用ActivityManagerService的checkGrantUriPermission函数            // 该函数内博检查copy方是否被赋予 URI_READ权限，如果没有则抛出异常            mAm.checkGrantUriPermission(uid, null, ContentProvider.getUriWithoutUserId(uri),                    Intent.FLAG_GRANT_READ_URI_PERMISSION,                    ContentProvider.getUserIdFromUri(uri, UserHandle.getUserId(uid)));        } catch (RemoteException e) {        } finally {            Binder.restoreCallingIdentity(ident);        }    }

粘贴方权限检查

–>ClipboardService.java::addActiveOwnerLocked

 private final void addActiveOwnerLocked(int uid, String pkg) {        /*调用PackageManagerService的getPackagerInfo函数得到相关信息，         校验PackagerInfo中的uid信息与当前调用的uid是否一致，如果不一致则抛出异常                    */        final IPackageManager pm = AppGlobals.getPackageManager();        final int targetUserHandle = UserHandle.getCallingUserId();        final long oldIdentity = Binder.clearCallingIdentity();        try {            PackageInfo pi = pm.getPackageInfo(pkg, 0, targetUserHandle);            if (pi == null) {                throw new IllegalArgumentException("Unknown package " + pkg);            }            if (!UserHandle.isSameApp(pi.applicationInfo.uid, uid)) {                throw new SecurityException("Calling uid " + uid                        + " does not own package " + pkg);            }        } catch (RemoteException e) {            // Can't happen; the package manager is in the same process        } finally {            Binder.restoreCallingIdentity(oldIdentity);        }        // clipboard.activePermissionOwners用来保存已经通过安全检查的package        PerUserClipboard clipboard = getClipboard();        if (clipboard.primaryClip != null && !clipboard.activePermissionOwners.contains(pkg)) {            final int N = clipboard.primaryClip.getItemCount();            for (int i=0; i<N; i++) {                grantItemLocked(clipboard.primaryClip.getItemAt(i), pkg, UserHandle.getUserId(uid));            }            clipboard.activePermissionOwners.add(pkg);        }    }

 private final void grantItemLocked(ClipData.Item item, String pkg, int userId) {        if (item.getUri() != null) {            grantUriLocked(item.getUri(), pkg, userId);        }        Intent intent = item.getIntent();        if (intent != null && intent.getData() != null) {            grantUriLocked(intent.getData(), pkg, userId);        }    }

private final void grantUriLocked(Uri uri, String pkg, int userId) {        /*            调用ActivityManagerService的grantUriPermissionFromOwner函数，            注意第二个参数传递的是CBS所在的进程的uid,该函数内部也检查权限            调用成功后，pasete就被授予了对应的uri的读权限        */        long ident = Binder.clearCallingIdentity();        try {            int sourceUserId = ContentProvider.getUserIdFromUri(uri, userId);            uri = ContentProvider.getUriWithoutUserId(uri);            mAm.grantUriPermissionFromOwner(mPermissionOwner, Process.myUid(), pkg,                    uri, Intent.FLAG_GRANT_READ_URI_PERMISSION, sourceUserId, userId);        } catch (RemoteException e) {        } finally {            Binder.restoreCallingIdentity(ident);        }    }