我有一个与 Android Wear集成的消息传递应用程序.与环聊类似,在Android Wear智能手表中选择通知时,您可以滑动到显示与所选消息对应的对话的第二张卡.我使用BigTextStyle通知实现它,但我需要知道BigTextStyle支持的最大字符数,这样我就可以在对话太大而无法完全适应时正确修剪对话.我在文档上找不到这个信息.

经过一些调查,max chars大约是5000,至少在Android Wear模拟器中是这样.因此,我可以这样做：

// scroll to the bottom of the notification card
NotificationCompat.WearableExtender extender = new NotificationCompat.WearableExtender().setStartScrollBottom(true);

// get conversation messages in a big single text
CharSequence text = getConversationText();

// trim text to its last 5000 chars
int start = Math.max(0,text.length() - 5000);
text = text.subSequence(start,text.length());

// set text into the big text style
NotificationCompat.BigTextStyle style = new NotificationCompat.BigTextStyle().bigText(text);

// build notification
Notification notification = new NotificationCompat.Builder(context).setStyle(style).extend(extender).build();

有谁知道适合BigTextStyle通知的确切字符数？它是否在不同设备之间变化？

简答
限制为5120个字符(5KB),但您无需限制邮件.这是在构建器上为您完成的.

详细解答

在您的代码中,您使用的是内部使用NotificationCompat.Builder的NotificationCompat.BigTextStyle.

当你调用setBigContentTitle时会发生这种情况

/**
     * Overrides ContentTitle in the big form of the template.
     * This defaults to the value passed to setContentTitle().
     */
    public BigTextStyle setBigContentTitle(CharSequence title) {
        mBigContentTitle = Builder.limitCharSequenceLength(title);
        return this;
    }

功能limitCharSequenceLength执行此操作

protected static CharSequence limitCharSequenceLength(CharSequence cs) {
        if (cs == null) return cs;
        if (cs.length() > MAX_CHARSEQUENCE_LENGTH) {
            cs = cs.subSequence(0,MAX_CHARSEQUENCE_LENGTH);
        }
        return cs;
    }

如果我们检查常量声明,我们发现了这一点

/**
     * Maximum length of CharSequences accepted by Builder and friends.
     *
     * <p>
     * Avoids spamming the system with overly large strings such as full e-mails.
     */
    private static final int MAX_CHARSEQUENCE_LENGTH = 5 * 1024;