Android 4.0 消息广播无法接收的原因

直接上一篇老外的文章：大意是：android 4.0为了防止一些malware（恶意软件）不经用户启动就在后台运行，默认安装的程序在用户启动前是完全被系统忽略的，即使程序注册了广播，系统也不会给该程序传递广播。只有程序被用户运行过之后，消息广播才会生效。而且，即使程序已经运行过了，如果被用户Force Stop（强制停止），又会回到被系统忽略的状态。这个问题其实从3.1的时候就已经有了，最近用4.0的系统测试才发现了这个问题的存在，引起不少麻烦。

Broadcast Regression Confirmed
In a previous post, I cited evidence that the BOOT_COMPLETED broadcast will not work out of the box on Android 3.1 until the user uses your app.
It’s actually somewhat bigger than that.
In the issue that I filed seeking clarification, Ms. Hackborn indicated:
Starting with 3.1 when applications are installed they are in a “stopped” state so they will not be able to run until the user explicitly launches them. Pressing Force Stop will return them to this state.
As a result, when applications are first installed, they are totally ignored by the system until and unless the user manually launches something: clicking on a launcher activity or adding an app widget, most likely.
Developers who had been relying upon getting some sort of system broadcast without user intervention will need to adjust their apps for Android 3.1.
As I wrote in the previous post:
I expect that most apps will be OK. For example, if your boot receiver is there to establish an AlarmManager schedule, you also needed to establish that schedule when the app is first run, so the user does not have to reboot their phone just to set up your alarms. That pattern doesnot change – it’s just that if the user happens to reboot the phone, it will not set up your alarms, until the user runs one of your activities.
UPDATE: To clarify the above quote, once the user runs the app for the first time (and does not Force Stop it), everything behaves as before — a reboot will cause BOOT_COMPLETED broadcasts to be received and so on. However, if the user installs the app, until and unless they run the app manually, no broadcasts will be received. And if the user force-stops the app, until and unless they run the app manually, no broadcasts will be received.
This change is not terribly shocking, as it ratchets up the security another notch by limiting ways malware can run without user knowledge. While it does not offer perfect security — the malware can still install its own copy of an Angry Birds launcher icon and hope users screw up — it is an improvement.