Android通知Notification中通过intent传参问题
1、问题场景：
安卓混合开发应用中，本地服务service接收服务器推送的告警消息，收到告警消息后发送通知Notification，当点击通知栏上的告警消息，需要跳转到前端实现的某个 历史告警信息页面，即在发送通知的pendingIntent中要传递 前端告警页面的url信息。问题出现为每次点击跳转后，intent中的参数url传递过去始终为空：
服务中发送通知：
Intent intent1 = new Intent(mContext, WebViewActivity.class);
Bundle bundle = new Bundle();
bundle.putString("url","http://www.baidu.com");
intent1.putExtras(bundle);
AFLog.d(TAG,"#####notification intent1=" + intent1.toString());
PendingIntent pi = PendingIntent.getActivity(mContext, 0, intent1, 0);
AFLog.d(TAG,"#####notification pi=" + pi.toString());
webview界面中响应通知接收参数的地方：
if (null != intent) {
Bundle data = intent.getExtras();
AFLog.d(TAG, "#####data = "+ (null ==data ? null : data.toString()));
if (null != data){
String url = data.getString("url");
AFLog.d(TAG, "#####url = "+ url);
}
}
测试结果总是data为空：
05-16 14:12:25.231 26313 26313 D WebViewActivity: #####data = null
2、问题分析
刚开始分析问题时总以为是自己代码在某个步骤将intent的传递参数漏掉了，后台在每一处传递都增加了日志显示，并没有问题，而且intent指定的跳转Activity 是能正常找到并启动的，也进入该Acitivity的onCreate 的生命周期，但是就是无法获取参数，百思不得其解。甚至开始将跳转的Activity改成单例模式 ：
android:launchMode="singleTask"
然后在
@Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
AFLog.d(TAG, "#####onNewIntent intent="+ ((null == intent)? null: intent.toString()));
if (null != intent) {
Bundle data = intent.getExtras();
AFLog.d(TAG, "#####data = "+ (null ==data ? null : data.toString()));
if (null != data){
String url = data.getString("url");
AFLog.d(TAG, "#####url = "+ url);
}
}
}
去获取参数，依然为空。我当然也知道这个问题和Activity的 launch mode 方式没有关系，但是人就是如此，当找不到问题的真正原因时，只能够在已有的观念中去怀疑，去尝试，所以有时候会因为自己的无知而怀疑人生。
最终还是通过网络找到了其他人的分析结果，刚开始其实就在查找是不是Notification 的使用问题，但是没有找到正确的方案，真正原因如下所示：
https://www.cnblogs.com/anrainie/articles/2383941.html
还是要对API接口的使用参数进行真正的深入了解，单纯的粘贴复制都是花架子。遇到问题时就是半吊子，一知半解而导致有时候像无头苍蝇一样乱撞，解决问题的效率就大打折扣了。
public @interface Flags {}
/**
* Flag indicating that this PendingIntent can be used only once.
* For use with {@link #getActivity}, {@link #getBroadcast}, and
* {@link #getService}. If set, after
* {@link #send()} is called on it, it will be automatically
* canceled for you and any future attempt to send through it will fail.
*/
public static final int FLAG_ONE_SHOT = 1<<30;
/**
* Flag indicating that if the described PendingIntent does not
* already exist, then simply return null instead of creating it.
* For use with {@link #getActivity}, {@link #getBroadcast}, and
* {@link #getService}.
*/
public static final int FLAG_NO_CREATE = 1<<29;
/**
* Flag indicating that if the described PendingIntent already exists,
* the current one should be canceled before generating a new one.
* For use with {@link #getActivity}, {@link #getBroadcast}, and
* {@link #getService}.
You can use
* this to retrieve a new PendingIntent when you are only changing the
* extra data in the Intent; by canceling the previous pending intent,
* this ensures that only entities given the new data will be able to
* launch it. If this assurance is not an issue, consider
* {@link #FLAG_UPDATE_CURRENT}.
*/
public static final int FLAG_CANCEL_CURRENT = 1<<28;
/**
* Flag indicating that if the described PendingIntent already exists,
* then keep it but replace its extra data with what is in this new
* Intent. For use with {@link #getActivity}, {@link #getBroadcast}, and
* {@link #getService}.
This can be used if you are creating intents where only the
* extras change, and don't care that any entities that received your
* previous PendingIntent will be able to launch it with your new
* extras even if they are not explicitly given to it.
*/
public static final int FLAG_UPDATE_CURRENT = 1<<27;
/**
* Flag indicating that the created PendingIntent should be immutable.
* This means that the additional intent argument passed to the send
* methods to fill in unpopulated properties of this intent will be
* ignored.
*/
public static final int FLAG_IMMUTABLE = 1<<26;
问题的关键就是这个flag参数的使用，改成如下就可以：
PendingIntent pi = PendingIntent.getActivity(mContext, 0, intent1, PendingIntent.FLAG_UPDATE_CURRENT);