Android 编程技巧之 ----- 解决短信监听 onChange 触发两次的问题

原文出处 : Android短信监听功能(解决onChange触发两次的问题), 作者 : lovelease

前言

项目要做短信验证码自动填充的功能，基本上两种方法：ContentObserver监听数据库、广播；

广播因为要在manifest里面配置接收器之类的 ，怕sdk使用者忘记，索性就选择了监听数据库。

遇到的问题是大部分手机收到一条短信时会触发两次onChange()方法，很多人提出的解决方法是记录smsId,判断如果是旧的就不做处理，是新的就做该做的事。起初这么做了，后来发现有时候自动填充会先填旧的，立马又填新的，会闪一下，虽然只是偶尔出现，但还是觉得不爽，于是抽空又招别的方法，总算找出来了，也是受到一些网友的启发，下面就分享出来，原理我不多说了，代码注释里都讲得很清楚。

package com.jackie.bindmobile;

import android.app.Activity;
import android.database.ContentObserver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Handler;
import android.text.TextUtils;
import android.util.Log;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
* Monitor sms database
*
* @author Jackie
*
*/
public class SmsContent extends ContentObserver {

private static final String TAG = SmsContent.class.getSimpleName();
private static final String MARKER = "YOUR_KEYWORD";
private Cursor cursor = null;
private Activity mActivity;

public SmsContent(Handler handler, Activity activity) {
super(handler);
this.mActivity = activity;
}

/**
* This method is called when a content change occurs.
* <p>
* Subclasses should override this method to handle content changes.
* </p>
*
* @param selfChange True if this is a self-change notification.
*/
@Override
public void onChange(boolean selfChange) {
super.onChange(selfChange);
Log.d(TAG, "onChange(boolean selfChange). selfChange=" + selfChange);
onChange(selfChange, null);
}

/**
* Notice: onChange will be triggered twice on some devices when a sms received,
* eg: samsung s7 edge(API.23) - twice
*     samsung note3(API.18) - once
* 06-15 11:45:48.706 D/SmsContent: onChange(boolean selfChange, Uri uri). selfChange=false, uri=content://sms/raw
* 06-15 11:45:49.466 D/SmsContent: onChange(boolean selfChange, Uri uri). selfChange=false, uri=content://sms/387
*
* Generally onChange will be triggered twice, first time is triggered by uri "content://sms/raw"(sms received,
* but have not written into inbox), second time is triggered by uri "content://sms/387"(number is sms id)
*
* Android official comments:
* This method is called when a content change occurs.
* Includes the changed content Uri when available.
* <p>
* Subclasses should override this method to handle content changes.
* To ensure correct operation on older versions of the framework that
* did not provide a Uri argument, applications should also implement
* the {@link #onChange(boolean)} overload of this method whenever they
* implement the {@link #onChange(boolean, Uri)} overload.
* </p><p>
* Example implementation:
* <pre><code>
* // Implement the onChange(boolean) method to delegate the change notification to
* // the onChange(boolean, Uri) method to ensure correct operation on older versions
* // of the framework that did not have the onChange(boolean, Uri) method.
* {@literal @Override}
* public void onChange(boolean selfChange) {
*     onChange(selfChange, null);
* }
*
* // Implement the onChange(boolean, Uri) method to take advantage of the new Uri argument.
* {@literal @Override}
* public void onChange(boolean selfChange, Uri uri) {
*     // Handle change.
* }
* </code></pre>
* </p>
*
* @param selfChange True if this is a self-change notification.
* @param uri The Uri of the changed content, or null if unknown.
*/
@Override
public void onChange(boolean selfChange, Uri uri) {
Log.d(TAG, "onChange(boolean selfChange, Uri uri). selfChange=" + selfChange + ", uri=" + uri);

/**
* 适配某些较旧的设备，可能只会触发onChange(boolean selfChange)方法，没有传回uri参数，
* 此时只能通过"content://sms/inbox"来查询短信
*/
if (uri == null) {
uri = Uri.parse("content://sms/inbox");
}
/**
* 06-15 11:45:48.706 D/SmsContent: onChange(boolean selfChange, Uri uri). selfChange=false, uri=content://sms/raw
* 06-15 11:45:49.466 D/SmsContent: onChange(boolean selfChange, Uri uri). selfChange=false, uri=content://sms/387
*
* Generally onChange will be triggered twice, first time is triggered by uri "content://sms/raw"(sms received,
* but have not written into inbox), second time is triggered by uri "content://sms/387"(number is sms id)
*/
if (uri.toString().equals("content://sms/raw")) {
return;
}
cursor = this.mActivity.getContentResolver().query(uri, null, null, null, null);
if (cursor != null) {
if (cursor.moveToFirst()) {
int id = cursor.getInt(cursor.getColumnIndex("_id"));
String body = cursor.getString(cursor.getColumnIndex("body"));
Log.d(TAG, "sms id: " + id + "\nsms body: " + body);
cursor.close();

// Already got sms body, do anything you want, for example: filter the verify code
getVerifyCode(body);
}
}
else {
Log.e(TAG, "error: cursor == null");
}
}

/**
* Register a monitor of changing of sms
*/
public void register() {
Log.d(TAG, "Register sms monitor");
this.mActivity.getContentResolver().registerContentObserver(
Uri.parse("content://sms/"), true, this);
}

/**
* Unregister the monitor of changing of sms
*/
public void unRegister() {
Log.d(TAG, "Unregister sms monitor");
this.mActivity.getContentResolver().unregisterContentObserver(this);
}

/**
* Get verify code from sms body
* @param str
* @return
*/
public String getVerifyCode(String str) {
String verifyCode = null;
if (smsContentFilter(str)) {
Log.d(TAG, "sms content matched, auto-fill verify code.");
verifyCode = getDynamicPassword(str);
}
else {
// Do nothing
Log.d(TAG, "sms content did not match, do nothing.");
}
return verifyCode;
}

/**
* Check if str is verification-code-formatted
*
* @param str
* @return
*/
private boolean smsContentFilter(String str) {
Log.d(TAG, "smsContentFilter. smsBody = " + str);
boolean isMatched = false;
if (!TextUtils.isEmpty(str)) {
// Check if str contains keyword
if (str.contains(MARKER)) {
Log.d(TAG, "This sms contains \"" + MARKER + "\"");
// Check if str contains continuous 6 numbers
Pattern  continuousNumberPattern = Pattern.compile("[0-9\\.]+");
Matcher m = continuousNumberPattern.matcher(str);
while(m.find()){
if(m.group().length() == 6) {
Log.d(TAG, "This sms contains continuous 6 numbers : " + m.group());
isMatched = true;
}
}
}
}
return isMatched;
}

/**
* Cut the continuous 6 numbers from str
*
* @param str sms content
* @return verification code
*/
private String getDynamicPassword(String str) {
Log.d(TAG, "getDynamicPassword. smsBody = " + str);
Pattern  continuousNumberPattern = Pattern.compile("[0-9\\.]+");
Matcher m = continuousNumberPattern.matcher(str);
String dynamicPassword = "";
while(m.find()){
if(m.group().length() == 6) {
Log.d(TAG, m.group());
dynamicPassword = m.group();
}
}

Log.d(TAG, "Verification code: " + dynamicPassword);
return dynamicPassword;
}
}

用法很简单，注册和注销一下就行：

package com.jackie.bindmobile;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;

public class BindMobileActivity extends Activity {

private static final String TAG = BindMobileActivity.class.getSimpleName();
private SmsContent smsContent;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

// Register sms monitor
smsContent = new SmsContent(new Handler(), mActivity);
smsContent.register();
}

@Override
protected void onDestroy() {
super.onDestroy();
// Unregister sms monitor
smsContent.unRegister();
}
}

结语

本文提供了解决短信监听时常见的 onChange 回调函数触发两次问题的方法, 暂且先不论代码中有可能造成内存泄漏的风险 (Activity 引用传递), 但解决问题的思想是很好的.