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. 
     * 
 
     * Subclasses should override this method to handle content changes. 
     * 
 
     * 
     * @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. 
     * 
 
     * 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. 
     * 
 
     * Example implementation: 
     * 
 
     * // 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. 
     * } 
     * 
 
     * 
 
     * 
     * @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.