原文地址：http://www.it165.net/pro/html/201407/17696.html

bootstrap结构

如图所示为bootstrap的项目结构

view sourceprint? 01.packageio.appium.android.bootstrap; 02. 03.importio.appium.android.bootstrap.exceptions.SocketServerException; 04. 05.importcom.android.uiautomator.testrunner.UiAutomatorTestCase; 06. 07./** 08.* The Bootstrap class runs the socket server. uiautomator开发的脚本，可以直接在pc端启动 09.*/ 10.publicclassBootstrapextendsUiAutomatorTestCase { 11. 12.publicvoidtestRunServer() { 13.SocketServer server; 14.try{ 15.// 启动socket服务器，监听4724端口。 16.server =newSocketServer(4724); 17.server.listenForever(); 18.}catch(finalSocketServerException e) { 19.Logger.error(e.getError()); 20.System.exit(1); 21.} 22. 23.} 24.}
该类继承自UiAutomatorTestCase。所以它才能通过adb shell uiautomator runtest AppiumBootstrap.jar -c io.appium.android.bootstrap.Bootstrap被执行。

该类很简单，就是启动线程，监听4724端口，该端口与appium通信。

然后走server.listenForever()方法。

SocketServer.java

view sourceprint? 01./** 02.* Listens on the socket for data, and calls {@link #handleClientData()} when 03.* it's available. 04.* 05.* @throws SocketServerException 06.*/ 07.publicvoidlistenForever()throwsSocketServerException { 08.Logger.debug("Appium Socket Server Ready"); 09.//读取strings.json文件的数据 10.UpdateStrings.loadStringsJson(); 11.// 注册两种监听器：AND和Crash 12.dismissCrashAlerts(); 13.finalTimerTask updateWatchers =newTimerTask() { 14.@Override 15.publicvoidrun() { 16.try{ 17.// 检查系统是否有异常 18.watchers.check(); 19.}catch(finalException e) { 20.} 21.} 22.}; 23.// 计时器，0.1秒后开始，每隔0.1秒执行一次。 24.timer.scheduleAtFixedRate(updateWatchers,100,100); 25. 26.try{ 27.client = server.accept(); 28.Logger.debug("Client connected"); 29.in =newBufferedReader(newInputStreamReader(client.getInputStream(), 30."UTF-8")); 31.out =newBufferedWriter(newOutputStreamWriter(client.getOutputStream(), 32."UTF-8")); 33.while(keepListening) { 34.// 获取客户端数据 35.handleClientData(); 36.} 37.in.close(); 38.out.close(); 39.client.close(); 40.Logger.debug("Closed client connection"); 41.}catch(finalIOException e) { 42.thrownewSocketServerException("Error when client was trying to connect"); 43.} 44.}

该方法中首先调用UpdateStrings.loadStringsJson();该方法如下:

UpdateStrings

view sourceprint? 01./** 02.* strings.json文件保存的是apk的strings.xml里的内容，在Bootstrap启动前由appium服务器解析并push到设备端的 03.* 04.* @return 05.*/ 06.publicstaticbooleanloadStringsJson() { 07.Logger.debug("Loading json..."); 08.try{ 09.finalString filePath ="/data/local/tmp/strings.json"; 10.finalFile jsonFile =newFile(filePath); 11.// json will not exist for apks that are only on device 12.// 你的case必须写明apk的路径，如果启动设备上已有的应用而case中没有app路径，此时json文件是不存在的 13.// because the node server can't extract the json from the apk. 14.if(!jsonFile.exists()) { 15.returnfalse; 16.} 17.finalDataInputStream dataInput =newDataInputStream( 18.newFileInputStream(jsonFile)); 19.finalbyte[] jsonBytes =newbyte[(int) jsonFile.length()]; 20.dataInput.readFully(jsonBytes); 21.// this closes FileInputStream 22.dataInput.close(); 23.finalString jsonString =newString(jsonBytes,"UTF-8"); 24.// 将读取出来的信息赋给Find类中的属性，以做后用 25.Find.apkStrings =newJSONObject(jsonString); 26.Logger.debug("json loading complete."); 27.}catch(finalException e) { 28.Logger.error("Error loading json: "+ e.getMessage()); 29.returnfalse; 30.} 31.returntrue; 32.}
然后回到ServerSocket类的listenForever()，此时执行到dismissCrashAlerts();该方法作用是注册一些监听器，观察是否有糖出口或者AND和crash的异常。

view sourceprint? 1.publicvoiddismissCrashAlerts() { 2.try{ 3.newUiWatchers().registerAnrAndCrashWatchers(); 4.Logger.debug("Registered crash watchers."); 5.}catch(finalException e) { 6.Logger.debug("Unable to register crash watchers."); 7.} 8.}
此时listenForever()方法里执行到注册心跳程序，每隔0.1秒开始执行一遍上面注册的监听器来检查系统是否存在异常。

view sourceprint? 01.finalTimerTask updateWatchers =newTimerTask() { 02.@Override 03.publicvoidrun() { 04.try{ 05.// 检查系统是否有异常 06.watchers.check(); 07.}catch(finalException e) { 08.} 09.} 10.}; 11.// 计时器，0.1秒后开始，每隔0.1秒执行一次。 12.timer.scheduleAtFixedRate(updateWatchers,100,100);
然后启动数据通道，接受客户端发来的数据和返回结果给客户端。

view sourceprint? 1.client = server.accept(); 2.Logger.debug("Client connected"); 3.in =newBufferedReader(newInputStreamReader(client.getInputStream(), 4."UTF-8")); 5.out =newBufferedWriter(newOutputStreamWriter(client.getOutputStream(), 6."UTF-8"));
接下来就是最重要的方法handleClientData();到此listenForever()方法的主要作用就完成了。现在来看handleClientData()方法做了啥。

view sourceprint? 01./** 02.* When data is available on the socket, this method is called to run the 03.* command or throw an error if it can't. 04.* 05.* @throws SocketServerException 06.*/ 07.privatevoidhandleClientData()throwsSocketServerException { 08.try{ 09.input.setLength(0);// clear 10. 11.String res; 12.inta; 13.// (char) -1 is not equal to -1. 14.// ready is checked to ensure the read call doesn't block. 15.while((a = in.read()) != -1&& in.ready()) { 16.input.append((char) a); 17.} 18.finalString inputString = input.toString(); 19.Logger.debug("Got data from client: "+ inputString); 20.try{ 21.final<a href="http://www.it165.net/pro/ydad/"target="_blank"class="keylink">Android</a>Command cmd = getCommand(inputString); 22.Logger.debug("Got command of type "+ cmd.commandType().toString()); 23.res = runCommand(cmd); 24.Logger.debug("Returning result: "+ res); 25.}catch(finalCommandTypeException e) { 26.res =new<a href="http://www.it165.net/pro/ydad/"target="_blank"class="keylink">Android</a>CommandResult(WDStatus.UNKNOWN_ERROR, e.getMessage()) 27..toString(); 28.}catch(finalJSONException e) { 29.res =newAndroidCommandResult(WDStatus.UNKNOWN_ERROR, 30."Error running and parsing command").toString(); 31.} 32.out.write(res); 33.out.flush(); 34.}catch(finalIOException e) { 35.thrownewSocketServerException("Error processing data to/from socket (" 36.+ e.toString() +")"); 37.} 38.}

该方法中读取客户端发来的数据，利用getCommand()方法获得AndroidCommand对象，然后执行runCommand()方法，获取直接的结果。那么该方法的作用就转移到了runCommand()。所以现在就来看runCommand()方法是啥意思啦。

view sourceprint? 01./** 02.* When {@link #handleClientData()} has valid data, this method delegates the 03.* command. 04.* 05.* @param cmd 06.* AndroidCommand 07.* @return Result 08.*/ 09.privateString runCommand(finalAndroidCommand cmd) { 10.AndroidCommandResult res; 11.if(cmd.commandType() == AndroidCommandType.SHUTDOWN) { 12.keepListening =false; 13.res =newAndroidCommandResult(WDStatus.SUCCESS,"OK, shutting down"); 14.}elseif(cmd.commandType() == AndroidCommandType.ACTION) { 15.try{ 16.res = executor.execute(cmd); 17.}catch(finalException e) { 18.res =newAndroidCommandResult(WDStatus.UNKNOWN_ERROR, e.getMessage()); 19.} 20.}else{ 21.// this code should never be executed, here for future-proofing 22.res =newAndroidCommandResult(WDStatus.UNKNOWN_ERROR, 23."Unknown command type, could not execute!"); 24.} 25.returnres.toString(); 26.} 27.}
该方法首先做了判断，判断命令数据哪种类型，主要有关机命令和动作命令，我们主要关注动作命令，因为动作有很多种。所以来关注第一个else if中的AndroidCommandExecutor.execute()方法。主线又转移到了该方法中了，切去瞅一眼。

AndroidCommandExecutor.java

view sourceprint? 01./** 02.* Gets the handler out of the map, and executes the command. 03.* 04.* @param command 05.* The {@link AndroidCommand} 06.* @return {@link AndroidCommandResult} 07.*/ 08.publicAndroidCommandResult execute(finalAndroidCommand command) { 09.try{ 10.Logger.debug("Got command action: "+ command.action()); 11. 12.if(map.containsKey(command.action())) { 13.returnmap.get(command.action()).execute(command); 14.}else{ 15.returnnewAndroidCommandResult(WDStatus.UNKNOWN_COMMAND, 16."Unknown command: "+ command.action()); 17.} 18.}catch(finalJSONException e) { 19.Logger.error("Could not decode action/params of command"); 20.returnnewAndroidCommandResult(WDStatus.JSON_DECODER_ERROR, 21."Could not decode action/params of command, please check format!"); 22.} 23.}
该方法中终于要执行命令的实体啦

view sourceprint? 1.if(map.containsKey(command.action())) { 2.returnmap.get(command.action()).execute(command); 3.}else{ 4.returnnewAndroidCommandResult(WDStatus.UNKNOWN_COMMAND, 5."Unknown command: "+ command.action()); 6.}

关键是上面这几行代码，调用了map.get(command.action()).execute(command).看来要想弄懂这个命令的意思，肯定得知道map里存放的对象是哪些，那么在该类中找到map的初始化代码:

view sourceprint? 01.static{ 02.map.put("waitForIdle",newWaitForIdle()); 03.map.put("clear",newClear()); 04.map.put("orientation",newOrientation()); 05.map.put("swipe",newSwipe()); 06.map.put("flick",newFlick()); 07.map.put("drag",newDrag()); 08.map.put("pinch",newPinch()); 09.map.put("click",newClick()); 10.map.put("touchLongClick",newTouchLongClick()); 11.map.put("touchDown",newTouchDown()); 12.map.put("touchUp",newTouchUp()); 13.map.put("touchMove",newTouchMove()); 14.map.put("getText",newGetText()); 15.map.put("setText",newSetText()); 16.map.put("getName",newGetName()); 17.map.put("getAttribute",newGetAttribute()); 18.map.put("getDeviceSize",newGetDeviceSize()); 19.map.put("scrollTo",newScrollTo()); 20.map.put("find",newFind()); 21.map.put("getLocation",newGetLocation()); 22.map.put("getSize",newGetSize()); 23.map.put("wake",newWake()); 24.map.put("pressBack",newPressBack()); 25.map.put("dumpWindowHierarchy",newDumpWindowHierarchy()); 26.map.put("pressKeyCode",newPressKeyCode()); 27.map.put("longPressKeyCode",newLongPressKeyCode()); 28.map.put("takeScreenshot",newTakeScreenshot()); 29.map.put("updateStrings",newUpdateStrings()); 30.map.put("getDataDir",newGetDataDir()); 31.map.put("performMultiPointerGesture",newMultiPointerGesture()); 32.map.put("openNotification",newOpenNotification()); 33.}
豁然开朗，该map是<String,CommandHandler>形式的map。value值对应的都是一个个的对象，这些对象都继承与CommandHandler，里面都有execute方法，该方法就是根据命令的不同调用不同的对象来执行相关代码获取结果。从map的定义可以看出，appium可以操作手机的命令还不少，我用过的有scrollTo,updateStrings,getDataDir等，上面还有截图、打开通知栏、按下等还没用过，但通过这些命令你也可以了解appium可以做哪些事。

继承CommandHandler的对象有很多，我挑一个来讲讲它具体是干嘛的，其他的我以后会挨个讲,就挑click吧。

加入现在传过来的命令后缀是click的话，那么它会调用Click对象的execute方法。

Click.java

view sourceprint? 01.packageio.appium.android.bootstrap.handler; 02. 03.importcom.android.uiautomator.core.UiDevice; 04.importcom.android.uiautomator.core.UiObjectNotFoundException; 05.importio.appium.android.bootstrap.*; 06.importorg.json.JSONException; 07. 08.importjava.util.ArrayList; 09.importjava.util.Hashtable; 10. 11./** 12.* This handler is used to click elements in the Android UI. 13.* 14.* Based on the element Id, click that element. 15.* 16.*/ 17.publicclassClickextendsCommandHandler { 18. 19./* 20.* @param command The {@link AndroidCommand} 21.* 22.* @return {@link AndroidCommandResult} 23.* 24.* @throws JSONException 25.* 26.* @see io.appium.android.bootstrap.CommandHandler#execute(io.appium.android. 27.* bootstrap.AndroidCommand) 28.*/ 29.@Override 30.publicAndroidCommandResult execute(finalAndroidCommand command) 31.throwsJSONException { 32.if(command.isElementCommand()) { 33.try{ 34.finalAndroidElement el = command.getElement(); 35.el.click(); 36.returngetSucce***esult(true); 37.}catch(finalUiObjectNotFoundException e) { 38.returnnewAndroidCommandResult(WDStatus.NO_SUCH_ELEMENT, 39.e.getMessage()); 40.}catch(finalException e) {// handle NullPointerException 41.returngetErrorResult("Unknown error"); 42.} 43.}else{ 44.finalHashtable<String, Object> params = command.params(); 45.finalDouble[] coords = { Double.parseDouble(params.get("x").toString()), 46.Double.parseDouble(params.get("y").toString()) }; 47.finalArrayList<Integer> posVals = absPosFromCoords(coords); 48.finalbooleanres = UiDevice.getInstance().click(posVals.get(0), 49.posVals.get(1)); 50.returngetSucce***esult(res); 51.} 52.} 53.}
该类就一个execute方法这根独苗，execute方法中会先判断传入的参数对象是坐标值还是元素值，如果是元素值那么直接调用AndroidElement中的click方法，一会我们再去看这个方法。如果是坐标的话，它会干什么呢。它会调用UiDevice的click方法，用过UiAutomator的人都知道它是uiautomator包中的类。所以说appium在api16以上的机器上使用的uiautomator机制。貌似有人觉得这好像easy了点。那好吧，我们再分析一个touchDown命令，如果传过来的命令后缀是touchDown，那么它会调用TouchDown对象的execute方法。

view sourceprint? 1.map.put("touchDown",newTouchDown());

这个类里面的execute方法就有点意思啦。

TouchDown.java

view sourceprint? 01.packageio.appium.android.bootstrap.handler; 02. 03.importcom.android.uiautomator.common.ReflectionUtils; 04.importcom.android.uiautomator.core.UiObjectNotFoundException; 05.importio.appium.android.bootstrap.Logger; 06. 07.importjava.lang.reflect.Method; 08. 09./** 10.* This handler is used to perform a touchDown event on an element in the 11.* Android UI. 12.* 13.*/ 14.publicclassTouchDownextendsTouchEvent { 15. 16.@Override 17.protectedbooleanexecuteTouchEvent()throwsUiObjectNotFoundException { 18.printEventDebugLine("TouchDown"); 19.try{ 20.finalReflectionUtils utils =newReflectionUtils(); 21.finalMethod touchDown = utils.getControllerMethod("touchDown",int.class, 22.int.class); 23.return(Boolean) touchDown.invoke(utils.getController(), clickX, clickY); 24.}catch(finalException e) { 25.Logger.debug("Problem invoking touchDown: "+ e); 26.returnfalse; 27.} 28.} 29.}
该方法里用到了反射，调用uiautomator里的隐藏api来执行按下操作。就不具体讲了，后面会挨个说一遍的。

总结

说了这么多废话，尝试着用流程图描述一遍吧。