手机自动化测试：Appium源码分析之跟踪代码分析五

手机自动化测试：Appium源码分析之跟踪代码分析五

手机自动化测试是未来很重要的测试技术，作为一名测试人员应该熟练掌握，POPTEST举行手机自动化测试的课程，希望可以训练出优秀的手机测试开发工程师。

queue

我们先了解一下事件的集中处理方式，参考文章。从这篇文章可以知道，nodejs提供了一个Async库，该库就是用来处理事件的。里面就有这一个queue。
在上一篇文章我们讲到了initQueue,我们这次再来看看： Android.prototype.initQueue = function () { this.queue = async.queue(function (task, cb) { var action = task.action, params = task.params; this.cbForCurrentCmd = cb; if (this.adb && !this.shuttingDown) { this.uiautomator.sendAction(action, params, function (response) { this.cbForCurrentCmd = null; if (typeof cb === 'function') { this.respond(response, cb); } }.bind(this)); } else { this.cbForCurrentCmd = null; var msg = "Tried to send command to non-existent Android device, " + "maybe it shut down?"; if (this.shuttingDown) { msg = "We're in the middle of shutting down the Android device, " + "so your request won't be executed. Sorry!"; } this.respond({ status: status.codes.UnknownError.code , value: msg }, cb); } }.bind(this), 1);};Async库中queue的定义一般如下所示：var q = async.queue(function(task, callback) { log(‘worker is processing task: ‘, task.name); task.run(callback);}, 1);上面定义了一个工作线程为1的队列。当队列正在处理事件时，其他事件就一直等待。所以当我们使用queue的push方法时，queue会自己唤起然后执行，如果正在执行，push添加进来的事件会等到下一次执行。

uiautomator.sendAction

上面的请求，最终调用的是devices/android/uiautomator的sendAction的方法: UiAutomator.prototype.sendAction = function (action, params, cb) { if (typeof params === "function") { cb = params; params = {}; } var extra = {action: action, params: params}; this.sendCommand('action', extra, cb);};然后转向sendCommand方法

uiautomator.sendCommand

UiAutomator.prototype.sendCommand = function (type, extra, cb) { if (this.cmdCb !== null) { logger.warn("Trying to run a command when one is already in progress. " + "Will spin a bit and try again"); var start = Date.now(); var timeoutMs = 10000; var intMs = 200; var waitForCmdCbNull = function () { if (this.cmdCb === null) { this.sendCommand(type, extra, cb); } else if ((Date.now() - start) < timeoutMs) { setTimeout(waitForCmdCbNull, intMs); } else { cb(new Error("Never became able to push strings since a command " + "was in process")); } }.bind(this); waitForCmdCbNull(); } else if (this.socketClient) { this.resendLastCommand = function () { this.sendCommand(type, extra, cb); }.bind(this); if (typeof extra === "undefined" || extra === null) { extra = {}; } var cmd = {cmd: type}; cmd = _.extend(cmd, extra); var cmdJson = JSON.stringify(cmd) + "\n"; this.cmdCb = cb; var logCmd = cmdJson.trim(); if (logCmd.length > 1000) { logCmd = logCmd.substr(0, 1000) + "..."; } this.debug("Sending command to android: " + logCmd); this.socketClient.write(cmdJson); } else { cb({ status: status.codes.UnknownError.code , value: "Tried to send command to non-existent Android socket, " + "maybe it's shutting down?" }); }};最终会向设备端的socket发送一条命令，关于设备端接受命令以及如何处理，请查看我之前写的关于appium中bootstrap源码分析相关文章