如何在 MonkeyRunner 中捕获 SocketExceptions？

Question

在使用 MonkeyRunner 时，我经常会收到如下错误：

120830 18:39:32.755:S [MainThread] [com.android.chimpchat.adb.AdbChimpDevice] Unable to get variable: display.density
120830 18:39:32.755:S [MainThread] [com.android.chimpchat.adb.AdbChimpDevice]java.net.SocketException: Connection reset

根据我的阅读，有时 adb 连接会变坏，您需要重新连接。唯一的问题是，我无法赶上SocketException。我将像这样包装我的代码：

try:
    density = self.device.getProperty('display.density')
except:
    print 'This will never print.'

但显然异常并没有一直引发到调用者。我已经验证 MonkeyRunner/jython 可以按照我期望的方式捕获 Java 异常：

>>> from java.io import FileInputStream
>>> def test_java_exceptions():
...     try:
...         FileInputStream('bad mojo')
...     except:
...         print 'Caught it!'
...
>>> test_java_exceptions()
Caught it!

我该如何处理这些套接字异常？

Answer 1

每次启动 MonkeyRunner 时都会出现该错误，因为脚本停止时设备上的 monkey --port 12345 命令并未停止。这是猴子的错误。

解决此问题的更好方法是在将SIGINT 发送到您的脚本时杀死猴子（当您ctrl+c 时）。换句话说：$ killall com.android.commands.monkey。

快速的方法：

from sys, signal
from com.android.monkeyrunner import MonkeyRunner, MonkeyDevice

device = None

def execute():
    device = MonkeyRunner.waitForConnection()
    # your code

def exitGracefully(self, signum, frame):
    signal.signal(signal.SIGINT, signal.getsignal(signal.SIGINT))
    device.shell('killall com.android.commands.monkey')
    sys.exit(1)

if __name__ == '__main__'
    signal.signal(signal.SIGINT, exitGracefully)
    execute()

编辑： 作为附录，我还找到了一种注意到 Java 错误的方法：Monkey Runner throwing socket exception broken pipe on touuch

Answer 2

以下是我最终使用的解决方法。任何可能遭受 adb 失败的函数只需要使用以下装饰器：

from subprocess import call, PIPE, Popen
from time import sleep

def check_connection(f):
    """
    adb is unstable and cannot be trusted.  When there's a problem, a
    SocketException will be thrown, but caught internally by MonkeyRunner
    and simply logged.  As a hacky solution, this checks if the stderr log 
    grows after f is called (a false positive isn't going to cause any harm).
    If so, the connection will be repaired and the decorated function/method
    will be called again.

    Make sure that stderr is redirected at the command line to the file
    specified by config.STDERR. Also, this decorator will only work for 
    functions/methods that take a Device object as the first argument.
    """
    def wrapper(*args, **kwargs):
        while True:
            cmd = "wc -l %s | awk '{print $1}'" % config.STDERR
            p = Popen(cmd, shell=True, stdout=PIPE)
            (line_count_pre, stderr) = p.communicate()
            line_count_pre = line_count_pre.strip()

            f(*args, **kwargs)

            p = Popen(cmd, shell=True, stdout=PIPE)
            (line_count_post, stderr) = p.communicate()
            line_count_post = line_count_post.strip()

            if line_count_pre == line_count_post:
                # the connection was fine
                break
            print 'Connection error. Restarting adb...'
            sleep(1)
            call('adb kill-server', shell=True)
            call('adb start-server', shell=True)
            args[0].connection = MonkeyRunner.waitForConnection()

    return wrapper

因为这可能会创建一个新连接，所以您需要将当前连接包装在一个 Device 对象中，以便可以对其进行更改。这是我的设备类（大部分类是为了方便，唯一需要的是connection 成员：

class Device:
    def __init__(self):
        self.connection = MonkeyRunner.waitForConnection()
        self.width = int(self.connection.getProperty('display.width'))
        self.height = int(self.connection.getProperty('display.height'))
        self.model = self.connection.getProperty('build.model')

    def touch(self, x, y, press=MonkeyDevice.DOWN_AND_UP):
        self.connection.touch(x, y, press)

如何使用装饰器的示例：

@check_connection
def screenshot(device, filename):
    screen = device.connection.takeSnapshot()
    screen.writeToFile(filename + '.png', 'png')