python – 從次要執行緒將stdout和stderr重定向到PyQt4 QTextEdit

首先,1為了實現執行緒不安全,許多堆疊溢位的例子是！

解決方案是使用執行緒安全物件(如Python Queue.Queue)來調解資訊的傳輸.我附下了一些示例程式碼,將stdout重定向到Python Queue.該佇列由QThread讀取,QThread通過Qt的訊號/時隙機制將內容傳送到主執行緒(發出訊號是執行緒安全的).然後,主執行緒將文字寫入文字編輯.

希望這是明確的,如果不是,請隨時問問題！

編輯：請注意,提供的程式碼示例不會很好地清理QThreads,所以當您退出時會收到警告.我會把它留給你擴充套件到你的用例並清理執行緒

import sys
from Queue import Queue
from PyQt4.QtCore import *
from PyQt4.QtGui import *

# The new Stream Object which replaces the default stream associated with sys.stdout
# This object just puts data in a queue!
class WriteStream(object):
def __init__(self,queue):
self.queue = queue

def write(self, text):
self.queue.put(text)

# A QObject (to be run in a QThread) which sits waiting for data to come through a Queue.Queue().
# It blocks until data is available, and one it has got something from the queue, it sends
# it to the "MainThread" by emitting a Qt Signal 
class MyReceiver(QObject):
mysignal = pyqtSignal(str)

def __init__(self,queue,*args,**kwargs):
QObject.__init__(self,*args,**kwargs)
self.queue = queue

@pyqtSlot()
def run(self):
while True:
text = self.queue.get()
self.mysignal.emit(text)

# An example QObject (to be run in a QThread) which outputs information with print
class LongRunningThing(QObject):
@pyqtSlot()
def run(self):
for i in range(1000):
print i

# An Example application QWidget containing the textedit to redirect stdout to
class MyApp(QWidget):
def __init__(self,*args,**kwargs):
QWidget.__init__(self,*args,**kwargs)

self.layout = QVBoxLayout(self)
self.textedit = QTextEdit()
self.button = QPushButton('start long running thread')
self.button.clicked.connect(self.start_thread)
self.layout.addWidget(self.textedit)
self.layout.addWidget(self.button)

@pyqtSlot(str)
def append_text(self,text):
self.textedit.moveCursor(QTextCursor.End)
self.textedit.insertPlainText( text )

@pyqtSlot()
def start_thread(self):
self.thread = QThread()
self.long_running_thing = LongRunningThing()
self.long_running_thing.moveToThread(self.thread)
self.thread.started.connect(self.long_running_thing.run)
self.thread.start()

# Create Queue and redirect sys.stdout to this queue
queue = Queue()
sys.stdout = WriteStream(queue)

# Create QApplication and QWidget
qapp = QApplication(sys.argv)
app = MyApp()
app.show()

# Create thread that will listen on the other end of the queue, and send the text to the textedit in our application
thread = QThread()
my_receiver = MyReceiver(queue)
my_receiver.mysignal.connect(app.append_text)
my_receiver.moveToThread(thread)
thread.started.connect(my_receiver.run)
thread.start()

qapp.exec_()