Qt - 如何将 QProcess 的标准输出重定向到 TextEdit答案

【问题标题】：Qt - How to redirect QProcess' stdout to TextEditQt - 如何将 QProcess 的标准输出重定向到 TextEdit
【发布时间】：2015-12-12 21:32:10
【问题描述】：

我正在尝试使用wget 打印下载网站的过程输出在小部件 (textEdit) 中，但它什么也不打印，但是在终端中它可以工作。

示例

命令：

wget --no-clobber --convert-links --random-wait -r -p -E -e robots=off -U mozilla http://site/path`

输出：

Resolving ******... 54.239.26.173
Connecting to *****|54.239.26.173|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: ‘/index.html’
...

我的代码：

void downloadWebsite::on_pushButton_clicked()
{
    input = ui->lineEdit->text();
    if(input.isEmpty())
    QMessageBox::information(this,"Error","Not an url / webpage !");
    else{
        QProcess *getDownload = new QProcess(this);
        getDownload->setProcessChannelMode(QProcess::MergedChannels); //it prints everything , even errors
        QString command = "wget --no-clobber --convert-links --random-wait -r -p -E -e robots=off -U mozilla " + input;
        getDownload->start("sh",QStringList() << "-c" <<"cd ;"+command);


        QByteArray outputLog = getDownload->readAllStandardOutput();
        getDownload->waitForFinished();
        getDownload->close();

        QString outputToString(outputLog);
        ui->textEdit->setText(outputToString);

    }
}

我做错了什么？

谢谢。

【问题讨论】：

标签： c++ qt stdout qprocess

【解决方案1】：

连接到信号readyReadStandardOutput。更像这样的东西（但未经测试）：

connect(getDownload, SIGNAL(readyReadStandardOutput()), this, SLOT(readOutput()));

当然 connect 应该在开始之前调用。和信号处理程序：

void downloadWebsite::readOutput(){
    while(getDownload->canReadLine()){
       ui->textEdit->setText(getDownload->readLine());
    }
    // somebuffer.append(getDownload->readAllStandardOutput());
}

正如你所见，canReadLine 应该被调用，所以 getDownload 必须可用。

【讨论】：

嗨，它仍然没有打印任何内容。
我设法让它工作，显然问题是我有 getDownload->waitForFinished();和 getDownload->close();。这取消了我的输出。谢谢。

【解决方案2】：

我找到了一些解决方案。（我是 Qt 新手，但希望它会有所帮助）：

mainwindow.h

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

signals:
    void proccessFinished(int exitCode, QProcess::ExitStatus status);

public slots:
    void runCommand();
    void readCommand();
    void stopCommand(int exitCode, QProcess::ExitStatus exitStatus);

//private or public?
private slots:
    void error(QProcess::ProcessError error);
    void stateChanged(QProcess::ProcessState state);

private:
    Ui::MainWindow *ui;
    QProcess *cmd;
};

mainwindow.cpp

include "mainwindow.h"
include "ui_mainwindow.h"
include <QDebug>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    cmd = new QProcess(this);
    cmd->setProcessChannelMode(QProcess::MergedChannels);
    //button click
    connect(ui->btnRun, SIGNAL (clicked()), this, SLOT (runCommand()));
    // process has some data to read
    connect(cmd, SIGNAL (readyRead()), this, SLOT (readCommand()));
    //process finished
    connect(cmd, SIGNAL (finished(int, QProcess::ExitStatus)), this, SLOT (stopCommand(int, QProcess::ExitStatus)));
}

MainWindow::~MainWindow()
{
    delete ui;
    cmd->close(); //? how to do it right?
    delete cmd;
}


void MainWindow::runCommand()
{
    ui->output->append("Run process...");
    cmd->start("ping -n 15 google.com");
    // ??? the best way to continue here???
}

void MainWindow::readCommand(){
    ui->output->append(cmd->readAll()); //output is QTextBrowser
}
void MainWindow::stopCommand(int exitCode, QProcess::ExitStatus exitStatus){
    ui->output->append(cmd->readAll());
    ui->output->append("cmd finished");
    ui->output->append(QString::number(exitCode));
}

void MainWindow::error(QProcess::ProcessError error)
{
       qDebug() <<"Error" << error;
}

void MainWindow::stateChanged(QProcess::ProcessState state)
{
    qDebug() << "Process::stateChanged" << state;
}

【讨论】：