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FileIO 是一个常用的 QML 扩展组件，用于在 QML 中读写文件。虽然 Qt 没有内置 FileIO 组件，但开发者通常会创建自定义的 FileIO 组件或使用第三方库来实现文件操作功能。

自定义 FileIO 组件基础

基本属性

属性	类型	默认值	说明
source	string	""	要操作的文件路径
text	string	""	文件内容(读写时使用)
status	enumeration	FileIO.Null	当前操作状态
errorString	string	""	错误描述信息

Status 枚举值

值	说明
FileIO.Null	未进行任何操作
FileIO.Ready	准备就绪
FileIO.Reading	正在读取
FileIO.Writing	正在写入
FileIO.Error	发生错误

常用方法

方法	参数	返回值	说明
read()	-	string	读取文件内容
write(text)	text: string	bool	写入内容到文件
append(text)	text: string	bool	追加内容到文件
remove()	-	bool	删除文件
exists()	-	bool	检查文件是否存在
copy(dest)	dest: string	bool	复制文件到目标路径
rename(newName)	newName: string	bool	重命名文件

常用信号

信号	参数	说明
sourceChanged()	-	文件路径改变时触发
textChanged()	-	文件内容改变时触发
statusChanged()	-	操作状态改变时触发
errorOccurred(message)	message: string	发生错误时触发
readCompleted()	-	读取完成时触发
writeCompleted()	-	写入完成时触发

实现示例

C++ 后端实现 (FileIO.h)

cpp

#include <QObject>
#include <QFile>
#include <QTextStream>class FileIO : public QObject {Q_OBJECTQ_PROPERTY(QString source READ source WRITE setSource NOTIFY sourceChanged)Q_PROPERTY(QString text READ text WRITE setText NOTIFY textChanged)Q_PROPERTY(QString errorString READ errorString NOTIFY errorOccurred)public:explicit FileIO(QObject *parent = nullptr);QString source() const;QString text() const;QString errorString() const;Q_INVOKABLE bool read();Q_INVOKABLE bool write();Q_INVOKABLE bool append(const QString& data);Q_INVOKABLE bool remove();Q_INVOKABLE bool exists() const;public slots:void setSource(const QString& source);void setText(const QString& text);signals:void sourceChanged();void textChanged();void errorOccurred(const QString& msg);private:QString m_source;QString m_text;QString m_errorString;
};

C++ 后端实现 (FileIO.cpp)

cpp

#include "FileIO.h"FileIO::FileIO(QObject *parent) : QObject(parent) {}QString FileIO::source() const { return m_source; }
QString FileIO::text() const { return m_text; }
QString FileIO::errorString() const { return m_errorString; }void FileIO::setSource(const QString& source) {if (m_source != source) {m_source = source;emit sourceChanged();}
}void FileIO::setText(const QString& text) {if (m_text != text) {m_text = text;emit textChanged();}
}bool FileIO::read() {if (m_source.isEmpty()) {m_errorString = "Source is empty";emit errorOccurred(m_errorString);return false;}QFile file(m_source);if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {m_errorString = file.errorString();emit errorOccurred(m_errorString);return false;}QTextStream in(&file);setText(in.readAll());file.close();return true;
}bool FileIO::write() {if (m_source.isEmpty()) {m_errorString = "Source is empty";emit errorOccurred(m_errorString);return false;}QFile file(m_source);if (!file.open(QIODevice::WriteOnly | QIODevice::Text)) {m_errorString = file.errorString();emit errorOccurred(m_errorString);return false;}QTextStream out(&file);out << m_text;file.close();return true;
}bool FileIO::append(const QString& data) {if (m_source.isEmpty()) {m_errorString = "Source is empty";emit errorOccurred(m_errorString);return false;}QFile file(m_source);if (!file.open(QIODevice::Append | QIODevice::Text)) {m_errorString = file.errorString();emit errorOccurred(m_errorString);return false;}QTextStream out(&file);out << data;file.close();return true;
}bool FileIO::remove() {if (m_source.isEmpty()) {m_errorString = "Source is empty";emit errorOccurred(m_errorString);return false;}return QFile::remove(m_source);
}bool FileIO::exists() const {if (m_source.isEmpty())return false;return QFile::exists(m_source);
}

QML 使用示例

qml

import QtQuick 2.15
import QtQuick.Controls 2.15
import MyComponents 1.0  // 注册的C++组件Column {spacing: 10FileIO {id: fileIOsource: "test.txt"onErrorOccurred: console.log("Error:", message)onReadCompleted: console.log("Read completed")onWriteCompleted: console.log("Write completed")}TextArea {id: textAreawidth: 300height: 200text: fileIO.textonTextChanged: fileIO.text = text}Row {spacing: 5Button {text: "读取文件"onClicked: fileIO.read()}Button {text: "保存文件"onClicked: fileIO.write()}Button {text: "追加内容"onClicked: fileIO.append("\nAppended text")}Button {text: "删除文件"onClicked: fileIO.remove()}Button {text: "检查存在"onClicked: console.log("文件存在:", fileIO.exists())}}
}

替代方案

如果你不想使用C++扩展，可以使用以下纯QML方案：

纯QML实现 (需要Qt.labs模块)

qml

import QtQuick 2.15
import QtQuick.Controls 2.15
import Qt.labs.platform 1.1 as PlatformItem {function readFile(fileUrl) {var xhr = new XMLHttpRequest()xhr.open("GET", fileUrl, false)xhr.send()return xhr.status === 200 ? xhr.responseText : ""}function writeFile(fileUrl, content) {var xhr = new XMLHttpRequest()xhr.open("PUT", fileUrl, false)xhr.send(content)return xhr.status === 200 || xhr.status === 0}// 使用示例Component.onCompleted: {var content = readFile("file:///path/to/file.txt")console.log(content)writeFile("file:///path/to/file.txt", "New content")}
}

高级用法

异步文件操作

qml

import QtQuick 2.15
import QtQuick.Controls 2.15Item {function asyncReadFile(fileUrl, callback) {var xhr = new XMLHttpRequest()xhr.onreadystatechange = function() {if (xhr.readyState === XMLHttpRequest.DONE) {callback(xhr.status === 200 ? xhr.responseText : null)}}xhr.open("GET", fileUrl)xhr.send()}function asyncWriteFile(fileUrl, content, callback) {var xhr = new XMLHttpRequest()xhr.onreadystatechange = function() {if (xhr.readyState === XMLHttpRequest.DONE) {callback(xhr.status === 200 || xhr.status === 0)}}xhr.open("PUT", fileUrl)xhr.send(content)}// 使用示例Button {text: "异步读取"onClicked: {asyncReadFile("file:///path/to/file.txt", function(content) {if (content !== null) {console.log("读取成功:", content)} else {console.log("读取失败")}})}}
}

文件对话框集成

qml

import QtQuick 2.15
import QtQuick.Controls 2.15
import Qt.labs.platform 1.1Column {spacing: 10FileIO {id: fileIO}TextArea {id: textAreawidth: 400height: 300text: fileIO.text}FileDialog {id: openDialogtitle: "打开文件"folder: StandardPaths.writableLocation(StandardPaths.DocumentsLocation)onAccepted: {fileIO.source = openDialog.filefileIO.read()}}FileDialog {id: saveDialogtitle: "保存文件"folder: StandardPaths.writableLocation(StandardPaths.DocumentsLocation)fileMode: FileDialog.SaveFileonAccepted: {fileIO.source = saveDialog.filefileIO.text = textArea.textfileIO.write()}}Row {spacing: 5Button {text: "打开"onClicked: openDialog.open()}Button {text: "保存"onClicked: saveDialog.open()}}
}

注意：实际使用时，请根据项目需求选择合适的实现方式，并注意文件系统权限问题。