java读取文件显示进度条的实现方法

Java读取文件并显示进度条的实现方法可以分为以下几步：

步骤一：获取文件大小

File file = new File("文件路径");
long fileSize = file.length();

步骤二：读取文件并更新进度条

FileInputStream fileInputStream = new FileInputStream(file);
byte[] buffer = new byte[4096];
int len = -1;
int readSize = 0;
while ((len = fileInputStream.read(buffer)) != -1) {
    // 处理读取的数据
    readSize += len;
    double percent = readSize * 100.0 / fileSize;
    updateProgressBar(percent);
}

步骤三：更新进度条

private void updateProgressBar(double percent) {
    // 更新进度条，示例代码略
}

下面提供两个完整的示例代码。

示例一：Swing界面实现进度条

import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

public class FileProgressBar extends JFrame {
    private JLabel label;
    private JProgressBar progressBar;

    public FileProgressBar(String filePath) throws HeadlessException, FileNotFoundException {
        super("文件读取进度条");
        setSize(400, 100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Container contentPane = getContentPane();

        File file = new File(filePath);
        long fileSize = file.length();

        label = new JLabel("文件读取进度：0%");
        progressBar = new JProgressBar();
        progressBar.setMaximum(100);
        progressBar.setValue(0);

        JPanel panel = new JPanel();
        panel.setLayout(new FlowLayout());
        panel.add(label);
        panel.add(progressBar);

        contentPane.add(panel);

        FileInputStream fileInputStream;
        try {
            fileInputStream = new FileInputStream(file);
        } catch (FileNotFoundException e) {
            throw e;
        }

        byte[] buffer = new byte[4096];
        int len = -1;
        int readSize = 0;
        while ((len = fileInputStream.read(buffer)) != -1) {
            // 处理读取的数据
            readSize += len;
            double percent = readSize * 100.0 / fileSize;
            updateProgressBar(percent);
        }

        fileInputStream.close();
    }

    private void updateProgressBar(double percent) {
        label.setText(String.format("文件读取进度：%.2f%%", percent));
        progressBar.setValue((int) percent);
    }

    public static void main(String[] args) throws FileNotFoundException {
        new FileProgressBar("文件路径").setVisible(true);
    }
}

示例二：JavaFX界面实现进度条

import javafx.application.Application;
import javafx.concurrent.Task;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.ProgressBar;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

import java.io.*;

public class FileProgressBar extends Application {
    private Label label;
    private ProgressBar progressBar;

    @Override
    public void start(Stage primaryStage) throws Exception {
        primaryStage.setTitle("文件读取进度条");

        File file = new File("文件路径");
        long fileSize = file.length();

        label = new Label("文件读取进度：0%");
        progressBar = new ProgressBar();
        progressBar.setProgress(0);

        VBox vBox = new VBox();
        vBox.setPadding(new Insets(20));
        vBox.setSpacing(20);
        vBox.getChildren().addAll(label, progressBar);

        Scene scene = new Scene(vBox, 400, 100);
        primaryStage.setScene(scene);

        Task<Void> readTask = new Task<>() {
            @Override
            protected Void call() throws Exception {
                FileInputStream fileInputStream;
                try {
                    fileInputStream = new FileInputStream(file);
                } catch (FileNotFoundException e) {
                    throw e;
                }

                byte[] buffer = new byte[4096];
                int len = -1;
                int readSize = 0;
                while ((len = fileInputStream.read(buffer)) != -1) {
                    // 处理读取的数据
                    readSize += len;
                    double percent = readSize * 100.0 / fileSize;
                    updateProgress(percent, 100);
                }
                fileInputStream.close();

                return null;
            }

            @Override
            protected void done() {
                label.setText("文件读取完成");
            }
        };

        progressBar.progressProperty().bind(readTask.progressProperty());

        new Thread(readTask).start();

        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}