如何用java绘制.wav音频文件的时域图

要用Java绘制一个.wav音频文件的时域图，可以按照以下步骤进行：

1. 读取.wav文件，获取其中的音频数据。
2. 将音频数据转换为可绘制的格式，比如BufferedImage。
3. 绘制时域图，将转换后的音频数据按照时间序列进行绘制，形成一条连续的波形线。

下面是一个用Java绘制.wav音频文件时域图的示例代码：

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.UnsupportedAudioFileException;

public class WaveformGenerator {
    public static void main(String[] args) {
        // 指定.wav文件路径
        String filePath = "test.wav";
        
        // 读取.wav文件，获取音频数据
        try (AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(new File(filePath))) {
            int bytesPerFrame = audioInputStream.getFormat().getFrameSize();
            int numBytes = (int) (audioInputStream.getFrameLength() * bytesPerFrame);
            byte[] audioBytes = new byte[numBytes];
            int numBytesRead = 0;
            while (numBytesRead < audioBytes.length) {
                int numBytesRemaining = audioBytes.length - numBytesRead;
                int numBytesToRead = audioInputStream.read(audioBytes, numBytesRead, numBytesRemaining);
                if (numBytesToRead == -1) {
                    break;
                }
                numBytesRead += numBytesToRead;
            }
            
            // 将音频数据转换为可绘制的格式
            int width = 1000; // 绘制区域宽度
            int height = 500; // 绘制区域高度
            BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            Graphics g = image.getGraphics();
            g.setColor(Color.WHITE);
            g.fillRect(0, 0, width, height);
            int numSamples = numBytes / bytesPerFrame;
            int samplesPerPixel = numSamples / width;
            int numPixels = numSamples / samplesPerPixel;
            int yCenter = height / 2;
            int oldX = 0, oldY = yCenter;
            g.setColor(Color.BLACK);
            
            // 绘制时域图
            for (int i = 1; i < numPixels; i++) {
                int sum = 0;
                for (int j = 0; j < samplesPerPixel; j++) {
                    int index = (i - 1) * samplesPerPixel + j;
                    int sample = 0;
                    if (bytesPerFrame == 1) {
                        sample = audioBytes[index];
                    } else if (bytesPerFrame == 2) {
                        sample = audioBytes[index * 2] + (audioBytes[index * 2 + 1] << 8);
                    }
                    sum += sample;
                }
                int x = i;
                int y = yCenter + (sum / samplesPerPixel) / 65536;
                g.drawLine(oldX, oldY, x, y);
                oldX = x;
                oldY = y;
            }
            
            // 将绘制结果保存为图片文件
            File outputfile = new File("waveform.png");
            ImageIO.write(image, "png", outputfile);
        } catch (UnsupportedAudioFileException | IOException e) {
            e.printStackTrace();
        }
    }
}

需要注意的是，上述代码只适用于采样精度为8或16位、单声道的.wav文件。如果需要处理其他类型的音频文件，需要对代码进行相应的修改。