Java中Byte数组与InputStream相互转换实现方式

byte[] byteArray = {72, 101, 108, 108, 111}; // "Hello"的ASCII码
InputStream inputStream = new ByteArrayInputStream(byteArray);

import org.apache.commons.io.input.ClosedInputStream;
import org.apache.commons.io.IOUtils;
byte[] byteArray = {72, 101, 108, 108, 111};
InputStream inputStream = IOUtils.toInputStream(new String(byteArray), "UTF-8");

public static byte[] inputStreamToByteArray(InputStream inputStream) throws IOException {
    ByteArrayOutputStream buffer = new ByteArrayOutputStream();
    int nRead;
    byte[] data = new byte[1024];
    while ((nRead = inputStream.read(data, 0, data.length)) != -1) {
        buffer.write(data, 0, nRead);
    }
    buffer.flush();
    return buffer.toByteArray();
}

// Java 9及以上版本
byte[] byteArray = inputStream.readAllBytes();

import org.apache.commons.io.IOUtils;
byte[] byteArray = IOUtils.toByteArray(inputStream);

import java.io.*;
import org.apache.commons.io.IOUtils;
public class ByteArrayInputStreamConversion {
    public static void main(String[] args) {
        try {
            // 原始数据
            String text = "Hello, World!";
            byte[] originalBytes = text.getBytes("UTF-8");
            // 1. byte[] 转 InputStream
            System.out.println("\n1. byte[] 转 InputStream:");
            InputStream inputStream1 = new ByteArrayInputStream(originalBytes);
            // 使用流读取数据
            int content;
            while ((content = inputStream1.read()) != -1) {
                System.out.print((char) content);
            }
            inputStream1.close();
            // 2. InputStream 转 byte[]
            System.out.println("\n\n2. InputStream 转 byte[]:");
            InputStream inputStream2 = new ByteArrayInputStream(originalBytes);
            // 方法1: 使用ByteArrayOutputStream
            byte[] bytes1 = inputStreamToByteArray(inputStream2);
            System.out.println("方法1结果: " + new String(bytes1, "UTF-8"));
            inputStream2.close();
            // 方法2: 使用Java 9+的readAllBytes()
            InputStream inputStream3 = new ByteArrayInputStream(originalBytes);
            byte[] bytes2 = inputStream3.readAllBytes();
            System.out.println("方法2结果: " + new String(bytes2, "UTF-8"));
            inputStream3.close();
            // 方法3: 使用Apache Commons IO
            InputStream inputStream4 = new ByteArrayInputStream(originalBytes);
            byte[] bytes3 = IOUtils.toByteArray(inputStream4);
            System.out.println("方法3结果: " + new String(bytes3, "UTF-8"));
            inputStream4.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static byte[] inputStreamToByteArray(InputStream inputStream) throws IOException {
        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        int nRead;
        byte[] data = new byte[1024];
        while ((nRead = inputStream.read(data, 0, data.length)) != -1) {
            buffer.write(data, 0, nRead);
        }
        buffer.flush();
        return buffer.toByteArray();
    }
}

// 处理大文件的InputStream
public static void processLargeInputStream(InputStream inputStream) throws IOException {
    byte[] buffer = new byte[8192]; // 8KB缓冲区
    int bytesRead;
    while ((bytesRead = inputStream.read(buffer)) != -1) {
        // 处理读取到的数据
        processChunk(buffer, bytesRead);
    }
}
private static void processChunk(byte[] buffer, int length) {
    // 处理数据块的逻辑
}