【Java】byte数组与流的相互转换

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Java 中 字节流与Inputstream的互相转换

1. File/FileInputStream → byte[]

File -> FileInputStream -> new byte[input.available] -> InputStream.read()

File file = new File("file.txt");
InputStream input = new FileInputStream(file);
byte[] bytes = new byte[input.available()];
input.read(bytes);

2. byte[] → InputStream

new ByteArrayInputStream(bytes);

byte[] bytes = new byte[1024];
InputStream input = new ByteArrayInputStream(bytes);

3. byte[] → File

File -> OutputStram -> BufferedOutputStream -> bufferedOutput.write(bytes);

// bytes = ..... 或 传入一个byte[]
File file = new File('');
OutputStream output = new FileOutputStream(file);
BufferedOutputStream bufferedOutput = new BufferedOutputStream(output);
bufferedOutput.write(bytes);

4. InputStream → OutputStream

使用缓存循环读取InputStream，适用于一些无法直接获取InputStream.available()的场景。

public static byte[] getStreamBytes(InputStream is) throws Exception {  ByteArrayOutputStream baos = new ByteArrayOutputStream();  byte[] buffer = new byte[1024];  int len = 0;  while ((len = is.read(buffer)) != -1) {  baos.write(buffer, 0, len);  }  byte[] b = baos.toByteArray();  is.close();  baos.close();  return b;  
}

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