java流

99. ByteArrayOutputStream转化为ByteArrayInputStream

 ByteArrayOutputStream baos = xxx;
 i = new ByteArrayInputStream(baos.toByteArray())

100.将inputstream转换为byte[]

https://blog.youkuaiyun.com/yogima/article/details/128500056

100.1 方式一

直接使用IOUtils

byte[] bytes = IOUtils.toByteArray(inputStream);

<dependency>
       <groupId>commons-io</groupId>
       <artifactId>commons-io</artifactId>
       <version>2.6</version>
</dependency>

100.2 方式二

private static ByteArrayOutputStream cloneInputStream(InputStream input) throws IOException {
        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len;
            while ((len = input.read(buffer)) > -1) {
                baos.write(buffer, 0, len);
            }
            baos.flush();
            return baos;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        } finally {
            input.close();
        }
    }
....
ByteArrayOutputStream baos = cloneInputStream(i);//直接复制流,不要重用,否则需要用reset重置位置,bmp文件还不支持重置会报错
                    // 打开两个新的输入流
baos.toByteArray();  

101.将inputstream转成outputstream

IOUtils.copy(inputStream, outputStream);