ServletOutputStream 如何转 InputStream

如果您想将 `ServletOutputStream` 转换为 `InputStream`，可以使用 `PipedInputStream` 和 `PipedOutputStream` 来实现。

1. 创建 `PipedInputStream` 和 `PipedOutputStream` 对象：

PipedOutputStream pipedOutputStream = new PipedOutputStream();
PipedInputStream pipedInputStream = new PipedInputStream(pipedOutputStream);

2. 在 `ServletOutputStream` 中写入数据，并将数据通过 `PipedOutputStream` 写入 `PipedInputStream`：

ServletOutputStream servletOutputStream = response.getOutputStream();
byte[] data = "Hello World".getBytes();
servletOutputStream.write(data);
servletOutputStream.flush();
servletOutputStream.close();
pipedOutputStream.write(data);
pipedOutputStream.flush();
pipedOutputStream.close();

3. 最后，您可以从 `PipedInputStream` 中读取数据：

int length = 0;
byte[] buffer = new byte[1024];
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
while ((length = pipedInputStream.read(buffer)) != -1) {
    byteArrayOutputStream.write(buffer, 0, length);
}
byte[] result = byteArrayOutputStream.toByteArray();
System.out.println(new String(result));

完整代码示例：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/plain");
    ServletOutputStream servletOutputStream = response.getOutputStream();
    byte[] data = "Hello World".getBytes();
    servletOutputStream.write(data);
    servletOutputStream.flush();
    servletOutputStream.close();

    PipedOutputStream pipedOutputStream = new PipedOutputStream();
    PipedInputStream pipedInputStream = new PipedInputStream(pipedOutputStream);
    pipedOutputStream.write(data);
    pipedOutputStream.flush();
    pipedOutputStream.close();

    int length = 0;
    byte[] buffer = new byte[1024];
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    while ((length = pipedInputStream.read(buffer)) != -1) {
        byteArrayOutputStream.write(buffer, 0, length);
    }
    byte[] result = byteArrayOutputStream.toByteArray();
    System.out.println(new String(result));
}