java http 传输二进制流_文件以二进制流POST的HTTP请求

你可以使用 Java 中的 HttpURLConnection 类来发送 HTTP POST 请求，将文件以二进制流的形式传输。以下是一个示例代码：

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpBinaryPost {
    public static void main(String[] args) throws Exception {
        String url = "http://example.com/upload";
        File file = new File("example.pdf");

        // Create a boundary string
        String boundary = Long.toHexString(System.currentTimeMillis());

        // Set the content type to multipart/form-data with the specified boundary
        String contentType = "multipart/form-data; boundary=" + boundary;
        URL connectionUrl = new URL(url);

        HttpURLConnection conn = (HttpURLConnection) connectionUrl.openConnection();
        conn.setDoOutput(true);
        conn.setDoInput(true);
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", contentType);

        // Open a stream to write the request body
        OutputStream outputStream = conn.getOutputStream();
        PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputStream, "UTF-8"), true);

        // Write the boundary and content disposition header
        writer.append("--" + boundary).append("\r\n");
        writer.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + file.getName() + "\"").append("\r\n");

        // Write the content type
        writer.append("Content-Type: " + URLConnection.guessContentTypeFromName(file.getName())).append("\r\n");
        writer.append("Content-Transfer-Encoding: binary").append("\r\n");
        writer.append("\r\n");

        // Write the file content
        FileInputStream inputStream = new FileInputStream(file);
        byte[] buffer = new byte[4096];
        int bytesRead;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }

        // Write the end of the boundary
        writer.append("\r\n");
        writer.append("--" + boundary + "--").append("\r\n");

        // Close the streams
        inputStream.close();
        outputStream.close();
        writer.close();

        // Read the response from the server
        BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }
        reader.close();
    }
}

在上面的代码中，我们首先创建一个 HttpURLConnection 对象并设置请求的方法和请求头部。然后我们打开一个输出流并使用 PrintWriter 对象将请求体写入流中。我们首先写入一个边界字符串，然后写入文件的内容类型和文件名。接下来，我们使用 FileInputStream 读取文件内容并将其写入输出流中。最后，我们写入请求体的结束边界并关闭流。最后，我们读取服务器的响应并打印出来。