如何使用java创建分块/混合请求

基础概念

分块请求（Chunked Request）和混合请求（Multipart Request）是两种常见的HTTP请求方式。分块请求通常用于传输大量数据，数据被分割成多个小块逐个发送。混合请求则常用于文件上传，允许同时发送文本数据和二进制文件。

类型

分块请求：HTTP请求体被分割成多个部分，每个部分单独发送。
混合请求：HTTP请求体包含多个部分，每个部分可以是文本或二进制数据。

应用场景

分块请求：大文件下载、实时数据流传输。
混合请求：文件上传、表单提交包含文件和其他数据。

示例代码

分块请求示例

import java.io.*;
import java.net.*;

public class ChunkedRequestExample {
    public static void main(String[] args) throws IOException {
        URL url = new URL("http://example.com/upload");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Transfer-Encoding", "chunked");

        try (OutputStream outputStream = connection.getOutputStream();
             OutputStreamWriter writer = new OutputStreamWriter(outputStream)) {
            String data = "This is a large chunk of data.";
            byte[] bytes = data.getBytes();
            int chunkSize = 1024;
            for (int i = 0; i < bytes.length; i += chunkSize) {
                int length = Math.min(chunkSize, bytes.length - i);
                writer.write(new String(bytes, i, length));
                writer.flush();
            }
        }

        int responseCode = connection.getResponseCode();
        System.out.println("Response Code: " + responseCode);
    }
}

混合请求示例

import java.io.*;
import java.net.*;

public class MultipartRequestExample {
    public static void main(String[] args) throws IOException {
        URL url = new URL("http://example.com/upload");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW");

        try (OutputStream outputStream = connection.getOutputStream();
             PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputStream, "UTF-8"), true)) {
            // Send text data
            writer.append("------WebKitFormBoundary7MA4YWxkTrZu0gW\r\n");
            writer.append("Content-Disposition: form-data; name=\"username\"\r\n");
            writer.append("\r\n");
            writer.append("JohnDoe\r\n");
            writer.flush();

            // Send file data
            File file = new File("example.txt");
            writer.append("------WebKitFormBoundary7MA4YWxkTrZu0gW\r\n");
            writer.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + file.getName() + "\"\r\n");
            writer.append("Content-Type: text/plain\r\n");
            writer.append("\r\n");
            writer.flush();
            Files.copy(file.toPath(), outputStream);
            outputStream.flush();
            writer.append("\r\n");
            writer.flush();

            writer.append("------WebKitFormBoundary7MA4YWxkTrZu0gW--\r\n");
            writer.flush();
        }

        int responseCode = connection.getResponseCode();
        System.out.println("Response Code: " + responseCode);
    }
}