java发送http请求上传大文件

Java发送HTTP请求上传大文件可以使用Java自带的HTTP库(HttpURLConnection)或者第三方HTTP请求库(如Apache HttpClient、OkHttp)实现。以下是使用Java自带的HTTP库(HttpURLConnection)上传大文件的示例代码：

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpUploadDemo {
    public static void main(String[] args) {
        try {
            // 创建URL对象
            URL url = new URL("http://example.com/api/upload");

            // 创建HTTP连接对象
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            // 设置请求方法为POST
            connection.setRequestMethod("POST");

            // 设置请求头参数
            connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW");

            // 设置是否向HttpURLConnection输出，默认false
            connection.setDoOutput(true);

            // 获取文件对象
            File file = new File("path/to/your/file");

            // 设置请求体参数
            DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());
            outputStream.writeBytes("------WebKitFormBoundary7MA4YWxkTrZu0gW\r\n");
            outputStream.writeBytes("Content-Disposition: form-data; name=\"file\"; filename=\"" + file.getName() + "\"\r\n");
            outputStream.writeBytes("Content-Type: application/octet-stream\r\n\r\n");

            // 读取文件内容并写入请求体
            FileInputStream fileInputStream = new FileInputStream(file);
            byte[] buffer = new byte[1024];
            int bytesRead = -1;
            while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }
            fileInputStream.close();

            // 添加请求体结束标记
            outputStream.writeBytes("\r\n------WebKitFormBoundary7MA4YWxkTrZu0gW--\r\n");

            // 发送请求
            int responseCode = connection.getResponseCode();

            // 读取响应内容
            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            StringBuilder response = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                response.append(line);
            }
            reader.close();

            // 输出响应内容
            System.out.println(responseCode);
            System.out.println(response.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

请将URL和请求头参数替换为您要访问的API的实际值。其中，使用了DataOutputStream将文件内容写入请求体，以避免在内存中存储整个文件内容导致内存溢出。