使用 java http post 传输一个几十G的 input stream 时，Content-Length 要怎么设置？会造成内存占用过高吗

在使用 Java HTTP POST 传输几十G的 input stream 时，Content-Length 应该设置为实际 input stream 的大小（单位为字节）。如果不设置，可能会导致传输过程中出现错误。另外，由于 Java HTTP POST 请求默认使用的是 chunked 编码，因此如果要使用 Content-Length，需要在设置 Content-Length 后将 http request header 中的 Transfer-Encoding 字段设置为 null。

在传输过程中，由于是一次性将整个 input stream 传输过去，因此可能会占用大量的内存。为了避免内存占用过高，可以考虑使用分块传输，将 input stream 拆分成多个 chunk，分批传输。这样可以减小每次传输的数据量，降低内存占用。

相关问题

请以stream: true和长连接 的方式写一个方法，能直接被外部传参进行访问的实现。

以下是一个使用 stream: true 和长连接方式的方法示例，可以通过传递参数进行访问：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class OpenAIJavaExample {
    public static void main(String[] args) {
        try {
            String apiKey = "YOUR_API_KEY";
            String prompt = "Hello, world!";
            String model = "gpt-3.5-turbo";
            int maxTokens = 10;

            String response = OpenAIJavaExample.sendRequest(apiKey, prompt, model, maxTokens);

            System.out.println("Response: " + response);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static String sendRequest(String apiKey, String prompt, String model, int maxTokens) throws IOException {
        String url = "https://api.openai.com/v1/engines/" + model + "/completions";
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        // Set the request method and headers
        con.setRequestMethod("POST");
        con.setRequestProperty("Content-Type", "application/json");
        con.setRequestProperty("Authorization", "Bearer " + apiKey);

        // Build the JSON request body
        String requestBody = "{\"prompt\": \"" + prompt + "\", \"max_tokens\": " + maxTokens + ", \"stream\": true}";
        con.setDoOutput(true);
        try (OutputStream os = con.getOutputStream()) {
            byte[] input = requestBody.getBytes("utf-8");
            os.write(input, 0, input.length);
        }

        // Send the request and get the response
        int responseCode = con.getResponseCode();
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        return response.toString();
    }
}

您可以将此代码放在一个类中，并通过传递参数调用 `sendRequest` 方法来访问 OpenAI API。请记得将 `YOUR_API_KEY` 替换为您自己的 API 密钥，并根据需要修改其他参数。

Java编写http服务器和http客户端，服务器多线程处理客户端请求，可以实现GET、HEAD、POST请求，可以通过浏览器看到服务器信息的代码

好的，以下是一个使用Java编写的简单的HTTP服务器和HTTP客户端示例代码，可以处理GET、HEAD、POST请求，并且支持多线程处理客户端请求，同时可以通过浏览器查看服务器信息。

HTTP服务器代码：

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.util.Date;

public class HttpServer {
    private static final int PORT = 8080;

    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(PORT);

            while (true) {
                Socket clientSocket = serverSocket.accept();
                new Thread(() -> {
                    try {
                        handleClientRequest(clientSocket);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }).start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (serverSocket != null) {
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private static void handleClientRequest(Socket clientSocket) throws IOException {
        InputStream input = clientSocket.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(input));

        OutputStream output = clientSocket.getOutputStream();
        PrintWriter writer = new PrintWriter(output, true);

        String requestLine = reader.readLine();
        String[] requestLineTokens = requestLine.split("\\s+");

        String method = requestLineTokens[0];
        String uri = requestLineTokens[1];
        String httpVersion = requestLineTokens[2];

        System.out.println("Received " + method + " request for " + uri + " from " + clientSocket.getRemoteSocketAddress());

        if (!method.equalsIgnoreCase("GET") && !method.equalsIgnoreCase("HEAD") && !method.equalsIgnoreCase("POST")) {
            writer.println("HTTP/1.1 501 Not Implemented");
            writer.println("Date: " + new Date());
            writer.println("Server: Simple Java HTTP Server");
            writer.println("Content-Type: text/plain");
            writer.println();
            writer.println("HTTP method not supported: " + method);
            return;
        }

        int contentLength = 0;
        String line;
        while ((line = reader.readLine()) != null) {
            if (line.isEmpty()) {
                break;
            }

            if (line.startsWith("Content-Length: ")) {
                contentLength = Integer.parseInt(line.substring("Content-Length: ".length()));
            }
        }

        if (method.equalsIgnoreCase("POST")) {
            char[] buffer = new char[contentLength];
            reader.read(buffer, 0, contentLength);
            String requestBody = new String(buffer);
            System.out.println("Request body: " + requestBody);
        }

        File file = new File("." + uri);
        if (file.isDirectory()) {
            file = new File(file, "index.html");
        }

        if (!file.exists()) {
            writer.println("HTTP/1.1 404 Not Found");
            writer.println("Date: " + new Date());
            writer.println("Server: Simple Java HTTP Server");
            writer.println("Content-Type: text/plain");
            writer.println();
            writer.println("File not found: " + uri);
            return;
        }

        String contentType = guessContentType(file.getName());

        byte[] content = readFileContents(file);

        writer.println("HTTP/1.1 200 OK");
        writer.println("Date: " + new Date());
        writer.println("Server: Simple Java HTTP Server");
        writer.println("Content-Type: " + contentType);
        writer.println("Content-Length: " + content.length);
        writer.println();

        if (method.equalsIgnoreCase("GET")) {
            output.write(content);
        }

        output.flush();
        output.close();

        clientSocket.close();
    }

    private static byte[] readFileContents(File file) throws IOException {
        try (FileInputStream fis = new FileInputStream(file);
             ByteArrayOutputStream bos = new ByteArrayOutputStream()) {
            byte[] buffer = new byte[1024];
            int read;
            while ((read = fis.read(buffer)) != -1) {
                bos.write(buffer, 0, read);
            }
            return bos.toByteArray();
        }
    }

    private static String guessContentType(String name) {
        if (name.endsWith(".html") || name.endsWith(".htm")) {
            return "text/html";
        } else if (name.endsWith(".jpg") || name.endsWith(".jpeg")) {
            return "image/jpeg";
        } else if (name.endsWith(".gif")) {
            return "image/gif";
        } else if (name.endsWith(".png")) {
            return "image/png";
        } else if (name.endsWith(".css")) {
            return "text/css";
        } else if (name.endsWith(".js")) {
            return "application/javascript";
        } else {
            return "application/octet-stream";
        }
    }
}

HTTP客户端代码：

import java.io.*;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;

public class HttpClient {
    private static final String SERVER_HOST = "localhost";
    private static final int SERVER_PORT = 8080;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        while (true) {
            System.out.println("Enter HTTP method (GET, HEAD, POST):");
            String method = scanner.nextLine().toUpperCase();

            System.out.println("Enter resource URI:");
            String uri = scanner.nextLine();

            try (Socket socket = new Socket(SERVER_HOST, SERVER_PORT)) {
                OutputStream output = socket.getOutputStream();
                PrintWriter writer = new PrintWriter(output, true);

                writer.println(method + " " + uri + " HTTP/1.1");
                writer.println("Host: " + SERVER_HOST + ":" + SERVER_PORT);

                if (method.equals("POST")) {
                    System.out.println("Enter request body:");
                    String requestBody = scanner.nextLine();
                    writer.println("Content-Length: " + requestBody.getBytes().length);
                    writer.println();
                    writer.print(requestBody);
                } else {
                    writer.println();
                }

                InputStream input = socket.getInputStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(input, StandardCharsets.UTF_8));

                String line;
                while ((line = reader.readLine()) != null) {
                    System.out.println(line);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

上述代码中，我们使用Socket和ServerSocket类实现了一个简单的HTTP服务器和HTTP客户端。服务器支持处理GET、HEAD和POST请求，可以通过浏览器查看服务器信息。客户端可以向服务器发送GET、HEAD和POST请求，并且可以手动输入请求体。同时，服务器使用多线程处理客户端请求，可以同时处理多个客户端请求。

需要注意的是，这只是一个简单的示例，实际应用中可能需要更复杂的代码来处理更多的HTTP请求和响应头信息。