Nodejs 安卓客户端上传文件怎么写？

Node.js 安卓客户端上传文件怎么写？

在安卓应用中上传文件到Node.js服务器通常涉及使用HTTP客户端来发送请求。在Android端，你可以使用HttpURLConnection或者第三方库如Retrofit或Volley来实现文件上传功能。本文将通过一个简单的示例来展示如何使用HttpURLConnection来实现这一功能。

Android 端代码

首先，你需要创建一个方法来处理文件上传。这里我们假设你已经有一个选择文件的方法，并且文件路径存储在一个字符串变量中。

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

public class FileUploader {

    public void uploadFile(String filePath) {
        HttpURLConnection connection = null;
        DataOutputStream outputStream = null;
        FileInputStream fileInputStream = null;

        String lineEnd = "\r\n";
        String twoHyphens = "--";
        String boundary = "*****";

        int bytesRead, bytesAvailable, bufferSize;
        byte[] buffer;
        int maxBufferSize = 1 * 1024 * 1024; // 1MB

        try {
            File file = new File(filePath);
            fileInputStream = new FileInputStream(file);

            URL url = new URL("http://your-nodejs-server.com/upload");
            connection = (HttpURLConnection) url.openConnection();
            connection.setDoInput(true); // 允许输入流
            connection.setDoOutput(true); // 允许输出流
            connection.setUseCaches(false); // 不使用缓存
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Connection", "Keep-Alive");
            connection.setRequestProperty("ENCTYPE", "multipart/form-data");
            connection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
            connection.setRequestProperty("file", filePath);

            outputStream = new DataOutputStream(connection.getOutputStream());
            outputStream.writeBytes(twoHyphens + boundary + lineEnd);
            outputStream.writeBytes("Content-Disposition: form-data; name=\"file\";filename=\"" + filePath + "\"" + lineEnd);
            outputStream.writeBytes(lineEnd);

            bytesAvailable = fileInputStream.available();
            bufferSize = Math.min(bytesAvailable, maxBufferSize);
            buffer = new byte[bufferSize];

            bytesRead = fileInputStream.read(buffer, 0, bufferSize);

            while (bytesRead > 0) {
                outputStream.write(buffer, 0, bufferSize);
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);
            }

            outputStream.writeBytes(lineEnd);
            outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

            int serverResponseCode = connection.getResponseCode();
            String serverResponseMessage = connection.getResponseMessage();

            fileInputStream.close();
            outputStream.flush();
            outputStream.close();

            System.out.println("Server Response is: " + serverResponseMessage + ": " + serverResponseCode);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Node.js 端代码

接下来，我们需要在Node.js服务器端设置一个路由来接收上传的文件。这里我们将使用Express框架和Multer中间件来处理文件上传。

const express = require('express');
const multer = require('multer');
const path = require('path');

const app = express();
const storage = multer.diskStorage({
    destination: function (req, file, cb) {
        cb(null, 'uploads/');
    },
    filename: function (req, file, cb) {
        cb(null, Date.now() + path.extname(file.originalname)); // 使用时间戳作为文件名
    }
});

const upload = multer({ storage: storage });

app.post('/upload', upload.single('file'), (req, res) => {
    if (!req.file) {
        return res.status(400).send('No file uploaded.');
    }
    res.send(`File uploaded successfully. Filename: ${req.file.filename}`);
});

app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

总结

以上代码展示了如何在Android端使用HttpURLConnection上传文件到Node.js服务器，并在服务器端使用Express和Multer处理文件上传。确保你的Node.js服务器正在运行，并且可以访问你指定的URL。