用JAVA实现后端文件上传接口，上传到七牛云

首先，您需要安装七牛云 Java SDK，可以使用以下命令安装：

$ mvn install com.qiniu:qiniu-java-sdk:7.2.14

然后，您可以使用以下代码实现后端文件上传接口：

import com.qiniu.common.QiniuException;
import com.qiniu.http.Response;
import com.qiniu.storage.Configuration;
import com.qiniu.storage.Region;
import com.qiniu.storage.UploadManager;
import com.qiniu.storage.model.DefaultPutRet;
import com.qiniu.util.Auth;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

public class FileUploader {
    private static final String ACCESS_KEY;
    private static final String SECRET_KEY;
    private static final String BUCKET;
    private static final String DOMAIN;

    static {
        Properties prop = new Properties();
        try {
            prop.load(new FileInputStream("config.properties"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        ACCESS_KEY = prop.getProperty("ACCESS_KEY");
        SECRET_KEY = prop.getProperty("SECRET_KEY");
        BUCKET = prop.getProperty("BUCKET");
        DOMAIN = prop.getProperty("DOMAIN");
    }

    public static String upload(String filePath) {
        // 构造一个带指定 Region 对象的配置类
        Configuration cfg = new Configuration(Region.region2());
        // 其他参数参考类注释
        UploadManager uploadManager = new UploadManager(cfg);
        // 生成上传凭证，然后准备上传
        Auth auth = Auth.create(ACCESS_KEY, SECRET_KEY);
        String upToken = auth.uploadToken(BUCKET);
        try {
            Response response = uploadManager.put(filePath, null, upToken);
            // 解析上传成功的结果
            DefaultPutRet putRet = new Gson().fromJson(response.bodyString(), DefaultPutRet.class);
            return DOMAIN + "/" + putRet.key;
        } catch (QiniuException ex) {
            Response r = ex.response;
            System.err.println(r.toString());
            try {
                System.err.println(r.bodyString());
            } catch (QiniuException ex2) {
                // ignore
            }
            return null;
        }
    }
}

在上