在阿里云云存储OSS中下载文件时设置文件名的办法：
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLEncoder;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import com.aliyun.openservices.oss.OSSClient;
import com.aliyun.openservices.oss.model.GeneratePresignedUrlRequest;
import com.aliyun.openservices.oss.model.ObjectMetadata;
import com.aliyun.openservices.oss.model.PutObjectResult;
import com.aliyun.openservices.oss.model.ResponseHeaderOverrides;
import java
