本文实例为大家分享了如何利用oss实现下载功能的具体代码，供大家参考，具体内容如下
目前我接触的实现下载功能有3种方式。第一种，就是把要下载的内容写到本地目录，然后把目录返回给前端，利用a标签下载。第二种，本地不允许访问，挂载目录，使目录可以对外访问，同样的，把目录返给前端下载。第三种，使用第三方存储，其中阿里云oss就是一种可以用来实现的对象存储。
首先，导入依赖包
<dependency> <groupId>com.aliyun.oss</groupId> <artifactId>aliyun-sdk-oss</artifactId> <version>3.6.0</version> </dependency>
参数类
public class OssParams { public static final String endpoint = "oss-cn-hangzhou.aliyuncs.com"; public static final String accessKeyId = ""; public static final String accessKeySecret = ""; public static final String bucketName = ""; public static final String rootName = "";//根目录}
工具类
import com.aliyun.oss.ClientException;import com.aliyun.oss.OSS;import com.aliyun.oss.OSSClientBuilder;import com.aliyun.oss.OSSException;import com.aliyun.oss.model.AppendObjectRequest;import com.aliyun.oss.model.ObjectMetadata;import org.joda.time.DateTime;import org.slf4j.Logger;import org.slf4j.LoggerFactory; import java.io.ByteArrayInputStream;import java.net.URL;import java.util.Date;import java.util.concurrent.atomic.AtomicLong; import static OssParams.bucketName; /** * 先做单例对象调用，防止多线程并发bug * 后期加入线程锁控制后，做成公共utils */public class WriteLeadsOssUtils { private static Logger LOG = LoggerFactory.getLogger(WriteLeadsOssUtils.class.getName()); private static final String fileSub = ".csv"; private AtomicLong atomicLong = new AtomicLong(0L); private WriteLeadsOssUtils() { } private static class BuildWriteOSS { private static final WriteLeadsOssUtils instance = new WriteLeadsOssUtils(); } public static WriteLeadsOssUtils getInstance() { return BuildWriteOSS.instance; } private OSS getOssClient() { return new OSSClientBuilder().build(OssParams.endpoint, OssParams.accessKeyId, OssParams.accessKeySecret); } public URL writeJSONObjectFile(String content,String fileName) { // 创建OSSClient实例。 OSS ossClient = getOssClient(); try { DateTime currentTime = new DateTime(System.currentTimeMillis());// String objectName = OssParams.rootName + currentTime.toString("yyyy-MM-dd-HH") + fileSub; String objectName = OssParams.rootName + fileName;// AppendObjectRequest appendObjectRequest = null; String data = content; ossClient.putObject(bucketName, objectName, new ByteArrayInputStream(content.getBytes())); Date expiration = new Date(System.currentTimeMillis() + 3600L * 1000 * 24 * 180); URL url = ossClient.generatePresignedUrl(bucketName, objectName, expiration); LOG.info("{} saved to OSS, url={}", objectName,url.toString());// for (IngestLeadingRequest param : params) {// String jsonStr = JSONObject.toJSONString(param);// JSONObject object = JSONObject.parseObject(jsonStr);// data += object.toJSONString() + "\n";// } //文件不存在// if (!ossClient.doesObjectExist(OssParams.bucketName, objectName)) {// atomicLong.set(0L);// appendObjectRequest = getAppendObjectRequest(data, true, objectName);// appendObjectRequest.setPosition(0L);// } else {// appendObjectRequest = getAppendObjectRequest(data, false, objectName);// }// AppendObjectResult appendObjectResult = ossClient.appendObject(appendObjectRequest);// atomicLong.set(appendObjectResult.getNextPosition());// System.gc(); return url; } catch (OSSException e) { e.printStackTrace(); return null; } catch (ClientException e) { e.printStackTrace(); return null; } finally { ossClient.shutdown(); } } /** * flag标志位，true为新文件，false为追加文件 * * @param data * @param flag * @param objectName * @return */ private AppendObjectRequest getAppendObjectRequest(String data, Boolean flag, String objectName) { ObjectMetadata meta = new ObjectMetadata(); // 指定上传的内容类型。 meta.setContentType("text/plain;charset=utf-8"); if (flag == true) { return new AppendObjectRequest(bucketName, objectName, new ByteArrayInputStream(data.getBytes()), meta); } else { return new AppendObjectRequest(bucketName, objectName, new ByteArrayInputStream(data.getBytes()), meta).withPosition(atomicLong.get()); } }}
调用方法
WriteLeadsOssUtils.getInstance().writeJSONObjectFile("hello");//将hello作为内容存入oss，并获得可以下载的url
利用上述方式，可以直接将可以下载的url返回给前端，直接用窗口打开就可以下载。
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本文标题: java利用oss实现下载功能
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