目录
对象存储背景
阿里云OSS
对象存储背景
单节点环境下，文件往往存储在tomcat服务器内，随着业务需求的增多，单节点已不能满足需求，项目架构需要扩展到多节点（见下图），此时文件经过nginx转发存储到某一个节点，在分布式架构下对文件的访问就存在问题（文件存储到节点A，查看文件请求到节点B访问不了文件）。
在分布式环境下，需要引入集中管理文件的节点服务，改进如下：
分布式文件服务解决方案有很多，常见的有：独立搭建文件服务器，如基于开源FastDFS搭建；引入第三方云储存方案，如基于阿里云的OSS；相比独立搭建文件服务器，云存储方案有诸多优势：SDK使用简单、运维成本低、图形化的管理控制台、提供强大的文件处理功能、CDN加速、服务扩展简单等，本文重点讲述基于阿里云的OSS方案。
阿里云OSS
使用步骤如下：
1、【阿里云官网】开通OSS服务
2、【阿里云官网】创建Bucket
重点关注标签有：Bucket 名称、Endpoint，本文新建的Bucket 名称 = gingko-sawyer，Endpoint = oss-cn-beijing.aliyuncs.com
3、【阿里云官网】创建并使用RAM账号进行API访问或日常运维，请登录RAM控制台创建RAM账号，创建AccessKey，并将AccessKeyId和AccessKeySecret设置到本地电脑环境变量中。
4、后台编写代码实现基于阿里云OSS文件上传及下载
4.1、添加aliyun.oss依赖
<dependency><groupId>com.aliyun.oss</groupId><artifactId>aliyun-sdk-oss</artifactId><version>3.17.4</version>
</dependency>4.2、修改配置，增加对oss的支持
server:port: 8080
#aliyun oss config
aliyun:oss:endpoint: oss-cn-beijing.aliyuncs.comregion: cn-beijingbucket-name: gingko-sawyerfoler-prefix: oss/host: https://gingko-sawyer.oss-cn-beijing.aliyuncs.com
4.3 文件上传&下载程序
package com.ginko.aliyunoss.controller;import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.CredentialsProviderFactory;
import com.aliyun.oss.common.auth.EnvironmentVariableCredentialsProvider;
import com.aliyun.oss.common.comm.Protocol;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import java.io.File;
import java.io.InputStream;@RestController
@RequestMapping("oss")
@Slf4j
public class OSSController {@Value("${aliyun.oss.endpoint}")private String endpoint;@Value("${aliyun.oss.region}")private String region;@Value("${aliyun.oss.bucket-name}")private String bucketName;@Value("${aliyun.oss.foler-prefix}")private String folerPrefix;//上传到oss中具体的文件夹目录@Value("${aliyun.oss.host}")private String host;@PostMapping("/upload")public String upload(@RequestParam("file") MultipartFile file) throws Exception {// 创建 ClientBuilderConfiguration 实例，用于配置 OSS 客户端参数ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();// 设置签名算法版本为 V4clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);// 设置使用 HTTPS 协议访问 OSS，保证传输安全性clientBuilderConfiguration.setProtocol(Protocol.HTTPS);// 创建 OSS 客户端实例OSS ossClient = OSSClientBuilder.create()// endpoint.endpoint(this.endpoint)// 从环境变量中获取访问凭证（需提前配置 OSS_ACCESS_KEY_ID 和 OSS_ACCESS_KEY_SECRET）.credentialsProvider(CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider())// 设置客户端配置.clientConfiguration(clientBuilderConfiguration)// 设置region.region(this.region).build();try {// 填写Bucket名称String bucketName = this.bucketName;// 填写Object完整路径，完整路径中不能包含Bucket名称，例如exampledir/exampleobject.txt。String objectName = this.folerPrefix + file.getOriginalFilename();InputStream inputStream = file.getInputStream();// 创建PutObjectRequest对象。PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, objectName, inputStream);// 创建PutObject请求。PutObjectResult result = ossClient.putObject(putObjectRequest);System.out.println(result);} finally {// 当OSSClient实例不再使用时，调用shutdown方法以释放资源ossClient.shutdown();}return "success";}@PostMapping("/download")public String download() throws Exception {// Endpoint以华东1（杭州）为例，其它Region请按实际情况填写。String endpoint = this.endpoint;//从环境变量中获取访问凭证。运行本代码示例之前，请确保已设置环境变量OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();// 填写Bucket名称，例如examplebucket。String bucketName = this.bucketName;// 填写不包含Bucket名称在内的Object完整路径，例如testfolder/exampleobject.txt。String objectName = this.folerPrefix + "1.png";// 填写Object下载到本地的完整路径。String pathName = "D:\\rename.png";// 填写Bucket所在地域。以华东1（杭州）为例，Region填写为cn-hangzhou。String region = this.region;// 创建OSSClient实例。// 当OSSClient实例不再使用时，调用shutdown方法以释放资源。ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);OSS ossClient = OSSClientBuilder.create().endpoint(endpoint).credentialsProvider(credentialsProvider).clientConfiguration(clientBuilderConfiguration).region(region).build();try {// 下载Object到本地文件，并保存到指定的本地路径中。如果指定的本地文件存在会覆盖，不存在则新建。// 如果未指定本地路径，则下载后的文件默认保存到示例程序所属项目对应本地路径中。ObjectMetadata object = ossClient.getObject(new GetObjectRequest(bucketName, objectName), new File(pathName));} catch (OSSException oe) {System.out.println("Caught an OSSException, which means your request made it to OSS, "+ "but was rejected with an error response for some reason.");System.out.println("Error Message:" + oe.getErrorMessage());System.out.println("Error Code:" + oe.getErrorCode());System.out.println("Request ID:" + oe.getRequestId());System.out.println("Host ID:" + oe.getHostId());} catch (ClientException ce) {System.out.println("Caught an ClientException, which means the client encountered "+ "a serious internal problem while trying to communicate with OSS, "+ "such as not being able to access the network.");System.out.println("Error Message:" + ce.getMessage());} finally {if (ossClient != null) {ossClient.shutdown();}}return "success";}
}
5、测试，通过postman模拟上传及下载文件
如下图所示，1.png文件已经被上传到oss中，rename.png是从oss下载到本地的文件
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