在java项目中你可能会有以下需求：用户上传本地图片，然后展示在网页上。本篇文章将使用阿里云oss实现上传图片到oss，oss生成url。

一、准备工作

首先进入阿里云，按如下操作

进入创建页面，修改读写权限为公共读

然后进入bucket，创建AccessKey

创建后，保存好AccessKeyID和AccessKey Secret

二、代码

将以下依赖添加到项目的pom.xml文件中

<dependency>
    <groupId>com.aliyun.oss</groupId>
    <artifactId>aliyun-sdk-oss</artifactId>
    <version>3.15.1</version>
</dependency>

<dependency>
    <groupId>javax.xml.bind</groupId>
    <artifactId>jaxb-api</artifactId>
    <version>2.3.1</version>
</dependency>
<dependency>
    <groupId>javax.activation</groupId>
    <artifactId>activation</artifactId>
    <version>1.1.1</version>
</dependency>
<!-- no more than 2.3.3-->
<dependency>
    <groupId>org.glassfish.jaxb</groupId>
    <artifactId>jaxb-runtime</artifactId>
    <version>2.3.3</version>
</dependency>

创建一个工具类，用于配置aliyunoss

添加以下代码：（注意修改）

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.PutObjectRequest;
import com.aliyun.oss.model.PutObjectResult;

import java.io.FileInputStream;
import java.io.InputStream;

public class AliOssUtil {

    // Endpoint以华东1（杭州）为例，其它Region请按实际情况填写。
    private static final String ENPOINT = "地区";
    // 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();
    private static final String ACCESS_KEY_ID="你的ID";
    private static final String ACCESS_KEY_SECRT="KEY";
    // 填写Bucket名称，例如examplebucket。
    private static final String BUCKETNAME = "你的bucket名称";

    public static String uploadFile(String objectName, InputStream in) throws Exception {

        // 创建OSSClient实例。
        OSS ossClient = new OSSClientBuilder().build(ENPOINT,ACCESS_KEY_ID,ACCESS_KEY_SECRT);
        String url = "";

        try {
            // 填写字符串。
            String content = "Hello OSS，你好世界";

            // 创建PutObjectRequest对象。
            PutObjectRequest putObjectRequest = new PutObjectRequest(BUCKETNAME, objectName,in);

            // 如果需要上传时设置存储类型和访问权限，请参考以下示例代码。
            // ObjectMetadata metadata = new ObjectMetadata();
            // metadata.setHeader(OSSHeaders.OSS_STORAGE_CLASS, StorageClass.Standard.toString());
            // metadata.setObjectAcl(CannedAccessControlList.Private);
            // putObjectRequest.setMetadata(metadata);

            // 上传字符串。
            PutObjectResult result = ossClient.putObject(putObjectRequest);
            //url组成:http://bucket名称.区域节点
            url = "https://" + BUCKETNAME + "." + ENPOINT.substring(ENPOINT.lastIndexOf("/")+1)+"/"+objectName;

        } 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 url;
    }
}

然后在控制类中使用

@RestController
public class FileUploadController {

    @PostMapping("/upload")
    public Result<String> upload(MultipartFile file) throws Exception {
        String originalFilename = file.getOriginalFilename();
        //保证文件名字唯一，防止文件覆盖
        String filename = UUID.randomUUID().toString()+originalFilename.substring(originalFilename.lastIndexOf("."));
        String url = AliOssUtil.uploadFile(filename,file.getInputStream());
        return Result.success(url);
    }

}

三、测试接口

这里使用apifox进行测试

发送请求后，可以看到图片已经存储到oss上，并且返回了地址。