使用阿里云OSS的服务端签名后直传功能的方法

<dependency>
 <groupId>com.aliyun.oss</groupId>
 <artifactId>aliyun-sdk-oss</artifactId>
 <version>3.10.2</version>
</dependency>

// Endpoint以杭州为例，其它Region请按实际情况填写。
String endpoint = "http://oss-cn-hangzhou.aliyuncs.com";
// 阿里云主账号AccessKey拥有所有API的访问权限，风险很高。强烈建议您创建并使用RAM账号进行API访问或日常运维，请登录 https://ram.console.aliyun.com 创建RAM账号。
String accessKeyId = "<yourAccessKeyId>";
String accessKeySecret = "<yourAccessKeySecret>";

// 创建OSSClient实例。
OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);

// 创建PutObjectRequest对象。
PutObjectRequest putObjectRequest = new PutObjectRequest("<yourBucketName>", "test", new File("C:\Users\82131\Desktop\logo.jpg"));

// 上传文件。
ossClient.putObject(putObjectRequest);

// 关闭OSSClient。
ossClient.shutdown(); 

@RestController
public class OssController {

 @RequestMapping("/oss/policy")
 public Map<String, String> policy() {
  String accessId = "<yourAccessKeyId>"; // 请填写您的AccessKeyId。
  String accessKey = "<yourAccessKeyId>"; // 请填写您的AccessKeySecret。
  String endpoint = "oss-cn-shenzhen.aliyuncs.com"; // 请填写您的 endpoint。
  String bucket = "bucket-name"; // 请填写您的 bucketname 。
  String host = "https://" + bucket + "." + endpoint; // host的格式为 bucketname.endpoint

  String format = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
  String dir = format + "/"; // 用户上传文件时指定的前缀。

  Map<String, String> respMap = new LinkedHashMap<String, String>();
  // 创建OSSClient实例。
  OSS ossClient = new OSSClientBuilder().build(endpoint, accessId, accessKey);
  try {
   long expireTime = 30;
   long expireEndTime = System.currentTimeMillis() + expireTime * 1000;
   Date expiration = new Date(expireEndTime);
   // PostObject请求最大可支持的文件大小为5 GB，即CONTENT_LENGTH_RANGE为5*1024*1024*1024。
   PolicyConditions policyConds = new PolicyConditions();
   policyConds.addConditionItem(PolicyConditions.COND_CONTENT_LENGTH_RANGE, 0, 1048576000);
   policyConds.addConditionItem(MatchMode.StartWith, PolicyConditions.COND_KEY, dir);

   String postPolicy = ossClient.generatePostPolicy(expiration, policyConds);
   byte[] binaryData = postPolicy.getBytes("utf-8");
   String encodedPolicy = BinaryUtil.toBase64String(binaryData);
   String postSignature = ossClient.calculatePostSignature(postPolicy);

   respMap.put("accessid", accessId);
   respMap.put("policy", encodedPolicy);
   respMap.put("signature", postSignature);
   respMap.put("dir", dir);
   respMap.put("host", host);
   respMap.put("expire", String.valueOf(expireEndTime / 1000));

  } catch (Exception e) {
   // Assert.fail(e.getMessage());
   System.out.println(e.getMessage());
  } finally {
   ossClient.shutdown();
  }
  return respMap;
 }
}

<template>
 <div>
 <el-upload
  action="http://colablog.oss-cn-shenzhen.aliyuncs.com"
  :data="dataObj"
  list-type="picture"
  :multiple="false"
  :show-file-list="showFileList"
  :file-list="fileList"
  :before-upload="beforeUpload"
  :on-remove="handleRemove"
  :on-success="handleUploadSuccess"
  :on-preview="handlePreview"
 >
  <el-button size="small" type="primary">点击上传</el-button>
  <div slot="tip" class="el-upload__tip">只能上传jpg/png文件，且不超过10MB</div>
 </el-upload>
 <el-dialog :visible.sync="dialogVisible">
  <img width="100%" :src="fileList[0].url" alt="">
 </el-dialog>
 </div>
</template>
<script>

export default {
 name: 'SingleUpload',
 props: {
 value: String
 },
 data() {
 return {
  dataObj: {
  policy: '',
  signature: '',
  key: '',
  ossaccessKeyId: '',
  dir: '',
  host: ''
  // callback:'',
  },
  dialogVisible: false
 }
 },
 computed: {
 imageUrl() {
  return this.value
 },
 imageName() {
  if (this.value != null && this.value !== '') {
  return this.value.substr(this.value.lastIndexOf('/') + 1)
  } else {
  return null
  }
 },
 fileList() {
  return [{
  name: this.imageName,
  url: this.imageUrl
  }]
 },
 showFileList: {
  get: function() {
  return this.value !== null && this.value !== '' && this.value !== undefined
  },
  set: function(newValue) {
  }
 }
 },
 methods: {
 emitInput(val) {
  this.$emit('input', val)
 },
 handleRemove(file, fileList) {
  this.emitInput('')
 },
 handlePreview(file) {
  this.dialogVisible = true
 },
 getUUID() {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, c => {
  return (c === 'x' &#63; (Math.random() * 16 | 0) : ('r&0x3' | '0x8')).toString(16)
  })
 },
 beforeUpload(file) {
  const _self = this
  return new Promise((resolve, reject) => {
  // 前后端提交post异步请求获取签名信息
  this.postRequest('/oss/policy')
   .then((response) => {
   _self.dataObj.policy = response.policy
   _self.dataObj.signature = response.signature
   _self.dataObj.ossaccessKeyId = response.accessid
   _self.dataObj.key = response.dir + this.getUUID() + '_${filename}'
   _self.dataObj.dir = response.dir
   _self.dataObj.host = response.host
   resolve(true)
   }).catch(err => {
   reject(false)
   })
  })
 },
 handleUploadSuccess(res, file) {
  console.log('上传成功...')
  this.showFileList = true
  this.fileList.pop()
  this.fileList.push({ name: file.name, url: this.dataObj.host + '/' + this.dataObj.key.replace('${filename}', file.name) })
  this.emitInput(this.fileList[0].url)
 }
 }
}
</script>

<template>
 <div>
 <el-form :model="admin" label-width="60px">
  <el-form-item label="头像">
  <single-upload v-model="admin.userImg" />
  </el-form-item>
 </el-form>
 </div>
</template>
<script>
import singleUpload from '@/components/upload/singleUpload'
export default {
 components: {
 singleUpload
 },
 data() {
 return {
  admin: {
  userImg: ''
  }
 }
 }
}
</script>