一、前言

上一篇《使用springboot+vue实现阿里云oss上传》写了如何使用springboot+vue实现阿里云oss文件上传。这种方式虽然通用，但有个弊端就是当上传大文件时，容易导致文件还未上传完页面请求就超时了，如果想把oss的文件路径保存到数据库则无法实现。

针对这个阿里云也推出了直传的方式。这个方式避免文件传输到后台再转存到oss，大大缩减了上传时间，并且支持分片上传方式，对于大文件处理非常高效。

其整个流程是：前端通过后台请求OSS policy签名，前端拿到签名后直接把文件上传到阿里云oss，上传成功后OSS通过回调把上传结果返回给后端，下面我们来看具体实现。

二、前端实现逻辑

我们通过对上一篇的上传组件进行一个改造。
OssFileUpload组件

<template>
  <div class="upload-file">
    <el-upload
        :multiple="multiple"
        :accept="accept.join(',')"
        action="#"
        :http-request="handleUpload"
        :before-upload="handleBeforeUpload"
        :file-list="fileList"
        :limit="limit"
        :on-exceed="handleExceed"
        :show-file-list="false"
        :data="data"
        class="upload-file-uploader"
        ref="fileUpload"
    >
      <!-- 上传按钮 -->
      <el-button size="mini" type="primary">选取文件</el-button>
      <template v-if="multiple"> （按住Ctrl键多选）</template>
      <!-- 上传提示 -->
      <div class="el-upload__tip" slot="tip" v-if="showTip && fileList.length<=0">
        请上传
        <template v-if="limit"> 最多 <b style="color: #f56c6c">{{ limit }}个</b></template>
        <template v-if="fileSize"> 大小不超过 <b style="color: #f56c6c">{{ fileSize }}MB</b></template>
        <template v-if="fileType"> 格式为 <b style="color: #f56c6c">{{ fileType.join("/") }}</b></template>
        的文件
      </div>
    </el-upload>

    <!-- 文件列表 -->
    <transition-group class="upload-file-list el-upload-list el-upload-list--text" name="el-fade-in-linear" tag="ul" height="485">
      <li v-for="(file, index) in fileList" :key="file.uid || index "
          class="el-upload-list__item ele-upload-list__item-content">
        <el-link :href="file.url" :underline="false" target="_blank">
          <span class="el-icon-document"> {{ file.name }} </span>
        </el-link>
        <div class="ele-upload-list__item-content-action">
          <el-link :underline="false" @click="handleDelete(index)" type="danger" style="width: 50px">删除</el-link>
        </div>
      </li>
    </transition-group>
  </div>
</template>

<script>
import {handleMD5} from '@/utils/md5';
import {getOssPolicy} from "@/api/file";
import {POST} from "@/utils/request";
export default {
  name: "OssFileUpload",
  props: {
    // 是否可多选
    multiple: {
      type: Boolean,
      default: true,
    },
    // 值
    value: [String, Object, Array],
    // 数量限制
    limit: {
      type: Number,
      default: 5,
    },
    // 大小限制(MB)
    fileSize: {
      type: Number,
      default: 5,
    },
    // 文件类型, 例如['png', 'jpg', 'jpeg']
    fileType: {
      type: Array,
      default: () => ["doc", "xls", "xlsx", "ppt", "txt", "pdf"],
    },
    accept: {
      type: Array,
      default: () => [".doc", ".xls", ".xlsx", ".ppt", ".txt", ".pdf"],
    },
    // 是否显示提示
    isShowTip: {
      type: Boolean,
      default: true
    },
    // 是否重命名
    rename: {
      type: Boolean,
      default: false
    }
  },
  data() {
    return {
      number: 0,
      uploadList: [],
      fileList: [],
      data: {}
    };
  },
  watch: {
    value: {
      handler(val) {
        if (val) {
          let temp = 1;
          // 首先将值转为数组
          const list = Array.isArray(val) ? val : this.value.split(',');
          // 然后将数组转为对象数组
          this.fileList = list.map(item => {
            if (typeof item === "string") {
              item = {name: item.name, url: item.url};
            }
            item.uid = item.uid || new Date().getTime() + temp++;
            return item;
          });
        } else {
          this.fileList = [];
          return [];
        }
      },
      deep: true,
      immediate: true
    },
    rename: {
      handler(val) {
        this.data = {rename: val}
      },
      deep: true,
      immediate: true
    }
  },
  computed: {
    // 是否显示提示
    showTip() {
      return this.isShowTip && (this.fileType || this.fileSize);
    },
  },
  methods: {
    // 上传前校检格式和大小
    handleBeforeUpload(file) {
      // 校检文件类型
      if (this.fileType) {
        const fileName = file.name.split('.');
        const fileExt = fileName[fileName.length - 1];
        const isTypeOk = this.fileType.indexOf(fileExt) >= 0;
        if (!isTypeOk) {
          this.$modal.msgError(`文件格式不正确, 请上传${this.fileType.join("/")}格式文件!`);
          return false;
        }
      }
      // 校检文件大小
      if (this.fileSize) {
        const isLt = file.size / 1024 / 1024 < this.fileSize;
        if (!isLt) {
          this.$modal.msgError(`上传文件大小不能超过 ${this.fileSize} MB!`);
          return false;
        }
      }
      this.$modal.loading("正在上传文件，请稍候...");
      this.number++;
      return true;
    },
    // 文件个数超出
    handleExceed() {
      this.$modal.msgError(`上传文件数量不能超过 ${this.limit} 个!`);
    },
    // 删除文件
    handleDelete(index) {
      this.fileList.splice(index, 1);
      this.$emit("input", this.listToString(this.fileList));
    },
    // 上传结束处理
    uploadedSuccessfully() {
      if (this.number > 0 && this.uploadList.length === this.number) {
        this.fileList = this.fileList.concat(this.uploadList);
        this.uploadList = [];
        this.number = 0;
        this.$emit("input", this.listToString(this.fileList));
        this.$modal.closeLoading();
      }
    },
    /** 上传按钮操作 */
    handleUpload (file) {
      // 计算文件的MD5，根据文件大小进行分片处理
      handleMD5(file.file).then(md5 => {
        const data = {
          fileName: file.file.name,
          md5: md5,
          rename: this.rename
        };
        getOssPolicy(data).then((response) => {
          let data = response.data
          let formData = new FormData();
          formData.append('OSSAccessKeyId', data.accessKeyId);
          formData.append('signature', data.signature);
          formData.append('policy', data.policy);
          formData.append('key',data.filePath);
          formData.append('callback',data.callback);
          formData.append('success_action_status', 200);
          formData.append('file',file.file);
          POST(data.host, formData).then((res) => {
            let data = res.data
            if (data.code !== 0) {
              this.$modal.msgError(data.msg);
              return;
            }
            this.uploadList.push({name: data.data.filename, url: data.data.url});
            this.uploadedSuccessfully();
            this.$modal.msgSuccess("上传成功");
          });
        });
      });
    },
    // 对象转成指定字符串分隔
    listToString(list, separator) {
      let strs = "";
      separator = separator || ",";
      for (let i in list) {
        strs += list[i].url + separator;
      }
      return strs != '' ? strs.substr(0, strs.length - 1) : '';
    }
  }
};
</script>

<style scoped lang="scss">
.upload-file-uploader {
  margin-bottom: 5px;
}

.upload-file-list {
  max-height: 420px;
  overflow-y: auto;
}

.upload-file-list .el-upload-list__item {
  border: 1px solid #e4e7ed;
  line-height: 2;
  margin-bottom: 10px;
  position: relative;
}

.upload-file-list .ele-upload-list__item-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: inherit;
}

.ele-upload-list__item-content-action .el-link {
  margin-right: 10px;
}
</style>

这里使用的是spark-md5来计算文件MD5，测试下来比crypto-js要快不少。

import SparkMD5 from 'spark-md5'

// 计算md5
export function handleMD5(file) {
  return new Promise((resolve, reject) => {
    let start = new Date().getTime()
    const slice = File.prototype.slice || File.prototype.mozSlice || File.prototype.webkitSlice
    const fileReader = new FileReader()
    //分片大小
    const chunkSize = 2097152
    //计算分片数
    const chunks = Math.ceil(file.size / chunkSize)
    let currentChunk = 0
    //注意点，网上都是 这一步都是有问题的， SparkMD5.ArrayBuffer()
    const spark = new SparkMD5.ArrayBuffer()
    fileReader.onload = function (e) {
      spark.append(e.target.result)
      currentChunk++
      if (currentChunk < chunks) {
        loadNext()
      } else {
      	//计算后的结果
        const md5 = spark.end(false)        
        console.info('md5:' + md5)
        console.info("take:" + (new Date().getTime() - start) + "ms")
        resolve(md5)
      }
    }
    fileReader.onerror = function () {
      console.warn('FileReader error.')
      reject('compute file md5 error')
    }

    const loadNext = () => {
      const start = currentChunk * chunkSize
      const end = ((start + chunkSize) >= file.size) ? file.size : start + chunkSize
      // 注意这里的 fileRaw
      fileReader.readAsArrayBuffer(slice.call(file, start, end))
    }

    loadNext()
  })
}

POST 的定义，使用axios

export const POST = async (url, form) => {
  try {
    return await axios.post(`${url}`, form);
  } catch (error) {
    return error;
  }
};

使用示例

<template>
  <div class="app-container">
	<el-dialog title="文件上传" :visible.sync="open" width="700px" append-to-body>
      <el-form ref="form" :model="form" :rules="rules" label-width="120px">
        <el-form-item label="文件标识" prop="code">
          <el-input v-model="form.code" clearable maxlength="50" show-word-limit style="width: 250px"/>
        </el-form-item>
        <el-form-item label="是否重命名文件" prop="rename">
          <el-radio-group v-model="rename">
            <el-radio :label="false">否</el-radio>
            <el-radio :label="true">是</el-radio>
          </el-radio-group>
        </el-form-item>
        <el-form-item label="选择文件" prop="file" class="is-required">
          <!--只能上传1个最大100M的视频文件-->
          <oss-file-upload ref="upload" :fileType="fileType" :accept="accept" :fileSize="100" :limit="1" :multiple="false" :value="form.files" :rename="rename"/>
        </el-form-item>
        <el-form-item label="备注" prop="remark">
          <el-input type="textarea" :rows="3" v-model="form.remark" clearable maxlength="500" show-word-limit/>
        </el-form-item>
      </el-form>
      <div slot="footer" class="dialog-footer">
        <el-button type="primary" @click="submitForm">确 定</el-button>
        <el-button @click="cancel">取 消</el-button>
      </div>
    </el-dialog>
  </div>
</template>

<script>
import { add } from "@/api/xxx"; // 请求后台的接口封装
import OssFileUpload from "@/components/OssFileUpload";
export default {
   name: "demo",
   components: {
    OssFileUpload 
   },
   data() {
    return {
      // 自定义允许上传的文件格式，也可以使用组件里面定义的默认格式
      fileType: ['avi', 'mp4', 'mov', 'wmv', 'flv', 'mpeg', 'webm'],
      accept: ['.avi', '.mp4', '.mov', '.wmv', '.flv', '.mpeg', '.webm'],
      // 是否重命名
      rename: false,
      // 表单参数
      form: {
        code: undefined,
        remark: undefined,
        url: undefined,
        files: []
      },
      // 表单校验
      rules: {
      	code: [{required: true, message: "文件标识不能为空", trigger: "blur"}],
     	files: [{type: 'array', required: true, message: "文件不能为空", trigger: "blur"}]
 	  }
    }
   },
   methods: {
   	/** 提交按钮 */
    submitForm: function () {
        this.$refs["form"].validate(valid => {
            if (valid) {
                this.form.files = this.$refs.upload.fileList
                if (!Array.isArray(this.form.files) || this.form.files.length <= 0) {
                    this.$alert("请上传附件");
                    return false;
                }
                console.info(this.form)
                add(this.form).then(() => {
                    this.$modal.msgSuccess("操作成功");
                    this.open = false;
                });
            }
        });
    },            
  	...
  }
}
</script>

<style lang="scss" scoped>
::v-deep {
  .el-dialog__body {
    padding: 10px 10px 20px 10px;
  }
}
</style>

效果如下：

上传成功后再上传其他文件时效果

三、后端实现逻辑

controller

/**
 * 生成OSS policy
 *
 * @param request 请求
 * @return 结果
 */
@PostMapping("/policy")
public Result<OssPolicyInfo> generateOssPolicy(@RequestBody @Valid GetOssPolicyRequest request) {
    OssPolicyInfo ossPolicyInfo = ossService.getPolicy(request);
    return Result.success(ossPolicyInfo);
}

/**
 * 文件上传到OSS的回调处理
 *
 * @param servletRequest 回调request
 * @return 验证结果
 */
@PostMapping("/oss/callback")
public Result callback(HttpServletRequest servletRequest) {
	//servletRequest -> map
    Map<String, String> callbackMap = HttpRequestUtil.commonHttpRequestParamConvert(servletRequest);
    String filename = callbackMap.get("filename");
    String name = filename.substring(filename.lastIndexOf("/") + 1);
    //文件访问地址
    String url = ExternalUrl.OSS_HOST + "/" + filename;
    callbackMap.put("url", url);
    callbackMap.put("filename", name);
    return Result.success(callbackMap);
}

service

@Resource
private AliyunOssConfig config;

private OSSClient getOSSClient() {
   return (OSSClient) new OSSClientBuilder().build(config.getEndPoint(), config.getKeyId(), config.getSecret());
}
    
@Override
public OssPolicyInfo getPolicy(GetOssPolicyRequest request) {
    OSSClient ossClient = getOSSClient();
    try {
        Long fileId = new SnowFlakeGenerator().nextId();
        String fileName = request.getFileName();
        if (request.getRename()) {
            // 重命名
            fileName = fileId + "." + FilenameUtils.getExtension(fileName);
        }
        String filePath = String.format("file/%s", fileName);
        // 30s内上传有效
        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1 GB，即CONTENT_LENGTH_RANGE为1024*1024*1024。
        PolicyConditions policyConditions = new PolicyConditions();
        policyConditions.addConditionItem(PolicyConditions.COND_CONTENT_LENGTH_RANGE, 0, 1073741824);
        policyConditions.addConditionItem(MatchMode.Exact, PolicyConditions.COND_KEY, filePath);

        String postPolicy = ossClient.generatePostPolicy(expiration, policyConditions);
        byte[] binaryData = postPolicy.getBytes(StandardCharsets.UTF_8);
        String encodedPolicy = BinaryUtil.toBase64String(binaryData);
        String postSignature = ossClient.calculatePostSignature(postPolicy);

        OssPolicyInfo ossPolicyInfo = new OssPolicyInfo()
                .setAccessKeyId(config.getKeyId())
                .setPolicy(encodedPolicy)
                .setSignature(postSignature)
                .setFilePath(filePath)
                .setHost(ExternalUrl.OSS_HOST) //OSS地址
                .setExpire(expireEndTime / 1000);
		//如果需要回调，默认为true
        if (request.getNeedCallback()) {
            String callbackUrl = "/oss/callback";
            String callbackBody = String.format("filename=${object}&size=${size}&md5=%s", request.getMd5());
            JSONObject callback = new JSONObject();
            callback.put("callbackUrl", callbackUrl);
            callback.put("callbackBody", callbackBody);
            callback.put("callbackBodyType", "application/x-www-form-urlencoded");
            String encodedCallbackBody = BinaryUtil.toBase64String(callback.toString().getBytes());
            ossPolicyInfo.setCallback(encodedCallbackBody);
        }
        return ossPolicyInfo;
    } catch (Exception e) {
        log.error("Oss generate post policy fail");
        throw new ServerErrorException("服务器错误");
    } finally {
        ossClient.shutdown();
    }
}

AliyunOssConfig

@Data
@Configuration
@ConfigurationProperties(prefix = "aliyun.oss")
public class AliyunOssConfig {
   private String endPoint;
   private String keyId;
   private String secret;
   private String bucketName;
}

GetOssPolicyRequest

@Data
public class GetOssPolicyRequest {
    @NotBlank
    private String fileName;
    private String md5;
    private Boolean needCallback = true;
    private Boolean rename = false;
}

值得注意的是/oss/callback这个地址需要使用公网，阿里云能回调成功才行。

本篇介绍到这里，需要帮到大家。麻烦多多点赞，谢谢！