demo/post_sign.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>Form 表单简单上传</title>
    <style>
      h1,
      h2 {
        font-weight: normal;
      }
      #msg {
        margin-top: 10px;
      }
    </style>
  </head>
  <body>
    <h1>Form 表单简单上传（兼容 IE8）</h1>
    <div>最低兼容到 IE6 上传，不支持 onprogress</div>

    <form
      id="form"
      target="submitTarget"
      action=""
      method="post"
      enctype="multipart/form-data"
      accept="*/*"
    >
      <input id="name" name="name" type="hidden" value="" />
      <input name="success_action_status" type="hidden" value="200" />
      <input
        id="success_action_redirect"
        name="success_action_redirect"
        type="hidden"
        value=""
      />
      <input id="key" name="key" type="hidden" value="" />
      <input id="policy" name="policy" type="hidden" value="" />
      <input
        id="q-sign-algorithm"
        name="q-sign-algorithm"
        type="hidden"
        value=""
      />
      <input id="q-ak" name="q-ak" type="hidden" value="" />
      <input id="q-key-time" name="q-key-time" type="hidden" value="" />
      <input id="q-signature" name="q-signature" type="hidden" value="" />
      <input name="Content-Type" type="hidden" value="" />
      <input
        id="x-cos-security-token"
        name="x-cos-security-token"
        type="hidden"
        value=""
      />

      <!-- file 字段放在表单最后，避免文件内容过长影响签名判断和鉴权 -->
      <input id="fileSelector" name="file" type="file" />
      <input id="submitBtn" type="button" value="提交" />
    </form>
    <iframe
      id="submitTarget"
      name="submitTarget"
      style="display: none"
      frameborder="0"
    ></iframe>

    <div id="msg"></div>

    <script>
      (function () {
        const form = document.getElementById('form');
        let prefix = '';

        // 对更多字符编码的 url encode 格式
        const camSafeUrlEncode = function (str) {
          return encodeURIComponent(str)
            .replace(/!/g, '%21')
            .replace(/'/g, '%27')
            .replace(/\(/g, '%28')
            .replace(/\)/g, '%29')
            .replace(/\*/g, '%2A');
        };

        // 计算签名
        const getAuthorization = function (options, callback) {
          // 替换为自己服务端地址 获取post上传签名
          const url = `http://127.0.0.1:3000/post-policy?ext=${options.ext}`;
          const xhr = new XMLHttpRequest();
          xhr.open('GET', url, true);
          xhr.onreadystatechange = function (e) {
            if (xhr.readyState === 4) {
              if (/^2\d\d$/.test('' + xhr.status)) {
                let credentials;
                try {
                  const result = JSON.parse(e.target.responseText);
                  credentials = result;
                } catch (e) {
                  callback('获取签名出错');
                }
                if (credentials) {
                  callback(null, {
                    SecurityToken: credentials.sessionToken,
                    cosKey: credentials.cosKey,
                    cosHost: credentials.cosHost,
                    policy: credentials.policy,
                    qAk: credentials.qAk,
                    qKeyTime: credentials.qKeyTime,
                    qSignAlgorithm: credentials.qSignAlgorithm,
                    qSignature: credentials.qSignature,
                  });
                } else {
                  console.error(xhr.responseText);
                  callback('获取签名出错');
                }
              } else {
                callback('获取签名出错');
              }
            }
          };
          xhr.send();
        };

        // 监听上传完成
        let Key;
        const submitTarget = document.getElementById('submitTarget');
        const showMessage = function (err, data) {
          console.log(err || data);
          document.getElementById('msg').innerText = err
            ? err
            : '上传成功，ETag=' + data.ETag;
        };
        submitTarget.onload = function () {
          let search;
          try {
            search = submitTarget.contentWindow.location.search.substr(1);
          } catch (e) {
            showMessage('文件 ' + Key + ' 上传失败');
          }
          if (search) {
            const items = search.split('&');
            let i = 0;
            let arr = [];
            const data = {};
            for (i = 0; i < items.length; i++) {
              arr = items[i].split('=');
              data[arr[0]] = decodeURIComponent(arr[1] || '');
            }
            showMessage(null, {
              url: prefix + camSafeUrlEncode(Key).replace(/%2F/g, '/'),
              ETag: data.etag,
            });
          } else {
          }
        };

        // 发起上传
        document.getElementById('submitBtn').onclick = function (e) {
          const filePath = document.getElementById('fileSelector').value;
          if (!filePath) {
            document.getElementById('msg').innerText = '未选择上传文件';
            return;
          }
          let ext = '';
          const lastDotIndex = filePath.lastIndexOf('.');
          if (lastDotIndex > -1) {
            // 这里获取文件后缀 由服务端生成最终上传的路径
            const ext = filePath.substring(lastDotIndex + 1);
          }
          getAuthorization({ ext }, function (err, AuthData) {
            const protocol =
              location.protocol === 'https:' ? 'https:' : 'http:';
            prefix = protocol + '//' + AuthData.cosHost;
            form.action = prefix;
            Key = AuthData.cosKey;
            // 在当前目录下放一个空的 empty.html 以便让接口上传完成跳转回来
            document.getElementById('success_action_redirect').value =
              location.href.substr(0, location.href.lastIndexOf('/') + 1) +
              'empty.html';
            document.getElementById('key').value = AuthData.cosKey;
            document.getElementById('policy').value = AuthData.policy;
            document.getElementById('q-sign-algorithm').value =
              AuthData.qSignAlgorithm;
            document.getElementById('q-ak').value = AuthData.qAk;
            document.getElementById('q-key-time').value = AuthData.qKeyTime;
            document.getElementById('q-signature').value = AuthData.qSignature;
            document.getElementById('x-cos-security-token').value =
              AuthData.SecurityToken || '';
            form.submit();
          });
        };
      })();
    </script>
  </body>
</html>