从http请求返回承诺-Java 学习之路

预先检查api中的图像是否确实存在 . 我使用'q'作为我的promise库和'request'lib来发出http请求 . 我正在尝试返回所有成功请求的图像的数组，如下所示：

.then((data)=> {
  return q.all(data.map((elem) => {
    let deferred = q.defer()
    request(`https://address/path/${elem}.jpg`, (error, response) => {
      if (!error, response.statusCode === 200) {
        deferred.resolve(elem)
      }
    })
    return deferred.promise
  })
  )
})
.then((result)=> {
   console.log('Array of existing images', result)//Result should contain all image id's which had status code 200
})

我希望这会返回所有请求状态为200的结果 . 对于 q.all() ，我希望在完成所有承诺后返回该函数 .

1 回答

我想，你shuld添加一个链，你清理非200图像例如，喜欢

.then((data)=> {
    return q.all(data.map((elem) => {
            let deferred = q.defer()
            request(`https://address/path/${elem}.jpg`, (error, response) => {
                if (!error) {
                    deferred.resolve({img:elem, status : response.statusCode})
                }else{
                    deferred.reject({elem: 'error'})
                }
            });
            return deferred.promise
        })
    )
})
.then((result)=> {
        let onlyGoodImages = [];
        result.map((elem) => {
            if (elem.status == 200){
                onlyGoodImages.push(elem.img);
            }
        });
        return onlyGoodImages;
    }
)
.then((result)=> {
    console.log('Array of existing images', result)//Result should contain all image id's which had status code 200
})

回复于 2024-05-03T07:19:52+08:00

从http请求返回承诺

1 回答

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