如何使用 React-Native-fs 读取 JSON 文件

我有一个包含内容的 asset.json 文件，需要在反应本机应用程序中读取它。 我已经认为它必须手动复制到本机实现，并且我可以验证文件是否存在（并且可读：-rw-r--r--）。 由于它在那里并且我正在使用承诺来获取它，请告诉我输出何时仍然：

{"_40":0,"_65":0,"_55":null,"_72":null}

而不是文件的内容。

const path = RNFetchBlob.fs.dirs.DocumentDir + '/' + ASSET_FILENAME;
  if (await RNFS.exists(path)){
    console.log("BLAH EXISTS");
  } else {
    console.log("BLAH DOES NOT EXIST");
  }
  const asset_content = await RNFS.readFile(path);
  console.log("local asset_content:", asset_content);
  const assets = JSON.parse(asset_content);
  console.log("local assets:", assets);

输出是：

[10:03:55] I | ReactNativeJS ▶︎ BLAH EXISTS

[10:03:55] I | ReactNativeJS ▶︎ 'local asset_content:', '{"_40":0,"_65":0,"_55":null,"_72":null}'

[10:03:55] I | ReactNativeJS ▶︎ 'local assets:', { _40: 0, _65: 0, _55: null, _72: null }

另一方面，如果我使用promisify无论出于何种原因，正如一些帖子中所建议的那样，应用程序在调用承诺的文件读取时冻结。 这里是应用了更改的代码：

 const path = RNFetchBlob.fs.dirs.DocumentDir + '/' + ASSET_FILENAME;
  if (await RNFS.exists(path)){
    console.log("BLAH EXISTS");
  } else {
    console.log("BLAH DOES NOT EXIST");
  }
  const readFileAsync = promisify(RNFS.readFile);
  const asset_content = await readFileAsync(path);
  console.log("local asset_content:", asset_content);
  const assets = JSON.parse(asset_content);
  console.log("local assets:", assets);

及其输出：

[10:24:16] I | ReactNativeJS ▶︎ BLAH EXISTS

文件不大，只有 81 行有效的 JSON。 现在，如果我使用承诺来检查是否有任何异常，如下所示：

  const path = RNFetchBlob.fs.dirs.DocumentDir + '/' + ASSET_FILENAME;
  if (await RNFS.exists(path)){
    console.log("BLAH EXISTS");
  } else {
    console.log("BLAH DOES NOT EXIST");
  }
  const readFileAsync = promisify(RNFS.readFile);
  let asset_content = null;
  readFileAsync(path, 'utf8')
    .then((str) => {
      console.log("got result: ", str);
      asset_content = str;
    })
    .catch((e) => {
      console.log("got error:", e);
    });
  console.log("local asset_content:", asset_content);
  const assets = JSON.parse(asset_content);
  console.log("local assets:", assets);

我仍然没有异常，结果为空：

[10:45:00] I | ReactNativeJS ▶︎ BLAH EXISTS

[10:45:00] I | ReactNativeJS ▶︎ 'local asset_content:', null

[10:45:00] I | ReactNativeJS ▶︎ 'local assets:', null

当我摆脱 Promisify 并离开 Promise 处理时，我又回到了开始的地方：

  const path = RNFetchBlob.fs.dirs.DocumentDir + '/' + ASSET_FILENAME;
  if (await RNFS.exists(path)){
    console.log("BLAH EXISTS");
  } else {
    console.log("BLAH DOES NOT EXIST");
  }
  let asset_content = null;
  RNFS.readFile(path, 'utf8')
    .then((str) => {
      console.log("got result: ", str);
      asset_content = str;
    })
    .catch((e) => {
      console.log("got error:", e);
    });
  console.log("local asset_content:", asset_content);
  const assets = JSON.parse(asset_content);
  console.log("local assets:", assets);

output:

[10:49:45] I | ReactNativeJS ▶︎ BLAH EXISTS

[10:49:45] I | ReactNativeJS ▶︎ 'local asset_content:', null

[10:49:45] I | ReactNativeJS ▶︎ 'local assets:', null

[10:49:45] I | ReactNativeJS ▶︎ 'got result: ', '{"_40":0,"_65":0,"_55":null,"_72":null}'

请帮忙。文件处理对于我们的应用程序至关重要。

更新： 以下是 ASSET_FILE 引用的 asset.json 文件的内容：

{
  "protobuf": [
    {
      "name": "tiny-fovapp-4c",
      "lite": false,
      "compressed": false,
      "selected": false
    },
    {
      "name": "tiny-yolo-4c-quantized",
      "lite": true,
      "compressed": true,
      "selected": false
    },
    {
      "name": "tiny-yolo-4c",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "modelFilePath": "ai/protobuf/tiny-yolo-4c.pb",
      "labelsFilePath": "ai/protobuf/tiny-yolo-4c-labels.txt",
      "lite": false,
      "compressed": false,
      "selected": true
    },
    {
      "name": "tiny-yolo-4c",
      "lite": true,
      "compressed": false,
      "selected": false
    }
  ],
  "testImages": [
    {
      "name": "IMG_6924.jpg",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/IMG_6924.jpg"
    },
    {
      "name": "IMG_6924.png",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/IMG_6924.png"
    },
    {
      "name": "IMG_6929.jpg",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/IMG_6929.jpg"
    },
    {
      "name": "Part1.png",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/Part1.png"
    },
    {
      "name": "Part1_10.png",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/Part1_10.png"
    }
  ],
  "parts": [
    {
      "name": "Part1",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "modelFilename": "ai/models/Part1.png",
      "drawingFilename": "ai/drawings/Part1.png",
      "annotationFilename": "ai/annotations/Part1.xml"
    },
    {
      "name": "Part2",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "modelFilename": "ai/models/Part2.png",
      "drawingFilename": "ai/drawings/Part2.png",
      "annotationFilename": "ai/annotations/Part2.xml"
    },
    {
      "name": "Part3",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "modelFilename": "ai/models/Part3.png",
      "drawingFilename": "ai/drawings/Part3.png",
      "annotationFilename": "ai/annotations/Part3.xml"
    }
  ]
}

在react-native应用程序中读取json文件的步骤：-

1. 将其导入到您的组件中

import ASSET_FILE from '../assets/files/asset.json';

// 进口filename from '资产文件的路径';

2.现在在一个函数中

jsonParser(){
    var data = JSON.parse(JSON.stringify(ASSET_FILE));
    var tempProtobuf = []
    var temptestImages= []
    var tempparts= []
    tempProtobuf = data.Protobuf
    temptestImages = data.testImages
    tempparts = data.parts
}

// Now three of your objects are there in tempProtobuf, temptestImages, tempparts array respectively.

如果要在应用程序中显示，请迭代或保存状态。

希望这有帮助...谢谢:)