嘗試將JSON檔案或字串轉換為CSV檔案會得到一個空的CSV檔案

因此，我嘗試將 JSON 檔案（我已使用 Google Sheets API 匯出為 JSON）轉換為 CSV 檔案，即使在該位置正確放置了一個 JSON 檔案，或者嘗試使用字串，它也顯示為 null指標例外或回傳一個空的 CSV 檔案。

示例 JSON 檔案：

{
  "range": "products!A1:E4",
  "majorDimension": "ROWS",
  "values": [
    [
      "product_name",
      "price"
    ],
    [
      "Rugrats - Bedtime Bash [VHS]",
      "36.95"
    ],
    [
      "Teenage Mutant Ninja Turtles II - The Secret of the Ooze [VHS]",
      "29.89"
    ],
    [
      "Teenage Mutant Ninja Turtles II - The Secret of the Ooze [VHS]",
      "29.89"
    ]
  ]
}

我在這里嘗試使用的示例代碼將它們轉換為 CSV，

JSONObject output = new JSONObject(<String or file location that holds JSON file>);
File finalFile=new File(<Destination file path>);
JSONArray docs = output.getJSONArray("values");
String csv = CDL.toString(docs);
FileUtils.writeStringToFile(finalFile, csv);

我是否在代碼中犯了任何錯誤，或者我應該使用不同的 Java 代碼來處理這個 JSON？

uj5u.com熱心網友回復：

為什么不直接從 Sheets API 回應中撰寫（此示例摘自Java Sheet API quick-start）

public static void main(String... args) throws IOException, GeneralSecurityException {
    // Build a new authorized API client service.
    final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
    final String spreadsheetId = "<SHEET_ID>";
    final String range = "<SHEET_RANGE>";
    Sheets service = new Sheets.Builder(HTTP_TRANSPORT, JSON_FACTORY, getCredentials(HTTP_TRANSPORT))
            .setApplicationName(APPLICATION_NAME)
            .build();
    ValueRange response = service.spreadsheets().values()
            .get(spreadsheetId, range)
            .execute();
    List<List<Object>> values = response.getValues();
    if (values == null || values.isEmpty()) {
        System.out.println("No data found.");
    } else {
        /* Create a new writer */
        PrintWriter writer = new PrintWriter("data.csv");
        for (List<Object> list : values) {
            /* Building the string */
            StringBuilder str = new StringBuilder();
            str.append(list.get(0).toString()   ",");
            str.append(list.get(1).toString()   "\n");
            writer.write(str.toString());
        }
        /* Closing the writer */
        writer.close();
    }
}

無論如何，如果您正確讀取 JSON 物件，則機制將完全相同。

更新

如果您想直接從 JSON 讀取資料，可以使用此示例（使用GSON）：

public class SheetResponse {
    private String range;
    private String majorDimensions; 
    private List<List<Object>> values;
}

public static void main(String... args) throws IOException, GeneralSecurityException {
    // Build a new authorized API client service.
    var gson = new Gson();
    var reader = new JsonReader(new FileReader("test.json"));
    SheetResponse sR = gson.fromJson(reader, SheetResponse.class);
    PrintWriter writer = new PrintWriter("data.csv");
    for (List<Object> list : sR.values) {
        /* Building the string */
        StringBuilder str = new StringBuilder();
        str.append(list.get(0).toString()   ",");
        str.append(list.get(1).toString()   "\n");
        writer.write(str.toString());
    }
    /* Closing the writer */
    writer.close();
}

針對一般情況進行了更新

public static void main(String... args) throws IOException, GeneralSecurityException {
    // Build a new authorized API client service.
    var gson = new Gson();
    var reader = new JsonReader(new FileReader("test.json"));
    SheetResponse sR = gson.fromJson(reader, SheetResponse.class);
    PrintWriter writer = new PrintWriter("data.csv");

    for (int i = 0; i < sR.values.size(); i  ) {
        var valueRow = sR.values.get(i);
        StringBuilder str = new StringBuilder();
        for (int j = 0; j < valueRow.size(); j  ) {
            if (j == valueRow.size() - 1) {
                str.append(valueRow.get(j).toString()   "\n");
            } else {
                str.append(valueRow.get(j).toString()   ",");
            }
        }
        writer.write(str.toString());
    }
    /* Closing the writer */
    writer.close();
}

檔案

• PrintWriter
• StringBuilder

標籤：爪哇 json CSV 谷歌表格

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