无法从文件中读取数据

Question

我正试图从CSV文件中读取值，该文件存在于包com.example中。但是当我用以下语法运行代码时:

DataModel model = new FileDataModel(new File("Dataset.csv"));

上面写着:

java.io.FileNotFoundException: Dataset.csv

我也试过使用:

DataModel model = new FileDataModel(new File("/com/example/Dataset.csv"));

仍然不能工作。任何帮助都会很有帮助。谢谢。

Answer 1

如果这是来自org.apache.mahout.cf.taste.impl.model.file的FileDataModel，那么它不能接受输入流，只需要一个文件。问题是你不能假设这个文件对你来说是那么容易的(见这个问题的答案)。

最好读取文件的内容并将其保存到临时文件中，然后将该临时文件传递给FileDataModel。

InputStream initStream = getClass().getClasLoader().getResourceAsStream("Dataset.csv");
//simplistic approach is to put all the contents of the file stream into memory at once
//  but it would be smarter to buffer and do it in chunks
byte[] buffer = new byte[initStream.available()];
initStream.read(buffer);
//now save the file contents in memory to a temporary file on the disk
//choose your own temporary location - this one is typical for linux
String tempFilePath = "/tmp/Dataset.csv";  
File tempFile = new File(tempFilePath);
OutputStream outStream = new FileOutputStream(tempFile);
outStream.write(buffer);
DataModel model = new FileDataModel(new File(tempFilePath));
...

Answer 2

public class ReadCVS {
  public static void main(String[] args) {
    ReadCVS obj = new ReadCVS();
    obj.run();
  }
  public void run() {
    String csvFile = "file path of csv";
    BufferedReader br = null;
    String line = "";
    String cvsSplitBy = ",";
    try {
        br = new BufferedReader(new FileReader(csvFile));
        while ((line = br.readLine()) != null) {
                // Do stuff here
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (br != null) {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    System.out.println("Done");
  }
}

Answer 3

CSV文件，存在于包com.example

您可以使用getResource()或getResourceAsStream()从包内访问资源。例如

InputStream is = getClass().getResourceAsStream("/com/example/Dataset.csv");//uses absolute (package root) path
BufferedReader br = new BufferedReader(new InputStreamReader(is));
//read from BufferedReader

(注意为简洁，上面省略了异常处理和文件关闭)