如何使用FileUtils在JUnit Test中從資源目錄讀取csv文件

Question

在標准Maven項目的資源目錄中包含一個csv文件，如下所示：

src/main/resources/fruits.csv
src/test/resources/fruits.csv

fruits.csv

Type, Quantity
apple, 50
banana, 60
orange, 70

使用以下庫

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
</dependency>

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-csv</artifactId>
    <version>1.0</version>
</dependency>

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.4</version>
</dependency>

水果（標准POJO）

public class Fruit {

    private String type
    private int quantity;

    public Fruit(String type, int quantity) {
        this.type = type;
        this.quantity = quantity;
    }

    // Getters & Setters
}

CsvFileReader

public class CsvFileReader {

    private static final String [] FILE_HEADER = {""};

    private static final String TYPE = "Type";
    private static final String QUANTITY + "Quantity";

    public static List<Candidate> readCsvFile(File fileName) {
        FileReader fileReader = null;
        CSVParser csvFileParser = null;

        CSVFormat csvFormat = CSVFormat.DEFAULT.withHeader(FILE_HEADER);
        List<Candidate> fruits = null;
        try {
            fruits = new ArrayList<>();
            String file = FileUtils.readFileToString(fileName);
            fileReader = new FileReader(file);
            csvFileParser = new CSVParser(fileReader, csvFormat);
            List<CSVRecord> records = csvFileParser.getRecords();

            for (int i = 1; i < records.size(); i++) {
                CSVRecord record = records.get(i);
                Fruit fruit = new Fruit(record.get(TYPE), Integer.parseInt(QUANTITY));
                fruits.add(fruit);
            }
        } 
        catch(Throwable t) {
            t.printStackTrace();
        } 
        finally {
            try {
                fileReader.close();
                csvFileParser.close();
            } catch(IOException e) {
                e.printStackTrace();
            }
        }
        return fruits;
    }
}

CsvFileReaderTest（JUnit 4測試用例）：

public class CsvFileReaderTest {

    File csvFile = null;

    @Before
    public void setUp() throws Exception {
        String userDir = System.getProperty("user.dir");
        String filePath = userDir + File.separator + "src" + File.separator + "main" + File.separator + "resources" + File.separator;
        csvFile = FileUtils.getFile(filePath + "fruits.csv");
    }
}

當我在Eclipse中運行JUnit測試用例時：

java.io.FileNotFoundException: Type, Quantity
apple, 50
banana, 60
orange, 70
(File name too long)
    at java.io.FileInputStream.open(Native Method)
    at java.io.FileInputStream.<init>(FileInputStream.java:146)
    at java.io.FileInputStream.<init>(FileInputStream.java:101)
    at java.io.FileReader.<init>(FileReader.java:58)

似乎正在讀取文件，但問題是FileName太長？

我究竟做錯了什么？

Answer 1

FileReader構造函數需要傳遞文件內容的文件路徑。 您可以直接使用采用CSV String CSVParser構造函數。

csvFileParser = new CSVParser(file /*This is already file content*/, csvFormat);

**編輯**

更好的辦法是獲取資源的閱讀器，並將其傳遞給CSVParser構造函數：

reader = new BufferedReader(new InputStreamReader(
                       this.getClass().getResourceAsStream("fruits.csv")));
csvFileParser = new CSVParser(reader, csvFormat);