java - getResourceAsStream 方法返回 null InputStream

Question

此类读取 CSV 文件。

public class ReadCSVFile {

    private static final String SEMICOLON_DELIMITER = ";";


    public Map<Integer,Company> listFromFile(String csvFile) throws IOException {

        BufferedReader br = null;

        br = new BufferedReader(new 
        InputStreamReader(ReadCSVFile.class.getResourceAsStream(csvFile)));

        Map<Integer,Company> companyHashMap = new HashMap();

        String line;

        br.readLine();

        while ((line = br.readLine()) != null) {

            int pos = line.indexOf(SEMICOLON_DELIMITER);
            String companyCode = line.substring(0,pos);
            String companyName = line.substring(pos +1, line.length());

            companyHashMap.put(Integer.parseInt(companyCode), new Company(Integer.parseInt(companyCode), companyName));
        }

        return companyHashMap;
    }
}

这是对 ReadCSVFile 类的测试:

public class ReadCSVFileTest {

private ReadCSVFile readCSVFile;

@Before
public void before(){

    readCSVFile = new ReadCSVFile();
}

@Test
public void shouldExtractCompanyFromCSV() throws IOException {

    Map<Integer, Company> result = readCSVFile.listFromFile("test_company_list.csv");
    Assert.assertEquals(2,result.size());
    Assert.assertEquals("Goldman Sachs Group Inc",result.get(65).getCompanyName());
    Assert.assertEquals("Repsol YPF SA (Please refer to Repsol SA and YPF SA)",result.get(66).getCompanyName());
}

最后，这是读取 test_company_list.csv 的文件，我用来比较测试结果:

 RepRisk Company ID;Company Name
65;Goldman Sachs Group Inc
66;Repsol YPF SA (Please refer to Repsol SA and YPF SA)

测试失败，我有这个消息:

java.lang.NullPointerException
    at java.io.Reader.<init>(Reader.java:78)
    at java.io.InputStreamReader.<init>(InputStreamReader.java:72)
    at app.ReadCSVFile.listFromFile(ReadCSVFile.java:21)
    at ReadCSVFileTest.shouldExtractCompanyFromCSV(ReadCSVFileTest.java:23)

我的程序有什么问题？我认为 JUnit 的设置是正确的。

行ReadCSVFile.java:21是这一行:

br = new BufferedReader(new InputStreamReader(ReadCSVFile.class.getResourceAsStream(csvFile)));

改为 (ReadCSVFileTest.java:23) 行:

 Map<Integer, Company> result = readCSVFile.listFromFile("test_company_list.csv");

Answer 1

请阅读getResourceAsStream 文档。

• @param name name of the desired resource
  • @return A {@link java.io.InputStream} object or {@code null} if
  • no resource with this name is found

您确定您发送的 csvFile 文件在正确的路径中吗？看来你必须使用绝对名称