getResourceAsStream返回null

Question

为什么InputStream istream = this.getClass().getResourceAsStream("/isrs.csv")返回的是null？

public void run() {
        // 创建reader对象
        CSVReader reader = null;

        try {
            // 创建输入流
            final InputStream istream = this.getClass().getResourceAsStream("/isrs.csv");

            if (istream == null) {
                System.out.println("Cannot access data set, make sure the resources are available.");
                System.exit(1);
            }
            // 如果输入流不为空，初始化reader对象
            reader = new CSVReader(new InputStreamReader(istream));

            String[] nextLine;
            while ((nextLine = reader.readNext()) != null) {
                System.out.println(Arrays.toString(nextLine));
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        } finally {
            // 释放资源
            // 如果reader不为空，则关闭
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        }
    }

Answer 1

是不是存放文件的路径不对，我这里在eclipse下测试，发现需要将文件存放在eclise的bin目录下的某个工程目录下才可以。

测试如下：

参考链接：
https://www.cnblogs.com/macwhirr/p/8116583.html
https://mvnrepository.com/artifact/com.opencsv/opencsv
https://mvnrepository.com/artifact/org.apache.commons/commons-collections4
https://mvnrepository.com/artifact/org.apache.commons/commons-text
https://mvnrepository.com/artifact/org.apache.commons/commons-lang3
https://mvnrepository.com/artifact/commons-beanutils/commons-beanutils

使用OpenCSV在Java中读写CSV - 知乎 介绍这是专门 针对Java CSV读写库的简短系列文章的最后一篇，也是上一篇文章（使用Apache Commons CSV用Java读写CSV）的直接延续。OpenCSV OpenCSV是最简单易懂的CSV解析器之一，它使用标准Reader/Writer类并CSVRe… https://zhuanlan.zhihu.com/p/343069880

package com.csv.test;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;

import com.opencsv.CSVReader;
import com.opencsv.exceptions.CsvValidationException;

public class TestReadCsv {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        TestReadCsv trc = new TestReadCsv();
        try {
            trc.run();
        } catch (CsvValidationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    
     
    public void run() throws CsvValidationException {
        
            // https://mvnrepository.com/artifact/com.opencsv/opencsv
            // https://mvnrepository.com/artifact/org.apache.commons/commons-collections4
            // https://mvnrepository.com/artifact/org.apache.commons/commons-text
            // https://mvnrepository.com/artifact/org.apache.commons/commons-lang3
            // https://mvnrepository.com/artifact/commons-beanutils/commons-beanutils
            // https://zhuanlan.zhihu.com/p/343069880
            // 创建reader对象
            CSVReader reader = null;
     
            try {
                // https://www.cnblogs.com/macwhirr/p/8116583.html
                // 在eclipse中测试，需要是放在bin目录的某个工程目录下，我这里是使用"/com/csv"工程目录
                // 创建输入流
                final InputStream istream = this.getClass().getResourceAsStream("/com/csv/isrs.csv");
     
                if (istream == null) {
                    System.out.println("Cannot access data set, make sure the resources are available.");
                    System.exit(1);
                }
                // 如果输入流不为空，初始化reader对象
                reader = new CSVReader(new InputStreamReader(istream));
     
                String[] nextLine;
                while ((nextLine = reader.readNext()) != null) {
                    System.out.println(Arrays.toString(nextLine));
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            } finally {
                // 释放资源
                // 如果reader不为空，则关闭
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        }
}