JAVA生成CSV文件，并向文件中追加内容

@Test
    public void writeObjectToFile() throws Exception {
        for (int i=0; i< 5; i++) {
            RandomAccessFile randomFile = null;
            String fileName = ResourceUtils.getURL("classpath:").getPath() + "a.csv";
            String[] headArr = new String[]{"PointId", "X", "Y"};
            try {
                // 打开一个随机访问文件流，按读写方式
                randomFile = new RandomAccessFile(fileName, "rw");
                // 文件长度，字节数

                if (randomFile.length()==0) {
                    randomFile.writeBytes(String.join(",", headArr));
                    randomFile.writeBytes("\r\n");
                }
                // 将写文件指针移到文件尾。
                long fileLength = randomFile.length();
                randomFile.seek(fileLength);
                randomFile.writeBytes("aa,22222,33333");
                randomFile.writeBytes("\r\n");
            } catch (IOException e) {
                e.printStackTrace();
            } finally{
                if(randomFile != null){
                    try {
                        randomFile.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }