解决方案时super不能成为java中的第一行构造函数

我正在使用CSVReader类,它将本地文件作为输入.但现在,我需要能够读取本地文件以及具有URL路径的文件(如 http://example.com/example.txt).为此,我想从CSVReader派生一个类,用于标识文件是本地文件还是URL,然后使用构造函数第一行中的super()将InputStream传递给父文件.这样做的优雅方式是什么？

public class FileReader extends CsvReader{
    public FileReader(){
        if (fileName != null) {

               if (fileName.trim().startsWith("http:")) {
                // it is URL
                URL url = new URL(fileName);
                inputStream = new BufferedReader(new InputStreamReader(
                        url.openStream(),charset),StaticSettings.MAX_FILE_BUFFER_SIZE); 
               }else{
                //it is a local file
                inputStream = new BufferedReader(new InputStreamReader(
                        new FileInputStream(fileName),StaticSettings.MAX_FILE_BUFFER_SIZE);
               } 

            }
            //Now pass the input stream to CsvReader
            super(inputStream,delimiter,charset);  //error - super has to be first line of constructor
    }
}

解决方法

你可以编写辅助方法：

super(createReader(createInputStream(resouce),"UTF-8"),";");

您的辅助方法可能如下所示：

public static InputStream createInputStream(String resource)
{
     resource = resource.trim();

     if (resource.startsWith("http:"))
     {
          return new URL(resource).openStream();
     } else
     {
          return new FileInputStream(new File(resource));
     }
}

public static BufferedReader createReader(InputStream is,String charset)
{
     return new BufferedReader(new InputStreamReader(is,charset));
}