读取逗号分隔配置文件的最佳方法是什么？

Question

我有一个逗号分隔的配置文件.空行被忽略,无效行需要出错:

FOO,酒吧

foo2,bar3

我想将这个文件读入一个HashMap键(foo)与值(bar)映射的位置.

做这个的最好方式是什么？

Answer 1

如果您可以使用x = y而不是x,y那么您可以使用Properties类.

如果你确实需要x,y然后查看java.util.Scanner,你可以设置分隔符用作分隔符(javadoc显示了这样做的例子).

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

class Main
{
    public static void main(final String[] argv)
    {
        final File file;

        file = new File(argv[0]);

        try
        {
            final Scanner scanner;

            scanner = new Scanner(file);

            while(scanner.hasNextLine())
            {
                if(scanner.hasNext(".*,"))
                {
                    String key;
                    final String value;

                    key = scanner.next(".*,").trim();

                    if(!(scanner.hasNext()))
                    {
                        // pick a better exception to throw
                        throw new Error("Missing value for key: " + key);
                    }

                    key   = key.substring(0, key.length() - 1);
                    value = scanner.next();

                    System.out.println("key = " + key + " value = " + value);
                }
            }
        }
        catch(final FileNotFoundException ex)
        {
            ex.printStackTrace();
        }
    }
}

和属性版本(解析方式更简单,因为没有)

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.util.Properties;

class Main
{
    public static void main(final String[] argv)
    {
        Reader reader;

        reader = null;

        try
        {
            final Properties properties;

            reader = new BufferedReader(
                            new FileReader(argv[0]));
            properties = new Properties();
            properties.load(reader);
            System.out.println(properties);
        }
        catch(final IOException ex)
        {
            ex.printStackTrace();
        }
        finally
        {
            if(reader != null)
            {
                try
                {
                    reader.close();
                }
                catch(final IOException ex)
                {
                    ex.printStackTrace();
                }
            }
        }
    }
}

Answer 2

最好的办法是使用java.util.Scanner类读取配置文件中的值,使用逗号作为分隔符.链接到Javadoc:

http://java.sun.com/j2se/1.5.0/docs/api/java/util/Scanner.html

示例是:

Scanner sc = new Scanner(new File("thing.config"));
sc.useDelimiter(",");
while (sc.hasNext()) {
   String token = sc.next();
}