FileReader的编码问题

有一个UTF-8编码的文本文件，用FileReader读取到一个字符串，然后转换字符集：str=new String(str.getBytes(),"UTF-8");结果大部分中文显示正常，但最后仍有部分汉字显示为问号！

public static List<String> getLines( String fileName )
{
    List<String> lines = new ArrayList<String>();
    try
    {
        BufferedReader br = new BufferedReader(new FileReader(fileName));
        String line = null;
        while( ( line = br.readLine() ) != null )
            lines.add(new String(line.getBytes("GBK"), "UTF-8"));
        br.close();
    }
    catch( FileNotFoundException e )
    {
    }
    catch( IOException e )
    {
    }
    return lines;
}

public static List<String> getLines( String fileName ) { List<String> lines = new ArrayList<String>(); try { BufferedReader br = new BufferedReader(new FileReader(fileName)); String line = null; while( ( line = br.readLine() ) != null ) lines.add(new String(line.getBytes("GBK"), "UTF-8")); br.close(); } catch( FileNotFoundException e ) { } catch( IOException e ) { } return lines; }

文件读入时是按OS的默认字符集即GBK解码的，我先用默认字符集GBK编码str.getBytes(“GBK”)，此时应该还原为文件中的字节序列了，然后再按UTF-8解码，生成的字符串按理说应该就应该是正确的。

为什么结果中还是有部分乱码呢？
问题出在FileReader读取文件的过程中，FileReader继承了InputStreamReader，但并没有实现父类中带字符集参数的构造函数，所以FileReader只能按系统默认的字符集来解码，然后在UTF-8 -> GBK -> UTF-8的过程中编码出现损失，造成结果不能还原最初的字符。

原因明确了，用InputStreamReader代替FileReader，InputStreamReader isr=new InputStreamReader(new FileInputStream(fileName),"UTF-8");这样读取文件就会直接用UTF-8解码，不用再做编码转换。

public static List<String> getLines( String fileName )
{
    List<String> lines = new ArrayList<String>();
    try
    {
        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), "UTF-8"));
        String line = null;
        while( ( line = br.readLine() ) != null )
            lines.add(line);
        br.close();
    }
    catch( FileNotFoundException e )
    {
    }
    catch( IOException e )
    {
    }
    return lines;
}

public static List<String> getLines( String fileName ) { List<String> lines = new ArrayList<String>(); try { BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), "UTF-8")); String line = null; while( ( line = br.readLine() ) != null ) lines.add(line); br.close(); } catch( FileNotFoundException e ) { } catch( IOException e ) { } return lines; }