我正在尝试编写一个自定义读取器，用于读取具有定义字段数的记录（位于两行中）。
例如

1,2,3,4("," can be there or not)
,5,6,7,8

我的要求是读取记录并将其作为单个记录推入mapper，如 {1,2,3,4,5,6,7,8} . 请提供一些信息。
更新：

public boolean nextKeyValue() throws IOException, InterruptedException {
    if(key == null) {
        key = new LongWritable();
    }

    //Current offset is the key
    key.set(pos); 

    if(value == null) {
        value = new Text();
    }

    int newSize = 0;
    int numFields = 0;
    Text temp = new Text();
    boolean firstRead = true;

    while(numFields < reqFields) {
        while(pos < end) {
            //Read up to the '\n' character and store it in 'temp'
            newSize = in.readLine(  temp, 
                                    maxLineLength, 
                                    Math.max((int) Math.min(Integer.MAX_VALUE, end - pos), 
                                             maxLineLength));

            //If 0 bytes were read, then we are at the end of the split
            if(newSize == 0) {
                break;
            }

            //Otherwise update 'pos' with the number of bytes read
            pos += newSize;

            //If the line is not too long, check number of fields
            if(newSize < maxLineLength) {
                break;
            }

            //Line too long, try again
            LOG.info("Skipped line of size " + newSize + " at pos " + 
                        (pos - newSize));
        }

        //Exit, since we're at the end of split
        if(newSize == 0) {
            break;
        }
        else {
            String record = temp.toString();
            StringTokenizer fields = new StringTokenizer(record,"|");

            numFields += fields.countTokens();

            //Reset 'value' if this is the first append
            if(firstRead) {
                value = new Text();
                firstRead = false;
            }

            if(numFields != reqFields) {
                value.append(temp.getBytes(), 0, temp.getLength());
            }
            else {
                value.append(temp.getBytes(), 0, temp.getLength());
            }
        }
    }

    if(newSize == 0) {
        key = null;
        value = null;
        return false;
    }
    else {
        return true;
    }
}

}
这是我正在尝试的nextkeyvalue方法。但是Map器仍然没有得到正确的值。reqfields是4。