使用Hadoop Map-Reduce删除不可打印字符

Question

我试图处理一个HDFS文件，其中有不可打印的chracters。我希望使用MapReduce删除这些字符。

我曾尝试使用Pig TextLoader和MR TextInputFormat（在MR程序中），结果将记录从遇到不可打印字符的位置拆分为多个。下面是示例数据：

===数据==(2条记录）=

 4614:2011-12-20-08.45.08.169176^2011-12-20-18.15.08.100008^597^0^57^ZUKA^Grase^^^Grase,Dr^^^N^N^N^Dr^KG^ONLY INFORMATION ENTERED^UNKNOWN^0     ^      ^^^611190362
�^0^^^^^^0^Grase,Dr^^^, ,^^^^^^597^^^<fnm>DR</fnm><lnm>GRASE</lnm>^^^^^^^^SINGLE^0^0
6063:2010-07-04-04.00.00.100001^2010-07-04-04.01.00.180144^017^0^095^WEETE    ^Wien^^^Wien,Colock^^^N^N^N^Colock^KG^ONLY INFORMATION ENTERED^UNKNOWN^0     ^      ^295111915^^������9905^0^^^^^^0^Wien,Colock^40001 KIN RD^300 CAMORE ST^500 BLACK AVE^Woesfield, HA, 43723.^John Ball^^^25719110^617^������9905^^<fnm>COLOCK</fnm><lnm>WIEN</lnm>^^^^^^^^SINGLE^0^0

下面是我使用基本UDF所做的尝试（代码片段如下）。不过，该程序正在对>0x80的charcters进行条带化，但对拆分的记录执行条带化。

任何帮助/指针将不胜感激！！

        /*
     * 
     * Pig Code:
     * register '/basepath/udf/DIF.jar'
    rel1 = LOAD '/user/home/test' USING USING TextLoader();
    rel2 = FOREACH rel1 GENERATE StripNonPrintable(s) as recordline;
    dump rel2;

     * 
     */

  //Imports    

    public class StripNonPrintable extends EvalFunc<String>
    {
         public String exec(Tuple input) throws IOException {
             if (input == null || input.size() == 0)
                 return null;
             try{

                    String s = new String();
                     s = (String)input.get(0);
                    //s = "2001-12-20-08.45.08.169176^2001-12-20-08.45.08.131408^597^0^57^ZUCKA^Grase^^^Grase,Dr^^^N^N^N^Dr^KG^ONLY INFORMATION ENTERED^UNKNOWN^0     ^      ^^^6785790362�^0^^^^^^0^Grase,Dr^^^, ,^^^^^^597^^^<fnm>DR</fnm><lnm>GRASE</lnm>^^^^^^^^SINGLE^0^0";

                    int length = s.length();
                    char[] oldChars = new char[length];
                    s.getChars(0, length, oldChars, 0);
                    int newLen = 0;
                    for (int j = 0; j < length; j++) {
                        char ch = oldChars[j];
                        if (ch < 0x80  ) {
                            oldChars[newLen] = ch;
                            newLen++;
                        }
                    }
                    s = new String(oldChars, 0, newLen);

                    //System.out.println("New String = \n " + s);

                    return s;
             }catch(Exception e){
                 return null ;
             }
         }

     }

Answer 1

包java.lang.character。有一个函数gettype，该函数：

返回一个值，该值指示字符的一般类别

导入java.lang.character并替换：

if (ch < 0x80  )

int c = Character.getType(ch);
if(c != Character.CONTROL || 
            c != Character.CONNECTOR_PUNCTUATION || 
            c != Character.CURRENCY_SYMBOL || 
            c != Character.DASH_PUNCTUATION || 
            c != Character.DECIMAL_DIGIT_NUMBER || 
            c != Character.ENCLOSING_MARK || 
            c != Character.END_PUNCTUATION || 
            c != Character.FINAL_QUOTE_PUNCTUATION || 
            c != Character.INITIAL_QUOTE_PUNCTUATION || 
            c != Character.LETTER_NUMBER || 
            c != Character.LOWERCASE_LETTER || 
            c != Character.MATH_SYMBOL || 
            c != Character.MODIFIER_LETTER || 
            c != Character.MODIFIER_SYMBOL || 
            c != Character.OTHER_LETTER || 
            c != Character.OTHER_NUMBER || //remove it if you want to get rid of ½ 
            c != Character.OTHER_PUNCTUATION || 
            c != Character.OTHER_SYMBOL || 
            c != Character.START_PUNCTUATION || 
            c != Character.TITLECASE_LETTER || 
            c != Character.UPPERCASE_LETTER)