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【Java】 Java API 读取HDFS的单文件

作者:金宝 / 发布于2017/6/2/ 718

HDFS上的单文件：

-bash-3.2$ hadoop fs -ls /user/pms/ouyangyewei/data/input/combineorder/repeat_rec_category  
Found 1 items  
-rw-r--r--   2 deploy supergroup        520 2014-08-14 17:03 /user/pms/ouyangyewei/data/input/combineorder/repeat_rec_category/repeatRecCategory.txt  
文件内容：
-bash-3.2$ hadoop fs -cat /user/pms/ouyangyewei/data/input/combineorder/repeat_rec_category/repeatRecCategory.txt | more  
8104  
960985  
5472  
971917  
5320  
971895  
971902  
971922  
958261  
972047  
972050  

Java API使用FileSystem方式 读取HDFS单文件的方法
/** 
 * 获取可重复推荐的类目，以英文逗号分隔 
 * @param filePath 
 * @param conf 
 * @return 
 */  
public String getRepeatRecCategoryStr(String filePath) {  
    final String DELIMITER = "\t";  
    final String INNER_DELIMITER = ",";  
      
    String categoryFilterStrs = new String();  
    BufferedReader br = null;  
    try {  
        FileSystem fs = FileSystem.get(new Configuration());  
        FSDataInputStream inputStream = fs.open(new Path(filePath));  
        br = new BufferedReader(new InputStreamReader(inputStream));  
          
        String line = null;  
        while (null != (line = br.readLine())) {  
            String[] strs = line.split(DELIMITER);  
            categoryFilterStrs += (strs[0] + INNER_DELIMITER);  
        }  
    } catch (IOException e) {  
        e.printStackTrace();  
    } finally {  
        if (null != br) {  
            try {  
                br.close();  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
    }  
      
    return categoryFilterStrs;  
}

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