读写hdfs文件（工作笔记）

import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.Map;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Maps;


public class LoadHdfsTemplate {
    static final Logger logger = LoggerFactory
            .getLogger(LoadHdfsTemplate.class);
    
    protected FileSystem fileSystem ;
    
    private String hdfsPath = "/template/template.txt";
    
    public final boolean checkFile(String filePath) {
        boolean exists = false;
        try {
            Path path = new Path(filePath);
            exists = fileSystem.exists(path);
        } catch (IOException e) {
            logger.error("接口模板文件不存在！", e);
        } catch (Exception e) {
            logger.error("", e);
        }
        return exists;
    }
    
    public Map<String,Object> readHdfsFile() throws IOException{
        fileSystem = FileSystem.get(new Configuration());
        Path path = new Path(hdfsPath);
        InputStream in = fileSystem.open(path);
        List<String> lines = IOUtils.readLines(in);
        if(null == lines || lines.isEmpty()){
            return null;
        }
        Map<String,Object> map =  Maps.newConcurrentMap();
        int rowNum = 0;
        for(String line : lines){
            rowNum++;
            String[] content = line.split("    ");
            String code = content[0].trim();
            String template = content[1].trim();
            if(StringUtils.isEmpty(line) || StringUtils.isEmpty(template)){
                logger.error("第{}条模板格式错误！内容为:{}",rowNum,line);
                continue;
            }
            map.put(code, template);
        }
        return map;
        
    }

    public void setHdfsPath(String hdfsPath) {
        this.hdfsPath = hdfsPath;
    }
}

 应用场景为，读取hdfs上的文件，并转化成<k,v>形式存入内存。