HDFS For Java详解大数据

package cn.hwadee.wuyang.hdfs.utils; 
 
import java.io.ByteArrayOutputStream; 
import java.io.IOException; 
import java.io.OutputStream; 
import java.net.URI; 
 
import org.apache.hadoop.conf.Configuration; 
import org.apache.hadoop.fs.FSDataInputStream; 
import org.apache.hadoop.fs.FileStatus; 
import org.apache.hadoop.fs.FileSystem; 
import org.apache.hadoop.fs.Path; 
import org.apache.hadoop.io.IOUtils; 
 
public class ConfigurationUtil { 
 
    private static String url = "hdfs://192.168.193.201:9000"; 
 
    private static String user = "wuyang"; 
 
    private static FileSystem fs; 
 
    /** 
     * 获取文件系统 
     * @return 
     */ 
    public static FileSystem getFileSystem(){ 
        Configuration conf = new Configuration(); 
        try { 
            return FileSystem.get(URI.create(url), conf, user); 
        } catch (Exception e) { 
            return null; 
        } 
    } 
 
    /** 
     * 创建文件夹 
     * @param path 
     * @throws IOException  
     */ 
    public static Boolean createFileDir(Path path) throws IOException{ 
        Configuration conf = new Configuration(); 
        try { 
            fs = FileSystem.get(URI.create(url), conf, user); 
            if(!fs.exists(path)){ 
                fs.mkdirs(path); 
                System.out.println(path.getName()+"文件夹创建成功！！！"); 
                return true; 
            } 
            return false; 
        } catch (Exception e) { 
            e.getMessage(); 
            return false; 
        }finally { 
            fs.close(); 
        } 
    } 
 
    /** 
     * 删除文件 
     * @param path 
     * @throws IOException  
     */ 
    public static Boolean deleteFile(Path path) throws IOException{ 
        Configuration conf = new Configuration(); 
        try { 
            fs = FileSystem.get(URI.create(url), conf, user); 
            if(fs.exists(path)){ 
                fs.delete(path, true); 
                System.out.println(path.getName()+"文件删除成功！！！"); 
                return true; 
            } 
            return false; 
        } catch (Exception e) { 
            e.getMessage(); 
            return false; 
        }finally { 
            fs.close(); 
        } 
    } 
 
    /** 
     * 重命名 
     * @param name1 
     * @param name2 
     * @throws IOException  
     */ 
    public static Boolean fileRename(Path name1,Path name2) throws IOException { 
        Configuration conf = new Configuration(); 
        try { 
            fs = FileSystem.get(URI.create(url), conf, user); 
            if (fs.exists(name1)) { 
                fs.rename(name1, name2); 
                System.out.println(name2.getName()+"替换"+name1.getName()+"成功!!!"); 
                return true; 
            } 
            return false; 
        } catch (Exception e) { 
            e.getMessage(); 
            return false; 
        }finally { 
            fs.close(); 
        } 
    } 
 
    /** 
     * 创建文件 
     * @param path 
     * @return 
     */ 
    public static Boolean createFile(Path path){ 
        Configuration conf = new Configuration(); 
        try { 
            fs = FileSystem.get(URI.create(url), conf, user); 
            if(!fs.exists(path)){ 
                fs.create(path); 
                System.out.println(path.getName()+"文件创建成功！！！"); 
                return true; 
            }else{ 
                System.out.println(path.getName()+"文件已经存在！！！"); 
                return false; 
            } 
 
        }catch (Exception e) { 
            e.getMessage(); 
            return false; 
        }finally { 
            try { 
                fs.close(); 
            } catch (IOException e) { 
                e.getMessage(); 
            } 
        } 
    } 
 
    /** 
     * 获取path下文件 
     * @param path 
     * @return 
     */ 
    public static FileStatus[] listFile(Path path){ 
        Configuration conf = new Configuration(); 
        try { 
            fs = FileSystem.get(URI.create(url), conf, user); 
            if(fs.exists(path)){ 
                FileStatus[] list = fs.listStatus(path); 
                System.out.println("文件长度:"+list.length); 
                return list; 
            } 
            return null; 
        } catch (Exception e) { 
            e.getMessage(); 
            return null; 
        }    
    } 
 
    /** 
     * 从hdfs上下载文件 
     * @param hdfspath 
     * @param locationpath 
     * @return 
     */ 
    public static Boolean downLoadFileFromHDFS(Path hdfspath,Path locationpath){ 
        Configuration conf = new Configuration(); 
        try { 
            fs = FileSystem.get(URI.create(url), conf, user); 
            if(fs.exists(hdfspath)){ 
                fs.copyToLocalFile(hdfspath, locationpath); 
                System.out.println("download: from" + hdfspath.getName() + " to " + locationpath.getName()); 
                return true; 
            } 
            return false; 
        } catch (Exception e) { 
            e.getMessage(); 
            return false; 
        }finally { 
            try { 
                fs.close(); 
            } catch (IOException e) { 
                e.getMessage(); 
            } 
        }    
    } 
 
     /** 
     * 拷贝文件到HDFS 
     * @param local 
     * @param remote 
     * @throws IOException 
     */ 
    public static Boolean copyFileToHDFS(String local, String remote) throws IOException { 
        Configuration conf = new Configuration(); 
        try { 
            fs = FileSystem.get(URI.create(url), conf, user); 
            fs.copyFromLocalFile(new Path(local), new Path(remote)); 
            System.out.println("copy from: " + local + " to " + remote); 
            return true; 
        } catch (Exception e) { 
            e.getMessage(); 
            return false; 
        }finally { 
            try { 
                fs.close(); 
            } catch (IOException e) { 
                e.getMessage(); 
            } 
        }    
    } 
 
    /** 
     * 查看文件中的内容 
     * @param remoteFile 
     * @return 
     * @throws IOException 
     * @throws InterruptedException  
     */ 
    public static String catFile(String remoteFile) throws IOException, InterruptedException { 
        Path path = new Path(remoteFile); 
        Configuration conf = new Configuration(); 
        fs = FileSystem.get(URI.create(url), conf, user); 
        FSDataInputStream fsdis = null; 
 
        OutputStream baos = new ByteArrayOutputStream(); 
        String str = null; 
        try { 
            fsdis = fs.open(path); 
            IOUtils.copyBytes(fsdis, baos, 4096, false); 
            str = baos.toString(); 
        } finally { 
            IOUtils.closeStream(fsdis); 
            fs.close(); 
        } 
        return str; 
    } 
}