标签：hdfs api java代码分析与实例 hadopapi
HDFS API的java代码分析与实例
1.HDFS常用的方法，我已经写好，我们看一下
// Create()方法，直接在HDFS中写入一个新的文件，path为写入路径，text为写入的文本内容
public static void Create(String path,String text) throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000"); //Hadoop的Master的IP地址
FileSystem hdfs=FileSystem.get(conf);
byte[] buff=text.getBytes();
Path dfs=new Path(path);
FSDataOutputStream outputStream=hdfs.create(dfs);
outputStream.write(buff,0,buff.length);
System.out.println("文件创建成功！");
}
//从HDFS中删除一个文件，path为文件的地址
public static void delete(String path) throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem hdfs=FileSystem.get(conf);
Path delef=new Path(path);
boolean isDeleted=hdfs.delete(delef,false);
System.out.println("Delete?"+isDeleted);
System.out.println("文件删除成功！");
}
//查找一个文件在位于哪个Hadoop节点上，path为文件的地址
public static void findLocation(String path) throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem hdfs=FileSystem.get(conf);
Path fpath=new Path(path);
FileStatus filestatus = hdfs.getFileStatus(fpath);
BlockLocation[] blkLocations = hdfs.getFileBlockLocations(filestatus, 0, filestatus.getLen());
int blockLen = blkLocations.length;
for(int i=0;i<blockLen;i++){
String[] hosts = blkLocations[i].getHosts();
System.out.println("文件的位置为：");
System.out.println("block_"+i+"_location:"+hosts[0]);
}
}
//将所有的Hadoop节点，列出来
public static List getNodes() throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem fs=FileSystem.get(conf);
DistributedFileSystem hdfs = (DistributedFileSystem)fs;
DatanodeInfo[] dataNodeStats = hdfs.getDataNodeStats();
List list = new ArrayList();
for(int i=0; i<dataNodeStats.length;i++) {
list.add( dataNodeStats[i].getHostName());
}
return list;
}
//显示Hadoop根节点中所有的文件，注意根节点为"\"
public static List listAllFile() throws IOException {
String path = "hdfs://192.168.1.220:9000/";
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem hdfs=FileSystem.get(conf);
Path listf =new Path(path);
FileStatus stats[]=hdfs.listStatus(listf);
List list = new ArrayList();
for(int i=0; i<stats.length;i++) {
list.add( stats[i].getPath().toString() );
}
return list;
}
//显示path路径下的所有的文件
public static List listFile(String path) throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem hdfs=FileSystem.get(conf);
Path listf =new Path(path);
FileStatus stats[]=hdfs.listStatus(listf);
List list = new ArrayList();
for(int i=0; i<stats.length;i++) {
list.add( stats[i].getPath().toString() );
}
return list;
}
//新建一个文件夹，path为新建后的文件地址
public static void mkdir(String path) throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem hdfs=FileSystem.get(conf);
Path dfs=new Path(path);
hdfs.mkdirs(dfs);
}
//重命名一个文件，path为全路径
public static void rename(String oldPath,String newPath) throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem hdfs=FileSystem.get(conf);
Path frpaht=new Path(oldPath); //旧的文件名
Path topath=new Path(newPath); //新的文件名
boolean isRename=hdfs.rename(frpaht, topath);
String result=isRename?"成功":"失败";
System.out.println("文件重命名结果为："+result);
}
//上传一个文件到Hadoop中的path路径下， path为全路径
public static void upload(String filepath,String hdfsPath) throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem hdfs=FileSystem.get(conf);
Path src =new Path(filepath); //本地文件
Path dst =new Path(hdfsPath); //HDFS为止
hdfs.copyFromLocalFile(src, dst);
System.out.println("Upload to"+" "+conf.get("fs.default.name"));
FileStatus files[]=hdfs.listStatus(dst);
for(FileStatus file:files){
System.out.println(file.getPath());
}
System.out.println("文件上传成功！");
}
//查看一个文件的详细信息，path为文件的全路径
public static void showFile(String path) throws IOException {
Configuration conf=new Configuration();
conf.set("fs.default.name", "hdfs://192.168.1.220:9000");
FileSystem hdfs=FileSystem.get(conf);
Path p = new Path(path);
FileStatus fileStatus = hdfs.getFileStatus(p);
System.out.println("文件路径："+fileStatus.getPath());
System.out.println("块的大小："+fileStatus.getBlockSize());
System.out.println("文件所有者："+fileStatus.getOwner()+":"+fileStatus.getGroup());
System.out.println("文件权限："+fileStatus.getPermission());
System.out.println("文件长度："+fileStatus.getLen());
System.out.println("备份数："+fileStatus.getReplication());
System.out.println("修改时间："+fileStatus.getModificationTime());
}
本文出自 “你若盛开，清风自来” 博客，请务必保留此出处http://iqdutao.blog.51cto.com/2597934/1792333
标签：hdfs api java代码分析与实例 hadopapi
原文地址：http://iqdutao.blog.51cto.com/2597934/1792333
