<%@ page
contentType="text/html; charset=UTF-8"
import="javax.servlet.*"
import="javax.servlet.http.*"
import="java.io.*"
import="java.util.*"
import="java.net.*"
import="org.apache.hadoop.dfs.*"
import="org.apache.hadoop.io.*"
import="org.apache.hadoop.conf.*"
import="java.text.DateFormat"
%>
<%!
static JspHelper jspHelper = new JspHelper();
public void generateFileChunks(JspWriter out, HttpServletRequest req)
throws IOException {
long startOffset = 0;
int chunkSizeToView = 0;
String referrer = req.getParameter("referrer");
boolean noLink = false;
if (referrer == null) {
noLink = true;
}
String filename = req.getParameter("filename");
if (filename == null) {
out.print("Invalid input (filename absent)");
return;
}
String chunkSizeToViewStr = req.getParameter("chunkSizeToView");
if (chunkSizeToViewStr != null && Integer.parseInt(chunkSizeToViewStr) > 0)
chunkSizeToView = Integer.parseInt(chunkSizeToViewStr);
else chunkSizeToView = jspHelper.defaultChunkSizeToView;
if (!noLink)
out.print("");
else
out.print("" + filename + "
");
out.print("Chunk Size to view (in bytes, upto file's DFS blocksize): ");
out.print("");
out.print("
");
out.print("");
if (!noLink)
out.print("");
//fetch the block from the datanode that has the last block for this file
DFSClient dfs = new DFSClient(jspHelper.nameNodeAddr,
jspHelper.conf);
LocatedBlock blocks[] = dfs.namenode.open(filename);
if (blocks == null || blocks.length == 0) {
out.print("No datanodes contain blocks of file "+filename);
dfs.close();
return;
}
LocatedBlock lastBlk = blocks[blocks.length - 1];
long blockSize = lastBlk.getBlock().getNumBytes();
long blockId = lastBlk.getBlock().getBlockId();
DatanodeInfo chosenNode;
try {
chosenNode = jspHelper.bestNode(lastBlk);
} catch (IOException e) {
out.print(e.toString());
dfs.close();
return;
}
InetSocketAddress addr = DataNode.createSocketAddr(chosenNode.getName());
//view the last chunkSizeToView bytes while Tailing
if (blockSize >= chunkSizeToView)
startOffset = blockSize - chunkSizeToView;
else startOffset = 0;
out.print("");
dfs.close();
}
%>
Hadoop DFS File Viewer
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Hadoop, 2006.