📄 tail.jsp

📁 hadoop:Nutch集群平台
💻 JSP
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<%@ 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("<h2><a href=\"" + referrer + "\">" + filename + "</a></h2>");    else      out.print("<h2>" + filename + "</h2>");    out.print("<b>Chunk Size to view (in bytes, upto file's DFS blocksize): </b>");    out.print("<input type=\"text\" name=\"chunkSizeToView\" value=" +              chunkSizeToView + " size=10 maxlength=10>");    out.print("&nbsp;&nbsp;<input type=\"submit\" name=\"submit\" value=\"Refresh\"><hr>");    out.print("<input type=\"hidden\" name=\"filename\" value=\"" + filename +              "\">");    if (!noLink)      out.print("<input type=\"hidden\" name=\"referrer\" value=\"" +                 referrer+ "\">");    //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("<textarea cols=\"100\" rows=\"25\" wrap=\"virtual\" READONLY>");    jspHelper.streamBlockInAscii(addr, blockId, blockSize, startOffset, chunkSizeToView, out);    out.print("</textarea>");    dfs.close();  }%><html><meta http-equiv="refresh" content=60><title>Hadoop DFS File Viewer</title><body><form action="/tail.jsp" method=GET><%    generateFileChunks(out,request);%></form><hr><h2>Local logs</h2><a href="/logs/">Log</a> directory<hr><a href="http://lucene.apache.org/hadoop">Hadoop</a>, 2006.<br></body></html>
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