/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.util;
import java.io.*;
import java.util.Calendar;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.httpclient.URIException;
import org.apache.commons.httpclient.util.URIUtil;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import com.google.common.base.Preconditions;
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class ServletUtil {
/**
* Initial HTML header
*/
public static PrintWriter initHTML(ServletResponse response, String title
) throws IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>\n"
+ "<link rel='stylesheet' type='text/css' href='/static/hadoop.css'>\n"
+ "<title>" + title + "</title>\n"
+ "<body>\n"
+ "<h1>" + title + "</h1>\n");
return out;
}
/**
* Get a parameter from a ServletRequest.
* Return null if the parameter contains only white spaces.
*/
public static String getParameter(ServletRequest request, String name) {
String s = request.getParameter(name);
if (s == null) {
return null;
}
s = s.trim();
return s.length() == 0? null: s;
}
/**
* @return a long value as passed in the given parameter, throwing
* an exception if it is not present or if it is not a valid number.
*/
public static long parseLongParam(ServletRequest request, String param)
throws IOException {
String paramStr = request.getParameter(param);
if (paramStr == null) {
throw new IOException("Invalid request has no " + param + " parameter");
}
return Long.valueOf(paramStr);
}
public static final String HTML_TAIL = "<hr />\n"
+ "<a href='http://hadoop.apache.org/core'>Hadoop</a>, "
+ Calendar.getInstance().get(Calendar.YEAR) + ".\n"
+ "</body></html>";
/**
* HTML footer to be added in the jsps.
* @return the HTML footer.
*/
public static String htmlFooter() {
return HTML_TAIL;
}
/**
* Generate the percentage graph and returns HTML representation string
* of the same.
*
* @param perc The percentage value for which graph is to be generated
* @param width The width of the display table
* @return HTML String representation of the percentage graph
* @throws IOException
*/
public static String percentageGraph(int perc, int width) throws IOException {
assert perc >= 0; assert perc <= 100;
StringBuilder builder = new StringBuilder();
builder.append("<table border=\"1px\" width=\""); builder.append(width);
builder.append("px\"><tr>");
if(perc > 0) {
builder.append("<td cellspacing=\"0\" class=\"perc_filled\" width=\"");
builder.append(perc); builder.append("%\"></td>");
}if(perc < 100) {
builder.append("<td cellspacing=\"0\" class=\"perc_nonfilled\" width=\"");
builder.append(100 - perc); builder.append("%\"></td>");
}
builder.append("</tr></table>");
return builder.toString();
}
/**
* Generate the percentage graph and returns HTML representation string
* of the same.
* @param perc The percentage value for which graph is to be generated
* @param width The width of the display table
* @return HTML String representation of the percentage graph
* @throws IOException
*/
public static String percentageGraph(float perc, int width) throws IOException {
return percentageGraph((int)perc, width);
}
/**
* Escape and encode a string regarded as within the query component of an URI.
* @param value the value to encode
* @return encoded query, null if the default charset is not supported
*/
public static String encodeQueryValue(final String value) {
try {
return URIUtil.encodeWithinQuery(value, "UTF-8");
} catch (URIException e) {
throw new AssertionError("JVM does not support UTF-8"); // should never happen!
}
}
/**
* Escape and encode a string regarded as the path component of an URI.
* @param path the path component to encode
* @return encoded path, null if UTF-8 is not supported
*/
public static String encodePath(final String path) {
try {
return URIUtil.encodePath(path, "UTF-8");
} catch (URIException e) {
throw new AssertionError("JVM does not support UTF-8"); // should never happen!
}
}
/**
* Parse and decode the path component from the given request.
* @param request Http request to parse
* @param servletName the name of servlet that precedes the path
* @return decoded path component, null if UTF-8 is not supported
*/
public static String getDecodedPath(final HttpServletRequest request, String servletName) {
try {
return URIUtil.decode(getRawPath(request, servletName), "UTF-8");
} catch (URIException e) {
throw new AssertionError("JVM does not support UTF-8"); // should never happen!
}
}
/**
* Parse the path component from the given request and return w/o decoding.
* @param request Http request to parse
* @param servletName the name of servlet that precedes the path
* @return path component, null if the default charset is not supported
*/
public static String getRawPath(final HttpServletRequest request, String servletName) {
Preconditions.checkArgument(request.getRequestURI().startsWith(servletName+"/"));
return request.getRequestURI().substring(servletName.length());
}
}