requestresponseservlet.java

来自「JAVA Servlet2.3外文书籍源码」· Java 代码 · 共 158 行

JAVA
158 行
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package basicServlets;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;

/**
 * Title:        Professional Java Servlet Programming - Chapter 2
 * Description:  Servlet to demonstrat the use of request and response objects
 * Copyright:    Copyright (c) 2001
 * @author Andrew Harbourne-Thomas
 * @version 1.0
 */
public class RequestResponseServlet extends GenericServlet
{
  /**
   * Output a web page with request information and response data.
   *
   * @param request The object containing the client request
   * @param response The object used to send the response back
   */
  public void service(ServletRequest request, ServletResponse response)
    throws ServletException, IOException
  {
    StringBuffer requestTable = getRequestTable(request);
    StringBuffer responseTable = getResponseTable(request, response);

    response.setContentType("text/html");
    PrintWriter out = response.getWriter();

    //HTML page
    out.println("<html><head><title>RequestResponseServlet</title></head><body>");
    out.println("<h1>Request Information</h1>" + requestTable + "<hr>");
    out.println("<h1>Response Information</h1>" + responseTable);
    out.println("</body></html>");
    out.close();
  }

  /**
   * Prepare a HTML table of information about the request made.
   *
   * @param request The object containing the client request
   * @return String containing the table
   */
  private StringBuffer getRequestTable(ServletRequest request)
  {
    HTMLTable table = new HTMLTable();

    table.appendTitleRow("Parameters");
    Enumeration e = request.getParameterNames();
    while (e.hasMoreElements())
    {
      String paramName = (String)e.nextElement();
      String[] paramValues = request.getParameterValues(paramName);
      if (paramValues != null)
      {
        for (int i = 0; i < paramValues.length; i++)
        {
          table.appendRow("Parameter: <code>" + paramName + "</code>", paramValues[i]);
        }
      }
    }

    table.appendTitleRow("Headers");
    int requestLength = request.getContentLength();
    if (requestLength == -1)
    {
      table.appendRow("Request Length", "(Not Specified)");
    }
    else
    {
       table.appendRow("Request Length", requestLength);
    }
    table.appendRow("Content Type", request.getContentType());
    table.appendRow("Request Protocol", request.getProtocol());


    table.appendTitleRow("Attributes");
    request.setAttribute("My Attribute", "My Attribute Value");
    request.setAttribute("Another Attribute", "123");

    Enumeration enum = request.getAttributeNames();
    while (enum.hasMoreElements())
    {
      String attributeName = (String)enum.nextElement();
      Object attributeValue = request.getAttribute(attributeName);
      if (attributeValue != null)
      {
        table.appendRow("Attribute: <code>" + attributeName + "</code>",
                        attributeValue.toString());
      }
    }

    table.appendTitleRow("Path Information");
    table.appendRow("Request Scheme", request.getScheme());
    table.appendRow("Request Server", request.getServerName());
    table.appendRow("Request Port", request.getServerPort());

    table.appendTitleRow("Security");
    table.appendRow("Secure Request", request.isSecure());

    table.appendTitleRow("Internationalization");
    Locale locale = request.getLocale();
    table.appendRow("Preferred Locale", locale.toString());
    table.appendRow("Country (ISO Code)", locale.getCountry());
    table.appendRow("Country", locale.getDisplayCountry());
    table.appendRow("Language", locale.getDisplayLanguage());
    table.appendRow("Locale Name", locale.getDisplayName());
    table.appendRow("Character Encoding", request.getCharacterEncoding());

    table.appendTitleRow("Client Information");
    table.appendRow("Client IP Address", request.getRemoteAddr());
    table.appendRow("Client Name", request.getRemoteHost());

    return table.toStringBuffer();

  }

  /**
   * Prepare a HTML table of information about the response made.
   *
   * @param request Gives access to the request object
   * @param response Gives access to the response object
   * @return String containing the table
   */
  private StringBuffer getResponseTable(ServletRequest request,
                                        ServletResponse response)
  {
    HTMLTable table = new HTMLTable();

    table.appendTitleRow("Internationalization");
    Locale locale = response.getLocale();
    table.appendRow("Response Locale", locale.toString());
    table.appendRow("Country (ISO Code)", locale.getCountry());
    table.appendRow("Country", locale.getDisplayCountry());
    table.appendRow("Language", locale.getDisplayLanguage());
    table.appendRow("Locale Name", locale.getDisplayName());
    response.setLocale(locale);
    table.appendRow("Character Encoding", response.getCharacterEncoding());

    table.appendTitleRow("Buffering");
    int buffer = response.getBufferSize();
    table.appendRow("Buffer Size", buffer);

    //we need this for our dispatcher servlet to indicate that the
    //response is already committed
    String written = (String) request.getAttribute("buffer");

    if (!response.isCommitted() && !"written".equalsIgnoreCase(written))
    {
      response.setBufferSize(buffer + 1);
    }
    table.appendRow("Is Response Committed", new Boolean(response.isCommitted()).toString());

    return table.toStringBuffer();
  }
}

requestresponseservlet.java - 源码说明

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