requesthandler.java

来自「此程序都是企业级 的数据库开发程序 全面揭示了JAVA对数据库的操作」· Java 代码 · 共 59 行

package mvc;

import java.io.*;
import java.util.*;

/*
 * The two classes imported can be found as part of the J2EE v1.2.2 distribution available
 * from Sun's web site.  These classes are part of the J2EE.jar that comes with the
 * distribution.  If you have not downloaded this Jar you can also find the
 * classes in JBoss/Tomcat distributions.  For the bundled JBoss/Tomcat distribution
 * these jars were located in:
 * javax.servlet.http.HttpServletRequest  -%JBOSS DIRECTORY%/tomcat/lib/servlet.jar
 * javax.naming.InitialContext            - %JBOSS DIRECTORY%/jboss/lib/ext/ejb.jar
 */
import javax.servlet.http.HttpServletRequest;
import javax.naming.InitialContext;

/*
 * The org.w3c.dom.Document class is located in the Xalan jar.
 */
import org.w3c.dom.Document;

import mvc.templates.*;

public class RequestHandler {

  /*
   * The process method is used to process a user request sent by the end-user.
   * It reads the request and action variables from the HttpServletRequest
   * parameter passed in.  The request parameter returned from the HttpServletRequest
   * object is used to instantiate our EJB.  The action parameter is used to define
   * whether the retrieve or post method of the instantiated bean is called.
   */
  public Document process(HttpServletRequest _request) throws Exception {

    /* Step 1 - Retrieving the class parameters from the HttpServletRequest object */
    String requestValue = _request.getParameter("Request");
    String actionValue = _request.getParameter("Action");

    /* Step 2 - Looking up and retrieving the desired EJB from JBoss */
    InitialContext ctx = new InitialContext();
    MVCHome home = (MVCHome) ctx.lookup(requestValue);
    MVCObject mvcComponent = home.create();

    /* Step 3 - Deciding where to invoke the Retrieve or Post Method on the Bean */
    if (actionValue.equals("Retrieve")) {
      return mvcComponent.retrieve(_request);
    } 

    if (actionValue.equals("Post")) {
      System.out.println("I am in the post");
      return mvcComponent.post(_request);
    } 

    /* Step 4 - If the value is neither Retrieve or Post throw an exception */
    throw new Exception("RequestHandler.process:  Action passed is not a Retrieve or a Post");
  } 
}