Java/JSP/Beans — различия между версиями

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Текущая версия на 07:10, 1 июня 2010

Bean property display

<%@ taglib uri="http://java.sun.ru/jstl/core" prefix="c" %>
<jsp:useBean id="emailer" class="com.jexp.EmailBean"/>
<jsp:setProperty name="emailer" property="*" />
<html>
<head><title>Bean property display</title></head>
<body>
<h2>Here are the EmailBean properties</h2>
<strong>SMTP host: </strong><c:out value="${emailer.smtpHost}" /><br />
<strong>Email recipient: </strong><c:out value="${emailer.to}" /><br />
<strong>Email sender: </strong><c:out value="${emailer.from}" /><br />
<strong>Email subject: </strong><c:out value="${emailer.subject}" /><br />
<strong>Email content: </strong><c:out value="${emailer.content}" /><br />
</body>
</html>





Beans with scriptlet

<%@ page import="com.jexp.Book" %>
<%
  Book myBook = (Book) session.getAttribute("myBookBean");
  if ( myBook == null)
  {
    myBook = new Book();
    myBook.setAuthor("Joe");
    session.setAttribute("myBookBean", myBook);
  } // end of if ()
%>
  
<html>
  <head><title>JavaBean usage with scriptlets (1)</title></head>
  <body>
    This page creates a JavaBean if you don"t already have one.<P></P>
    Click  to go to a page that retrieves it.
  </body>
</html>
//useAndSet2.jsp
<html>
  <head><title>JavaBean usage - getProperty tag</title></head>
  <body>
    This page retrieves a JavaBean, and its properties.<P>
    <table border="1">
      <th>JavaBean property</th><th>Value</th>
      <tr><td>id</td>    <td><jsp:getProperty name="myBookBean" property="id"     /></td></tr>
      <tr><td>title</td> <td><jsp:getProperty name="myBookBean" property="title"  /></td></tr>
      <tr><td>author</td><td><jsp:getProperty name="myBookBean" property="author" /></td></tr>
      <tr><td>price</td> <td><jsp:getProperty name="myBookBean" property="price"  /></td></tr>
    </table>
  </body>
</html>





Calling a Private Method

// JSP file
<HTML>
    <HEAD>
        <TITLE>Calling a Private Method</TITLE>
    </HEAD>
    <BODY>
        <H1>Calling a Private Method</H1>
        <jsp:useBean id="bean1" class="beans.Message" />
        The message is: <jsp:getProperty name="bean1" property="message" /> 
        <BR>
        <jsp:setProperty name="bean1" property="message" value="Hello again!" />
        Now the message is: <jsp:getProperty name="bean1" property="message" />
    </BODY>
</HTML>

///////////////////////////////////////
//Java Source Code
package beans;
import java.io.Serializable;
public class Message implements Serializable
{
    private String message = "Hello from JSP!";
    public void setMessage(String m) 
    {
        this.message = m;
    }
    public String getMessage() 
    {
        return privateMessage();
    }
    private String privateMessage() 
    {
        return this.message;
    }
    public Message() 
    {
    }
}





Get Set Properties JSTL

//File: index.jsp
<html>
    <head>
        <title>Using a JavaBean</title>
    </head>
    <body>
    <h2>Using a JavaBean</h2>
    <jsp:useBean id="myCar" class="beans.CarBean" />
    I have a <jsp:getProperty name="myCar" property="make" /> <br />
    <jsp:setProperty name="myCar" property="make" value="Ferrari" />
 
    Now I have a <jsp:getProperty name="myCar" property="make" />
    </body>
</html>

//////////////////////////////////////////////////////////////
//Java Bean
package beans;
import java.io.Serializable;
public class CarBean implements Serializable 
{
  private String make = "Company";
  private double cost = 100.00;
  private double taxRate = 17.5;
  public CarBean() {}
  public String getMake()
  {
    return make;
  }
  public void setMake(String make)
  {
    this.make = make;
  }
  public double getPrice()
  {
    double price = (cost + (cost * (taxRate/100)));
    return price;
  }
}





Getting a Property Value

//File: index.jsp
<HTML>
  <HEAD>
    <TITLE>Getting a Property Value</TITLE>
  </HEAD>
  <BODY>
    <H1>Getting a Property Value</H1>
    <jsp:useBean id="bean1" class="beans.Message" />
    The message is: <jsp:getProperty name="bean1" property="message" /> 
  </body>
</html>

////////////////////////////////////////////
//Java Bean Class
package beans;
public class Message
{
    private String message = "Hello from JSP!";
    public String getMessage() 
    {
        return message;
    }
    public Message() 
    {
    }
}





JSP and Java beans 3

/*
<%@ taglib uri="http://java.sun.ru/jstl/core" prefix="c" %>
<jsp:useBean id="priceFetcher" class="com.jexp.StockPriceBean" />
<html>
<head><title>Price Fetch</title></head>
<body>
<c:choose>
    <c:when test="${empty param.symbol}">
   <h2>Please submit a valid stock symbol</h2>
   <form method="POST" action ="<c:out value="${pageContext.request.contextPath}" />/priceFetch.jsp">
   <table border="0"><tr><td valign="top">
   Stock symbol: </td>  <td valign="top"><input type="text" name="symbol" size="10"></td></tr><tr><td valign="top"><input type="submit" value="Submit Info"></td></tr></table></form>
   </c:when>
   <c:otherwise>
   <h2>Here is the latest value of <c:out value="${param.symbol}" /></h2>
       <jsp:setProperty name="priceFetcher" property="symbol" value="<%= request.getParameter(\"symbol\") %>" />
       <jsp:getProperty name="priceFetcher" property="latestPrice"/>
   </c:otherwise>
 </c:choose> 
</body>
</html>
*/
package com.jexp;  
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.MalformedURLException;
import javax.swing.text.html.HTMLEditorKit.ParserCallback;
import javax.swing.text.MutableAttributeSet;
import javax.swing.text.html.parser.ParserDelegator;
public class StockPriceBean {
    /**  
     *   The URL base for requesting a stock price; it looks like
     *   "http://finance.yahoo.ru/q?d=t&s="
     */
     private static final String urlBase =  "http://finance.yahoo.ru/q?d=t&s=";
    
    /**  
     *   The character stream of HTML that is parsed for the stock price 
     *    returned by java.net.URL.openStream()
     *   
     *   see java.net.URL
     *   @see java.io.BufferedReader
     */
    private BufferedReader webPageStream = null;
     
    /**  
     *   The java.net.URL object that represents the stock Web page
     *   
     */
     private URL stockSite = null;
    
    /**  
     *   The ParserDelegator object for which ParserDelegator.parse() is
     *   called for the Web page
     *
     *   @see javax.swing.text.html.parser.ParserDelegator
     */
     private ParserDelegator htmlParser = null;
    
    /**  
     *   The MyParserCallback object (inner class); this object is an
     *   argument to the ParserDelegator.parse() method
     *
     *   @see javax.swing.text.html.HTMLEditorKit.ParserCallback
     */
     private MyParserCallback callback = null;
    /**  
     *   This String holds the HTML text as the Web page is parsed.
     *   
     *   @see MyParserCallback
     */
     private String htmlText = "";
   private String symbol = "";
     private float stockVal = 0f;
  //A JavaBean has to have a no-args constructor (we explicitly show this 
  //constructor as a reminder; the compiler would have generated a default
  //constructor with no arguments automatically
  public StockPriceBean() {}
  
  //Setter or mutator method for the stock symbol
  public void setSymbol(String symbol){
  
      this.symbol = symbol;
  }
   
  class MyParserCallback extends ParserCallback {
      //bread crumbs that lead us to the stock price
      private boolean lastTradeFlag = false; 
      private boolean boldFlag = false;
  
    public MyParserCallback(){
    
      //Reset the enclosing class" instance variable
    if (stockVal != 0)
          stockVal = 0f;
    
   }
        
    public void handleStartTag(javax.swing.text.html.HTML.Tag t,
      MutableAttributeSet a,int pos) {
        
        if (lastTradeFlag && (t == javax.swing.text.html.HTML.Tag.B )){
            
            boldFlag = true;
       }
        
    }//handleStartTag
    public void handleText(char[] data,int pos){
              
        htmlText  = new String(data);
    
    //System.out.println(htmlText);
      
        if (htmlText.indexOf("No such ticker symbol.") != -1){
             
          throw new IllegalStateException(
      "Invalid ticker symbol in handleText() method.");
                
        }  else if (htmlText.equals("Last Trade:")){
                    
            lastTradeFlag = true;
                    
        } else if (boldFlag){
                
            try{
                
                stockVal = new Float(htmlText).floatValue();
            } catch (NumberFormatException ne) {
                    
                try{
                        
                    // tease out any commas in the number using 
                    //NumberFormat
                        
                    java.text.NumberFormat nf = java.text.NumberFormat.
                      getInstance();
                    
                    Double f = (Double) nf.parse(htmlText);
                    
                    stockVal =  (float) f.doubleValue();
                     
                } catch (java.text.ParseException pe){
                        
                     throw new IllegalStateException(
                "The extracted text " + htmlText +
                         " cannot be parsed as a number!");
                        
                 }//try
            }//try
            
            lastTradeFlag = false;
            boldFlag = false;
      
         }//if
                
      } //handleText
  }//MyParserCallback
  public float getLatestPrice() throws IOException,MalformedURLException {
      stockSite = new URL(urlBase + symbol);
       
      webPageStream = new BufferedReader(new InputStreamReader(stockSite.
       openStream()));
     
      htmlParser = new ParserDelegator();
     
      callback = new MyParserCallback();//ParserCallback
     
      synchronized(htmlParser){  
  
          htmlParser.parse(webPageStream,callback,true);
       }//synchronized
     
    //reset symbol
    symbol = "";
     return stockVal;
  }//getLatestPrice
}//StockPriceBean





JSP and Java beans (JavaBeans) 1

/*
Beginning JavaServer Pages
Vivek Chopra, Jon Eaves, Rupert Jones, Sing Li, John T. Bell
ISBN: 0-7645-7485-X
*/





JSP and Java beans (JavaBeans) 2

/*
Beginning JavaServer Pages
Vivek Chopra, Jon Eaves, Rupert Jones, Sing Li, John T. Bell
ISBN: 0-7645-7485-X
*/





JSP email valid check

//validCheck.jsp
/*
<%@page contentType="text/html"%>
<%@ taglib uri="http://java.sun.ru/jstl/core" prefix="c" %>
<jsp:useBean id="chk" class="com.jexp.ClientValidator" >
<jsp:setProperty name="chk" property="*" />
</jsp:useBean>
<%-- get valid property from ClientValidator bean --%>
<c:set var="isValid" value="${chk.valid}" />
<c:if test="${isValid}">
    <c:set var="email" value="${chk.email}" scope="request" />
  <c:set var="password" value="${chk.password}" scope="request" />
</c:if>
<html>
<head><title>Client Checker</title></head>
<body>
<h2>Welcome</h2>
   
     <strong>Email</strong>: 
    <c:out value="${email}" /><br><br>
    <strong>Password</strong>: 
    <c:out value="${password}" />
</body>
</html>
*/
package com.jexp;
public class ClientValidator implements java.io.Serializable{
String email;
String password;
boolean valid;
public ClientValidator(){
    this.valid=false;}
public boolean isValid(){
  /* Use a Data Access Object to validate the email and password.
        If the validation does not fail then set this.valid to true*/
   this.valid=true;
   return valid;
   
   }
public void setEmail(String _email){
     if(_email != null && _email.length() > 0)
        email = _email;
    else
         email = "Unknown";
}
public String getEmail(){
    return email; }
public void setPassword(String _password){
     if(_password != null && _password.length() > 0)
        password = _password;
    else
         password = "Unknown"; 
}
public String getPassword(){
    return password; }
}





JSP Standard Actions: set property

/*
Beginning JavaServer Pages
Vivek Chopra, Jon Eaves, Rupert Jones, Sing Li, John T. Bell
ISBN: 0-7645-7485-X
*/

<html>
<head>
</head>
<body>
  <jsp:useBean id="myProduct" class="com.wrox.begjsp.ch03.Product">
    <jsp:setProperty name="myProduct" property="sku" value="12345"/>
    <jsp:setProperty name="myProduct" property="name" value="DSL Modem"/>
  </jsp:useBean>
<table border="1">
 <tr>
    <td>Sku:</td><td><%= myProduct.getSku() %></td>
 </tr>
<tr>
    <td>Name:</td><td>${myProduct.name}</td>
 </tr>
</table>
  <jsp:useBean id="myMap"  class="java.util.HashMap" />
  <jsp:useBean id="myMap2"  class="java.util.HashMap"  type="java.util.Map"/>

 </body>
</html>





JSP with Java bean

<%@ page import="java.util.*" %>
<html>
  <head>
    <title>WishList</title>
    <jsp:useBean class="com.jexp.WishList" id="wishList" scope="session"/>
    <jsp:useBean class="com.jexp.WishListItems" id="wishListItems" scope="application" />
  </head>
  <body>
    <% Enumeration e = request.getParameterNames(); %>
    <% Set map = wishList.getMap(); %>
    <% while(e.hasMoreElements()){
      String key = (String)e.nextElement();
        if(key.equals(wishListItems.getItem(0).getId())){
          map.add(wishListItems.getItem(0));
        }
        if(key.equals(wishListItems.getItem(1).getId())){
          map.add(wishListItems.getItem(1));
        }
        if(key.equals(wishListItems.getItem(2).getId())){
          map.add(wishListItems.getItem(2));
        }
        if(key.equals(wishListItems.getItem(3).getId())){
          map.add(wishListItems.getItem(3));
        }
        if(key.equals(wishListItems.getItem(4).getId())){
          map.add(wishListItems.getItem(4));
        }
      } %>
      Items currently In your Wish List:<br>
      <% if(map.size()==0){ %>
           There are no items in your Wish List<br>
 <%   }
      else {
        Set set = map; %>
        <% if (set!=null){
            com.jexp.Item[] keys = new com.jexp.Item[0];
            keys = (com.jexp.Item[])set.toArray(keys);
            for (int i=0;i<keys.length;i++){ %>
              <%=keys[i].getName()%><%="<br>"%>
   <%       }
          }
      }%>
    <br>
  </body>
</html>
package com.jexp;
public class Item {
  private String id;
  private String name;
  
  public Item(){}
  
  public Item(String s, String t){
    name=s;
    id=t;
  }
  
  public String getId(){
    return id;
  }
  
  public String getName(){
    return name;
  }
}


package com.jexp;
import javax.servlet.http.HttpSessionBindingListener;
import javax.servlet.http.HttpSessionBindingEvent;
import java.util.Set;
import java.util.HashSet;
import java.util.Iterator;
public class WishList implements HttpSessionBindingListener {
  private Set map = new HashSet();
  public Set getMap(){
    return map;
  }
  //Session binding methods
  public void valueBound(HttpSessionBindingEvent e){
    System.out.println("The WishList has been Bound!");
  }
  public void valueUnbound(HttpSessionBindingEvent e){
    Item[] keys = new Item[0];
    System.out.println("Getting values...");
    Iterator it = map.iterator();
    while(it.hasNext()){
      Item item = (Item)it.next();
      System.out.println(item.getName());
    }
  }
}

package com.jexp;
public class WishListItems {
  
  private Item[] items = {
        new Item("ID 1","Name 1"),
        new Item("ID 2","Name 2"),
        new Item("ID 3","Name 3"),
        new Item("ID 4","Name 4"),
        new Item("ID 5","Name 5")
        };
    
  public Item getItem(int i){
    if (items[i]!=null){
      return items[i];
    }
    
    else {
      return null;
    }
  }
  
}





Set Property Value

Using a Constructor

//File: index.jsp
<HTML>
    <HEAD>
        <TITLE>Using a Constructor</TITLE>
    </HEAD>
    <BODY>
    <H1>Using a Constructor</H1>
    <% beans.Message m = new beans.Message("Hello from JSP!"); %>
    The message is: <%= m.msg() %> 
  </BODY>
</HTML>

///////////////////////////////////////////////////////////////////////////
//File: Message.java
package beans;
public class Message
{
    String msg;
    public Message(String message) 
    {
        msg = message;
    }
    public String msg() {
      return msg;
    }
}





Using a Java Bean Jsp

//////////////////////////////////////       
//File: index.jsp       
       
<%@ page import="beans.MessageBean" %>
<HTML>
  <HEAD>
    <TITLE>Using a JavaBean</TITLE>
  </HEAD>
  <BODY>
    <h1>Using a JavaBean</h1>
    <% MessageBean m = new MessageBean(); %>
    The message is: <%= m.msg() %> 
  </BODY>
</HTML>
//////////////////////////////////////////////////
//File: MessageBean.java
package beans;

public class MessageBean
{
    public MessageBean() 
    {
    }
    public String msg() 
    {
        return "Hello from JSP!";
    }
}





Using Bean Counter JSP

//File: BeanCounter.jsp
<HTML>
<HEAD>
</HEAD>
<BODY>
<%@ page language="java" %>
<jsp:useBean id="counter" scope="session" class="beans.Counter" />
<jsp:setProperty name="counter" property="count" param="count" />
<%
    out.println("Count from scriptlet code : "
      + counter.getCount() + "<BR>");
%>
Count from jsp:getProperty :
  <jsp:getProperty name="counter" property="count" /><BR>
</BODY>
</HTML>
///////////////////////////////////////////////////////////
//File: Counter.java
package beans;
import java.io.Serializable;
public class Counter implements Serializable{
  // Initialize the bean on creation
  int count = 0;
  // Parameterless Constructor
  public Counter() {
  }
  // Property Getter
  public int getCount() {
    // Increment the count property, with every request
    count++;
    return this.count;
  }
  // Property Setter
  public void setCount(int count) {
    this.count = count;
  }
}





Using Package Jsp

Using UseBean in Jsp

Источник — «http://jexp.ru/index.php?title=Java/JSP/Beans&oldid=8717»