JavaEE5学习笔记13-JSF集成AJAX使用经验总结

JSF也支持AJAX，ajax4jsf是专门为JSF提供的AJAX框架。他的工作原理就是在客户端加载一个AJAX引擎，在这个引擎之上是呈现给用户的JSF页面，引擎之下就是JSF框架，也就是正常的JSF生命周期。换句话说页面上的组件一旦配置了ajax4jsf标签，那么该组件的JSF生命周期一直生活在ajax4jsf的阴影之下。用了ajax4jsf，开发者可以不用像以往的JSP页面那样，写js脚本，页面html组件触发js事件后，进行ajax请求，而是像组件监听器一样，对组件的事件进行一个监听，触发事件后，开始ajax引擎预处理，之后再走JSF生命周期。生命图形如下
JavaEE5学习笔记13-JSF集成AJAX使用经验总结
首先下载ajax4jsf-1.1.1.jar，从山寨网站http://www.java2s.com/Code/Jar/JKL/Downloadajax4jsf111jar.htm可以下载其jar包。之后再下载通用的一些jar包

commons-beanutils.jar
commons-collections.jar
commons-digester.jar
commons-logging.jar
oscache-2.4.1.jar

web.xml内容加入

<!--JSF的ajax配置 AJAX4JSF-->
	<filter>
		<display-name>Ajax4jsf Filter</display-name>
		<filter-name>ajax4jsf</filter-name>
		<filter-class>org.ajax4jsf.Filter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>ajax4jsf</filter-name>
		<servlet-name>Faces Servlet</servlet-name>
		<dispatcher>REQUEST</dispatcher>
		<dispatcher>FORWARD</dispatcher>
		<dispatcher>INCLUDE</dispatcher>
	</filter-mapping>

这里声明一个过滤器，对servler名称叫做Faces Servlet的请求进行过滤，Faces Servlet就是JSF的javax.faces.webapp.FacesServlet。org.ajax4jsf.Filter正是ajax4jsf-1.1.1.jar中的过滤器。使得ajax的filter将会作用于直接从客户端过来的request，通过forward过来的request，通过include过来的request。就是这样一个过滤器拦截了所有的JSF请求。

使用AJAX功能的页面代码

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<%@ taglib uri="https://ajax4jsf.dev.java.net/ajax" prefix="a4j" %>
	<head>
		<title>用户登录页面</title>
	</head>

	<body>
		<f:view>
			<a4j:region id="a4j_2">
				<h2>
					用户登录页面
				</h2>
				<h:form id="loginForm">
					<h:panelGrid columns="3">
						<h:outputLabel value="用户名"></h:outputLabel>
						<h:inputText id="txtUserName" value="#{UserBean.userName}">
							<a4j:support actionListener="#{UserBean.validateUserName}"
								event="onblur" reRender="result"></a4j:support>
						</h:inputText>
						<h:panelGroup>
							<h:message for="txtUserName"></h:message>
							<h:outputText value="#{UserBean.validUserMsg}" id="result"
								style="color:red" />
						</h:panelGroup>
						<h:outputLabel value="密码"></h:outputLabel>
						<h:inputSecret id="txtPwd" value="#{UserBean.password}"></h:inputSecret>
						<h:message for="txtPwd"></h:message>

						<h:outputLabel value="验证码"></h:outputLabel>
						<h:panelGroup>
							<h:inputText id="txtCode" value="#{UserBean.code}" size="10" />
							<a4j:outputPanel id="detail_media">
								<a4j:commandLink reRender="detail_media">
									<a4j:mediaOutput element="img" cacheable="false"
										session="false" createContent="#{UserBean.paint}"
										value="#{imageData}" mimeType="image/jpeg" border="0" />
								</a4j:commandLink>
							</a4j:outputPanel>
						</h:panelGroup>
						<h:outputText value="#{UserBean.validateCodeMsg}"
							style="color:red" />
					</h:panelGrid>
					<h:panelGrid columns="3">
						<h:outputLabel value="账户"></h:outputLabel>
						<h:inputText id="myname" value="#{UserBean.myname}">
							<a4j:support actionListener="#{UserBean.isHaveName}"
								event="onblur" reRender="result2"></a4j:support>
						</h:inputText>
						<h:panelGroup>
							<h:message for="myname"></h:message>
							<h:outputText value="#{UserBean.validUserMsg}" id="result2"
								style="color:red" />
						</h:panelGroup>
					</h:panelGrid>
					<h:commandButton action="#{UserBean.login}" value="提交" />
				</h:form>
			</a4j:region>
		</f:view>
	</body>
</html>

注意：

1):使用ajax功能必须加入ajax4jsf标签声明

<%@ taglib uri="https://ajax4jsf.dev.java.net/ajax" prefix="a4j" %>

2):声明一个ajax作用域

<a4j:region id="a4j_2">…………</a4j:region>

在这个作用域范围内的组件都可以使用AJAX功能。

3):对组件进行显示的ajax声明，告诉引擎，这个组件需要进行ajax引擎处理，引擎过后才能交给JSF生命周期

<a4j:support actionListener="#{UserBean.validateUserName}" event="onblur" reRender="result"></a4j:support>

4):ajax4jsf也有相应的组件，比如用ajax的方式输出一个图形容器

<a4j:outputPanel id="detail_media">
		<a4j:commandLink reRender="detail_media">
			<a4j:mediaOutput element="img" cacheable="false"
				session="false" createContent="#{UserBean.paint}"
					value="#{imageData}" mimeType="image/jpeg" border="0" />
			</a4j:commandLink>
</a4j:outputPanel>

托管Bean如下

/**
 *  ClassName: UserBean.java
 *  created on Nov 1, 2007
 *  Copyrights 2007-2008 qjyong All rights reserved.
 *  EMail: [email protected]
 */
package ajax;

import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.faces.context.FacesContext;
import javax.faces.event.ActionEvent;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpSession;

/**
 * @author qiujy
 * @version 1.0
 *
 */
public class UserBean {
	private String userName;
	private String password;
	private String code; //用户输入的验证码
	
	private String validUserMsg;
	private String validateCodeMsg;
	
	
	private String myname;
	
	public String getMyname() {
		return myname;
	}
	public void setMyname(String myname) {
		this.myname = myname;
	}
	/**
	 * @return the code
	 */
	public String getCode() {
		return code;
	}
	/**
	 * @param code the code to set
	 */
	public void setCode(String code) {
		this.code = code;
	}
	/**
	 * @return the validUserMsg
	 */
	public String getValidUserMsg() {
		return validUserMsg;
	}
	/**
	 * @param validUserMsg the validUserMsg to set
	 */
	public void setValidUserMsg(String validUserMsg) {
		this.validUserMsg = validUserMsg;
	}
	/**
	 * @return the userName
	 */
	public String getUserName() {
		return userName;
	}
	/**
	 * @param userName the userName to set
	 */
	public void setUserName(String userName) {
		this.userName = userName;
	}
	/**
	 * @return the password
	 */
	public String getPassword() {
		return password;
	}
	/**
	 * @param password the password to set
	 */
	public void setPassword(String password) {
		this.password = password;
	}
	/**
	 * @return the validateCodeMsg
	 */
	public String getValidateCodeMsg() {
		return validateCodeMsg;
	}
	/**
	 * @param validateCodeMsg the validateCodeMsg to set
	 */
	public void setValidateCodeMsg(String validateCodeMsg) {
		this.validateCodeMsg = validateCodeMsg;
	}
	

	public void validateUserName(ActionEvent event){
		System.out.println("input name===" + this.userName);
		if(!userName.matches("\\w{6,20}")){
			this.validUserMsg = "用户名不合法!";
		}
	}
	
	public void paint(OutputStream out, Object data) throws IOException {
	    if (data instanceof ImageData) {    
	    	ImageData imageData = (ImageData) data;    
	        // 生成一个在1000－9999之间的随机数
	    	Random randomNumber = new Random();
	        String keyCode = randomNumber.nextInt(8999) + 1000 + "";
	        //把产生的随机数保存到session中
	        HttpSession session = (HttpSession)FacesContext.getCurrentInstance()
	        							.getExternalContext().getSession(true);
	        
	        session.setAttribute("keyCode", keyCode);

	        //生成干扰线的随机数
	        int outPutLine = 0;    
	        outPutLine = randomNumber.nextInt(100);    
	        
	        BufferedImage img = new BufferedImage(imageData.getWidth(),    
	        		imageData.getHeight(), BufferedImage.TYPE_INT_RGB); 
	        
	        Graphics2D g = img.createGraphics();
	        g.setBackground(imageData.getBackground());    
	        g.setColor(imageData.getDrawColor());
	        g.setFont(imageData.getTextFont());
	        //画矩形
	        g.clearRect(0, 0, imageData.getWidth(), imageData.getHeight());
	        //画干扰线
	        g.drawLine(outPutLine, outPutLine, imageData.getWidth()    
	                - outPutLine, imageData.getHeight() - outPutLine);
	        //画产生的随机数
	        g.drawString(keyCode, 10, 16);
	        g.dispose();
	        
	        ImageIO.write(img, "jpeg", out);
	    }
	}

	public String login(){
		System.out.println("user--code" + this.getCode());
		//从session中取出验证码
		HttpSession session = (HttpSession)FacesContext.getCurrentInstance()
									.getExternalContext().getSession(true);
		String keyCode = (String)session.getAttribute("keyCode");
		
		if(keyCode.equals(this.getCode())){
			return "success";
		}else{
			this.validateCodeMsg = "验证码不正确";
			return null;
		}
	}
	
	public void isHaveName(ActionEvent event){
		System.out.println("input myname ===" + this.myname);
		if("liuyan".equalsIgnoreCase(myname)){
			this.validUserMsg = "用户重复！";
		}
	}

}

在此用到了一个辅助类

/**
 *  ClassName: ImageData.java
 *  created on Nov 28, 2007
 *  Copyrights 2007-2008 qjyong All rights reserved.
 *  EMail: [email protected]
 */
package ajax;

import java.awt.Color;
import java.awt.Font;

/**
 * @author qiujy
 * @version 1.0
 * 
 */
public class ImageData implements java.io.Serializable {

	private int width = 60;

	private int height = 20;

	private Color background = new Color(0xDCDCDC);

	private Color drawColor = Color.black;

	private Font textFont = new Font("Times New Roman", Font.PLAIN, 18);

	/**
	 * @return the width
	 */
	public int getWidth() {
		return width;
	}

	/**
	 * @param width the width to set
	 */
	public void setWidth(int width) {
		this.width = width;
	}

	/**
	 * @return the height
	 */
	public int getHeight() {
		return height;
	}

	/**
	 * @param height the height to set
	 */
	public void setHeight(int height) {
		this.height = height;
	}

	/**
	 * @return the background
	 */
	public Color getBackground() {
		return background;
	}

	/**
	 * @param background the background to set
	 */
	public void setBackground(Color background) {
		this.background = background;
	}

	/**
	 * @return the drawColor
	 */
	public Color getDrawColor() {
		return drawColor;
	}

	/**
	 * @param drawColor the drawColor to set
	 */
	public void setDrawColor(Color drawColor) {
		this.drawColor = drawColor;
	}

	/**
	 * @return the textFont
	 */
	public Font getTextFont() {
		return textFont;
	}

	/**
	 * @param textFont the textFont to set
	 */
	public void setTextFont(Font textFont) {
		this.textFont = textFont;
	}
}

这是用于图形显示的。

显示效果如下

输入不正确的信息，鼠标焦点离开控件显示如下效果
JavaEE5学习笔记13-JSF集成AJAX使用经验总结
输入正确的数值后，焦点离开效果如下

看一下生成后的源代码，页面引入/a4j.res/org.ajax4jsf.framework.ajax.AjaxScript.faces文件，这个文件是一个js函数库文件。

<script type='text/javascript' src='/JSFDemo/a4j.res/org.ajax4jsf.framework.ajax.AjaxScript.faces'></script>

再看看使用了ajax4jsf进行事件监听的组件的源代码编程如下html代码

<td><label>
用户名</label></td>
<td><input id="loginForm:txtUserName" type="text" name="loginForm:txtUserName" onblur="A4J.AJAX.Submit('a4j_2','loginForm',event,{'parameters':{'loginForm:_id2':'loginForm:_id2'} ,'actionUrl':'/JSFDemo/ajax/main.faces'} )" /></td>
<td>

另一个组件源码如下

<td><input id="loginForm:myname" type="text" name="loginForm:myname" onblur="A4J.AJAX.Submit('a4j_2','loginForm',event,{'parameters':{'loginForm:_id14':'loginForm:_id14'} ,'actionUrl':'/JSFDemo/ajax/main.faces'} )" /></td>
<td>

同样是对onblur进行了js事件处理。至于那个随机数字图片源代码如下

<td><label>
验证码</label></td>
<td><input id="loginForm:txtCode" type="text" name="loginForm:txtCode" size="10" /><span id="loginForm:detail_media"><a href="#" id="loginForm:_id9" name="loginForm:_id9" onclick="A4J.AJAX.Submit('a4j_2','loginForm',event,{'parameters':{'loginForm:_id9':'loginForm:_id9'} ,'actionUrl':'/JSFDemo/ajax/main.faces'} );return false;"><img id="loginForm:_id10" src="/JSFDemo/a4j.res/org.ajax4jsf.framework.resource.UserResource/n/n/-1487394660/DATA/eAFlUk1rE1EUvZ0mtRGqsa3Wr0XVIrh5Wdiuoou2EhpIW2hsUQPCy8ybZNKZedP37iSjoht.gAVXgiAuXPmx8Te4UetWhOLSjfQ31Pte0y8cmBnu5b5zzj3vfNiBvFYwLVWL8Q7PpjvaZ77ikehJtc6U0DJVrmCrWqiVfjG1qoI7HDmYZ2zmrwO5Goy4SnAU8zJGESPCaK3Du7wU8rhVWm52hIvlGpwQWRIQ5gY8g4EaDEfSC.xAeP063-VhKmyRJaTquoHImM9doZkro0TGhM3qSEQLMvSEqvOuUPe.fr798vXWogNODQpuyLVeogWOa6ijCuIWaTip6YxnMfpMCFcJnOk07lOJkC0KbEtvLog9OlWNkjBVMNawOzGzE-vvtPnj3puivhE6AFlCduQQ8gkPYrQ7DiJc-Q96zSx5BBlh2Lg7J3hMJKNHSebNLuX3535--rb14NU-h9NVMG6sYYFkyykmKdJ2gkf2QvY-WUJDRTt0RO6xAYQz157sMzMr-mlibD9lgsCqEW8Jc80fLyc7vx5OMAfyVRhqi6DVxirke4GHbbKzyd31lpJp7CEU9y6d97A0L0OpyO6Cp3jPFsbts3TpKDKsUEwQTh-Om0bZOjhOIm8ZFVY8QTF7euDdxPPii5spqajAkM.DpM1JhU1MDRxXI1w6hHMN-56GekLxKTeg4KtW044jOI1Kg0AO4nbRMsPu9vZ2QhYYpeeNV7v0moaCkQM1RumXtzN.vv9e04MwVIULPnXqQgU8DB4Lz1i2JpQOZFyBQiIpC3XqVyGn7S-v8VEoajDur4iNVGgU3ixSOJspUkEOGaZSikFYWuC6jbwZCvIxF1OkjbCc1Towu2kEwqj5JGTl3SASenJJ9CZXZMTj7B8chjyM.faces" border="0" /></a></span></td>
<td><span style="color:red"></span></td>

这个图片的链接url比较长，直接在浏览器打开这个长长地连接后可以看到如下效果
JavaEE5学习笔记13-JSF集成AJAX使用经验总结
ajax4jsf引擎将标签转换成相应的javascript、html，之后交给ajax引擎，进行预处理，之后在提交到JSF，之后再走完6个生命周期（正常的话），之后再返回给ajax引擎，引擎负责呈献给web前端展示效果。