java – 我的第一个反向ajax应用程序
作者：互联网
我想了解反向ajax,我发现了一个名为ICEPush的小工具,我认为这可能是一个很好的起点.我无法实现一个非常简单的应用程序.
我正在关注这个tutorial,但是我使用的是Glassfish 3.1而不是Eclipse,我使用的是NetBeans 7.1
我完全按照教程中的说法完成,请参阅我的代码.
这是将成为Ajax推送目标的页面：
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core">
<h:head>
<title>Easy Ajax Push - Color</title>
</h:head>
<h:body>
<h:dataTable value="#{messageBean.textList}" var="current">
<h:column>
<h:outputText value="#{current.text}"
style="color: #{current.color};"/>
</h:column>
</h:dataTable>
<hr width="100%"/>
<h:form>
<h:panelGrid columns="4">
Choose a Color:
<h:commandButton value="Red"
action="#{colorBean.chooseColor}"
style="color: white; background-color: red;">
<f:setPropertyActionListener target="#{colorBean.color}" value="red"/>
</h:commandButton>
<h:commandButton value="Blue"
action="#{colorBean.chooseColor}"
style="color: white; background-color: blue;">
<f:setPropertyActionListener target="#{colorBean.color}" value="blue"/>
</h:commandButton>
<h:commandButton value="Green"
action="#{colorBean.chooseColor}"
style="color: white; background-color: green;">
<f:setPropertyActionListener target="#{colorBean.color}" value="green"/>
</h:commandButton>
</h:panelGrid>
</h:form>
</h:body>
</html>
以下是需要的2个托管bean：
ColorBean.java
@ManagedBean(name="colorBean")
@ViewScoped
public class ColorBean implements Serializable {
private static final String PUSH_GROUP = "colorPage";
@ManagedProperty(value="#{messageBean}")
private MessageBean messageBean;
private String color = "black";
private String sessionId;
public ColorBean() {
PushRenderer.addCurrentSession(PUSH_GROUP);
FacesContext fcontext = FacesContext.getCurrentInstance();
HttpSession session = (HttpSession)fcontext.getExternalContext().getSession(false);
sessionId = session.getId();
}
public void setMessageBean(MessageBean messageBean) {
this.messageBean = messageBean;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public String chooseColor() {
messageBean.addToList(sessionId, color);
PushRenderer.render(PUSH_GROUP);
return null;
}
}
MessageBean.java
@ManagedBean(name="messageBean")
@ApplicationScoped
public class MessageBean implements Serializable {
private static final int MAX_SIZE = 25;
private List<TextModel> textList = new ArrayList<TextModel>(0);
public MessageBean() {
}
public List<TextModel> getTextList() {
return textList;
}
public void setTextList(List<TextModel> textList) {
this.textList = textList;
}
public void addToList(String sessionId, String color) {
textList.add(makeTextModel(sessionId, color));
if (textList.size() > MAX_SIZE) {
textList.clear();
}
}
private TextModel makeTextModel(String sessionId, String color) {
return new TextModel("User with session ID of " + sessionId + " selected color \"" + color + "\".",
color);
}
}
还有一个简单的pojo来表示正在呈现的文本.
TextModel.java
public class TextModel implements Serializable {
private String text;
private String color;
public TextModel() {
}
public TextModel(String text, String color) {
this.text = text;
this.color = color;
}
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public String toString() {
return text;
}
}
我正在使用IceFaces 3.0.1版,这就是我的web.xml的样子：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<context-param>
<param-name>javax.faces.PROJECT_STAGE</param-name>
<param-value>Development</param-value>
</context-param>
<context-param>
<param-name>javax.faces.STATE_SAVING_METHOD</param-name>
<param-value>server</param-value>
</context-param>
<context-param>
<param-name>javax.faces.FACELETS_SKIP_COMMENTS</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>org.icefaces.mandatoryResourceConfiguration</param-name>
<param-value/>
</context-param>
<context-param>
<param-name>org.icefaces.ace.theme</param-name>
<param-value>sam</param-value>
</context-param>
<context-param>
<param-name>javax.faces.VALIDATE_EMPTY_FIELDS</param-name>
<param-value>false</param-value>
</context-param>
<context-param>
<param-name>com.icesoft.faces.gmapKey</param-name>
<param-value>ABQIAAAADlu0ZiSTam64EKaCQr9eTRTOTuQNzJNXRlYRLknj4cQ89tFfpxTEqxQnVWL4k55OPICgF5_SOZE06A</param-value>
</context-param>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet>
<servlet-name>Resource Servlet</servlet-name>
<servlet-class>com.icesoft.faces.webapp.CompatResourceServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/faces/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.jsf</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/icefaces/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Resource Servlet</servlet-name>
<url-pattern>/xmlhttp/*</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>
30
</session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>faces/index.xhtml</welcome-file>
</welcome-file-list>
</web-app>
这段代码给了我3个问题：
1 – 当我运行应用程序并单击其中一些按钮时,得到一个异常,表示我无法调用一个在另一个内部使用一个托管bean,因为它们的范围不兼容：
WARNING: queued exception javax.faces.FacesException: Unable to create
managed bean colorBean. The following problems were found:
– The scope of the object referenced by expression #{messageBean}, request, is shorter than the referring managed beans (colorBean) scope of view
2 – 在控制台中我一直看到一条消息说：
WARNING: PWC4011: Unable to set request character encoding to UTF-8
from context /ReverseAjaxExample, because request parameters have
already been read, or ServletRequest.getReader() has already been
called
3 – 如果我在托管bean中将@ApplicationScope更改为@ViewScope并将@ViewScope更改为@ApplicationScope,则第一个问题消失,我可以看到应用程序如何工作,但反向ajax不起作用,因为其他浏览器不显示变化.而且我也一直在控制台看到警告PWC4011
我从来没有使用反向Ajax,但我从理论的角度理解它.如果你能帮我修一下这个简单的应用,我真的很感激.
解决方法:
很多时候我碰巧花了几个小时调试,而错误的原因只是最简单的事情.
在这里我回答我自己的问题,表明我的错误是多么愚蠢：
而不是使用
javax.enterprise.context.ApplicationScoped
我应该用
javax.faces.bean.ApplicationScoped
原因是我没有使用Context和依赖注入,我只是使用JSF托管bean.
多亏了这个,我记得它,我只是重构了进口,就是这样
Ctrl Space不喜欢我:)
标签：icefaces,java,jsf,java-ee,reverse-ajax 来源： https://codeday.me/bug/20190902/1789304.html