导航规则是JSF Framework提供的那些规则，用于描述单击按钮或链接时要显示的视图.
可以在JSF配置文件中定义导航规则faces-config.xml中.它们可以在托管bean中定义.
导航规则可以包含可以显示结果视图的条件. JSF 2.0也提供隐式导航，其中不需要定义导航规则.
JSF 2.0提供自动查看页面解析程序名为隐式导航的机制.在这种情况下，您只需要将视图名称放在action属性中，JSF将在已部署的应用程序中自动搜索正确的视图页面.
在任何操作属性中设置视图名称JSF UI组件.
<h:form> <h3>Using JSF outcome</h3> <h:commandButton action = "page2" value = "Page2" /> </h:form>
在这里，当点击 Page2 按钮时，JSF将解析视图名称 page2 as page2 .xhtml扩展名，并在当前目录中找到相应的视图文件 page2.xhtml .
在托管bean中定义一个方法以返回视图名称.
@ManagedBean(name = "navigationController", eager = true)
@RequestScoped
public class NavigationController implements Serializable {
public String moveToPage1() {
return "page1";
}
}使用托管bean获取任何JSF UI组件的action属性中的视图名称.
<h:form>
<h3> Using Managed Bean</h3>
<h:commandButton action = "#{navigationController.moveToPage1}"
value = "Page1" /glt;
</h:form>在这里，当点击 Page1 按钮时，JSF将解析视图名称 page1 as page1 .xhtml扩展名，并在当前目录中找到相应的视图文件 page1.xhtml .
使用托管bean，我们可以非常轻松地控制导航.查看托管bean中的以下代码.
@ManagedBean(name = "navigationController", eager = true)
@RequestScoped
public class NavigationController implements Serializable {
//this managed property will read value from request parameter pageId
@ManagedProperty(value = "#{param.pageId}")
private String pageId;
//condional navigation based on pageId
//if pageId is 1 show page1.xhtml,
//if pageId is 2 show page2.xhtml
//else show home.xhtml
public String showPage() {
if(pageId == null) {
return "home";
}
if(pageId.equals("1")) {
return "page1";
}else if(pageId.equals("2")) {
return "page2";
}else {
return "home";
}
}
}将pageId作为JSF UI组件中的请求参数传递.
<h:form>
<h:commandLink action = "#{navigationController.showPage}" value = "Page1">
<f:param name = "pageId" value = "1" />
</h:commandLink>
<h:commandLink action = "#{navigationController.showPage}" value = "Page2">
<f:param name = "pageId" value = "2" />
</h:commandLink>
<h:commandLink action = "#{navigationController.showPage}" value = "Home">
<f:param name = "pageId" value = "3" />
</h:commandLink>
</h:form>这里，当点击"Page1"按钮时.
JSF将使用参数pageId = 1
创建请求然后JSF将此参数传递给navigationController的托管属性pageId
现在调用navigationController.showPage()，它会在检查pageId后返回view1页面
JSF将将视图名称page1解析为page1.xhtml扩展名
在当前目录中查找相应的视图文件page1.xhtml
JSF提供导航解析选项，即使托管bean不同的方法返回相同的视图名称.
查看托管bean中的以下代码.
public String processPage1() {
return "page";
}
public String processPage2() {
return "page";
}要解析视图，请在 faces-config.xml
<navigation-rule>
<from-view-id>home.xhtml</from-view-id>
<navigation-case>
<from-action>#{navigationController.processPage1}</from-action>
<from-outcome>page</from-outcome>
<to-view-id>page1.jsf</to-view-id>
</navigation-case>
<navigation-case>
<from-action>#{navigationController.processPage2}</from-action>
<from-outcome>page</from-outcome>
<to-view-id>page2.jsf</to-view-id>
</navigation-case>
</navigation-rule>这里，点击Page1按钮 :
调用
navigationController.processPage1()将视图返回页面
JSF将解析视图名称 page1 视图名称为页面，而 faces-config中的from-action 是navigationController.processPage1
在当前目录中找到相应的视图文件 page1.xhtml
JSF默认执行服务器页面转发导航到另一个页面并且应用程序的URL不会更改.
要启用页面重定向，请在视图末尾附加 faces-redirect = true name.
<h:form> <h3>Forward</h3> <h:commandButton action = "page1" value = "Page1" /> <h3>Redirect</h3> <h:commandButton action = "page1?faces-redirect = true" value = "Page1" /> </h:form>
此处，当点击转发下的 Page1 按钮时，您将获得以下结果.
此处 Page1 重定向下的>按钮，您将得到以下结果.
让我们创建一个测试JSF应用程序来测试上述所有导航示例.
| Step | 描述 |
|---|---|
| 1 | 在包com.it1352.test 下创建一个名为 helloworld 的项目，如 JSF中所述 - 创建应用程序章节. |
| 2 | 在包 com.it1352.test 下创建 NavigationController.java ，如下所述. |
| 3 | 在 WEB-INF 文件夹下创建 faces-config.xml 并更新其内容，如下所述. |
| 4 | 更新 web.xml 在 WEB-INF 文件夹下，如下所述. |
| 5 | 创建 page1.xhtml 和 page2.xhtml 并修改 home.xhtml 在 webapp 文件夹下，如下所述. |
| 6 | 编译并运行应用程序以确保业务逻辑按照要求运行. |
| 7 | 最后，以war文件的形式构建应用程序并将其部署在Apache Tomcat Webserver中. |
| 8 | 使用适当的URL启动您的Web应用程序如下面最后一步所述. |
package com.it1352.test;
import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ManagedProperty;
import javax.faces.bean.RequestScoped;
@ManagedBean(name = "navigationController", eager = true)
@RequestScoped
public class NavigationController implements Serializable {
private static final long serialVersionUID = 1L;
@ManagedProperty(value = "#{param.pageId}")
private String pageId;
public String moveToPage1() {
return "page1";
}
public String moveToPage2() {
return "page2";
}
public String moveToHomePage() {
return "home";
}
public String processPage1() {
return "page";
}
public String processPage2() {
return "page";
}
public String showPage() {
if(pageId == null) {
return "home";
}
if(pageId.equals("1")) {
return "page1";
}else if(pageId.equals("2")) {
return "page2";
}else {
return "home";
}
}
public String getPageId() {
return pageId;
}
public void setPageId(String pageId) {
this.pageId = pageId;
}
}<?xml version = "1.0" encoding = "UTF-8"?>
<faces-config
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-facesconfig_2_0.xsd"
version = "2.0">
<navigation-rule>
<from-view-id>home.xhtml</from-view-id>
<navigation-case>
<from-action>#{navigationController.processPage1}</from-action>
<from-outcome>page</from-outcome>
<to-view-id>page1.jsf</to-view-id>
</navigation-case>
<navigation-case>
<from-action>#{navigationController.processPage2}</from-action>
<from-outcome>page</from-outcome>
<to-view-id>page2.jsf</to-view-id>
</navigation-case>
</navigation-rule>
</faces-config><!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" > <web-app> <display-name>Archetype Created Web Application</display-name> <context-param> <param-name>javax.faces.PROJECT_STAGE</param-name> <param-value>Development</param-value> </context-param> <context-param> <param-name>javax.faces.CONFIG_FILES</param-name> <param-value>/WEB-INF/faces-config.xml</param-value> </context-param> <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>*.jsf</url-pattern> </servlet-mapping> </web-app>
<?xml version = "1.0" encoding = "UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns = "http://www.w3.org/1999/xhtml" xmlns:h = "http://java.sun.com/jsf/html"> <h:body> <h2>This is Page1</h2> <h:form> <h:commandButton action = "home?faces-redirect = true" value = "Back To Home Page" /> </h:form> </h:body> </html>
<?xml version = "1.0" encoding = "UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns = "http://www.w3.org/1999/xhtml" xmlns:h = "http://java.sun.com/jsf/html"> <h:body> <h2>This is Page2</h2> <h:form> <h:commandButton action = "home?faces-redirect = true" value = "Back To Home Page" /> </h:form> </h:body> </html>
<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns = "http://www.w3.org/1999/xhtml"
xmlns:f = "http://java.sun.com/jsf/core"
xmlns:h = "http://java.sun.com/jsf/html">
<h:body>
<h2>Implicit Navigation</h2>
<hr />
<h:form>
<h3>Using Managed Bean</h3>
<h:commandButton action = "#{navigationController.moveToPage1}"
value = "Page1" />
<h3>Using JSF outcome</h3>
<h:commandButton action = "page2" value = "Page2" />
</h:form>
<br/>
<h2>Conditional Navigation</h2>
<hr />
<h:form>
<h:commandLink action = "#{navigationController.showPage}"
value="Page1">
<f:param name = "pageId" value = "1" />
</h:commandLink>
<h:commandLink action = "#{navigationController.showPage}"
value="Page2">
<f:param name = "pageId" value = "2" />
</h:commandLink>
<h:commandLink action = "#{navigationController.showPage}"
value = "Home">
<f:param name = "pageId" value = "3" />
</h:commandLink>
</h:form>
<br/>
<h2>"From Action" Navigation</h2>
<hr />
<h:form>
<h:commandLink action = "#{navigationController.processPage1}"
value = "Page1" />
<h:commandLink action = "#{navigationController.processPage2}"
value = "Page2" />
</h:form>
<br/>
<h2>Forward vs Redirection Navigation</h2>
<hr />
<h:form>
<h3>Forward</h3>
<h:commandButton action = "page1" value = "Page1" />
<h3>Redirect</h3>
<h:commandButton action = "page1?faces-redirect = true"
value = "Page1" />
</h:form>
</h:body>
</html>完成所有更改之后，让我们像在JSF - Create Application章节中那样编译并运行应用程序.如果您的应用程序一切正常，这将产生以下结果.
