Managed Beans

1、Managed beans的编写
1)采用注释的方式进行实例化
@ManagedBean/@ManagedBean(name="beanName")
@SessionScoped
public class className｛｝
2)在faces-config.xml文件进行配置
<managed-bean>
   <managed-bean-name>userBean</managed-bean-name>
   <managed-bean-class>完全类路径</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
2、给bean的属性注入值
1、采用注释方式注入
@ManagedBean
@SessionScoped
public class UserBean {

@ManagedProperty(value="Jane")
private String firstName;
@ManagedProperty(value="Doe")
private String lastName;

public String getFirstName() {
   return firstName;
  }
public void setFirstName(String firstName) {
  this.firstName = firstName;
}
public String getLastName() {
   return lastName;
  }
public void setLastName(String lastName) {
  this.lastName = lastName;
}
}
2、采用xml方式注入（fancs.config.xml）<managed-bean>
<managed-bean-name>userBean</managed-bean-name>
  <managed-bean-class>完全类路径</managed-bean-class>
  <managed-bean-scope>session</managed-bean-scope>
  <managed-property>
   <property-name>firstName</property-name>
   <value>Jane</value>
  </managed-property>
  <managed-property>
   <property-name>lastName</property-name>
   <value>Doe</value>
  </managed-property>
</managed-bean>
2.1、给list类型的属性注入值
<managed-bean>
...
<managed-property>
  <property-name>sportsInterests</property-name>
   <list-entries>
    <value>Cycling</value>
    <value>Running</value>
    <value>Swimming</value>
    <value>Kayaking</value>
    ...
   </list-entries>
  </managed-property>
</managed-bean>
注：</list-entries>默认的list泛型是String类型，如果要注入其他类型可以这样使用：
<managed-bean>
...
<managed-property>
<property-name>racePlacement</property-name>
  <list-entries>
   <value-class>java.lang.Integer</value-class>
   <value>23</value>
   <value>12</value>
   <value>3</value>
   <value>1</value>
    ...
  </list-entries>
</managed-property>
</managed-bean>
  Element        Description
。。<managed-property>    Same as before, the parent element for managed properties.

。。<property-name>       The name of the property, which must be of type array
         or java.util.List.
        
。。<property-class>    JSF uses the default type of ArrayList, but any other list concrete
          class could be specified here.
         
。。<list-entries>(1 to N)   Parent element of the <value-class>, list values defined in multiple
         <value> or <null-value> elements.
        
。。<value-class>     When not using the default list type of java.lang.String, one must
          specify the list item data type here. (Optional)
         
。。<value> or <null-value>  The <value> element provides the value with which to set the
             property. When initializing a property to a null value, a <null-value>
         tag is used instead.
         Note: The <null-value> element cannot be used for primitive data types.
注：list的类型可以这样读
  <h:outputText value="#{userBean.sportsInterests[0]}"/>
2.2给map类型的属性注入
<managed-bean>
...
<managed-property>
   <property-name>sportsInterests</property-name>
    <map-entries>
     <map-entry>
      <key>Cycling</key>
      <value>Any competitive athletic event where a bicycle is used.</value>
      </map-entry>
     <map-entry>
      <key>Running</key>
<value>Any competitive athletic event where the competitors are running or jogging.</value>
     </map-entry>
     <map-entry>
      <key>Swimming</key>
      <value>Any competitive athletic event where the competitors are swimmming.</value>
     </map-entry>
     <map-entry>
      <key>Kayaking</key>
      <value>Any competitive athletic event where the competitors use a kayak.</value>
     </map-entry>
    </map-entries>
    ...
   </managed-property>
</managed-bean>
注：map的类型可以这样读：
<h:outputText value="#{userBean.sportsInterests['Swimming']}"/>
   Element       Description
。。<managed-property>    Same as before, the parent element for managed properties.

。。<property-name>     The name of the property.

。。<property-class>    JSF uses the default type of HashMap, but any other Map concrete
         class could be specified here.
        
。。<map-entries>     Parent element of <key-class>, <value-class>, and Map entries.

。。<key-class>      Element specifying data type of the keys used in the map. When
         not specified, a java.lang.String is used as a default. (Optional)
        
。。<value-class>     Element specifying data type of the values used in the map.
         When not specified, a java.lang.String is also used as a default.(Optional)
        
。。<map-entry>(1 to N)    Parent element to a Map key/value element pair.

。。<key>       The key value used to look up an associated value.

。。<value>or<null-value>  The <value> element that is retrieved when the associated key
         is supplied. To initialize a Map property to a null value, a <nullvalue> tag is used.
         Note: The <null-value> element cannot be used for primitive data types.

3、Controlling Managed Bean Life Spans
#{userBean }
#{userBean }
#{userBean }
#{userBean }
1）@NoneScoped
像这样写在同一个页面中，只有一个请求，但是会实例化四次bean。
2）@RequestScoped
实例化一次，每次请求得到的对象都是不同的。即请求一次实例化一次。
3)@ViewScoped
  在同一页面内是同一对象的，但通过浏览器去刷新，每次都会实例化。
  4）@SessionScoped
  一次会话内都是同一对象，除非session失效或者超时。
  5）@ApplicationScoped
  存活于整个应用服务。