在struts2中如何定义全局session

在Struts2中，可以通过实现`org.apache.struts2.dispatcher.SessionMap`接口，创建一个自定义的session类，并在struts.xml文件中定义全局的session。

例如，我们可以创建一个名为`MySession`的session类，如下所示：

public class MySession implements SessionMap<String,Object> {

    private Map<String, Object> session;

    @Override
    public void clear() {
        session.clear();
    }

    @Override
    public boolean containsKey(Object arg0) {
        return session.containsKey(arg0);
    }

    @Override
    public boolean containsValue(Object arg0) {
        return session.containsValue(arg0);
    }

    @Override
    public Set<Map.Entry<String, Object>> entrySet() {
        return session.entrySet();
    }

    @Override
    public Object get(Object arg0) {
        return session.get(arg0);
    }

    @Override
    public boolean isEmpty() {
        return session.isEmpty();
    }

    @Override
    public Set<String> keySet() {
        return session.keySet();
    }

    @Override
    public Object put(String arg0, Object arg1) {
        return session.put(arg0, arg1);
    }

    @Override
    public void putAll(Map<? extends String, ? extends Object> arg0) {
        session.putAll(arg0);
    }

    @Override
    public Object remove(Object arg0) {
        return session.remove(arg0);
    }

    @Override
    public int size() {
        return session.size();
    }

    @Override
    public Collection<Object> values() {
        return session.values();
    }

    @Override
    public void invalidate() {
        session.clear();
    }

    @Override
    public boolean isNew() {
        return false;
    }

    @Override
    public void setMaxInactiveInterval(int interval) {
        // do nothing
    }

    @Override
    public int getMaxInactiveInterval() {
        return 0;
    }

    @Override
    public long getCreationTime() {
        return 0;
    }

    @Override
    public String getId() {
        return null;
    }

    @Override
    public long getLastAccessedTime() {
        return 0;
    }

    @Override
    public void removeValue(String key) {
        session.remove(key);
    }

    @Override
    public void setAttribute(String key, Object value) {
        session.put(key, value);
    }

    @Override
    public void putValue(String key, Object value) {
        session.put(key, value);
    }

    @Override
    public void removeAttribute(String key) {
        session.remove(key);
    }

    @Override
    public Object getAttribute(String key) {
        return session.get(key);
    }

    @Override
    public Enumeration<String> getAttributeNames() {
        return Collections.enumeration(session.keySet());
    }

    @Override
    public String[] getValueNames() {
        return session.keySet().toArray(new String[0]);
    }

    public void setSession(Map<String, Object> session) {
        this.session = session;
    }

}

然后在`struts.xml`文件中配置全局的session：

<constant name="struts.objectFactory" value="org.apache.struts2.spring.StrutsSpringObjectFactory" />
<constant name="struts.objectFactory.spring.autoWire.alwaysRespect" value="true" />
<constant name="struts.objectFactory.spring.useClassCache" value="true" />

<session-factory class="com.example.MySession">
    <property name="session">
        <map>
            <entry key="key1">
                <value>value1</value>
            </entry>
            <entry key="key2">
                <value>value2</value>
            </entry>
        </map>
    </property>
</session-factory>

这样就可以在整个应用程序中使用`MySession`类作为全局session了。