abstractmenudisplayer.java

Struts Menu这是为基于JSP和Struts的应用程序提供的Web菜单框架。菜单可以在一个XML文件中定义

/*
 * AbstractMenuDisplayer.java
 *
 * Created on March 30, 2002, 3:34 PM
 */
package net.sf.navigator.displayer;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;

import net.sf.navigator.menu.MenuComponent;
import net.sf.navigator.menu.PermissionsAdapter;

import org.apache.struts.util.MessageResources;


/**
 * Abstract implementation of <code>MenuDisplayer</code> that can be used as
 * a basis for other menu displayers.
 *
 * @author  ssayles
 * @version
 */
public abstract class AbstractMenuDisplayer implements MenuDisplayer {
    //~ Instance fields ========================================================

    protected String name;
    protected MessageResources displayStrings;
    protected JspWriter out;
    protected String target;

    /** Holds value of property permissionsAdapter. */
    protected PermissionsAdapter permissionsAdapter;
    protected MenuDisplayerMapping mapping;

    //~ Methods ================================================================

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getConfig() {
        String config = null;

        if (displayStrings != null) {
            config = displayStrings.getConfig();
        }

        return config;
    }

    public void setConfig(String config) {
        displayStrings = MessageResources.getMessageResources(config);
    }

    public void setConfig(MessageResources displayStrings) {
        this.displayStrings = displayStrings;
    }

    public String getTarget() {
        return target;
    }

    /**
     * Convenience method that will first return the target for the displayer
     * if it is not null.  If the displayer target is null, then it will
     * return <code>menu.getTarget()</code>.
     *
     * @return the target for the menu link.
     */
    protected String getTarget(MenuComponent menu) {
        String theTarget = null;

        if (target == null) {
            if (menu.getTarget() != null) {
                theTarget = menu.getTarget();
            }
        } else {
            theTarget = target;
        }

        return theTarget;
    }

    public void setTarget(String target) {
        this.target = target;
    }

    /**
     * Getter for property permissionsAdapter.
     * @return Value of property permissionsAdapter.
     */
    public PermissionsAdapter getPermissionsAdapter() {
        return this.permissionsAdapter;
    }

    /**
     * Setter for property permissionsAdapter.
     * @param permissionsAdapter New value of property permissionsAdapter.
     */
    public void setPermissionsAdapter(PermissionsAdapter permissionsAdapter) {
        this.permissionsAdapter = permissionsAdapter;
    }

    /**
     * Lifecycle method that should be called when the <code>MenuDisplayer</code>
     * is being prepared for use.
     *
     * @param pageContext The JSP pageContext to give the displayer access
     *              to any resources it may need.
     * @param mapping The menu displayer mapping used to embody the xml
     *              definition.
     */
    public void init(PageContext pageContext, MenuDisplayerMapping mapping) {
        this.out = pageContext.getOut();
        this.mapping = mapping;
    }

    public abstract void display(MenuComponent menu)
    throws JspException, IOException;

    public void end(PageContext pageContext) {}

    /**
     * Returns <code>true</code> if the specified component is usable.
     * If <code>permissionsAdapter</code> is not defined, this method will
     * return <code>true</code>.  Otherwise, the adapter will be used to check
     * permissions on the menu.
     *
     * @return <code>true</code> if the menu component is usable.
     * @param menu The menu component.
     */
    public boolean isAllowed(MenuComponent menu) {
        if (permissionsAdapter == null) {
            return true;
        } else {
            return permissionsAdapter.isAllowed(menu);
        }
    }
}