Spring已集成jsp的环境下同时集成Velocity，springvelocity,Spring集成Velo

Spring已集成jsp的环境下同时集成Velocity，springvelocity,Spring集成Velo

Spring集成Velocity时所需的扩展类

VelocityLayoutView.java

package com.my.velocity;import java.io.StringWriter;import java.util.Locale;import javax.servlet.http.HttpServletResponse;import org.apache.velocity.Template;import org.apache.velocity.context.Context;import org.apache.velocity.exception.ResourceNotFoundException;import org.springframework.core.NestedIOException;import org.springframework.web.servlet.view.velocity.VelocityToolboxView;public class VelocityLayoutView extends VelocityToolboxView {    /**     * The default {@link #setLayoutUrl(String) layout url}.     */    public static final String DEFAULT_LAYOUT_URL = "layout.vm";    public static final String DEFAULT_LAYOUT_DIR = "/";    /**     * The default {@link #setLayoutKey(String) layout key}.     */    public static final String DEFAULT_LAYOUT_KEY = "layout";    /**     * The default {@link #setScreenContentKey(String) screen content key}.     */    public static final String DEFAULT_SCREEN_CONTENT_KEY = "screen_content";    private String layoutUrl = DEFAULT_LAYOUT_URL;    private String layoutKey = DEFAULT_LAYOUT_KEY;    private String screenContentKey = DEFAULT_SCREEN_CONTENT_KEY;    private String layoutDir = DEFAULT_LAYOUT_DIR;    /**     * Set the layout template to use. Default is {@link #DEFAULT_LAYOUT_URL "layout.vm"}.     * @param layoutUrl the template location (relative to the template     * root directory)     */    public void setLayoutUrl(String layoutUrl) {        this.layoutUrl = layoutUrl;    }    public String getLayoutDir() {        return layoutDir;    }    public void setLayoutDir(String layoutDir) {        this.layoutDir = layoutDir;    }    /**     * Set the context key used to specify an alternate layout to be used instead     * of the default layout. Screen content templates can override the layout     * template that they wish to be wrapped with by setting this value in the     * template, for example:<br>     * <code>#set( $layout = "MyLayout.vm" )</code>     * <p>Default key is {@link #DEFAULT_LAYOUT_KEY "layout"}, as illustrated above.     * @param layoutKey the name of the key you wish to use in your     * screen content templates to override the layout template     */    public void setLayoutKey(String layoutKey) {        this.layoutKey = layoutKey;    }    /**     * Set the name of the context key that will hold the content of     * the screen within the layout template. This key must be present     * in the layout template for the current screen to be rendered.     * <p>Default is {@link #DEFAULT_SCREEN_CONTENT_KEY "screen_content"}:     * accessed in VTL as <code>$screen_content</code>.     * @param screenContentKey the name of the screen content key to use     */    public void setScreenContentKey(String screenContentKey) {        this.screenContentKey = screenContentKey;    }    /**     * Overrides <code>VelocityView.checkTemplate()</code> to additionally check     * that both the layout template and the screen content template can be loaded.     * Note that during rendering of the screen content, the layout template     * can be changed which may invalidate any early checking done here.     */    @Override    public boolean checkResource(Locale locale) throws Exception {        if (!super.checkResource(locale)) {            return false;        }        try {            // Check that we can get the template, even if we might subsequently get it again.            getTemplate(this.layoutUrl);            return true;        }        catch (ResourceNotFoundException ex) {            throw new NestedIOException("Cannot find Velocity template for URL [" + this.layoutUrl +                    "]: Did you specify the correct resource loader path?", ex);        }        catch (Exception ex) {            throw new NestedIOException(                    "Could not load Velocity template for URL [" + this.layoutUrl + "]", ex);        }    }    /**     * Overrides the normal rendering process in order to pre-process the Context,     * merging it with the screen template into a single value (identified by the     * value of screenContentKey). The layout template is then merged with the     * modified Context in the super class.     */    @Override    protected void doRender(Context context, HttpServletResponse response) throws Exception {        renderScreenContent(context);        // Velocity context now includes any mappings that were defined        // (via #set) in screen content template.        // The screen template can overrule the layout by doing        // #set( $layout = "MyLayout.vm" )        String layoutUrlToUse = (String) context.get(this.layoutKey);        if (layoutUrlToUse != null) {            if (logger.isDebugEnabled()) {                logger.debug("Screen content template has requested layout [" + layoutUrlToUse + "]");            }            if(this.layoutDir != null){                layoutUrlToUse = this.layoutDir + layoutUrlToUse;            }        }        else {            // No explicit layout URL given -> use default layout of this view.            layoutUrlToUse = this.layoutUrl;        }        mergeTemplate(getTemplate(layoutUrlToUse), context, response);    }    /**     * The resulting context contains any mappings from render, plus screen content.     */    private void renderScreenContent(Context velocityContext) throws Exception {        if (logger.isDebugEnabled()) {            logger.debug("Rendering screen content template [" + getUrl() + "]");        }        StringWriter sw = new StringWriter();        Template screenContentTemplate = getTemplate(getUrl());        screenContentTemplate.merge(velocityContext, sw);        // Put rendered content into Velocity context.        velocityContext.put(this.screenContentKey, sw.toString());    }}

VelocityResolver.java

package com.my.velocity;import org.springframework.web.servlet.view.AbstractUrlBasedView;import org.springframework.web.servlet.view.velocity.VelocityViewResolver;public class VelocityResolver extends VelocityViewResolver {    private String layoutUrl;    private String layoutKey;    private String screenContentKey;    private String layoutDir;    public String getLayoutDir() {        return layoutDir;    }    public void setLayoutDir(String layoutDir) {        this.layoutDir = layoutDir;    }    /**     * Set the layout template to use. Default is "layout.vm".     * @param layoutUrl the template location (relative to the template     * root directory)     * @see VelocityLayoutView#setLayoutUrl     */    public void setLayoutUrl(String layoutUrl) {        this.layoutUrl = layoutUrl;    }    /**     * Set the context key used to specify an alternate layout to be used instead     * of the default layout. Screen content templates can override the layout     * template that they wish to be wrapped with by setting this value in the     * template, for example:<br>     * <code>#set( $layout = "MyLayout.vm" )</code>     * <p>The default key is "layout", as illustrated above.     * @param layoutKey the name of the key you wish to use in your     * screen content templates to override the layout template     * @see VelocityLayoutView#setLayoutKey     */    public void setLayoutKey(String layoutKey) {        this.layoutKey = layoutKey;    }    /**     * Set the name of the context key that will hold the content of     * the screen within the layout template. This key must be present     * in the layout template for the current screen to be rendered.     * <p>Default is "screen_content": accessed in VTL as     * <code>$screen_content</code>.     * @param screenContentKey the name of the screen content key to use     * @see VelocityLayoutView#setScreenContentKey     */    public void setScreenContentKey(String screenContentKey) {        this.screenContentKey = screenContentKey;    }    /**     * Requires VelocityLayoutView.     * @see VelocityLayoutView     */    protected Class requiredViewClass() {        return VelocityLayoutView.class;    }    protected AbstractUrlBasedView buildView(String viewName) throws Exception {        VelocityLayoutView view = (VelocityLayoutView) super.buildView(viewName);        //设置模版文件(layout)的根目录        if(this.layoutDir != null){            view.setLayoutDir(this.layoutDir);        }        if (this.layoutUrl != null) {            view.setLayoutUrl(this.layoutUrl);        }        if (this.layoutKey != null) {            view.setLayoutKey(this.layoutKey);        }        if (this.screenContentKey != null) {            view.setScreenContentKey(this.screenContentKey);        }        return view;    }}