java Struts2和Freemarker整合应用静态页面详解编程语言

利用Struts2生成静态页面其实很灵活，很强大，尤其是利用Struts2对Freemarker较好的支持，充分利用Freemarker的模板功能来生成静态 页面。

基本思路为：利用Struts2对自定义result type的支持，自定义能够生成静态页面的result type，结合模板引擎Freemarker可以实现大批量静态页面的生成。

参看org.apache.struts2.views.freemarker.FreemarkerResult的代码实现，自定义了自己的生成静态页 面的result type。此种方案不单纯用于生成静态页面，其实也可以用于生成诸如wml、xhtml等内容，具体可以参考Struts2缺省提供的各种result type的实现。

package com.mobilesoft.esales.webapp.action;  
import java.io.BufferedWriter; 
import java.io.File; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.OutputStreamWriter; 
import java.io.Writer; 
import java.util.Locale;  
import javax.servlet.ServletContext; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse;  
import org.apache.struts2.ServletActionContext; 
import org.apache.struts2.dispatcher.StrutsResultSupport; 
import org.apache.struts2.views.freemarker.FreemarkerManager; 
import org.apache.struts2.views.util.ResourceUtil;  
import com.opensymphony.xwork2.ActionContext; 
import com.opensymphony.xwork2.ActionInvocation; 
import com.opensymphony.xwork2.LocaleProvider; 
import com.opensymphony.xwork2.inject.Inject; 
import com.opensymphony.xwork2.util.ValueStack;  
import freemarker.template.Configuration; 
import freemarker.template.ObjectWrapper; 
import freemarker.template.Template; 
import freemarker.template.TemplateException; 
import freemarker.template.TemplateModel; 
import freemarker.template.TemplateModelException;  
 
public class FreemarkerResult extends StrutsResultSupport {  
    private static final long serialVersionUID = -3778230771704661631L;  
    protected ActionInvocation invocation; 
    protected Configuration configuration; 
    protected ObjectWrapper wrapper; 
    protected FreemarkerManager freemarkerManager; 
    private Writer writer; 
    protected String location; 
    private String pContentType = “text/html”;  
    protected String fileName; // 要生成的静态页面名称 
    protected String filePath; // 要生成的静态页面的路径 
    protected String staticTemplate; // 用于生成静态页面Freemarker模板的路径  
    public FreemarkerResult() { 
        super(); 
    }  
    public FreemarkerResult(String location) { 
        super(location); 
    }  
    @Inject 
    public void setFreemarkerManager(FreemarkerManager mgr) { 
        this.freemarkerManager = mgr; 
    }  
    public void setContentType(String aContentType) { 
        pContentType = aContentType; 
    }  
    public String getContentType() { 
        return pContentType; 
    }  
    public void doExecute(String location, ActionInvocation invocation) 
            throws IOException, TemplateException { 
        this.location = location; 
        this.invocation = invocation; 
        this.configuration = getConfiguration(); 
        this.wrapper = getObjectWrapper();  
        this.fileName = (String) conditionalParse(fileName, invocation); 
        this.staticTemplate = (String) conditionalParse(staticTemplate, invocation); 
        this.filePath = ((String) conditionalParse(filePath, invocation)) == null ? “” 
                : ((String) conditionalParse(filePath, invocation));  
        if (!location.startsWith(”/”)) { 
            ActionContext ctx = invocation.getInvocationContext(); 
            HttpServletRequest req = (HttpServletRequest) ctx 
                    .get(ServletActionContext.HTTP_REQUEST); 
            String base = ResourceUtil.getResourceBase(req); 
            location = base + “/” + location; 
        }  
        //生成html页面的模板类 
        Template template = configuration.getTemplate(location, deduceLocale()); 
        // 生成静态页面的的模板类 
        Template staticTemplate = configuration.getTemplate(this.staticTemplate, 
                deduceLocale());  
        TemplateModel model = createModel(); 
        String path = ServletActionContext.getServletContext().getRealPath( 
                filePath) 
                + File.separator; 
        Writer out = new BufferedWriter(new OutputStreamWriter( 
                new FileOutputStream(path + fileName)));  
        if (preTemplateProcess(template, model)) { 
            try { 
                staticTemplate.process(model, out); 
                template.process(model, getWriter()); 
            } finally { 
                postTemplateProcess(template, model); 
                postTemplateProcess(staticTemplate, model); 
            } 
        } 
    }  
    protected Configuration getConfiguration() throws TemplateException { 
        return freemarkerManager.getConfiguration(ServletActionContext 
                .getServletContext()); 
    }  
    protected ObjectWrapper getObjectWrapper() { 
        return configuration.getObjectWrapper(); 
    }  
    public void setWriter(Writer writer) { 
        this.writer = writer; 
    }  
    protected Writer getWriter() throws IOException { 
        if (writer != null) { 
            return writer; 
        } 
        return ServletActionContext.getResponse().getWriter(); 
    }  
    protected TemplateModel createModel() throws TemplateModelException { 
        ServletContext servletContext = ServletActionContext 
                .getServletContext(); 
        HttpServletRequest request = ServletActionContext.getRequest(); 
        HttpServletResponse response = ServletActionContext.getResponse(); 
        ValueStack stack = ServletActionContext.getContext().getValueStack();  
        Object action = null; 
        if (invocation != null) 
            action = invocation.getAction(); // Added for NullPointException 
        return freemarkerManager.buildTemplateModel(stack, action, 
                servletContext, request, response, wrapper); 
    }  
    protected Locale deduceLocale() { 
        if (invocation.getAction() instanceof LocaleProvider) { 
            return ((LocaleProvider) invocation.getAction()).getLocale(); 
        } else { 
            return configuration.getLocale(); 
        } 
    }  
    protected void postTemplateProcess(Template template, TemplateModel data) 
            throws IOException { 
    }  
    protected boolean preTemplateProcess(Template template, TemplateModel model) 
            throws IOException { 
        Object attrContentType = template.getCustomAttribute(”content_type”);  
        if (attrContentType != null) { 
            ServletActionContext.getResponse().setContentType( 
                    attrContentType.toString()); 
        } else { 
            String contentType = getContentType();  
            if (contentType == null) { 
                contentType = “text/html”; 
            }  
            String encoding = template.getEncoding();  
            if (encoding != null) { 
                contentType = contentType + “; charset=” + encoding; 
            }  
            ServletActionContext.getResponse().setContentType(contentType); 
        }  
        return true; 
    }  
    public String getFileName() { 
        return fileName; 
    }  
    public void setFileName(String fileName) { 
        this.fileName = fileName; 
    }  
    public String getFilePath() { 
        return filePath; 
    }  
    public void setFilePath(String filePath) { 
        this.filePath = filePath; 
    }  
    public String getStaticTemplate() { 
        return staticTemplate; 
    }  
    public void setStaticTemplate(String staticTemplate) { 
        this.staticTemplate = staticTemplate; 
    } 
}