webwind源码分析（3）

模板部分:

TemplateFactory 抽象类:单类

//通过给定路径返回一个模板, 经典的抽象工厂模式
public Template loadTemplate(String path) throws Exception

 

两个子类:JspTemplateFactory 和VelocityTemplateFactory

VelocityTemplateFactory类:

初始化:

public void init(Config config) {
        String webAppPath = config.getServletContext().getRealPath("/");
        if (webAppPath==null) {
            String err = "Cannot get web application path. Are you deploy the application as a .war file?";
            log.warn(err);
            throw new ExceptionInInitializerError(err);
        }
        if (!webAppPath.endsWith("/") && !webAppPath.endsWith("\\"))
            webAppPath = webAppPath + File.separator;
        log.info("Detect web application path: " + webAppPath);
        log.info("init VelocityTemplateFactory...");
        rtInstance = new RuntimeInstance();
        // read property file:
//读取velocity的配置文件
        Properties props = readProperties(webAppPath + "/WEB-INF/velocity.properties");
        checkProperty(props);
        Set<?> keys = props.keySet();
        for(Object key : keys) {
            if(key instanceof String) {
                Object value = props.get(key);
                rtInstance.addProperty((String)key, value);
            }
        }
        try {
            if(rtInstance.getProperty(RuntimeConstants.FILE_RESOURCE_LOADER_PATH)==null) {
                rtInstance.setProperty(RuntimeConstants.FILE_RESOURCE_LOADER_PATH, webAppPath);
                log.info("Using web application context path as velocity template root path: " + webAppPath);
            }
            else {
                log.info("Velocity property \"" + RuntimeConstants.FILE_RESOURCE_LOADER_PATH + "\" has been specified in \"/WEB-INF/velocity.properties\".");
                log.info("To using web application context path, remove property \"" + RuntimeConstants.FILE_RESOURCE_LOADER_PATH + "\" from configuration file.");
            }
//初始化
            rtInstance.init();
            afterVelocityEngineInit(rtInstance);
        }
        catch(Exception e) {
            log.error("VelocityTemplateFactory init failed.", e);
            throw new ExceptionInInitializerError(e);
        }
    }

 

创建模板:

 

public Template loadTemplate(String path) throws Exception {
        if (log.isDebugEnabled())
            log.debug("Load Velocity template '" + path + "'.");
        return new VelocityTemplate(
                rtInstance.getTemplate(path, inputEncoding),
                null,
                outputEncoding
        );
    }

 

再看模板部分:

Template接口:

 

//使用模板引擎渲染

voidrender(HttpServletRequest request, HttpServletResponse response,Map<String, Object> model) throwsException;

 

JspTemplate模板:

public void render(HttpServletRequest request, HttpServletResponse response, Map<String, Object> model) throws Exception {
        Set<String> keys = model.keySet();
//向request中写入数据
        for (String key : keys) {
            request.setAttribute(key, model.get(key));
        }
//用当前的模板路径(jsp)得到一个Dispatcher, 然后跳转(forward)到这个页面上
//NOTES:
//使用forward的时候浏览器不知道它所请求的具体资源来源，所以地址栏不会变；
//使用redirect，服务端根据逻辑,发送一个状态码,告诉浏览器重新去请求那个地址.所以地址栏显示的是新的URL。
        request.getRequestDispatcher(path).forward(request, response);
    }

VelocityTemplate模板:

public void render(HttpServletRequest request, HttpServletResponse response, Map<String, Object> model) throws Exception {
        StringBuilder sb = new StringBuilder(64);
        sb.append(contentType==null ? "text/html" : contentType)
                .append(";charset=")
                .append(encoding==null ? "UTF-8" : encoding);
//设置头部信息
        response.setContentType(sb.toString());
        response.setCharacterEncoding(encoding==null ? "UTF-8" : encoding);
        // init context: 
        Context context = new VelocityContext(model);
        afterContextPrepared(context);
        // render: 获取渲染writer
        VelocityWriter vw = new VelocityWriter(response.getWriter());
        try {
//merge数据
            template.merge(context, vw);
            vw.flush();
        }
        finally {
            vw.recycle(null);
        }
    }

至此,模板部分也完了.很简单.