上一個項目使用的是spring MVC； 客戶需要做Ajax應用；所以就找了一些資料研究了一下，比如DWR，dojo， prototype，JSON-RPC, trimpath 等等，發現很多不適合我們，比如DWR要生成客戶端js，服務器端還要部署，麻煩；dojo又太慢了；經過一輪淘汰剩下了prototype和trimpath；所以最終就選這2個了；

Prototype在書寫普通的js時候，有很多好處，比如簡單，實用的很多函數；比如$()系列；

Trimpath提供一個客戶端的js模板，如果從服務器回來的數據很復雜，要動態改變Html元素是比較費力的事情；用trimpath就方便許多；

在模板語言的世界里，總有2個東西：模板和模板中的數據；trimpath的模板接受的數據是javascript object，模板則定義在一個不顯示的textarea里面；

所以有個問題就是：怎么讓ajax調用返回一個javascript對象？

后來，我終于發現了（想起了劉若英）JSON；發現json是個好東東；比xml輕量級，又可以很容易的轉換為javascript對象，而且還有java api；唉，開源的世界多美妙；

所以解決方案就是，在springmvc框架中，用response返回json string，給ajax 客戶端，然后生成javascript對象，然后，調用trimpath模板，然后，動態修改頁面。

代碼片段：

    public ModelAndView getClient(HttpServletRequest request, HttpServletResponse response) throws Exception {

        JSONObject jsonObject = new JSONObject();

        Client client=clientMgr.getClientByPk(Long.parseLong(request.getParameter("clientId")));

        jsonObject.add("client", client);

        return ajaxResponse(jsonObject, response);

    }

    protected ModelAndView ajaxResponse(JSONObject jsonObject, HttpServletResponse response) throws Exception {

        response.setContentType("application/x-json;charset=UTF-8");

        response.getWriter().print(jsonObject);

        return null;

    }

利用xpath，freemarker等技術，使得用戶通過xml配置文件，模板等簡單的方式，快速開發代碼和根據需求調整模板；

Dom4j對實現了xpath 1.0， 非常的好用；

所需jar ：dom4j-1.6.1.jar， jaxen-1.1-beta-7.jar

Code：

import junit.framework.TestCase;

import org.dom4j.*;

import org.dom4j.io.SAXReader;

import java.util.List;

import java.util.Iterator;

import java.io.File;

/**

 * Created by IntelliJ IDEA.

 * User: duanbin

 * Date: 2007-8-15

 * Time: 9:47:17

 * To change this template use File | Settings | File Templates.

 */

public class XPathTest extends TestCase {

    public void testXPathViaDom4jXpathV1() {

        printSelectedNodeValue("D:""xpath""src""test.xml");

    }

    /**

     * 利用XPath操作XML文件，打印指定節點或者屬性的值, using xpath 1.0

     *

     * @param filename String 待操作的XML文件（相對路徑或者絕對路徑）

     */

    public void printSelectedNodeValue(String filename) {

        try {

            SAXReader saxReader = new SAXReader();

            Document document = saxReader.read(new File(filename));

            List list;

            list = document.selectNodes("http://qn1:college/@leader[.!='leader1']");

            for (Object aList : list) {

                Attribute attribute = (Attribute) aList;

                System.out.println("http://qn1:college/@leader: " + attribute.getValue());

            }

            //打印所有student節點的屬性age值，如果有的話

//            list = document.selectNodes("/students/student/@age");

//            for (Object aList : list) {

//                Attribute attribute = (Attribute) aList;

//                System.out.println("/students/student/@age：" + attribute.getValue());

//            }

            //打印所有college節點值，如果有的話

//            list = document.selectNodes("/students/student");

//            for (Object aList1 : list) {

//                Element bookElement = (Element) aList1;

//                Iterator iterator = bookElement.elementIterator("college");

//                while (iterator.hasNext()) {

//                    Element titleElement = (Element) iterator.next();

//                    System.out.println("/students/student/college：" + titleElement.getText());

//                }

//            }

            //測試節點的一些方法

//            list = document.selectNodes("http://city");

//            for (Object aList2 : list) {

//                Element titleElement = (Element) aList2;

//                System.out.print("http://telephone：getName:" + titleElement.getName());

//                System.out.print(" ##getNodeType:" + titleElement.getNodeType());

//                System.out.print(" ##getTextTrim:" + titleElement.getTextTrim());

//                System.out.print(" ##getNamespaceURI:" + titleElement.getNamespaceURI());

//                System.out.print(" ##getNodeTypeName:" + titleElement.getNodeTypeName());

//                System.out.print(" ##getQualifiedName:" + titleElement.getQualifiedName());

//                System.out.print(" ##getUniquePath:" + titleElement.getUniquePath());

//                System.out.println(" ##getPath:" + titleElement.getPath());

//            }

            //打印所有name節點值，如果有的話，與上面college的取法不一樣

//            list = document.selectNodes("/students/student/name");

//            Iterator iter = list.iterator();

//            for (Object aList3 : list) {

//                Element titleElement = (Element) aList3;

//                System.out.println("/students/student/name：" + titleElement.getText());

//            }

        } catch (Exception ex) {

            ex.printStackTrace();

        }

    }

}

Test.xml:

<?xml version="1.0" encoding="UTF-8"?>

<students xmlns:qn1="http://qn1.com">

    <student age="259911911911"><!--如果沒有age屬性，默認的為20-->

        <qn1:name>崔衛兵</qn1:name>

        <college>PC學院</college>

        <telephone>62354666</telephone>

        <notes>男,1982年生,碩士，現就讀于北京郵電大學</notes>

        <addr><city>Beijing</city></addr>

    </student>

    <student>

        <name>cwb</name>

        <qn1:college leader="學院領導">PC學院</qn1:college><!--如果沒有leader屬性，默認的為leader-->

        <telephone>62358888</telephone>

        <notes>男,1987年生,碩士，現就讀于中國農業大學</notes>

    </student>

    <student>

        <name>xxxxx</name>

        <college leader="">xxx學院</college>

        <telephone>66666666</telephone>

        <notes>注視中，注釋中</notes>

    </student>

    <student age="9911911911">

        <name>yyyyyy</name>

        <qn1:college leader="leader1">yyyy學院</qn1:college>

        <telephone>88888888</telephone>

        <notes>注視中111，注釋中222</notes>

    </student>

</students>

Freemarker基本示例：

import freemarker.template.Configuration;

import freemarker.template.DefaultObjectWrapper;

import freemarker.template.Template;

import java.io.File;

import java.io.Writer;

import java.io.OutputStreamWriter;

import java.io.FileOutputStream;

import java.util.Map;

import java.util.HashMap;

import org.apache.log4j.Logger;

/**

 * Created by IntelliJ IDEA.

 * User: duanbin

 * Date: 2007-8-21

 * Time: 22:30:13

 * To change this template use File | Settings | File Templates.

 */

public abstract class BaseGenerator {

    protected Configuration cfg;

    protected final Logger logger = Logger.getLogger(this.getClass());

    public BaseGenerator() {

        try {

            cfg = getConfiguration(CodeEngineConfig.getTemplateDir());

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    public abstract void generate();

    protected void generateFile(String template, Map root, String fileName){

           try {

                File dist = new File(fileName);

                FileOutputStream fos = new FileOutputStream(dist);

                Writer out = new OutputStreamWriter(fos);

    //            Writer out2 = new OutputStreamWriter(System.out);

                cfg.getTemplate(template).process(root, out);

                out.flush();

                out.close();

                logger.info("Generated File: " + fileName);

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    protected Configuration getConfiguration(String tempDir) throws Exception {

        Configuration cfg = new Configuration();

        // Specify the data source where the template files come from.

        // Here I set a file directory for it:

        cfg.setDirectoryForTemplateLoading(

                new File(tempDir));

        // Specify how templates will see the data model. This is an advanced topic...

        // but just use this:

        cfg.setObjectWrapper(new DefaultObjectWrapper());

        return cfg;

    }

}

模板文件示例：

package ${package}.application.web;

import biz.web.framework.web.BaseController;

<#list managers! as mgr>

import ${package}.application.manager.${mgr};

</#list>

<#list services! as svc>

import ${package}.application.service.${svc};

</#list>

/**

 * Created by IntelliJ IDEA.

 * User: ${author!'admin'} "${r"${build.dir}"} "${'$'}{cfg.startDate}

 * Date: Sep 1, 2006

 * Time: 9:19:17 AM

 * To change this template use File | Settings | File Templates.

 */

public class ${name}Controller extends BaseController {

<#list managers! as mgr>

    protected ${mgr} ${mgr?uncap_first};

</#list>

<#list services! as svc>

    protected ${svc} ${svc?uncap_first};

</#list>

<#list managers! as mgr>

    public void set${mgr}(${mgr} ${mgr?uncap_first}) {

        this.${mgr?uncap_first} = ${mgr?uncap_first};

    }

</#list>

<#list services! as svc>

    public void set${svc}(${svc} ${svc?uncap_first}) {

        this.${svc?uncap_first} = ${svc?uncap_first};

    }

</#list>

     public ModelAndView list${name}(HttpServletRequest request, HttpServletResponse response) throws Exception {

        ModelAndView mav = new ModelAndView("update_${name?uncap_first}");

        Long user = getUserId();

        mav.addObject("userId", user);

        return mav;

    }

}

springside的文檔中有aop的配置；http://wiki.springside.org.cn/display/springside/Spring+Aop
里面有關于pointcut 表達式語言的表述；

里面也有官方文檔中文版的鏈接：http://www.redsaga.com/spring_ref/2.0/html/aop.html
我們用scheme-based aop 配置方式：
 <aop:config> ......    </aop:config>

Advisor方式：
假設我們有一個MethodBeforeAdvice 叫TestAdvice
；用于打印將要執行的方面名；
public class TestAdvice implements MethodBeforeAdvice {

    public void before(Method method, Object[] objects, Object object)
throws Throwable {
        System.out.println("method.getName() = " + method.getName());
        System.out.println("TestAdvice testing..." );
    }

}

配置如下：
 <bean id="testAdvice"
class="biz.pxzit.application.service.TestAdvice"/>
 <aop:config>
      <aop:advisor pointcut="execution(* biz..*Mgr.save*(..))"
advice-ref="testAdvice" order="1"/>

      ......
   </aop:config>

order是可選的，指定執行的次序；上面的配置語意是，在執行biz開頭的package下面任意以Mgr結尾的manager的save開頭的方法時候，執行testAdvice，因為是MethodBeforeAdvice
所以在save開頭方法執行前執行；

Aspect方式：
public class TestAdvice2  {

    public void goAfter(JoinPoint joinPoint) throws Throwable {
        System.out.println("TestAdvice2.goAfter
testing..."+joinPoint.getTarget());
        System.out.println("TestAdvice2.goAfter testing..." );
    }

}

配置如下：

 <bean id="testAdvice2"
class="biz.pxzit.application.service.TestAdvice2"/>
 <aop:config>
           ......
            <aop:aspect id="ddAspect" ref="testAdvice2">
            <aop:after method="goAfter"
                        pointcut="execution(* biz..*Mgr.*(..))"
                />
          .......
        </aop:aspect>

   </aop:config>
注意TestAdvice2的方法參數，這里用的是JoinPoint
joinPoint，還有很多細節，具體可以看文檔；
要使用<aop:aspect >節點，還需asm.jar
（3個，在springframework的lib下有）否則會報noclassfound
exception；

注意我之前配置的pointcut表達式是錯的，正確的是execution(*
biz..*Mgr.*(..))"；