使用Freemaker的示例(和servlet的搭配使用)

总体目录结构如下：

搭建完成后，效果和示例二是一样的。

1.新建项目FreemakerS ，将freemaker.jar 拷入lib下;
2.在新建com.shiryu.freeServlet.model包里新建以下文件：

实体类Guestbook.java

package com.shiryu.freeServlet.model;public class Guestbook {    private String name;    private String email;    private String message;    public Guestbook(String name, String email, String message) {        this.name = name;        this.email = email;        this.message = message;    }    public String getEmail() {        return email;    }    public String getMessage() {        return message;    }    public String getName() {        return name;    }}

Page.java

//用来传递模板文件template或则是跳转forwordpackage com.shiryu.freeServlet.model;import java.util.*;public class Page {    private String template;    private String forward;     private Map root = new HashMap();        //put具有四种形态，形参不同类型    public void put(String name,Object value){        root.put(name, value);    }        public void put(String name,int value){        root.put(name, value);    }        public void put(String name,double value){        root.put(name, value);    }        public void put(String name,boolean value){        root.put(name, value);    }    public String getTemplate() {        return template;    }    public void setTemplate(String template) {        forward=null;        this.template = template;    }    public String getForward() {        return forward;    }    public void setForward(String forward) {        template = null;        this.forward = forward;    }    public Map getRoot() {        return root;    }}

2.在新建com.shiryu.freeServlet.controller包下新建如下文件：

ControllerServlet.java

package com.shiryu.freeServlet.controller;import java.io.*;import java.lang.reflect.*;import java.util.Locale;import javax.servlet.*;import javax.servlet.http.*;import com.shiryu.freeServlet.model.Page;import freemarker.template.*;public class ControllerServlet extends HttpServlet {    private static final long serialVersionUID = 2621960985463765229L;    private Configuration cfg;    public void init() {        // 创建一个freemaker.template包中的configrution对象        cfg = new Configuration();       // 得到模板文件所在路径        cfg.setServletContextForTemplateLoading(getServletContext(),"templates");        // 将update dealy设置为0方便测试        cfg.setTemplateUpdateDelay(0);        // 在html错误被打印出来        cfg.setTemplateExceptionHandler(TemplateExceptionHandler.HTML_DEBUG_HANDLER);        // 使用beans封装应用        cfg.setObjectWrapper(ObjectWrapper.BEANS_WRAPPER);        cfg.setDefaultEncoding("UTF-8");        cfg.setOutputEncoding("UTF-8");        cfg.setLocale(Locale.getDefault());    }    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {        // 对action进行选择        String action = req.getServletPath();        if (action == null)            action = "index";        if (action.startsWith("/"))            //语法strVariable.substring(start, end)            //substring（int i）他的意思是从字符串的索引值为i开始截取(获得)字符串            action = action.substring(1);        //int lastIndexOf(int ch, int fromIndex) //从指定的索引处开始进行后向搜索，返回最后一次出现的指定字符在此字符串中的索引。        if (action.lastIndexOf(".") != -1) {            action = action.substring(0, action.lastIndexOf("."));        }        Method actionMethod = null;        //得到当前运行时对象所属的类对象，返回类对象的一个方法        //参数为此方法的名称字符串及所需参数的类对象类型数组try {            actionMethod = getClass().getMethod(action + "Action", new Class[] { HttpServletRequest.class, Page.class });        } catch (SecurityException e) {            e.printStackTrace();        } catch (NoSuchMethodException e) {            e.printStackTrace();        }        req.setCharacterEncoding(cfg.getOutputEncoding());        Page page = new Page();        try {            //方法调用，当前的对象数组            //例如：            //Class[] a=new Class[]{String[].class};             //Object[] b=new Object[]{new String[0]};             // 生成2个新的数组,第一个数组里存的是Class类型,第二个存放的是Object类型.             actionMethod.invoke(this, new Object[] { req, page });        } catch (IllegalArgumentException e) {            e.printStackTrace();        } catch (IllegalAccessException e) {            e.printStackTrace();        } catch (InvocationTargetException e) {            e.printStackTrace();        }        // 如果从page获得了template，进行页面输出        if (page.getTemplate() != null) {            Template t = cfg.getTemplate(page.getTemplate());            resp.setContentType("text/html; charset=" + cfg.getOutputEncoding());            resp.setHeader("Cache-Control","no-store,no-cache,must-revalidate," + "post-check=0, pre-check=0");            resp.setHeader("Pragma", "no-cache");            resp.setHeader("Expires", "Thu, 01 Dec 2010 00:00:00 GMT");            Writer out = resp.getWriter();            try {                t.process(page.getRoot(), out);            } catch (TemplateException e) {                e.printStackTrace();            }        }        // 如果page的指向不为空        else if (page.getForward() != null) {            RequestDispatcher rd = req.getRequestDispatcher(page.getForward());            rd.forward(req, resp);        }    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {        doGet(req, resp);    }}

GuestbookServlet.java

package com.shiryu.freeServlet.controller;import java.io.IOException;import java.util.*;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import com.shiryu.freeServlet.model.*;public class GuestbookServlet extends ControllerServlet {    private static final long serialVersionUID = 1385738680025723760L;    @SuppressWarnings("unchecked")    private ArrayList guestbooks = new ArrayList();    //各个action及其业务逻辑    @SuppressWarnings("unchecked")    public void indexAction(HttpServletRequest req, Page p) {        List snapShot;        synchronized (guestbooks) {            snapShot = (List) guestbooks.clone();        }        p.put("guestbooks", snapShot);        p.setTemplate("index.ftl");    }    @SuppressWarnings("unchecked")    public void formAction(HttpServletRequest req, Page p) throws IOException,            ServletException {        p.put("name", noNull(req.getParameter("name")));        p.put("email", noNull(req.getParameter("email")));        p.put("message", noNull(req.getParameter("message")));        List errors = (List) req.getAttribute("errors");        p.put("errors", errors == null ? new ArrayList() : errors);        p.setTemplate("form.ftl");    }    @SuppressWarnings("unchecked")    public void addAction(HttpServletRequest req, Page p) throws IOException,            ServletException {        List errors = new ArrayList();        String name = req.getParameter("name");        String email = req.getParameter("email");        String message = req.getParameter("message");        if (isBlank(name)) {            errors.add("please enter your name");        }        if (isBlank(message)) {            errors.add("please enter your message");        }        if (errors.isEmpty()) {            if (email == null)                email = "";            Guestbook book = new Guestbook(name.trim(), email.trim(), message);            synchronized (guestbooks) {                guestbooks.add(0, book);            }            p.put("entry", book);            p.setTemplate("add.ftl");        }else{            req.setAttribute("errors", errors);            p.setForward("form.a");        }    }    public static String noNull(String s) {        return s == null ? "" : s;    }    public static boolean isBlank(String s) {        return s == null || s.trim().length() == 0;    }}

3.编辑web.xml文件

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE web-app    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"    "http://java.sun.com/dtd/web-app_2_3.dtd"><web-app><display-name>Freemaker Servlet Application</display-name><servlet>   <servlet-name>guestbook</servlet-name>   <servlet-class>com.shiryu.freeServlet.controller.GuestbookServlet</servlet-class></servlet><servlet-mapping>     <servlet-name>guestbook</servlet-name>     <url-pattern>*.a</url-pattern></servlet-mapping></web-app>

4.以下是前webroot / template下的ftl文件：
lib下common.ftl 

<#macro page title><html><head>    <title>FreeMarker Example Web Application 2 - ${title?html}</title>    <meta http-equiv="Content-type" content="text/html; charset=${.output_encoding}"></head><body>    <h1>${title?html}</h1>    <hr>    <#nested>    <hr>    <table border="0" cellspacing=0 cellpadding=0 width="100%">      <tr valign="middle">        <td align="left">          <i>FreeMarker Example 2</i>        <td align="right">          <a href="http://freemarker.org"><img src="poweredby_ffffff.png" border=0></a>    </table></body></html></#macro>

index.ftl

<#import "/lib/common.ftl" as com><#escape x as x?html><@com.page title="Index"><a href="form.a">Add new message</a> | <a href="help.html">How this works?</a><#if guestbooks?size = 0>    <p>No messages.<#else>    <p>The messages are:    <table border=0 cellspacing=2 cellpadding=2 width="100%">      <tr align=center valign=top>        <th bgcolor="#C0C0C0">Name        <th bgcolor="#C0C0C0">Message      <#list guestbooks as e>        <tr align=left valign=top>          <td bgcolor="#E0E0E0">${e.name} <#if e.email?length != 0> (<a href="mailto:${e.email}">${e.email}</a>)</#if>          <td bgcolor="#E0E0E0">${e.message}      </#list>    </table></#if></@com.page></#escape>

form.ftl

<#import "/lib/common.ftl" as com><#escape x as x?html><@com.page title="Add Entry">   <!- - 错误的输出 - -><#if errors?size != 0>    <p><font color=red>Please correct the following problems:</font>    <ul>      <#list errors as e>        <li><font color=red>${e}</font>      </#list>    </ul></#if><form method="post" action="add.a">     Your name: <input type="text" name="name" value="${name}" size=51><br>     Your e-mail (optional): <input type="text" name="email" value="${email}" size=40><br>     Message:<br>      <textarea name="message" wrap="soft" rows=3 cols=50>${message}</textarea><br>     <input type="submit" value="Submit"></form><p><a href="index.a">Back to the index page</a></@com.page></#escape>

add.ftl

<#import "/lib/common.ftl" as com><#escape x as x?html><@com.page title="Entry added"><p>You have added the following entry to the guestbook:<p><b>Name:</b> ${entry.name}<#if entry.email?length != 0>    <p><b>Email:</b> ${entry.email}</#if><p><b>Message:</b> ${entry.message}<p><a href="index.a">Back to the index page...</a></@com.page></#escape>