本文介绍了XML建模，即把XML配置文件元素、属性和文本信息转换为对象的过程。阐述了建模思路，通过工厂模式解析XML生成指定对象以提高代码复用性。还给出两个应用示例，分别对mvc.xml和web.xml进行建模，创建对应实体类和工厂模式类。
xml建模
什么是建模：
将XML配置文件中的元素，属性，文本信息 转换成对象的过程叫XML建模。
建模的由来：
- 就是将指定的xml字符串当作对象来操作
- 如果说当对一个指定的xml格式字符串完成了建模操作
- 好处在于，只需要调用指定的方法就可以完成预定的字符串获取
建模的思路：
1、分析需要被建模的文件中有那几个对象
2、每个对象拥有的行为以及属性
3、定义对象从小到大（从里到外）
4、通过23种的设计模式中的工厂模式，解析xml生产出指定对象
好处：提高代码的复用性
应用一：对mvc.xml进行建模
mvc.xml文件代码
<?xml version="1.0" encoding="UTF-8"?>
<!-- config标签:可以包含0~N个action标签 -->
<config>
<!-- action标签:可以饱含0~N个forward标签 path:以/开头的字符串,并且值必须唯一 非空 type:字符串,非空 -->
<action path="/regAction" type="test.RegAction">
<!-- forward标签:没有子标签; name:字符串,同一action标签下的forward标签name值不能相同 ; path:以/开头的字符串
redirect:只能是false|true,允许空,默认值为false -->
<forward name="failed" path="/reg.jsp" redirect="false" />
<forward name="success" path="/login.jsp" redirect="true" />
</action>
<action path="/loginAction" type="test.LoginAction">
<forward name="failed" path="/login.jsp" redirect="false" />
<forward name="success" path="/main.jsp" redirect="true" />
</action>
</config>
建模分两步：
1、以面向对象的编程思想，描述xml资源文件
2、将xml文件中内容封装进model实体对象。
首先看mvc.xml里面有多少个标签
分别是：action forward config
定义对象从里到外
然后根据三个标签分别创建3个类，然后用config建一个工厂模式类对mvc.xml进行建模
ForwardModel类
package com.xhh.model;
public class ForwardModel {
private String name;
private String path;
private boolean redirect=true;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPath() {
return path;
}
public void setPath(String path) {
this.path = path;
}
public boolean isRedirect() {
return redirect;
}
public void setRedirect(boolean redirect) {
this.redirect = redirect;
}
}
ActionModel类
注：属性为String类型，子元素标签则是map的值，子元素标签的唯一标识则为map的值
package com.xhh.model;
import java.util.HashMap;
import java.util.Map;
public class ActionModel {
private String path;
private String type;
private Map <String,ForwardModel> fMap=new HashMap<>();
public String getPath() {
return path;
}
public void setPath(String path) {
this.path = path;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
/**
* 压栈
* @param forwardModel
*/
public void push(ForwardModel forwardModel) {
fMap.put(forwardModel.getName(), forwardModel);
}
/**
* 弹栈
* @return
*/
public ForwardModel pop(String name) {
return fMap.get(name);
}
}
ConfigModel类
package com.xhh.model;
import java.util.HashMap;
import java.util.Map;
public class ConfigModel {
private Map <String,ActionModel> aMap=new HashMap<>();
/**
* 压栈
* @param forwardModel
*/
public void push(ActionModel actionModel) {
aMap.put(actionModel.getPath(),actionModel);
}
/**
* 弹栈
* @return
*/
public ActionModel pop(String path) {
return aMap.get(path);
}
}
ConfigModelFactory工厂模式对mvc.xml进行建模
package com.xhh.model;
import java.io.InputStream;
import java.util.List;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
/**
* java中有23中设计模式
* 工厂模式：
* why:
* 能够提高代码的复用性
* how:只要建立一个方法，去生产指定的你需要的对象
* where:去生产指定的你需要的对象，以便重复使用
*
* 昨天来看：
* 反复操作xml文件，反复解析xml字符串
* xml文件-->ConfigModel
* 那么意味着我们需要反复操作configModel
* @author linyaodong
*
*/
public class ConfigModelFactory {
/**
* 默认资源文件mvc.xml是在放在建模的同包下
* @return
* @throws Exception
*/
public static ConfigModel build() throws DocumentException {
return build("mvc.xml");
}
/**
* 当资源文件，需要手动改变位置的情况下，那么需要调以下方法
* @param xmlPath
* @return
* @throws DocumentException
*/
public static ConfigModel build(String xmlPath) throws DocumentException {
ConfigModel configModel=new ConfigModel();
ActionModel actionModel=null;
ForwardModel forwardModel=null;
InputStream in= ConfigModelFactory.class.getResourceAsStream(xmlPath);
SAXReader reader=new SAXReader();
Document doc= reader.read(in);
List<Element> actionEles=doc.selectNodes("config/action");
for (Element actionEle : actionEles) {
actionModel =new ActionModel();
//填充actionModel
actionModel.setPath(actionEle.attributeValue("path"));
actionModel.setType(actionEle.attributeValue("type"));
List<Element> forwordEles=actionEle.selectNodes("forward");
for (Element forwordEle : forwordEles) {
forwardModel =new ForwardModel();
//填充forwardModel
forwardModel.setName(forwordEle.attributeValue("name"));
forwardModel.setPath(forwordEle.attributeValue("path"));
forwardModel.setRedirect(!"false".equals(forwordEle.attributeValue("redirect")));
actionModel.push(forwardModel);
}
configModel.push(actionModel);
}
return configModel;
}
public static void main(String[] args) throws DocumentException {
ConfigModel configModel = ConfigModelFactory.build();
ActionModel actionModel = configModel.pop("/loginAction");
System.out.println(actionModel.getType());
System.out.println(actionModel.pop("success").getPath());
}
}
运行结果：
应用二：
1、对web.xml进行建模
2、写一个servlet
3、通过url-pattern读取到servlet-class的值
web.xml文件代码
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<servlet>
<servlet-name>jrebelServlet</servlet-name>
<servlet-class>com.xhh.xml.JrebelServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>jrebelServlet</servlet-name>
<url-pattern>/jrebelServlet</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>jrebelServlet2</servlet-name>
<servlet-class>com.xhh.xml.JrebelServlet2</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>jrebelServlet2</servlet-name>
<url-pattern>/jrebelServlet2</url-pattern>
<url-pattern>/jrebelServlet3</url-pattern>
</servlet-mapping>
</web-app>
web.xml里面一共有6个标签
分别是：web-add ,servlet , servlet-name , servlet-class ,servlet-mapping
url-pattern
然后分别建6个实体类，然后在用web-add建一个工厂模式类对web.xml建模
ServletNameModel 类
package com.xhh.xml.model;
public class ServletNameModel {
private String context;
public String getContext() {
return context;
}
public void setContext(String context) {
this.context = context;
}
}
ServletClassModel类
package com.xhh.xml.model;
public class ServletClassModel {
private String context;
public String getContext() {
return context;
}
public void setContext(String context) {
this.context = context;
}
}
UrlPatternModel类
package com.xhh.xml.model;
public class UrlPatternModel {
private String context;
public String getContext() {
return context;
}
public void setContext(String context) {
this.context = context;
}
}
ServletModel类
package com.xhh.xml.model;
public class ServletModel {
private ServletNameModel servletNameModel;
private ServletClassModel servletClassModel;
public ServletNameModel getServletNameModel() {
return servletNameModel;
}
public void setServletNameModel(ServletNameModel servletNameModel) {
this.servletNameModel = servletNameModel;
}
public ServletClassModel getServletClassModel() {
return servletClassModel;
}
public void setServletClassModel(ServletClassModel servletClassModel) {
this.servletClassModel = servletClassModel;
}
}
ServletMappingModel类
package com.xhh.xml.model;
import java.util.ArrayList;
import java.util.List;
public class ServletMappingModel {
private ServletNameModel servletNameModel;
private List<UrlPatternModel> urlPatternModels = new ArrayList<>();
public ServletNameModel getServletNameModel() {
return servletNameModel;
}
public void setServletNameModel(ServletNameModel servletNameModel) {
this.servletNameModel = servletNameModel;
}
public void pushUrlPatternModel(UrlPatternModel urlPatternModel) {
urlPatternModels.add(urlPatternModel);
}
public List<UrlPatternModel> getUrlPatternModels() {
return urlPatternModels;
}
}
WebAppModel类
package com.xhh.xml.model;
import java.util.ArrayList;
import java.util.List;
public class WebAppModel {
private List<ServletModel> servletModels = new ArrayList<>();
private List<ServletMappingModel> servletMappingModels = new ArrayList<>();
public void pushServletModel(ServletModel servletModel) {
servletModels.add(servletModel);
}
public List<ServletModel> getServletModels() {
return servletModels;
}
public void pushServletMappingModel(ServletMappingModel servletMappingModel) {
servletMappingModels.add(servletMappingModel);
}
public List<ServletMappingModel> getServletMappingModels() {
return servletMappingModels;
}
}
WebAppModelFactory使用工厂模式对web.xml进行建模
package com.xhh.xml.model;
import java.io.InputStream;
import java.util.List;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
public class WebAppModelFactory {
public static WebAppModel buildWebAppModel() {
String xmlPath = "web.xml";
return buildWebAppModel(xmlPath);
}
/**
* 建模
*
* @param xmlPath
* @return
*/
public static WebAppModel buildWebAppModel(String xmlPath) {
InputStream in = WebAppModelFactory.class.getResourceAsStream(xmlPath);
SAXReader saxReader = new SAXReader();
WebAppModel webAppModel = new WebAppModel();
try {
Document doc = saxReader.read(in);
/**
* 将servlet的标签内容填充进WebApp
*/
List<Element> servletEles = doc.selectNodes("/web-app/servlet");
for (Element servletEle : servletEles) {
ServletModel servletModel = new ServletModel();
/**
* 给ServletModel填充xml的内容
*/
Element servletNameEle = (Element) servletEle.selectSingleNode("servlet-name");
Element servletClassEle = (Element) servletEle.selectSingleNode("servlet-class");
ServletNameModel servletNameModel = new ServletNameModel();
ServletClassModel servletClassModel = new ServletClassModel();
servletNameModel.setContext(servletNameEle.getText());
servletClassModel.setContext(servletClassEle.getText());
servletModel.setServletNameModel(servletNameModel);
servletModel.setServletClassModel(servletClassModel);
webAppModel.pushServletModel(servletModel);
}
/**
* 将servlet-mapping的标签内容填充进WebApp
*/
List<Element> servletMappingEles = doc.selectNodes("/web-app/servlet-mapping");
for (Element servletMappingEle : servletMappingEles) {
ServletMappingModel servletMappingModel = new ServletMappingModel();
/**
* 给ServletMappingModel填充xml的内容
*/
Element servletNameEle = (Element) servletMappingEle.selectSingleNode("servlet-name");
ServletNameModel servletNameModel = new ServletNameModel();
servletNameModel.setContext(servletNameEle.getText());
servletMappingModel.setServletNameModel(servletNameModel);
List<Element> urlPatternEles = servletMappingEle.selectNodes("url-pattern");
for (Element urlPatternEle : urlPatternEles) {
UrlPatternModel urlPatternModel = new UrlPatternModel();
urlPatternModel.setContext(urlPatternEle.getText());
servletMappingModel.pushUrlPatternModel(urlPatternModel);
}
webAppModel.pushServletMappingModel(servletMappingModel);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return webAppModel;
}
/**
* 通过浏览器输入的网址自动找到对应的后台处理类
* @param webAppModel 建模后的实体类
* @param url 浏览器访问的网址
* @return
*/
public static String getServletClassByUrl(WebAppModel webAppModel, String url) {
String servletClass = "";
/**
* 找到浏览器网址对应的servlet-name
*/
String servletName = "";
List<ServletMappingModel> servletMappingModels = webAppModel.getServletMappingModels();
for (ServletMappingModel servletMappingModel : servletMappingModels) {
List<UrlPatternModel> urlPatternModels = servletMappingModel.getUrlPatternModels();
for (UrlPatternModel urlPatternModel : urlPatternModels) {
if(url.equals(urlPatternModel.getContext())) {
ServletNameModel servletNameModel = servletMappingModel.getServletNameModel();
servletName = servletNameModel.getContext();
}
}
}
/**
* 找到servlet-name对应的后台处理类
*/
List<ServletModel> servletModels = webAppModel.getServletModels();
for (ServletModel servletModel : servletModels) {
ServletNameModel servletNameModel = servletModel.getServletNameModel();
if(servletName.equals(servletNameModel.getContext())) {
ServletClassModel servletClassModel = servletModel.getServletClassModel();
servletClass = servletClassModel.getContext();
}
}
return servletClass;
}
public static void main(String[] args) {
WebAppModel webAppModel = WebAppModelFactory.buildWebAppModel();
String res = getServletClassByUrl(webAppModel, "/jrebelServlet");
String res2 = getServletClassByUrl(webAppModel, "/jrebelServlet2");
String res3 = getServletClassByUrl(webAppModel, "/jrebelServlet3");
System.out.println(res);
System.out.println(res2);
System.out.println(res3);
}
}
运行结果：
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