javaee之xml和dtd的基础练习

从昨天的学习中，我学习到了xml的基础知识，包括dtd的约束基础

一、首先 是关于dtd的联系，关于这部分我们知识需要了解能够根据dtd约束来写出xml文件即可

1）首先是dtd文件：

<!ELEMENT TVSCHEDULE (CHANNEL+)>
<!ELEMENT CHANNEL (BANNER,DAY+)>
<!ELEMENT BANNER (#PCDATA)>
<!ELEMENT DAY (DATE,(HOLIDAY|PROGRAMSLOT+)+)>
<!ELEMENT HOLIDAY (#PCDATA)>
<!ELEMENT DATE (#PCDATA)>
<!ELEMENT PROGRAMSLOT (TIME,TITLE,DESCRIPTION?)>
<!ELEMENT TIME (#PCDATA)>
<!ELEMENT TITLE (#PCDATA)>
<!ELEMENT DESCRIPTION (#PCDATA)>
<!ATTLIST TVSCHEDULE NAME CDATA #REQUIRED>
<!ATTLIST CHANNEL CHAN CDATA #REQUIRED>
<!ATTLIST PROGRAMSLOT VTR CDATA #IMPLIED>
<!ATTLIST TITLE RATING CDATA #IMPLIED>
<!ATTLIST TITLE LANGUAGE CDATA #IMPLIED>


2）然后根据dtd写出xml
TVSCHEDULE ：是根标签 里面有一个子元素 <span style="font-family: Arial, Helvetica, sans-serif;">CHANNEL </span>

<span style="font-family: Arial, Helvetica, sans-serif;"></span><pre name="code" class="html">CHANNEL ：这个元素有 <span style="font-family: Arial, Helvetica, sans-serif;">BANNER,DAY这两个子元素</span>

<span style="font-family: Arial, Helvetica, sans-serif;"></span><pre name="code" class="html"><span style="font-family: Arial, Helvetica, sans-serif;">BANNER  ：这个元素可以随便写字符串，因为 #PCDATA</span>

<span style="font-family: Arial, Helvetica, sans-serif;">DAY ：这个元素中有 </span><span style="font-family: Arial, Helvetica, sans-serif;">DATE,HOLIDAY|PROGRAMSLOT 这几个子元素</span>

<span style="font-family: Arial, Helvetica, sans-serif;">HOLIDAY 和 DATE ： 这两个元素都可以随便写字符串 </span>

<span style="font-family: Arial, Helvetica, sans-serif;"></span><pre name="code" class="html"><span style="font-family: Arial, Helvetica, sans-serif;">PROGRAMSLOT  ：这里面有</span><span style="font-family: Arial, Helvetica, sans-serif;">TIME,TITLE,DESCRIPTION这几个子元素，也是可以写字符串</span>

<span style="font-family: Arial, Helvetica, sans-serif;"></span><pre name="code" class="html">TVSCHEDULE 的 NAME 属性 必须有，因为#REQUIRED<pre name="code" class="html">CHANNEL 的 CHAN 属性也是必须有<pre name="code" class="html">PROGRAMSLOT 的 VTR 属性、 <span style="font-family: Arial, Helvetica, sans-serif;">TITLE  的 RATING  属性 、  </span><span style="font-family: Arial, Helvetica, sans-serif;">TITLE 的 LANGUAGE  属性 是可选的，不一定必须有，因为#IMPLIED</span>

<span style="font-family: Arial, Helvetica, sans-serif;">
</span>

<span style="font-family: Arial, Helvetica, sans-serif;">3）、写出来之后便是</span>

<span style="font-family: Arial, Helvetica, sans-serif;"></span><pre name="code" class="html"><?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE TVSCHEDULE SYSTEM "xml_example.dtd">

<TVSCHEDULE NAME="acb">
<CHANNEL CHAN="abc">
<BANNER>abc</BANNER>
<DAY>
<DATE>abc</DATE>
<HOLIDAY>abc</HOLIDAY>
<HOLIDAY></HOLIDAY>
<PROGRAMSLOT VTR="abc">
<TIME>abc</TIME>
<TITLE LANGUAGE="abc" RATING="abc">abc</TITLE>
<DESCRIPTION>abc</DESCRIPTION>
</PROGRAMSLOT>
</DAY>

</CHANNEL>

</TVSCHEDULE>

二、 今天还学习到有关xml读取加载的一些基本操作

1）首先有一个xml文件

<?xml version="1.0" encoding="UTF-8" ?>
<Location>
<State Name="北京" Code="11">
<City Name="东城" Code="1" />
<City Name="西城" Code="2" />
<City Name="朝阳" Code="5" />
<City Name="丰台" Code="6" />
<City Name="石景山" Code="7" />
<City Name="海淀" Code="8" />
</State>
<State Name="天津" Code="12">
<City Name="和平" Code="1" />
<City Name="河东" Code="2" />
<City Name="河西" Code="3" />
<City Name="南开" Code="4" />
</State>
<State Name="河北" Code="13">
<City Name="石家庄" Code="1">
<Region Name="长安区" Code="2" />
<Region Name="桥东区" Code="3" />
<Region Name="桥西区" Code="4" />
<Region Name="新华区" Code="5" />
</City>
</State>
</Location>

2)、编写一个程序是用来加载xml文件的
import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class xml_example1 {

/**
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
//查找xml，首先创建DocumentBuilderFactory实例
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
//通过DocumentBuilderFactory实例来创建DocumentBuilder实例
DocumentBuilder builder = factory.newDocumentBuilder();
//通过DocumentBuilder的实例调用parse的方法来读取xml文件
Document doc = builder.parse("src/LocList.xml");

test04(doc);
}

//1、遍历所有的节点
public static void test01(Document doc){
Node item = doc.getElementsByTagName("Location").item(0);

//调用子节点的递归函数
getChilderNode(item);
}

private static void getChilderNode(Node node) {
// TODO Auto-generated method stub
//先得到当前的节点如果节点的类型是元素，则打印
if(node.getNodeType() == Node.ELEMENT_NODE){
System.out.println(node.getNodeName());
}
//再得到这个元素下的子元素遍历之，在递归
NodeList nodeList = node.getChildNodes();
for(int i=0;i<nodeList.getLength();i++){
Node item = nodeList.item(i);
getChilderNode(item);
}
}

//2、查询某一个节点
//2.1找寻名字为“东城”的节点和其他的属性
public static void test02(Document doc){
Element selement = (Element) doc.getElementsByTagName("State").item(0);
Element celement = (Element) selement.getElementsByTagName("City").item(0);

//System.out.println(celement.getTextContent());
//得到了名为“东城”这个city下的Name属性和Code属性
System.out.println(celement.getAttribute("Name"));
System.out.println(celement.getAttribute("Code"));

//得到City里面的文本内容
int index = selement.getElementsByTagName("City").getLength();
Element c = (Element) selement.getElementsByTagName("City").item(index-1);

System.out.println(c.getTextContent());
}

//3、修改某一个节点
//3.1添加一个State
public static void test03(Document doc) throws Exception{
Element element = doc.createElement("State");

//3.2在state元素中添加属性Name和Code
element.setAttribute("Name", "广东");
element.setAttribute("Code", "120");

//3.3在state中添加City和其他属性
Element celement = doc.createElement("City");
celement.setAttribute("Name","翁源");
celement.setAttribute("Code", "515");
celement.setTextContent("龙仙");

element.appendChild(celement);

Node root = doc.getElementsByTagName("Location").item(0);
root.appendChild(element);

//1、通过TransformerFactory来创建实例，调用newInstance方法
TransformerFactory transformerFactory = TransformerFactory.newInstance();
//2、通过TransformerFactory的实例来创建newTransformer对象
Transformer transformer = transformerFactory.newTransformer();
//3、用Transformer的对象的transform方法来修改xml文件
transformer.transform(new DOMSource(),new StreamResult("src/LocList.xml"));

}

public static void test04(Document doc) throws Exception{

Element selement = (Element) doc.getElementsByTagName("State").item(1);
Element celement = (Element) selement.getElementsByTagName("City").item(6);
celement.removeAttribute("Name");

Element celement1 = (Element) selement.getElementsByTagName("City").item(7);
selement.removeChild(celement1);

//1、通过TransformerFactory来创建实例，调用newInstance方法
TransformerFactory transformerFactory = TransformerFactory.newInstance();
//2、通过TransformerFactory的实例来创建newTransformer对象
Transformer transformer = transformerFactory.newTransformer();
//3、用Transformer的对象的transform方法来修改xml文件
transformer.transform(new DOMSource(),new StreamResult("src/LocList.xml"));

}

}

通过这几个案例我能够基本了解到了，关于xml和dtd 的相关知识