XML解析
XML解析
java中配置文件的三种配置位置及读取方式
db.properties文件
uname=zhangsw
upass=123
url=jdbc:mysql://localhost:3306/mybatis_ssm
driver_Class=com.mysql.jdbc.Driver
initPoolSize=5
maxPoolSize=20
1.读取根路径下的资源文件
加载根路径下的资源文件db.properties文件，到jvm称为流对象，"/"代表的是根路径->跟指的是src source folder->物理将代码分层， jvm不会读取这个文件夹
package com.zking;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class Demo1 {
public static void main(String[] args) throws IOException {
InputStream in=Demo1.class.getResourceAsStream("/db.properties");
// java.utils.properties
Properties p =new Properties();
// 此时p中就加载了流对象，从而就有了该资源文件的所有配置信息
p.load(in);
System.out.println(p.getProperty("uname"));
System.out.println(p.getProperty("upass"));
}
}
运行结果：
2、读取同包下的资源文件
package com.zking;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
/**
*
* @author zhangsw
*
*读取同包下的资源文件
*/
public class Demo2 {
public static void main(String[] args) throws IOException {
InputStream in=Demo2.class.getResourceAsStream("db.properties");
Properties p =new Properties();
// 此时p中就加载了流对象，从而就有了该资源文件的所有配置信息
p.load(in);
System.out.println(p.getProperty("uname"));
System.out.println(p.getProperty("upass"));
}
}
运行结果：
3、读取WEB-INF下的资源文件
package com.zking;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(name="demo",urlPatterns="/demo")
public class DemoServlet extends HttpServlet{
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
ServletContext context = req.getServletContext();
InputStream in = context.getResourceAsStream("/WEB-INF/db.properties");
Properties p = new Properties();
// 此时p中就加载了流对象，从而就有了该资源文件的所有配置信息
p.load(in);
System.out.println(p.getProperty("uname"));
System.out.println(p.getProperty("upass"));
}
}
运行结果：
dom4j+xpath解析xml文件
xml文件内容
<?xml version="1.0" encoding="UTF-8"?>
<students>
<student sid="s001">
<name>小明</name>
</student>
<student sid="s002">
<name>小芳</name>
</student>
<student sid='s003'>
<name>小王</name>
</student>
</students>
dom4j解析方式
package com.zking;
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;
/**
* dom4j+xpath解析xml
* @author zhangsw
*
*/
public class Demo3 {
public static void main(String[] args) throws DocumentException {
// TODO Auto-generated method stub
InputStream in= Demo3.class.getResourceAsStream("/students.xml");
SAXReader reader=new SAXReader();
Document document =reader.read(in);
List<Element>stuEles= document.selectNodes("/students/student");
for (Element stuEle : stuEles) {
if("s002".equals(stuEle.attributeValue("sid"))){
Element nameEle=(Element)stuEle.selectSingleNode("name");
System.out.println("sid="+stuEle.attributeValue("sid")+",name="+nameEle.getText());
}
}
}
}
xpath解析方式
package com.zking;
import java.io.InputStream;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
/**
*
* @author zhangsw
*
*/
public class Demo4 {
public static void main(String[] args) throws DocumentException {
InputStream in= Demo3.class.getResourceAsStream("/students.xml");
SAXReader reader=new SAXReader();
Document document =reader.read(in);
Element stuEles002 = (Element)document.selectSingleNode("/students/student[@sid='s002']");
Element nameEle =(Element) stuEles002.selectSingleNode("name");
System.out.println("sid="+stuEles002.attributeValue("sid")+",name="+nameEle.getText());
}
}
总结：
xpath相较于dom4j解析来说，更加的方便，因为xpath可以获取指定元素的指定属性。