bean
Java code
package bean;

public class db {
private String driver;
private String url;
private String uname;
private String upwd;
public String getDriver() {
    return driver;
}
public void setDriver(String driver) {
    this.driver = driver;
}
public String getUname() {
    return uname;
}
public void setUname(String uname) {
    this.uname = uname;
}
public String getUpwd() {
    return upwd;
}
public void setUpwd(String upwd) {
    this.upwd = upwd;
}
public String getUrl() {
    return url;
}
public void setUrl(String url) {
    this.url = url;
}
}





xml文件

<?xml version="1.0" encoding="UTF-8"?>
<数据库连接>
<连接 id ="1">
<driver>sun.jdbc.odbc.JdbcOdbcDriver </driver>
<url>jdbc:odbc:aaa </url>
<uname>"" </uname>
<upwd>"" </upwd>
</连接>
</数据库连接>


类
Java code
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import bean.db;
public class TestX {
    public static void main(String args[]){
        db b = new db();
        String driver = b.getDriver();
        String url=b.getUrl();
        String uname=b.getUname();
        String upwd=b.getUpwd();
        Connection con = null;
        ResultSet rs = null;
        Statement st = null;
        try {
            Class.forName(driver);
            con=DriverManager.getConnection(url, uname, upwd);
            st = con.createStatement();
            rs = st.executeQuery("select * from student");
            while(rs.next()){
                System.out.println(rs.getString("sid"));
               
            }
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static  void get() throws Exception{
        String driver ;
        String url;
        String uname;
        String upwd;
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document doc = db.parse("src\\a.xml");
        NodeList nl = doc.getElementsByTagName("连接");
        for (int i = 0; i < nl.getLength(); i++) {
            Element n = (Element) nl.item(i);
            System.out.println(n.getAttribute("id"));
            NodeList l = n.getElementsByTagName("driver");
            driver=l.item(0).getFirstChild().getNodeValue();
            NodeList l1 = n.getElementsByTagName("url");
            url=l1.item(0).getFirstChild().getNodeValue();
            NodeList l2 = n.getElementsByTagName("uname");
            uname=l2.item(0).getFirstChild().getNodeValue();
            NodeList l3 = n.getElementsByTagName("upwd");
            upwd=url=l3.item(0).getFirstChild().getNodeValue();
            db s = new db();
            s.setDriver(driver);
            s.setUrl(url);
            s.setUname(uname);
            s.setUpwd(upwd);
        }
        
    }

}







错误信息  Exception in thread "main" java.lang.NullPointerException
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at TestX.main(TestX.java:25)