读xml文件问题

Question

xml文件内容：
<database>
<localHost>myLocalHost</localHost>
<databaseName>myDatabaseName</databaseName>
</database>程序：import java.sql.*;
import javax.xml.parsers.*;
import org.w3c.dom.*;
public class readDatabase {
//public Connection conn;
//public Statement stmt;
public  static String  localHost="33";
public static  String db_name="";public void readDataBase()
{

}public static void readDatabase1(){
DocumentBuilderFactory theDocumentBuilderFactory=DocumentBuilderFactory.newInstance();
String path = "D:\\hy\\eclipse\\AddressBookSpace\\AddressBook\\WEB-INF";
path=path+"\\database.xml";
try{
DocumentBuilder theDocumentBuilder=theDocumentBuilderFactory.newDocumentBuilder();
Document theDocument=theDocumentBuilder.parse(path);
Element theParentElement = theDocument.getDocumentElement();
NodeList theNodeList = theParentElement.getElementsByTagName("database");for(int i=0;i<theNodeList.getLength();i++){Element theChildElement =(Element)theNodeList.item(i);
NodeList theChildNodeList=null;
//String outString="";theChildNodeList=theChildElement.getElementsByTagName("localHost");
localHost=(theChildNodeList.item(0)).getFirstChild().getNodeValue();
theChildNodeList=theChildElement.getElementsByTagName("databaseName");
db_name=(theChildNodeList.item(0)).getFirstChild().getNodeValue();
}
}
catch(Exception e){
e.printStackTrace();
}}
public static void main(String args[]){
readDatabase1();
System.out.println("ip="+localHost);
System.out.println("db_name="+db_name);}}
我执行了一下怎莫出来是空值。另外eclipse调试怎莫单步执行，好像没有.net方便啊。高手指点一下啊

Answer 1

Window→Open perspective→Debug
打开之后你就知道了，具体调试方法跟其他IDE大同小异

Answer 2

谢谢楼上，只是没有像.net中的即时窗口感觉方便。
另外，高手们能帮我看看程序的问题吗，我跟踪了一下theNodeList.getLength();长度为0，就是说没有数据读进来。韦什莫呢

Answer 3

我没用过.Net的调试，不太好比较，但感觉Eclipse的调试功能还算不错。楼主可能对Eclipse不熟悉，用多了习惯了就好了。至于程序，我测试测试看看。

Answer 4

搞定了，看以下代码：import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;import org.w3c.dom.Document;
import org.w3c.dom.NodeList;public class ReadDatabase {
    public static String localHost = "33";
    public static String db_name = "";    public static void readDatabase1() {        DocumentBuilderFactory theDocumentBuilderFactory = DocumentBuilderFactory.newInstance();
        String path = "D:\\hy\\eclipse\\AddressBookSpace\\AddressBook\\WEB-INF\\database.xml";
        try {
            DocumentBuilder theDocumentBuilder = theDocumentBuilderFactory.newDocumentBuilder();
            Document theDocument = theDocumentBuilder.parse(path);
            
            NodeList localHostList = theDocument.getElementsByTagName("localHost");
            if (localHostList.getLength() > 0) {
                localHost = (localHostList.item(0)).getFirstChild().getNodeValue();
            }
            
            NodeList databaseNameList = theDocument.getElementsByTagName("databaseName");
            if (databaseNameList.getLength() > 0) {
                db_name = (databaseNameList.item(0)).getFirstChild().getNodeValue();
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        }    }    public static void main(String args[]) {
        readDatabase1();
        System.out.println("ip=" + localHost);
        System.out.println("db_name=" + db_name);
    }}

Answer 5

多谢楼上，刚才搞了半天，也找到了这个方法，但是
(localHostList.item(0)).getFirstChild().getNodeValue();能取得值，
(localHostList.item(0)).getFirstChild().getNodeName()就不能取得节点的名称呢。郁闷

Answer 6

<root>   
        <server>         
            <ServerName>server</ServerName>        
        </server>   
        <database>   
            <DatabaseName>myDatabase</DatabaseName>  
    <UserName>myUserName</UserName> 
    <Password>myPassword</Password>
        </database>   
  </root> 
我现在把xml变成这样了，调了半天也没整好 。getNodeName()就得到#text，这是为什莫阿

Answer 7

因为我要得到的事节点的名称，根据节点名得到节点值，节点的值有可能会变，所以不能用getNodeValue();

Answer 8

按照你的需求，我又把代码重新写了一遍。
要注意的是，取得结点名称不是(localHostList.item(0)).getFirstChild().getNodeName()而是(localHostList.item(0)).getNodeName()
代码如下：import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;import org.w3c.dom.Document;
import org.w3c.dom.NodeList;public class ReadDatabase {
    public static String serverName;
    public static String databaseName;
    public static String userName;
    public static String password;    public static void readDatabase1() {        DocumentBuilderFactory theDocumentBuilderFactory = DocumentBuilderFactory.newInstance();
        String path = "D:\\database.xml";
        try {
            DocumentBuilder theDocumentBuilder = theDocumentBuilderFactory.newDocumentBuilder();
            Document theDocument = theDocumentBuilder.parse(path);
            theDocument.getDocumentElement();
            
            NodeList nodelist;
            
            nodelist = theDocument.getElementsByTagName("ServerName");
            if (nodelist.getLength() > 0) {
                serverName = (nodelist.item(0)).getFirstChild().getNodeValue();
                System.out.println(nodelist.item(0).getNodeName() + "=" + serverName);
            }
            
            nodelist = theDocument.getElementsByTagName("DatabaseName");
            if (nodelist.getLength() > 0) {
                databaseName = (nodelist.item(0)).getFirstChild().getNodeValue();
                System.out.println(nodelist.item(0).getNodeName() + "=" + databaseName);
            }
            
            nodelist = theDocument.getElementsByTagName("UserName");
            if (nodelist.getLength() > 0) {
                userName = (nodelist.item(0)).getFirstChild().getNodeValue();
                System.out.println(nodelist.item(0).getNodeName() + "=" + userName);
            }
            
            nodelist = theDocument.getElementsByTagName("Password");
            if (nodelist.getLength() > 0) {
                password = (nodelist.item(0)).getFirstChild().getNodeValue();
                System.out.println(nodelist.item(0).getNodeName() + "=" + password);
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        }    }    public static void main(String args[]) {
        readDatabase1();
    }}

Answer 9

以上代码的输出结果是：
ServerName=server
DatabaseName=myDatabase
UserName=myUserName
Password=myPassword

Answer 10

多谢初晨之阳。刚才自己也作了一下。import   javax.xml.transform.*;   
import   javax.xml.transform.dom.DOMSource;   
import   javax.xml.transform.stream.StreamResult; 
import   javax.xml.parsers.*;import   org.w3c.dom.*; public class readDatabaseXML {
public readDatabaseXML(){}
public static String ServerName=null;
public static String DatabaseName=null;
public static String FilePath=null;
public static String UserName=null;
public static String Password=null;

public void readXML()
{
try{
 
DocumentBuilderFactory   factory   =   DocumentBuilderFactory.newInstance();   
DocumentBuilder   builder=factory.newDocumentBuilder();  
String filePaht=FilePath;
Document   doc=builder.parse(filePaht);   
doc.normalize();   
  
NodeList   books   =doc.getDocumentElement().getChildNodes();   
Node   book;   
NodeList   lists;   

book=books.item(1); 
// 浏览查看   
for(int   i=1;i<books.getLength();i++)   
{   
book=books.item(i); 
                           //下面两句测试用
String sssss=books.item(i).toString();
System.out.println(sssss);
lists=book.getChildNodes();  
for(int   j=1;j<lists.getLength();j++)   
{   
if(lists.item(j).getNodeType()==Node.ELEMENT_NODE)
{
if(((Element)lists.item(j)).getNodeName().equals("ServerName"))
{
ServerName=((Element)lists.item(j)).getTextContent().toString();
}else if(((Element)lists.item(j)).getNodeName().equals("DatabaseName"))
{
DatabaseName=((Element)lists.item(j)).getTextContent().toString();
}else if(((Element)lists.item(j)).getNodeName().equals("UserName"))
{
UserName=((Element)lists.item(j)).getTextContent().toString();
}else if(((Element)lists.item(j)).getNodeName().equals("Password"))
{
Password=((Element)lists.item(j)).getTextContent().toString();
}
}
}   
}    
}
catch(Exception e)
{System.out.println(e);}
}}这句话
System.out.println(sssss);
打出这样的结果：
[server: null]
[#text:    
        ]
[database: null]
[#text:    
  ]
这是为什莫呢，我的xml是用文本编辑器写的，直接改了个后缀

Answer 11

感觉用初晨之阳你的方法更简单一些。能不能帮我解释一下下面的结果为什莫会出现呢，多谢了
[server: null]
[#text:    
        ]
[database: null]
[#text:    
  ]

Answer 12

你的代码基本上是对的，只有一点小问题，我帮你改了。代码如下：import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;public class readDatabaseXML {    public static String ServerName = null;
    public static String DatabaseName = null;
    public static String FilePath = null;
    public static String UserName = null;
    public static String Password = null;    public void readXML() {
        try {            DocumentBuilderFactory factory = DocumentBuilderFactory
                    .newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            String filePath = "D:\\database.xml";
            Document doc = builder.parse(filePath);
            doc.normalize();            NodeList books = doc.getDocumentElement().getChildNodes();
            Node book;
            NodeList lists;            // 浏览查看
            for (int i = 0; i < books.getLength(); i++) {
                book = books.item(i);
                lists = book.getChildNodes();
                for (int j = 1; j < lists.getLength(); j++) {
                    if (lists.item(j).getNodeType() == Node.ELEMENT_NODE) {
                        if (((Element) lists.item(j)).getNodeName().equals(
                                "ServerName")) {
                            ServerName = ((Element) lists.item(j))
                                    .getTextContent().toString();
                            System.out.println("ServerName=" + ServerName);
                        } else if (((Element) lists.item(j)).getNodeName()
                                .equals("DatabaseName")) {
                            DatabaseName = ((Element) lists.item(j))
                                    .getTextContent().toString();
                            System.out.println("DatabaseName=" + DatabaseName);
                        } else if (((Element) lists.item(j)).getNodeName()
                                .equals("UserName")) {
                            UserName = ((Element) lists.item(j))
                                    .getTextContent().toString();
                            System.out.println("UserName=" + UserName);
                        } else if (((Element) lists.item(j)).getNodeName()
                                .equals("Password")) {
                            Password = ((Element) lists.item(j))
                                    .getTextContent().toString();
                            System.out.println("Password=" + Password);
                        }
                    }
                }
            }
        } catch (Exception e) {
            System.out.println(e);
        }
    }}程序输出为：ServerName=server
DatabaseName=myDatabase
UserName=myUserName
Password=myPassword

Answer 13

多谢初晨之阳的帮助。我不太明白的是这句，
NodeList books = doc.getDocumentElement().getChildNodes();
取得了子节点，但我用循环打出来
book=books.item(i); 
String sssss=books.item(i).toString();
System.out.println(sssss);
得到了这样的结果，是为什莫呢。能指点我一下吗
[#text: 
]
[server: null]
[#text: 
]
[database: null]
[#text: 
]

Answer 14

String sssss=books.item(i).toString();
System.out.println(sssss);
你这样输出的只是books.item(i).toString()，而具体输出格式是由toString()方法决定的，并不一定能输出你想的ServerName等值。book = books.item(i);
lists = book.getChildNodes();
ServerName = ((Element) lists.item(j)).getTextContent().toString();
System.out.println("ServerName=" + ServerName);
这里的输出才是真正的输出ServerName的值。是books.item(i)再调用getChildNodes()得到list，然后再调用list每个元素的getTextContent()才能得到你想要的值。差别就在这里，前者相当于输出books.item(i)，后者相当于输出books.item(i).getChildNodes().getTextContent()