Home  >  Article  >  Backend Development  >  dom4j operates xml files (full)

dom4j operates xml files (full)

黄舟
黄舟Original
2017-02-09 14:14:531547browse

In the project, we use xml files a lot, whether it is parameter configuration or data interaction with other systems.
Today we will talk about using dom4j in Java to operate XML files.

The packages we need to introduce:

//文件包   
import java.io.ByteArrayOutputStream;   
import java.io.File;   
import java.io.FileWriter;   
//工具包   
import java.util.Iterator;   
import java.util.List;   
//dom4j包   
import org.dom4j.Attribute;   
import org.dom4j.Document;   
import org.dom4j.DocumentHelper;   
import org.dom4j.Element;   
import org.dom4j.io.OutputFormat;   
import org.dom4j.io.SAXReader;   
import org.dom4j.io.XMLWriter;

1. Convert the content of the XML file into String

  /** 
    * doc2String 
    * 将xml文档内容转为String 
    * @return 字符串 
    * @param document 
    */ 
   public static String doc2String(Document document) 
   { 
      String s = ""; 
      try 
      { 
           //使用输出流来进行转化 
           ByteArrayOutputStream out = new ByteArrayOutputStream(); 
           //使用GB2312编码 
           OutputFormat format = new OutputFormat("  ", true, "GB2312"); 
           XMLWriter writer = new XMLWriter(out, format); 
           writer.write(document); 
           s = out.toString("GB2312"); 
      }catch(Exception ex) 
      {             
           ex.printStackTrace(); 
      }       
      return s; 
   }

2. Convert the String that conforms to the XML format into XML Document

 /** 
    * string2Document 
    * 将字符串转为Document 
    * @return  
    * @param s xml格式的字符串 
    */ 
   public static Document string2Document(String s) 
   { 
      Document doc = null; 
      try 
      { 
           doc = DocumentHelper.parseText(s); 
      }catch(Exception ex) 
      {             
           ex.printStackTrace(); 
      } 
      return doc; 
   }

3. Save the Document object as an xml file locally

 /** 
    * doc2XmlFile 
    * 将Document对象保存为一个xml文件到本地 
    * @return true:保存成功  flase:失败 
    * @param filename 保存的文件名 
    * @param document 需要保存的document对象 
    */ 
   public static boolean doc2XmlFile(Document document,String filename) 
   { 
      boolean flag = true; 
      try 
      { 
            /* 将document中的内容写入文件中 */ 
            //默认为UTF-8格式,指定为"GB2312" 
            OutputFormat format = OutputFormat.createPrettyPrint(); 
            format.setEncoding("GB2312"); 
            XMLWriter writer = new XMLWriter(new FileWriter(new File(filename)),format); 
            writer.write(document); 
            writer.close();             
        }catch(Exception ex) 
        { 
            flag = false; 
            ex.printStackTrace(); 
        } 
        return flag;       
   }

4. Save the string in xml format as a local file. If the string format does not comply with xml rules, failure will be returned

/** 
    * string2XmlFile 
    * 将xml格式的字符串保存为本地文件,如果字符串格式不符合xml规则,则返回失败 
    * @return true:保存成功  flase:失败 
    * @param filename 保存的文件名 
    * @param str 需要保存的字符串 
    */ 
   public static boolean string2XmlFile(String str,String filename) 
   { 
      boolean flag = true; 
      try 
      { 
         Document doc =  DocumentHelper.parseText(str);        
         flag = doc2XmlFile(doc,filename); 
      }catch (Exception ex) 
      { 
         flag = false; 
         ex.printStackTrace(); 
      } 
      return flag; 
   }

5. Load an xml document

 /** 
    * load 
    * 载入一个xml文档 
    * @return 成功返回Document对象,失败返回null 
    * @param uri 文件路径 
    */ 
   public static Document load(String filename) 
   { 
      Document document = null; 
      try  
      {  
          SAXReader saxReader = new SAXReader(); 
          document = saxReader.read(new File(filename)); 
      } 
      catch (Exception ex){ 
          ex.printStackTrace(); 
      }   
      return document; 
   }

6. Demonstrate saving a String as an xml file

 /** 
    * xmlWriteDemoByString 
    * 演示String保存为xml文件 
    */ 
   public void xmlWriteDemoByString() 
   { 
      String s = ""; 
      /** xml格式标题 "<?xml version=&#39;1.0&#39; encoding=&#39;GB2312&#39;?>" 可以不用写*/ 
      s = "<config>\r\n" 
         +"   <ftp name=&#39;DongDian&#39;>\r\n" 
         +"     <ftp-host>127.0.0.1</ftp-host>\r\n" 
         +"     <ftp-port>21</ftp-port>\r\n" 
         +"     <ftp-user>cxl</ftp-user>\r\n" 
         +"     <ftp-pwd>longshine</ftp-pwd>\r\n" 
         +"     <!-- ftp最多尝试连接次数 -->\r\n" 
         +"     <ftp-try>50</ftp-try>\r\n" 
         +"     <!-- ftp尝试连接延迟时间 -->\r\n" 
         +"     <ftp-delay>10</ftp-delay>\r\n" 
         +"  </ftp>\r\n" 
         +"</config>\r\n"; 
      //将文件生成到classes文件夹所在的目录里    
      string2XmlFile(s,"xmlWriteDemoByString.xml");    
      //将文件生成到classes文件夹里    
      string2XmlFile(s,"classes/xmlWriteDemoByString.xml");   
   }

7. Demonstrate manually creating a Document and save it as an XML file

 /** 
    * 演示手动创建一个Document,并保存为XML文件 
    */ 
   public void xmlWriteDemoByDocument() 
   { 
        /** 建立document对象 */ 
        Document document = DocumentHelper.createDocument(); 
        /** 建立config根节点 */ 
        Element configElement = document.addElement("config"); 
        /** 建立ftp节点 */ 
        configElement.addComment("东电ftp配置"); 
        Element ftpElement = configElement.addElement("ftp"); 
        ftpElement.addAttribute("name","DongDian"); 
        /** ftp 属性配置 */ 
        Element hostElement = ftpElement.addElement("ftp-host"); 
        hostElement.setText("127.0.0.1"); 
        (ftpElement.addElement("ftp-port")).setText("21"); 
        (ftpElement.addElement("ftp-user")).setText("cxl"); 
        (ftpElement.addElement("ftp-pwd")).setText("longshine"); 
        ftpElement.addComment("ftp最多尝试连接次数"); 
        (ftpElement.addElement("ftp-try")).setText("50"); 
        ftpElement.addComment("ftp尝试连接延迟时间"); 
        (ftpElement.addElement("ftp-delay")).setText("10");     
        /** 保存Document */ 
        doc2XmlFile(document,"classes/xmlWriteDemoByDocument.xml"); 
   }

8. Demonstrate reading the value of a specific node in the file

  /** 
    *  演示读取文件的具体某个节点的值  
    */ 
   public static void xmlReadDemo() 
   { 
      Document doc = load("classes/xmlWriteDemoByDocument.xml"); 
      //Element root = doc.getRootElement(); 
      /** 先用xpath查找所有ftp节点 并输出它的name属性值*/ 
      List list = doc.selectNodes("/config/ftp" ); 
      Iterator it = list.iterator(); 
      while(it.hasNext()) 
      {    
          Element ftpElement = (Element)it.next(); 
          System.out.println("ftp_name="+ftpElement.attribute("name").getValue()); 
      } 
      /** 直接用属性path取得name值 */ 
      list = doc.selectNodes("/config/ftp/@name" ); 
      it = list.iterator(); 
      while(it.hasNext()) 
      {    
          Attribute attribute = (Attribute)it.next(); 
          System.out.println("@name="+attribute.getValue()); 
      } 
      /** 直接取得DongDian ftp的 ftp-host 的值 */ 
      list = doc.selectNodes("/config/ftp/ftp-host" ); 
      it = list.iterator(); 
      Element hostElement=(Element)it.next(); 
      System.out.println("DongDian&#39;s ftp_host="+hostElement.getText()); 
   }

9. Modify or delete a value or attribute

/** ftp节点删除ftp-host节点 */ 
ftpElement.remove(hostElement);  
/** ftp节点删除name属性 */ 
ftpElement.remove(nameAttribute); 
/** 修改ftp-host的值 */ 
hostElement.setText("192.168.0.1");  
/** 修改ftp节点name属性的值 */ 
nameAttribute.setValue("ChiFeng");


The above is the content of dom4j operating xml files (full). For more related content, please pay attention to the PHP Chinese website (www.php.cn)!


Statement:
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn