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dom4j operates xml files (full)

Feb 09, 2017 pm 02:14 PM

xml file

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;

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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 = &quot;&quot;; 
    try
    { 
         //使用输出流来进行转化 
         ByteArrayOutputStream out = new ByteArrayOutputStream(); 
         //使用GB2312编码 
         OutputFormat format = new OutputFormat(&quot;  &quot;, true, &quot;GB2312&quot;); 
         XMLWriter writer = new XMLWriter(out, format); 
         writer.write(document); 
         s = out.toString(&quot;GB2312&quot;); 
    }catch(Exception ex) 
    {             
         ex.printStackTrace(); 
    }       
    return s; 
 }

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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; 
  }

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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&quot;GB2312&quot; 
           OutputFormat format = OutputFormat.createPrettyPrint(); 
           format.setEncoding(&quot;GB2312&quot;); 
           XMLWriter writer = new XMLWriter(new FileWriter(new File(filename)),format); 
           writer.write(document); 
           writer.close();             
       }catch(Exception ex) 
       { 
           flag = false; 
           ex.printStackTrace(); 
       } 
       return flag;       
  }

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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; 
   }

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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; 
  }

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6. Demonstrate saving a String as an xml file

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

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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(&quot;config&quot;); 
       /** 建立ftp节点 */
       configElement.addComment(&quot;东电ftp配置&quot;); 
       Element ftpElement = configElement.addElement(&quot;ftp&quot;); 
       ftpElement.addAttribute(&quot;name&quot;,&quot;DongDian&quot;); 
       /** ftp 属性配置 */
       Element hostElement = ftpElement.addElement(&quot;ftp-host&quot;); 
       hostElement.setText(&quot;127.0.0.1&quot;); 
       (ftpElement.addElement(&quot;ftp-port&quot;)).setText(&quot;21&quot;); 
       (ftpElement.addElement(&quot;ftp-user&quot;)).setText(&quot;cxl&quot;); 
       (ftpElement.addElement(&quot;ftp-pwd&quot;)).setText(&quot;longshine&quot;); 
       ftpElement.addComment(&quot;ftp最多尝试连接次数&quot;); 
       (ftpElement.addElement(&quot;ftp-try&quot;)).setText(&quot;50&quot;); 
       ftpElement.addComment(&quot;ftp尝试连接延迟时间&quot;); 
       (ftpElement.addElement(&quot;ftp-delay&quot;)).setText(&quot;10&quot;);     
       /** 保存Document */
       doc2XmlFile(document,&quot;classes/xmlWriteDemoByDocument.xml&quot;); 
  }

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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(&quot;classes/xmlWriteDemoByDocument.xml&quot;); 
    //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(&quot;/config/ftp&quot; ); 
    Iterator it = list.iterator(); 
    while(it.hasNext()) 
    {    
        Element ftpElement = (Element)it.next(); 
        System.out.println(&quot;ftp_name=&quot;+ftpElement.attribute(&quot;name&quot;).getValue()); 
    } 
    /** 直接用属性path取得name值 */
    list = doc.selectNodes(&quot;/config/ftp/@name&quot; ); 
    it = list.iterator(); 
    while(it.hasNext()) 
    {    
        Attribute attribute = (Attribute)it.next(); 
        System.out.println(&quot;@name=&quot;+attribute.getValue()); 
    } 
    /** 直接取得DongDian ftp的 ftp-host 的值 */
    list = doc.selectNodes(&quot;/config/ftp/ftp-host&quot; ); 
    it = list.iterator(); 
    Element hostElement=(Element)it.next(); 
    System.out.println(&quot;DongDian&#39;s ftp_host=&quot;+hostElement.getText()); 
 }

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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(&quot;192.168.0.1&quot;);  
/** 修改ftp节点name属性的值 */
nameAttribute.setValue(&quot;ChiFeng&quot;);

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