dom4j operates xml files (full)-XML/RSS Tutorial-php.cn

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 = ""; 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; }

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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"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; }

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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 = ""; /** xml格式标题 "" 可以不用写*/ s = "\r\n" +" \r\n" +" 127.0.0.1\r\n" +" 21\r\n" +" cxl\r\n" +" longshine\r\n" +" \r\n" +" 50\r\n" +" \r\n" +" 10\r\n" +" \r\n" +"\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"); }

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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("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"); }

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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("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's ftp_host="+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("192.168.0.1"); /** 修改ftp节点name属性的值 */ nameAttribute.setValue("ChiFeng");

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