今天就來講一下Java 中使用dom4j來操作XML文件。

我們需要引入的包：

//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、將XML文件的內(nèi)容轉(zhuǎn)化為String

???/**?
????*?doc2String?
????*?將xml文檔內(nèi)容轉(zhuǎn)為String?
????*?@return?字符串?
????*?@param?document?
????*/?
???public?static?String?doc2String(Document?document)?
???{?
??????String?s?=?"";?
??????try?
??????{?
???????????//使用輸出流來進行轉(zhuǎn)化?
???????????ByteArrayOutputStream?out?=?new?ByteArrayOutputStream();?
???????????//使用GB2312編碼?
???????????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、將符合XML格式的String 轉(zhuǎn)化為XML Document

???/**?
????*?string2Document?
????*?將字符串轉(zhuǎn)為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、將Document對象保存為一個xml文件到本地

???/**?
????*?doc2XmlFile?
????*?將Document對象保存為一個xml文件到本地?
????*?@return?true:保存成功??flase:失敗?
????*?@param?filename?保存的文件名?
????*?@param?document?需要保存的document對象?
????*/?
???public?static?boolean?doc2XmlFile(Document?document,String?filename)?
???{?
??????boolean?flag?=?true;?
??????try?
??????{?
????????????/*?將document中的內(nèi)容寫入文件中?*/?
????????????//默認為UTF-8格式，指定為"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、將xml格式的字符串保存為本地文件，如果字符串格式不符合xml規(guī)則，則返回失敗

???/**?
????*?string2XmlFile?
????*?將xml格式的字符串保存為本地文件，如果字符串格式不符合xml規(guī)則，則返回失敗?
????*?@return?true:保存成功??flase:失敗?
????*?@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、載入一個xml文檔

???/**?
????*?load?
????*?載入一個xml文檔?
????*?@return?成功返回Document對象，失敗返回null?
????*?@param?uri?文件路徑?
????*/?
???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、演示String保存為xml文件

???/**?
????*?xmlWriteDemoByString?
????*?演示String保存為xml文件?
????*/?
???public?void?xmlWriteDemoByString()?
???{?
??????String?s?=?"";?
??????/**?xml格式標題?"<?xml?version='1.0'?encoding='GB2312'?>"?可以不用寫*/?
??????s?=?"<config>\r\n"?
?????????+"???<ftp?name='DongDian'>\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最多嘗試連接次數(shù)?-->\r\n"?
?????????+"?????<ftp-try>50</ftp-try>\r\n"?
?????????+"?????<!--?ftp嘗試連接延遲時間?-->\r\n"?
?????????+"?????<ftp-delay>10</ftp-delay>\r\n"?
?????????+"??</ftp>\r\n"?
?????????+"</config>\r\n";?
??????//將文件生成到classes文件夾所在的目錄里????
??????string2XmlFile(s,"xmlWriteDemoByString.xml");????
??????//將文件生成到classes文件夾里????
??????string2XmlFile(s,"classes/xmlWriteDemoByString.xml");???
???}

7、演示手動創(chuàng)建一個Document，并保存為XML文件

???/**?
????*?演示手動創(chuàng)建一個Document，并保存為XML文件?
????*/?
???public?void?xmlWriteDemoByDocument()?
???{?
????????/**?建立document對象?*/?
????????Document?document?=?DocumentHelper.createDocument();?
????????/**?建立config根節(jié)點?*/?
????????Element?configElement?=?document.addElement("config");?
????????/**?建立ftp節(jié)點?*/?
????????configElement.addComment("東電ftp配置");?
????????Element?ftpElement?=?configElement.addElement("ftp");?
????????ftpElement.addAttribute("name","DongDian");?
????????/**?ftp?屬性配置?*/?
????????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最多嘗試連接次數(shù)");?
????????(ftpElement.addElement("ftp-try")).setText("50");?
????????ftpElement.addComment("ftp嘗試連接延遲時間");?
????????(ftpElement.addElement("ftp-delay")).setText("10");?????
????????/**?保存Document?*/?
????????doc2XmlFile(document,"classes/xmlWriteDemoByDocument.xml");?
???}

8、演示讀取文件的具體某個節(jié)點的值

???/**?
????*??演示讀取文件的具體某個節(jié)點的值??
????*/?
???public?static?void?xmlReadDemo()?
???{?
??????Document?doc?=?load("classes/xmlWriteDemoByDocument.xml");?
??????//Element?root?=?doc.getRootElement();?
??????/**?先用xpath查找所有ftp節(jié)點?并輸出它的name屬性值*/?
??????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());?
??????}?
??????/**?直接用屬性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());?
???}

9、修改或刪除某個值或?qū)傩?/strong>