使用 dom4j 解析 XML

使用 dom4j 解析 XML

1.生成一个XML文件：

public   void  generateDocument()  ... {
         /** */ /**
         * 使用 DocumentHelper 类创建一个文档实例。 
         * DocumentHelper 是生成 XML 文档节点的 dom4j API 工厂类。
          */
        Document document  =  DocumentHelper.createDocument();
         /** */ /**
         * 使用 addElement() 方法创建根元素 catalog 。 
         * addElement() 用于向 XML 文档中增加元素。
          */
        Element catalogElement  =  document.addElement( " catalog " );
         /** */ /**
         * 在 catalog 元素中使用 addComment() 方法添加注释“An XML catalog”。 
          */
        catalogElement.addComment( " An XML catalog " );
         /** */ /**
         * 在 catalog 元素中使用 addElement() 方法增加 journal 元素。
          */
        Element journalElement  =  catalogElement.addElement( " journal " );
         /** */ /**
         * 使用 addAttribute() 方法向 journal 元素添加 title 和 publisher 属性。
          */
        journalElement.addAttribute( " title " ,  " XML Zone " );
        journalElement.addAttribute( " publisher " ,  " IBM developerWorks " );

         /** */ /**
         * 向 article 元素中添加 journal 元素。 
          */
        Element articleElement  =  journalElement.addElement( " article " );
         /** */ /**
         * 为 article 元素增加 level 和 date 属性。 
          */
        articleElement.addAttribute( " level " ,  " Intermediate " );
        articleElement.addAttribute( " date " ,  " December-2001 " );
         /** */ /**
         * 向 article 元素中增加 title 元素。 
          */
        Element titleElement  =  articleElement.addElement( " title " );
         /** */ /**
         * 使用 setText() 方法设置 article 元素的文本。 
          */
        titleElement.setText( " Java configuration with XML Schema " );
         /** */ /**
         * 在 article 元素中增加 author 元素。 
          */
        Element authorElement  =  articleElement.addElement( " author " );
         /** */ /**
         * 在 author 元素中增加 firstname 元素并设置该元素的文本。 
          */
        Element firstNameElement  =  authorElement.addElement( " firstname " );
        firstNameElement.setText( " Macello " );
         /** */ /**
         * 在 author 元素中增加 lastname 元素并设置该元素的文本。 
          */
        Element lastNameElement  =  authorElement.addElement( " lastname " );
        lastNameElement.setText( " Vitaletti " );

         try   ... {
            XMLWriter output  =   new  XMLWriter( new  FileWriter( new  File(
                     " demo/catalog.xml " )));
            output.write(document);
            output.close();
        }   catch  (IOException e)  ... {
            e.printStackTrace();
        }
}

生成的XML文件如下所示：

<? xml version="1.0" encoding="UTF-8" ?>
< catalog >
<!-- An XML catalog -->
     < journal  title ="XML Zone"  publisher ="IBM developerWorks" >
         < article  level ="Intermediate"  date ="December-2001" >
             < title > Java configuration with XML Schema </ title >
             < author >
                 < firstname > Macello </ firstname >
                 < lastname > Vitaletti </ lastname >
             </ author >
         </ article >
     </ journal >
</ catalog >

2.读取该文件，输出firstname和lastname：

public   void  outPutInfo(String filename) ... {
         try   ... { 
            File f  =   new  File(filename); 
            SAXReader reader  =   new  SAXReader(); 
            Document doc  =  reader.read(f); 
            
            List list  =  doc.selectNodes( " //article " );
            Iterator iter  =  list.iterator();
            
             while  (iter.hasNext())  ... {
                Element element  =  (Element) iter.next();
                Element nameElement  =   null ;
                Iterator iterator  =  element.elementIterator( " author " );
                 while  (iterator.hasNext())  ... {
                    nameElement  =  (Element) iterator.next();
                    System.out.println(nameElement.elementText( " firstname " ));
                    System.out.println(nameElement.elementText( " lastname " ));
                }
            }
        }   catch  (Exception e)  ... { 
            e.printStackTrace(); 
        }  
    }

3.修改该文件;

public   void  modifyDocument(String filename)  ... {
         try   ... {
            File inputXml  =   new  File(filename);
            
            SAXReader saxReader  =   new  SAXReader();
            Document document  =  saxReader.read(inputXml);

             /** */ /**
             * inputXml 是从 catalog.xml 创建的 java.io.File。
             * 使用 XPath 表达式从 article 元素中获得 level 节点列表。
             * 如果 level 属性值是“Intermediate”则改为“Introductory”。 
              */
            List list  =  document.selectNodes( " //article/@level " );
            Iterator iter  =  list.iterator();
             while  (iter.hasNext())  ... {
                Attribute attribute  =  (Attribute) iter.next();
                 if  (attribute.getValue().equals( " Intermediate " ))
                    attribute.setValue( " Introductory " );
            }

            list  =  document.selectNodes( " //article/@date " );
            iter  =  list.iterator();
             while  (iter.hasNext())  ... {
                Attribute attribute  =  (Attribute) iter.next();
                 if  (attribute.getValue().equals( " December-2001 " ))
                    attribute.setValue( " October-2002 " );

            }
            
             /** */ /**
             * 获取 article 元素列表，从 article 元素中的 title 元素得到一个迭代器，并修改 title 元素的文本。 
              */
            list  =  document.selectNodes( " //article " );
            iter  =  list.iterator();
             while  (iter.hasNext())  ... {
                Element element  =  (Element) iter.next();
                Iterator iterator  =  element.elementIterator( " title " );
                 while  (iterator.hasNext())  ... {
                    Element titleElement  =  (Element) iterator.next();
                     if  (titleElement.getText().equals(
                             " Java configuration with XML Schema " ))
                        titleElement
                                .setText( " Create flexible and extensible XML Schema " );

                }
            }

            list  =  document.selectNodes( " //article/author " );
            iter  =  list.iterator();
             while  (iter.hasNext())  ... {
                Element element  =  (Element) iter.next();
                Iterator iterator  =  element.elementIterator( " firstname " );
                 while  (iterator.hasNext())  ... {
                    Element firstNameElement  =  (Element) iterator.next();
                     if  (firstNameElement.getText().equals( " Marcello " ))
                        firstNameElement.setText( " Ayesha " );
                }
            }

            list  =  document.selectNodes( " //article/author " );
            iter  =  list.iterator();
             while  (iter.hasNext())  ... {
                Element element  =  (Element) iter.next();
                Iterator iterator  =  element.elementIterator( " lastname " );
                 while  (iterator.hasNext())  ... {
                    Element lastNameElement  =  (Element) iterator.next();
                     if  (lastNameElement.getText().equals( " Vitaletti " ))
                        lastNameElement.setText( " Malik " );

                }

            }
            XMLWriter output  =   new  XMLWriter( new  FileWriter( new  File(
                     " catalog-modified.xml " )));
            output.write(document);
            output.close();
        }   catch  (DocumentException e)  ... {
            System.out.println(e.getMessage());
        }   catch  (IOException e)  ... {
            System.out.println(e.getMessage());
        }
    }

更新后的XML文件 内容如下所示：

<? xml version="1.0" encoding="UTF-8" ?>
< catalog >
<!-- An XML catalog -->
     < journal  title ="XML Zone"  publisher ="IBM developerWorks" >
         < article  level ="Introductory"  date ="October-2002" >
             < title > Create flexible and extensible XML Schema </ title >
             < author >
                 < firstname > Macello </ firstname >
                 < lastname > Malik </ lastname >
             </ author >
         </ article >
     </ journal >
</ catalog >