SAX 解析到文件，缓存到内存

骑猪看日落 2022-03-11 14:49 154阅读 0赞

目的  
通过一个小的SAX例子，我们更清晰的理解SAX的工作原理。  
  
本文例子主要实现：  
1. 将每个Employee信息输出到自己的文件中，文件名是以Employee ID和Employee Name来命名的，注意，观察代码中是如何得到Employee ID和Employee Name；  
2. 将每个Employee信息存入到Map中，其中，Map中的每个Value对应一个Employee的Collection，Map中的每个Key对应该Employee的ID。

package shuai.study.sax.demo;  
          
        import java.io.File;  
        import java.io.IOException;  
        import java.util.Collection;  
        import java.util.HashMap;  
        import java.util.LinkedList;  
        import java.util.Map;  
          
        import javax.xml.parsers.ParserConfigurationException;  
        import javax.xml.parsers.SAXParser;  
        import javax.xml.parsers.SAXParserFactory;  
          
        import org.apache.commons.io.FileUtils;  
        import org.apache.commons.lang3.StringUtils;  
        import org.xml.sax.Attributes;  
        import org.xml.sax.SAXException;  
        import org.xml.sax.helpers.DefaultHandler;  
          
        /** 
         * @author shengshu 
         *  
         */  
        public class SaxHandler extends DefaultHandler {  
            private final static String leafNodeText = "|firstname|;|lastname|;|sex|;|country|;|province|;|city|;|village|;|mobile|;|mail|;|qq|;|postcode|;|profession|";  
          
            private Map<String, Collection<String>> companyMap = null;  
            private Collection<String> employeeCollection = null;  
          
            private String currentValue = null;  
            private String currentCharacters = null;  
          
            private StringBuffer idAndNameStringBuffer = null;  
          
            public SaxHandler(File inputFile) {  
                this.parseDocument(inputFile);  
            }  
          
            private void parseDocument(File inputFile) {  
                SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();  
          
                try {  
                    SAXParser saxParser = saxParserFactory.newSAXParser();  
                    saxParser.parse(inputFile, this);  
                } catch (ParserConfigurationException pce) {  
                    pce.printStackTrace();  
                } catch (SAXException saxe) {  
                    saxe.printStackTrace();  
                } catch (IOException ioe) {  
                    ioe.printStackTrace();  
                }  
            }  
          
            @Override  
            public void startDocument() throws SAXException {  
                super.startDocument();  
                this.companyMap = new HashMap<String, Collection<String>>();  
            }  
          
            @Override  
            public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {  
                if (qName.equalsIgnoreCase("Employee")) {  
                    this.employeeCollection = new LinkedList<String>();  
                    this.idAndNameStringBuffer = new StringBuffer();  
          
                    this.currentValue = attributes.getValue("ID");  
                }  
            }  
          
            @Override  
            public void characters(char[] buffer, int start, int length) {  
                this.currentCharacters = new String(buffer, start, length);  
            }  
          
            @Override  
            public void endElement(String uri, String localName, String qName) throws SAXException {  
                if (StringUtils.containsIgnoreCase(leafNodeText, "|" + qName + "|")) {  
                    this.employeeCollection.add(qName + ": " + this.currentCharacters);  
          
                    if (qName.equalsIgnoreCase("FirstName")) {  
                        this.idAndNameStringBuffer.append(this.currentCharacters);  
                    }  
          
                    if (qName.equalsIgnoreCase("LastName")) {  
                        this.idAndNameStringBuffer.append(this.currentCharacters);  
                    }  
                }  
          
                if (qName.equalsIgnoreCase("Employee")) {  
                    this.companyMap.put(this.currentValue, this.employeeCollection);  
          
                    this.idAndNameStringBuffer.append("-").append(this.currentValue);  
          
                    this.writeEmployee(employeeCollection, idAndNameStringBuffer.toString());  
                }  
            }  
          
            private void writeEmployee(Collection<String> employeeCollection, String fileName) {  
                String outputFileDirectory = SaxHandler.class.getResource("/file/output/").getPath();  
                String outputFilePath = outputFileDirectory + fileName + ".xml";  
                File outputFile = new File(outputFilePath);  
          
                try {  
                    FileUtils.writeLines(outputFile, employeeCollection, false);  
                } catch (IOException ioe) {  
                    ioe.printStackTrace();  
                }  
            }  
          
            @Override  
            public void endDocument() throws SAXException {  
                super.endDocument();  
            }  
          
            public Map<String, Collection<String>> getCompanyMap() {  
                return this.companyMap;  
            }  
          
        }

package shuai.study.sax.demo;  
          
        import java.io.File;  
        import java.util.Collection;  
        import java.util.Iterator;  
        import java.util.Map;  
        import java.util.Map.Entry;  
          
        /** 
         * @author shengshu 
         *  
         */  
        public class SaxDemo {  
            public static void displayCompany(Map<String, Collection<String>> companyMap) {  
                Iterator<Entry<String, Collection<String>>> companyIterator = companyMap.entrySet().iterator();  
          
                while (companyIterator.hasNext()) {  
                    Entry<String, Collection<String>> companyEntry = companyIterator.next();  
          
                    String id = companyEntry.getKey();  
                    System.out.println("============== Employee ID " + id + " Start ==============");  
          
                    Collection<String> employeeCollection = companyEntry.getValue();  
                    Iterator<String> employeeIterator = employeeCollection.iterator();  
          
                    while (employeeIterator.hasNext()) {  
                        String leafNodeAndValue = employeeIterator.next();  
                        System.out.println(leafNodeAndValue);  
                    }  
          
                    System.out.println("============== Employee ID " + id + " End ==============");  
                }  
            }  
          
            public static void main(String[] args) {  
                String inputFilePath = SaxDemo.class.getResource("/file/input/company.xml").getPath();  
                File inputFile = new File(inputFilePath);  
          
                SaxHandler saxHandler = new SaxHandler(inputFile);  
          
                Map<String, Collection<String>> companyMap = saxHandler.getCompanyMap();  
          
                SaxDemo.displayCompany(companyMap);  
            }  
        }

<?xml version = "1.0" encoding="UTF-8"?>  
          
        <Company>  
            <Employee ID="37">  
                <Name>  
                    <FirstName>Zhou</FirstName>  
                    <LastName>Shengshuai</LastName>  
                </Name>  
          
                <Sex>Male</Sex>  
          
                <Address>  
                    <Country>China</Country>  
                    <Province>ShanDong</Province>  
                    <City>LinYi</City>  
                    <Village>FengHuangYu</Village>  
          
                    <Contact>  
                        <Mobile>18108***778</Mobile>  
                        <Mail>zhoushengshuai2007@163.com</Mail>  
                        <QQ>254392398</QQ>  
                        <Postcode>276422</Postcode>  
                    </Contact>  
                </Address>  
          
                <Profession>Software</Profession>  
            </Employee>  
          
            <Employee ID="66">  
                <Name>  
                    <FirstName>Wang</FirstName>  
                    <LastName>Eric</LastName>  
                </Name>  
          
                <Sex>Male</Sex>  
          
                <Address>  
                    <Country>China</Country>  
                    <Province>HeBei</Province>  
                    <City>QinHuangDao</City>  
                    <Village>hhh</Village>  
          
                    <Contact>  
                        <Mobile>150*****955</Mobile>  
                        <Mail>eric@163.com</Mail>  
                        <QQ>666666666</QQ>  
                        <Postcode>111666</Postcode>  
                    </Contact>  
                </Address>  
          
                <Profession>Software</Profession>  
            </Employee>  
          
            <Employee ID="99">  
                <Name>  
                    <FirstName>Shi</FirstName>  
                    <LastName>Stone</LastName>  
                </Name>  
          
                <Sex>Male</Sex>  
          
                <Address>  
                    <Country>China</Country>  
                    <Province>HeNan</Province>  
                    <City>PingDingShan</City>  
                    <Village>nnn</Village>  
          
                    <Contact>  
                        <Mobile>186*****015</Mobile>  
                        <Mail>stone@163.com</Mail>  
                        <QQ>999999999</QQ>  
                        <Postcode>111999</Postcode>  
                    </Contact>  
                </Address>  
          
                <Profession>Software</Profession>  
            </Employee>  
        </Company>