### 1.簡介
Dom解析功能強大,可增刪改查,操作時會將XML文檔讀到內存,因此適用于小文檔;
SAX解析是從頭到尾逐行逐個元素解析,修改較為不便,但適用于只讀的大文檔;
SAX采用事件驅動的方式解析XML。套用網友的解釋:如同在電影院看電影一樣,從頭到尾看一遍,不能回退(Dom可來來回回讀取),在看電影的過程中,每遇到一個情節,都會調用大腦去接收處理這些信息。SAX也是相同的原理,每遇到一個元素節點,都會調用相應的方法來處理。在SAX的解析過程中,讀取到文檔開頭、文檔結尾,元素的開頭和元素結尾都會調用相應方法,我們可以在這些方法中進行相應事件處理。
對應方法:
~~~
public void startDocument() throws SAXException {
}
public void endDocument() throws SAXException {
}
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
}
public void endElement(String uri, String localName, String qName) throws SAXException {
}
~~~
我們還需一個方法來處理元素節點中間的文本節點(我們常誤以為元素節點的文本值)
~~~
public void characters(char[] ch, int start, int length) throws SAXException {
}
~~~
### 2.解析
解析步驟:
(1)通過SAXParserFactory的靜態方法newInstance()方法獲取SAXParserFactory實例對象factory
~~~
SAXParserFactory factory = SAXParserFactory.newInstance();
~~~
(2)通過SAXParserFactory實例的newSAXParser()方法返回SAXParser實例parser
~~~
SAXParser parser = factory.newSAXParser();
~~~
(3)創建一個類繼承DefaultHandler,重寫其中的一些方法進行業務處理
~~~
package com.qunar.handler;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class SAXParserHandler extends DefaultHandler{
// 用來標示解析開始
@Override
public void startDocument() throws SAXException {
}
// 用來標示解析結束
@Override
public void endDocument() throws SAXException {
}
// 用來遍歷XML文件的開始標簽
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
super.startElement(uri, localName, qName, attributes);
}
// 用來遍歷XML文件的結束標簽
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
super.endElement(uri, localName, qName);
}
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
super.characters(ch, start, length);
}
}
~~~
(4)創建Handler類對象實例
~~~
// 定義SAXParserHandler對象
SAXParserHandler handler = new SAXParserHandler();
~~~
(5)解析XML文檔
~~~
<?xml version="1.0" encoding="utf-8"?><bookstore>
<book category="Java">
<title lang="chi">Java多線程編程核心技術</title>
<author>高洪巖</author>
<year>2015</year>
<price>69.00</price>
</book>
<book category="C++">
<title lang="en">Effective C++: 55 Specific Ways to Improve Your Programs and Designs</title>
<author>Scott Meyers</author>
<year>2006</year>
<price>58.00</price>
</book>
<book category="Web">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2016</year>
<price>39.95</price>
</book>
</bookstore>
~~~
### 3.具體實例:
~~~
package com.qunar.handler;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class SAXParserHandler extends DefaultHandler{
private int bookIndex = 0;
// 用來標示解析開始
@Override
public void startDocument() throws SAXException {
System.out.println("SAX解析開始...");
}
// 用來標示解析結束
@Override
public void endDocument() throws SAXException {
System.out.println("SAX解析結束...");
}
// 用來遍歷XML文件的開始標簽
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
// 調用DefaultHandler類的startElement方法
super.startElement(uri, localName, qName, attributes);
// 開始解析book元素節點
if(qName.equals("book")){
++ bookIndex;
System.out.println("開始解析第" + bookIndex + "本書...");
// 已知book元素節點下的屬性名稱,根據屬性名稱獲取屬性值
/*String value = attributes.getValue("category");
System.out.println("value->"+value);*/
// 不知道book元素節點下的屬性名稱以及個數
int size = attributes.getLength();
for(int i = 0;i < size;++i){
System.out.println(attributes.getQName(i) + ":" + attributes.getValue(i));
}//for
}//if
else if(!qName.equals("bookstore")){
System.out.print(qName + ":");
}//else
}
// 用來遍歷XML文件的結束標簽
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
super.endElement(uri, localName, qName);
// 判斷一本書是否解析完
if(qName.equals("book")){
System.out.println("結束解析第" + bookIndex + "本書...");
}//if
}
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
super.characters(ch, start, length);
String text = new String(ch, start, length);
if(!text.trim().equals("")){
System.out.println(text);
}//if
}
}
~~~
~~~
package com.qunar.xml;
import java.io.IOException;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.SAXException;
import com.qunar.handler.SAXParserHandler;
/**
* SAX方式解析XML文檔
* @author sjf0115
*
*/
public class SAXXMLCode {
public static void main(String[] args) {
String path = "D:\\bookstore.xml";
try {
// 通過SAXParserFactory的靜態方法newInstance()方法獲取SAXParserFactory實例對象factory
SAXParserFactory factory = SAXParserFactory.newInstance();
// 通過SAXParserFactory實例的newSAXParser()方法返回SAXParser實例parser
SAXParser saxParser = factory.newSAXParser();
// 定義SAXParserHandler對象
SAXParserHandler handler = new SAXParserHandler();
// 解析XML文檔
saxParser.parse(path, handler);
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
~~~
**運行結果:**
<table cellspacing="0" cellpadding="0" style="border-collapse:collapse; border:1px solid rgb(187,187,187); width:1050px"><tbody><tr><td style="border-collapse:collapse; border:1px solid rgb(187,187,187); width:1049px"><br/><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">SAX解析開始...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">開始解析第1本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">category:Java</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">title:Java多線程編程核心技術</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">author:高洪巖</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">year:2015</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">price:69.00</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">結束解析第1本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">開始解析第2本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">category:C++</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">title:Effective?C++:?55?Specific?Ways?to?Improve?Your?Programs?and?Designs</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">author:Scott?Meyers</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">year:2006</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">price:58.00</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">結束解析第2本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">開始解析第3本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">category:Web</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">title:Learning?XML</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">author:Erik?T.?Ray</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">year:2016</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">price:39.95</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">結束解析第3本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">SAX解析結束...</span></div></td></tr></tbody></table>
### 4.解析并儲存于對象中
~~~
package com.qunar.bean;
/**
* book實體類
* @author sjf0115
*
*/
public class Book {
private String category;
private String title;
private String author;
private String year;
private String price;
private String lang;
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public String getYear() {
return year;
}
public void setYear(String year) {
this.year = year;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public String getLang() {
return lang;
}
public void setLang(String lang) {
this.lang = lang;
}
@Override
public String toString() {
return "category:" + category + " lang:" + lang + " title:" + title + " author:" + author + " year:" + year + " price:" + price;
}
}
~~~
~~~
package com.qunar.handler;
import java.util.ArrayList;
import java.util.List;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
import com.qunar.bean.Book;
public class SAXParserHandler extends DefaultHandler{
private Book book;
private int bookIndex = 0;
// 節點文本內容
private String text;
private List<Book> bookList = new ArrayList<Book>();
public List<Book> getBookList() {
return bookList;
}
// 用來標示解析開始
@Override
public void startDocument() throws SAXException {
System.out.println("SAX解析開始...");
}
// 用來標示解析結束
@Override
public void endDocument() throws SAXException {
System.out.println("SAX解析結束...");
}
// 用來遍歷XML文件的開始標簽
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
// 調用DefaultHandler類的startElement方法
super.startElement(uri, localName, qName, attributes);
// 開始解析book元素節點
if(qName.equals("book")){
// 創建一個book對象
book = new Book();
++ bookIndex;
System.out.println("開始解析第" + bookIndex + "本書...");
int size = attributes.getLength();
for(int i = 0;i < size;++i){
String attr = attributes.getQName(i);
// 屬性category
if(attr.equals("category")){
book.setCategory(attributes.getValue(i));
}//if
}//for
}//if
// 用于遍歷title節點中的屬性
else if(qName.equals("title")){
int size = attributes.getLength();
for(int i = 0;i < size;++i){
String attr = attributes.getQName(i);
// 屬性category
if(attr.equals("lang")){
book.setLang(attributes.getValue(i));
}//if
}//for
}//else
}
// 用來遍歷XML文件的結束標簽
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
super.endElement(uri, localName, qName);
// 判斷一本書是否解析完
if(qName.equals("book")){
bookList.add(book);
book = null;
System.out.println("結束解析第" + bookIndex + "本書...");
}//if
else if(qName.equals("title")){
book.setTitle(text);
}//else
else if(qName.equals("author")){
book.setAuthor(text);
}//else
else if(qName.equals("year")){
book.setYear(text);
}//else
else if(qName.equals("price")){
book.setPrice(text);
}//else
}
// 文本值
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
super.characters(ch, start, length);
text = new String(ch, start, length);
}
}
~~~
~~~
package com.qunar.xml;
import java.io.IOException;
import java.util.List;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.SAXException;
import com.qunar.bean.Book;
import com.qunar.handler.SAXParserHandler;
/**
* SAX方式解析XML文檔
* @author sjf0115
*
*/
public class SAXXMLCode {
public static void main(String[] args) {
String path = "D:\\bookstore.xml";
try {
// 通過SAXParserFactory的靜態方法newInstance()方法獲取SAXParserFactory實例對象factory
SAXParserFactory factory = SAXParserFactory.newInstance();
// 通過SAXParserFactory實例的newSAXParser()方法返回SAXParser實例parser
SAXParser saxParser = factory.newSAXParser();
// 定義SAXParserHandler對象
SAXParserHandler handler = new SAXParserHandler();
// 解析XML文檔
saxParser.parse(path, handler);
// 得到遍歷結果
List<Book> bookList = handler.getBookList();
System.out.println("遍歷結果:");
for (Book book : bookList) {
System.out.println(book);
}//for
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
~~~
**運行結果:**
<table cellspacing="0" cellpadding="0" style="border-collapse:collapse; border:1px solid rgb(187,187,187); width:1050px"><tbody><tr><td style="border-collapse:collapse; border:1px solid rgb(187,187,187); width:1049px"><br/><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">SAX解析開始...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">開始解析第1本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">結束解析第1本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">開始解析第2本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">結束解析第2本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">開始解析第3本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">結束解析第3本書...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">SAX解析結束...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">遍歷結果:</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">category:Java??lang:chi???title:Java多線程編程核心技術???author:高洪巖???year:2015???price:69.00</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">category:C++??lang:en???title:Effective?C++:?55?Specific?Ways?to?Improve?Your?Programs?and?Designs???author:Scott?Meyers???year:2006???price:58.00</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微軟雅黑">category:Web??lang:en???title:Learning?XML???author:Erik?T.?Ray???year:2016???price:39.95</span></div></td></tr></tbody></table>
- 前言
- [Hibernate開發之路](1)Hibernate配置
- [Hibernate開發之路](2)Hibernate問題
- [Hibernate開發之路](3)基礎配置
- [Hibernate開發之路](4)ID生成策略
- [Hibernate開發之路](5)聯合主鍵
- [設計模式實踐之路](1)單例模式
- [Java]UDP通信的簡單例子
- [Java]套接字地址InetAddress講解
- [Java開發之路](1)final關鍵字
- [Java開發之路](2)Java字符串
- [Java開發之路](3)Java常用類
- [Java開發之路](4)String、StringBuffer與StringBuilder詳解
- [Java開發之路](5)異常詳解
- [Java開發之路](6)File類的使用
- [Java開發之路](7)RandomAccessFile類詳解
- [Java開發之路](8)輸入流和輸出流
- [Java開發之路](9)對象序列化與反序列化
- [Java開發之路](10)DOM解析XML文檔
- [Java開發之路](11)SAX解析XML文檔
- [Java開發之路](12)JDOM和DOM4J解析XML文檔
- [Java開發之路](14)反射機制
- [Java開發之路](15)注解
- [Java開發之路](16)學習log4j日志
- [Java開發之路](18)關于Class.getResource和ClassLoader.getResource的路徑問題
- [Java開發之路](19)Long緩存問題
- [Java開發之路](20)try-with-resource 異常聲明
- [Java開發之路](21)Comparator與Comparable
- [Java]Java工程師成神之路
- [細說Java](1)圖說字符串的不變性
- [細說Java](2)Java中字符串為什么是不可變的
- [細說Java](3)創建字符串是使用&quot; &quot;還是構造函數?