DOM和SAX的最终作用是可以让我们利用java JavaScript等语言来获取xml文件中的节点及文本、属性等信息。
本文引自其他博客，内容易懂，为了节省时间，直接摘抄过来了。 JAVA 解析 XML 通常有两种方式，DOM 和 SAX。DOM 虽然是 W3C 的标准，提供了标准的解析方式，但它的解析效率一直不尽如人意，因为使用DOM解析XML时，解析器读入整个文档并构建一个驻留内存的树结构（节点树），然后您的代码才可以使用 DOM 的标准接口来操作这个树结构。但大部分情况下我们只对文档的部分内容感兴趣，根本就不用先解析整个文档，并且从节点树的根节点来索引一些我们需要的数据也是非常耗时的。
SAX是一种XML解析的替代方法。相比于文档对象模型DOM，SAX 是读取和操作 XML 数据的更快速、更轻量的方
法。SAX 允许您在读取文档时处理它，从而不必等待整个文档被存储之后才采取操作。它不涉及 DOM 所必需的开销和概念跳跃。 SAX API是一个基于事件的API ，适用于处理数据流，即随着数据的流动而依次处理数据。SAX API
在其解析您的文档时发生一定事件的时候会通知您。在您对其响应时，您不作保存的数据将会 被抛弃。
下面是一个SAX解析XML的示例（有点长，因为详细注解了SAX事件处理的所有方法），SAX API中主要有四种处理事件的接口，它们分别是ContentHandler，DTDHandler， EntityResolver 和 ErrorHandler 。下面的例子可能有点冗长，实际上只要继承DefaultHandler 类 ，再覆盖一部分 处理事件的方法 同样可以达到这个示例的效果，但为了纵观全局，还是看看SAX API里面所有主要的事件解析方法吧。（ 实际上DefaultHandler就是实现了上面的四个事件处理器接口，然后提供了每个抽象方法的默认实现。）
1，ContentHandler 接口 ：接收文档逻辑内容的通知 的处理器接口。
Java代码 收藏代码
'import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
class MyContentHandler implements ContentHandler{
StringBuffer jsonStringBuffer ;
int frontBlankCount = 0;
public MyContentHandler(){
jsonStringBuffer = new StringBuffer();
}
/*
* 接收字符数据的通知。
* 在DOM中 ch[begin:end] 相当于Text节点的节点值（nodeValue）
*/
@Override
public void characters(char[] ch, int begin, int length) throws SAXException {
StringBuffer buffer = new StringBuffer();
for(int i = begin ; i < begin+length ; i++){
switch(ch[i]){
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\");break;
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\r':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\r");break;
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n");break;
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t");break;
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"");break;
default : buffer.append(ch[i]);
}
}
System.out.println(this.toBlankString(this.frontBlankCount)+
">>> characters("+length+"): "+buffer.toString());
}
/*
* 接收文档的结尾的通知。
*/
@Override
public void endDocument() throws SAXException {
System.out.println(this.toBlankString(--this.frontBlankCount)+
">>> end document");
}
/*
* 接收文档的结尾的通知。
* 参数意义如下：
* uri ：元素的命名空间
* localName ：元素的本地名称（不带前缀）
* qName ：元素的限定名（带前缀）
*
*/
@Override
public void endElement(String uri,String localName,String qName)
throws SAXException {
System.out.println(this.toBlankString(--this.frontBlankCount)+
">>> end element : "+qName+"("+uri+")");
}
/*
* 结束前缀 URI 范围的映射。
*/
@Override
public void endPrefixMapping(String prefix) throws SAXException {
System.out.println(this.toBlankString(--this.frontBlankCount)+
">>> end prefix_mapping : "+prefix);
}
/*
* 接收元素内容中可忽略的空白的通知。
* 参数意义如下：
* ch : 来自 XML 文档的字符
* start : 数组中的开始位置
* length : 从数组中读取的字符的个数
*/
@Override
public void ignorableWhitespace(char[] ch, int begin, int length)
throws SAXException {
StringBuffer buffer = new StringBuffer();
for(int i = begin ; i < begin+length ; i++){
switch(ch[i]){
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\");break;
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\r':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\r");break;
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n");break;
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t");break;
case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"':buffer.append("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"");break;
default : buffer.append(ch[i]);
}
}
System.out.println(this.toBlankString(this.frontBlankCount)+">>> ignorable whitespace("+length+"): "+buffer.toString());
}
/*
* 接收处理指令的通知。
* 参数意义如下：
* target : 处理指令目标
* data : 处理指令数据，如果未提供，则为 null。
*/
@Override
public void processingInstruction(String target,String data)
throws SAXException {
System.out.println(this.toBlankString(this.frontBlankCount)+">>> process instruction : (target = \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\""
+target+"\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\",data = \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\""+data+"\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\")");
}
/*
* 接收用来查找 SAX 文档事件起源的对象。
* 参数意义如下：
* locator : 可以返回任何 SAX 文档事件位置的对象
*/
@Override
public void setDocumentLocator(Locator locator) {
System.out.println(this.toBlankString(this.frontBlankCount)+
">>> set document_locator : (lineNumber = "+locator.getLineNumber()
+",columnNumber = "+locator.getColumnNumber()
+",systemId = "+locator.getSystemId()
+",publicId = "+locator.getPublicId()+")");
}
/*
* 接收跳过的实体的通知。
* 参数意义如下：
* name : 所跳过的实体的名称。如果它是参数实体，则名称将以 '%' 开头，
* 如果它是外部 DTD 子集，则将是字符串 "[dtd]"
*/
@Override
public void skippedEntity(String name) throws SAXException {
System.out.println(this.toBlankString(this.frontBlankCount)+
">>> skipped_entity : "+name);
}
/*
* 接收文档的开始的通知。
*/
@Override
public void startDocument() throws SAXException {
System.out.println(this.toBlankString(this.frontBlankCount++)+
">>> start document ");
}
/*
* 接收元素开始的通知。
* 参数意义如下：
* uri ：元素的命名空间
* localName ：元素的本地名称（不带前缀）
* qName ：元素的限定名（带前缀）
* atts ：元素的属性集合
*/
@Override
public void startElement(String uri, String localName, String qName,
Attributes atts) throws SAXException {
System.out.println(this.toBlankString(this.frontBlankCount++)+
">>> start element : "+qName+"("+uri+")");
}
/*
* 开始前缀 URI 名称空间范围映射。
* 此事件的信息对于常规的命名空间处理并非必需：
* 当 http://xml.org/sax/features/namespaces 功能为 true（默认）时，
* SAX XML 读取器将自动替换元素和属性名称的前缀。
* 参数意义如下：
* prefix ：前缀
* uri ：命名空间
*/
@Override
public void startPrefixMapping(String prefix,String uri)
throws SAXException {
System.out.println(this.toBlankString(this.frontBlankCount++)+
">>> start prefix_mapping : xmlns:"+prefix+" = "
+"\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\""+uri+"\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"");
}
private String toBlankString(int count){
StringBuffer buffer = new StringBuffer();
for(int i = 0;i
buffer.append(" ");
return buffer.toString();
}
}'
2，DTDHandler 接口 ：接收与 DTD 相关的事件的通知的处理器接口。
Java代码 收藏代码
'import org.xml.sax.DTDHandler;
import org.xml.sax.SAXException;
public class MyDTDHandler implements DTDHandler {
/*
* 接收注释声明事件的通知。
* 参数意义如下：
* name - 注释名称。
* publicId - 注释的公共标识符，如果未提供，则为 null。
* systemId - 注释的系统标识符，如果未提供，则为 null。
*/
@Override
public void notationDecl(String name, String publicId, String systemId)
throws SAXException {
System.out.println(">>> notation declare : (name = "+name
+",systemId = "+publicId
+",publicId = "+systemId+")");
}
/*
* 接收未解析的实体声明事件的通知。
* 参数意义如下：
* name - 未解析的实体的名称。
* publicId - 实体的公共标识符，如果未提供，则为 null。
* systemId - 实体的系统标识符。
* notationName - 相关注释的名称。
*/
@Override
public void unparsedEntityDecl(String name,
String publicId,
String systemId,
String notationName) throws SAXException {
System.out.println(">>> unparsed entity declare : (name = "+name
+",systemId = "+publicId
+",publicId = "+systemId
+",notationName = "+notationName+")");
}
}'
3，EntityResolver 接口 ：是用于解析实体的基本接口。
Java代码 收藏代码
'import java.io.IOException;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
public class MyEntityResolver implements EntityResolver {
/*
* 允许应用程序解析外部实体。
* 解析器将在打开任何外部实体（顶级文档实体除外）前调用此方法
* 参数意义如下：
* publicId ： 被引用的外部实体的公共标识符，如果未提供，则为 null。
* systemId ： 被引用的外部实体的系统标识符。
* 返回：
* 一个描述新输入源的 InputSource 对象，或者返回 null，
* 以请求解析器打开到系统标识符的常规 URI 连接。
*/
@Override
public InputSource resolveEntity(String publicId, String systemId)
throws SAXException, IOException {
return null;
}
}
4，ErrorHandler接口 ：是错误处理程序的基本接口。
Java代码 收藏代码
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
public class MyErrorHandler implements ErrorHandler {
/*
* 接收可恢复的错误的通知
*/
@Override
public void error(SAXParseException e) throws SAXException {
System.err.println("Error ("+e.getLineNumber()+","
+e.getColumnNumber()+") : "+e.getMessage());
}
/*
* 接收不可恢复的错误的通知。
*/
@Override
public void fatalError(SAXParseException e) throws SAXException {
System.err.println("FatalError ("+e.getLineNumber()+","
+e.getColumnNumber()+") : "+e.getMessage());
}
/*
* 接收不可恢复的错误的通知。
*/
@Override
public void warning(SAXParseException e) throws SAXException {
System.err.println("Warning ("+e.getLineNumber()+","
+e.getColumnNumber()+") : "+e.getMessage());
}
}
Test 类的主方法打印解析books.xml时的事件信息。
Java代码 收藏代码
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import org.xml.sax.ContentHandler;
import org.xml.sax.DTDHandler;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;
public class Test {
public static void main(String[] args) throws SAXException,
FileNotFoundException, IOException {
//创建处理文档内容相关事件的处理器
ContentHandler contentHandler = new MyContentHandler();
//创建处理错误事件处理器
ErrorHandler errorHandler = new MyErrorHandler();
//创建处理DTD相关事件的处理器
DTDHandler dtdHandler = new MyDTDHandler();
//创建实体解析器
EntityResolver entityResolver = new MyEntityResolver();
//创建一个XML解析器（通过SAX方式读取解析XML）
XMLReader reader = XMLReaderFactory.createXMLReader();
/*
* 设置解析器的相关特性
* http://xml.org/sax/features/validation = true 表示开启验证特性
* http://xml.org/sax/features/namespaces = true 表示开启命名空间特性
*/
reader.setFeature("http://xml.org/sax/features/validation",true);
reader.setFeature("http://xml.org/sax/features/namespaces",true);
//设置XML解析器的处理文档内容相关事件的处理器
reader.setContentHandler(contentHandler);
//设置XML解析器的处理错误事件处理器
reader.setErrorHandler(errorHandler);
//设置XML解析器的处理DTD相关事件的处理器
reader.setDTDHandler(dtdHandler);
//设置XML解析器的实体解析器
reader.setEntityResolver(entityResolver);
//解析books.xml文档
reader.parse(new InputSource(new FileReader("books.xml")));
}
}'
books.xml 文件的内容如下：
Xml代码 收藏代码
Thinking in JAVA
Core JAVA2
C++ primer
控制台输出如下：
>>> set document_locator : (lineNumber = 1,columnNumber = 1,systemId = null,publicId = null)
>>> start document
Error (2,7) : Document is invalid: no grammar found.
Error (2,7) : Document root element "books", must match DOCTYPE root "null".
>>> start prefix_mapping : xmlns: = "http://test.org/books"
>>> start element : books(http://test.org/books)
>>> characters(2): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> characters(2): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> start element : book(http://test.org/books)
>>> characters(3): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> start element : name(http://test.org/books)
>>> characters(16): Thinking in JAVA
>>> end element : name(http://test.org/books)
>>> characters(2): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> end element : book(http://test.org/books)
>>> characters(2): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> start element : book(http://test.org/books)
>>> characters(3): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> start element : name(http://test.org/books)
>>> characters(10): Core JAVA2
>>> end element : name(http://test.org/books)
>>> characters(2): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> end element : book(http://test.org/books)
>>> characters(2): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> start element : book(http://test.org/books)
>>> characters(3): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> start element : name(http://test.org/books)
>>> characters(10): C++ primer
>>> end element : name(http://test.org/books)
>>> characters(2): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\t
>>> end element : book(http://test.org/books)
>>> characters(1): \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n
>>> end element : books(http://test.org/books)
>>> end prefix_mapping :
>>> end document
以上就是XML SAX解析详解的详细内容，更多请关注自由互联其它相关文章！