SAX逐行解析
SAX：SimpleAPIfor XML。基于事件驱动的解析方式，逐行解析数据。（采用协议回调机制）
NSXMLParser是iOS自带的XML解析类。采用SAX方式解析数据
解析过程由NSXMLParserDelegate协议方法回调
DOM解析
DOM：DocumentObjectModel（文档对象模型）。解析时需要将XML文件整体读入，并且将XML结构化成树状，使用时再通过树状结构读取相关数据
GdataxMLNode(这个类在下载包里面)是Google提供的开源XML解析类，对libxml2.dylib进行了Objective－C的封装
采用DOM方式解析数据
iOS中包含一个C语言的动态链接库libxml2.dylib，解析速度比NSXMLParser快
AppDelegate.m
#import"AppDelegate.h"
#import"MainViewController.h"
@implementationAppDelegate
-(BOOL)application:(UIApplication*)applicationdidFinishLaunchingWithOptions:(NSDictionary*)launchOptions
{
self.window=[[UIWindowalloc]initWithFrame:[[UIScreenmainScreen]bounds]];
//Overridepointforcustomizationafterapplicationlaunch.
self.window.backgroundColor=[UIColorwhiteColor];
[self.windowmakeKeyAndVisible];
MainViewController*mainVC=[[MainViewControlleralloc]init];
UINavigationController*naviVC=[[UINavigationControlleralloc]initWithRootViewController:mainVC];
self.window.rootViewController=naviVC;
[naviVCrelease];
[mainVCrelease];
[_windowrelease];
returnYES;
}
-(void)dealloc
{
[_windowrelease];
[superdealloc];
}
-(void)applicationWillResignActive:(UIApplication*)application
{
//Sentwhentheapplicationisabouttomovefromactivetoinactivestate.Thiscanoccurforcertaintypesoftemporaryinterruptions(suchasanincomingphonecallorSMSmessage)orwhentheuserquitstheapplicationanditbeginsthetransitiontothebackgroundstate.
//UsethismethodtopauSEOngoingtasks,disabletimers,andthrottledownOpenGLESframerates.Gamesshouldusethismethodtopausethegame.
}
-(void)applicationDidEnterBackground:(UIApplication*)application
{
//Usethismethodtoreleasesharedresources,saveuserdata,invalidatetimers,andstoreenoughapplicationstateinformationtorestoreyourapplicationtoitscurrentstateincaseitisterminatedlater.
//Ifyourapplicationsupportsbackgroundexecution,thismethodiscalledinsteadofapplicationWillTerminate:whentheuserquits.
}
-(void)applicationWillEnterForeground:(UIApplication*)application
{
//Calledaspartofthetransitionfromthebackgroundtotheinactivestate;hereyoucanundomanyofthechangesmadeonenteringthebackground.
}
-(void)applicationDidBecomeActive:(UIApplication*)application
{
//Restartanytasksthatwerepaused(ornotyetstarted)whiletheapplicationwasinactive.IftheapplicationwasprevIoUslyinthebackground,optionallyrefreshtheuserinterface.
}
-(void)applicationWillTerminate:(UIApplication*)application
{
//Calledwhentheapplicationisabouttoterminate.Savedataifappropriate.SeealsoapplicationDidEnterBackground:.
}
@end
MainViewController.m
#import"MainViewController.h"
#import"XMLSAXParser.h"
#import"JSONParser.h"
@interfaceMainViewController()
@end
@implementationMainViewController
-(id)initWithNibName:(NSString*)nibNameOrNilbundle:(NSBundle*)nibBundleOrNil
{
self=[superinitWithNibName:nibNameOrNilbundle:nibBundleOrNil];
if(self){
//Custominitialization
}
returnself;
}
-(void)viewDidLoad
{
[superviewDidLoad];
//Doanyadditionalsetupafterloadingtheview.
self.view.backgroundColor=[UIColorcyanColor];
//XMLSAX解析(逐行解析)
XMLSAXParser*parser=[[XMLSAXParseralloc]init];
[parserstartParse];
NSLog(@"解析后的%@",parser.array);
[parserrelease];
}
-(void)didReceiveMemoryWarning
{
[superdidReceiveMemoryWarning];
//DispoSEOfanyresourcesthatcanberecreated.
}
/*
#pragmamark-Navigation
//Inastoryboard-basedapplication,youwilloftenwanttodoalittlepreparationbeforenavigation
-(void)prepareForSegue:(UIStoryboardSegue*)seguesender:(id)sender
{
//Getthenewviewcontrollerusing[seguedestinationViewController].
//Passtheselectedobjecttothenewviewcontroller.
}
*/
@end
XMLSAXParser.h #import<Foundation/Foundation.h> @interfaceXMLSAXParser:NSObject<NSXMLParserDelegate> @property(nonatomic,retain)NSMutableArray*array;//装学生对象 @property(nonatomic,retain)NSString*tempStr;//临时健在节点内容 -(void)startParse;//开始解析,逐行解析 -(void)startDOMParse;//开始dom解析,按节点解析 @end
XMLSAXParser.m #import"XMLSAXParser.h" #import"Student.h" #import"GdataxMLNode.h" @implementationXMLSAXParser //XML解析:逐行解析 -(void)startParse; { //XML解析:逐行解析 //从文件列表中读取数据 //1.获取文件路径 NSString*sourcePath=[[NSBundlemainBundle]pathForResource:@"Student"ofType:@"xml"]; //2.通过路径把文件转换成NSData类型 NSData*data=[NSDatadataWithContentsOfFile:sourcePath]; //创建的时候需要给parser一个字符串数据(NSData) NSXMLParser*parser=[[NSXMLParseralloc]initWithData:data]; //设定代理人 parser.delegate=self; //开始对文件进行解析 [parserparse]; //内存管理 [parserrelease]; } -(void)parser:(NSXMLParser*)parserdidStartElement:(NSString*)elementNamenamespaceURI:(NSString*)namespaceURIqualifiedName:(NSString*)qNameattributes:(NSDictionary*)attributeDict { //当找到节点头的时候,体统调用这个方法 NSLog(@"节点头"); if([elementNameisEqualToString:@"students"]){ //当找到students节点头的时候,初始化数组 self.array=[NSMutableArrayarray]; }elseif([elementNameisEqualToString:@"student"]){ //当找到student节点时候,创建一个新的学生对象,添加到数组中 Student*stu=[[Studentalloc]init]; [self.arrayaddObject:stu]; [sturelease]; } } -(void)parser:(NSXMLParser*)parserfoundCharacters:(NSString*)string { //当找到节点内容的时候,调用 NSLog(@"节点内容"); //把内容保存起来,只要碰到节点内容,下一个肯定是节点尾 self.tempStr=string; } -(void)parser:(NSXMLParser*)parserdidEndElement:(NSString*)elementNamenamespaceURI:(NSString*)namespaceURIqualifiedName:(NSString*)qName { //当找到节点尾时候调用 NSLog(@"节点尾"); //取得之前保存的student对象 Student*stu=[self.arraylastObject];//核心代码,懂了没......... if([elementNameisEqualToString:@"name"]){ stu.name=self.tempStr; }elseif([elementNameisEqualToString:@"sex"]){ stu.sex=self.tempStr; }elseif([elementNameisEqualToString:@"phone"]){ stu.phone=self.tempStr; }elseif([elementNameisEqualToString:@"number"]){ stu.number=self.tempStr; } } //开始dom解析,按节点解析 -(void)startDOMParse { //按节点解析 //1.获取要解析文件的文件信息 NSString*xmlPath=[[NSBundlemainBundle]pathForResource:@"Student"ofType:@"xml"]; NSData*data=[NSDatadataWithContentsOfFile:xmlPath]; //参数1:要解析的xml串 //参数2:随便 //参数3:错误信息 GdataxMLDocument*doc=[[GdataxMLDocumentalloc]initWithData:dataoptions:0error:nil]; //2.获取文件的根节点 GdataxMLElement*rootElement=[docrootElement]; //3.进一步搜索所有的子节点 //返回一个装满了student节点(GdataxMLElement对象)的数组 NSArray*array=[rootElementelementsForName:@"student"]; self.array=[NSMutableArrayarray]; //4.遍历数组,把student节点的每个子节点取出来 for(GdataxMLElement*elementinarray){ Student*stu=[[Studentalloc]init]; GdataxMLElement*nameElement=[[elementelementsForName:@"name"]lastObject]; //从name节点中取值 NSString*name=[nameElementstringValue]; //给学生对象的属性赋值 stu.name=name; //把学生对象添加到数组中-----------其他的雷同 [self.arrayaddObject:stu]; [sturelease]; } } @end
Student.h #import<Foundation/Foundation.h> @interfaceStudent:NSObject @property(nonatomic,retain)NSString*number; @property(nonatomic,retain)NSString*name; @property(nonatomic,retain)NSString*sex; @property(nonatomic,copy)NSString*phone; @end
Student.m
#import"Student.h"
@implementationStudent
-(void)dealloc
{
[_namerelease];
[_numberrelease];
[_sexrelease];
[_phonerelease];
[superdealloc];
}
//当这个类的对象被NSLog输出时候,系统会先调用这个方法,如果这个方法被重写,就直接输出重写的内容,否则就输出系统默认的内容
-(NSString*)description
{
return[NSStringstringWithFormat:@"name:%@sex:%@phone:%@number:%@",self.name,self.sex,self.phone,self.number];
}
@end
这里需要注意的是添加第三方类的步骤:
直接添加第三方类是有错的
在GdataxMLNode.h中
// libxml includes require that the target Header Search Paths contain
//
// /usr/include/libxml2
// and Other Linker Flags contain
// -lxml2
在下面的对上面的文件中首先搜索Header Search 然后在第二行中添加上/usr/include/libxml2
然后同理搜索Other Linker-lxml2
这样第三方类就可以使用了 .
XML在不同的语言里解析方式都是一样的,只不过实现的语法不同而已。基本的解析方式有两种,一种叫SAX，另一种叫DOM。SAX是基于事件流的解析,DOM是基于XML文档树结构的解析.假设我们XML的内容和结构如下:
[xhtml]view plaincopy
<?xmlversion="1.0"encoding="UTF-8"?> <employees> <employee> <name>ddviplinux</name> <sex>m</sex> <age>30</age> </employee> </employees>
下面是解析XMl常用的Dom和Sex方法：
1.DOM生成和解析XML文档
为 XML 文档的已解析版本定义了一组接口。解析器读入整个文档，然后构建一个驻留内存的树结构，然后代码就可以使用 DOM 接口来操作这个树结构。优点：整个文档树在内存中，便于操作；支持删除、修改、重新排列等多种功能；缺点：将整个文档调入内存（包括无用的节点），浪费时间和空间；使用场合：一旦解析了文档还需多次访问这些数据；硬件资源充足（内存、cpu）。
[java]copy
publicvoidparserXml(StringfileName){
try{
DocumentBuilderFactorydbf=DocumentBuilderFactory.newInstance();
DocumentBuilderdb=dbf.newDocumentBuilder();
Documentdocument=db.parse(fileName);
NodeListemployees=document.getChildNodes();
for(inti=0;i<employees.getLength();i++){
Nodeemployee=employees.item(i);
NodeListemployeeInfo=employee.getChildNodes();
for(intj=0;j<employeeInfo.getLength();j++){
Nodenode=employeeInfo.item(j);
NodeListemployeeMeta=node.getChildNodes();
for(intk=0;k<employeeMeta.getLength();k++){
System.out.println(employeeMeta.item(k).getNodeName()+":"+employeeMeta.item(k).getTextContent());
}
}
}
System.out.println("解析完毕");
}catch(Exceptione){
System.out.println(e.getMessage());
}
}
2.SAX生成和解析XML文档
为解决DOM的问题，出现了SAX。SAX ，事件驱动。当解析器发现元素开始、元素结束、文本、文档的开始或结束等时，发送事件，程序员编写响应这些事件的代码，保存数据。优点：不用事先调入整个文档，占用资源少；SAX解析器代码比DOM解析器代码小，适于Applet，下载。缺点：不是持久的；事件过后，若没保存数据，那么数据就丢了；无状态性；从事件中只能得到文本，但不知该文本属于哪个元素；使用场合：Applet;只需XML文档的少量内容，很少回头访问；机器内存少；
copy
publicvoidparserXml(StringfileName){
SAXParserFactorysaxfac=SAXParserFactory.newInstance();
try{
SAXParsersaxparser=saxfac.newSAXParser();
InputStreamis=newFileInputStream(fileName);
saxparser.parse(is,newMySAXHandler());
}catch(Exceptione){
e.printStackTrace();
}
}