XML解析与创建（GDataXML）
一、XML解析
对于JSON解析，iOS5之前有比较多的开源三方类（如JSONKit等）支持，一行代码搞定；iOS5后JSON可以用原生API解析，不仅方便而且高效。但是XML解析原生的API不是很友好，解析也麻烦；还好可以用Google的GDataXML来解析，怎么集成GDataXML到工程请查看我以前的随笔，用GDataXML稍稍好解析一点，XML的解析原理可以理解成：脱衣模式，想要洗澡就要把衣服从外到里依次脱掉，然后每件衣服都可以看做是一个GDataElement，每一个GDataElement都有自己的值与属性，下面来解析以下XML数据。
XML文件数据（文件名位Attribute.xml）：
<list>
<OrderData xmlns:name_space="http://www.baidu.com" xmlns="http://www.google.com/hk" attribute="party's attribute" HASH="1408108039">od0</OrderData>
<OrderData HASH="208524692">
<id>97</id>
<customer>
<CustomerData HASH="2128670187">cd</CustomerData>
</customer>
<billingAddress>ba</billingAddress>
<deliveryAddress>da</deliveryAddress>
<orderDetail>
<list>
<OrderDetailData HASH="516790072">odd10</OrderDetailData>
<OrderDetailData HASH="11226247">odd11</OrderDetailData>
<OrderDetailData HASH="11226247">odd12</OrderDetailData>
</list>
</orderDetail>
<log>l</log>
</OrderData>
<OrderData HASH="1502226778">odd20</OrderData>
</list>
OC解析代码（所有element的值与属性用log来打印）：
+ (void)parseXMLDemo { NSError *error = nil; NSString *filePath0 = [[NSBundle mainBundle] pathForResource:@"Attribute" ofType:@"xml"]; NSData *xmldata0 = [[NSData alloc] initWithContentsOfFile:filePath0]; GDataXMLDocument *doc0 = [[GDataXMLDocument alloc] initWithData:xmldata0 options:0 error:&error]; GDataXMLElement *rootElement = doc0.rootElement; if(error != nil) { NSLog(@"Attribute.xml parsed error!\n%@", [error localizedDescription]); return; } NSLog(@"%@", rootElement); NSArray *messages = [rootElement elementsForName:@"OrderData"]; if (messages.count > 0) { for (GDataXMLElement *element in messages) { //取OrderData的HASH属性值 NSLog(@"attrute:%@", [[element attributeForName:@"HASH"] stringValue]); //获取所有命名空间nameSpaces NSArray *nameSpaces = [element namespaces];// if (nameSpaces.count > 0) { [nameSpaces enumerateObjectsUsingBlock:^(GDataXMLNode *node, NSUInteger idx, BOOL *stop) { //获取所有命名空间的名字与值 NSLog(@"|%@:%@|", [node name], [node stringValue]); }]; } //取OrderData的HASH属性值，如果没有值，取出来的则是所有子值的组合（这里是：97cdbadaodd10odd11odd12l） NSLog(@"OrderData:%@", [element stringValue]); //获取id子元素数组 NSArray *elementIDs = [element elementsForName:@"id"]; if (elementIDs.count > 0) { for (GDataXMLElement *eID in elementIDs) { NSLog(@"id:%d", [[eID stringValue] intValue]); // 获取ID的值 } } //获取customer子元素数组 NSArray *elementCustomers = [element elementsForName:@"customer"]; if (elementCustomers.count > 0) { for (GDataXMLElement *eID in elementCustomers) { NSArray *customerDatas = [eID elementsForName:@"CustomerData"]; if (customerDatas.count > 0) { for (GDataXMLElement *customerData in customerDatas) { NSLog(@"customerData:%@", [customerData stringValue]); // 获取customerData的值 NSLog(@"customerData-attrute:%@", [[customerData attributeForName:@"HASH"] stringValue]); // 获取customerData的HASH属性值 } } } } //获取billingAddress子元素数组 NSArray *elementBillingAddresses = [element elementsForName:@"billingAddress"]; if (elementBillingAddresses.count > 0) { for (GDataXMLElement *eID in elementBillingAddresses) { NSLog(@"billingAddress:%@", [eID stringValue]); // 获取billingAddress的值 } } //获取deliveryAddress子元素数组 NSArray *elementDeliveryAddressses = [element elementsForName:@"deliveryAddress"]; if (elementDeliveryAddressses.count > 0) { for (GDataXMLElement *eID in elementDeliveryAddressses) { NSLog(@"deliveryAddress:%@", [eID stringValue]);// 获取deliveryAddress的值 } } //获取orderDetail子元素数组 NSArray *elementOrderDetails = [element elementsForName:@"orderDetail"]; if (elementOrderDetails.count > 0) { for (GDataXMLElement *eID in elementOrderDetails) { NSArray *lists = [eID elementsForName:@"list"]; if (lists.count > 0) { for (GDataXMLElement *list in lists) { NSArray *OrderDetailDatas = [list elementsForName:@"OrderDetailData"]; if (OrderDetailDatas.count > 0) { for (GDataXMLElement *OrderDetailData in OrderDetailDatas) { NSLog(@"OrderDetailData-attribute:%@", [[OrderDetailData attributeForName:@"HASH"] stringValue]); NSLog(@"OrderDetailData:%@", [OrderDetailData stringValue]); } } } } } } //获取log子元素数组 NSArray *elementLogs = [element elementsForName:@"log"]; if (elementLogs.count > 0) { for (GDataXMLElement *eID in elementLogs) { NSLog(@"log:%@", [eID stringValue]);// 获取log的值 } } } } }
这样一层一层的解析是不是很清楚，妈妈在也不用担心我解不了复杂的XML了。在这里分享一个小技巧，获取节点的时候不用这样获取节点：GDataXMLElement *rootElement = doc.rootElement;
可以通过路径直接获取相应的节点：NSArray *nodes = [doc nodesForXPath:@"//Party/Player" error:&error];，这样做得好处是在一个比较复杂的XML文件中不用一层一层的遍历，直接取到直接想要的那层。
二、XML创建
XML创建与解析是一个逆过程，可以理解为：穿衣模式，冬天起床，创衣服的顺序依次是穿里衣，毛衣，外套等。创建XML文件也是一样，先创建添加最里层元素（GDataXMLElement），那么下面我们来创建有以下数据的xml文件
<Party xmlns:name space="http://www.baidu.com" xmlns="http://www.google.com/hk" attribute="party's attribute"> <Player> <Name>Butch</Name> <Level>1</Level> <Class>Fighter</Class> </Player> <Player> <Name>Shadow</Name> <Level>2</Level> <Class>Rogue</Class> </Player> <Player> <Name>Crak</Name> <Level>3</Level> <Class>Wizard</Class> </Player> </Party>
为了在简化创建的代码与逻辑，我们先创建Player与Party两个OC类
// Player.h文件 #import <Foundation/Foundation.h> typedef enum { RPGClassFighter = 0, RPGClassRogue, RPGClassWizard } RPGClass; @interface Player : NSObject @property (copy, nonatomic) NSString *name; @property int level; @property RPGClass rpgClass; - (id)initWithName:(NSString *)aName level:(int)aLevel rpgClass:(RPGClass)aRPGClass; @end // Player.m文件 #import "Player.h" @implementation Player - (id)initWithName:(NSString *)aName level:(int)aLevel rpgClass:(RPGClass)aRPGClass { if (self = [super init]) { _name = aName; _level = aLevel; _rpgClass = aRPGClass; } return self; } @end // Party.h文件 #import <Foundation/Foundation.h> @interface Party : NSObject @property (strong, nonatomic) NSMutableArray *players; @end // Party.m #import "Party.h" #import "Player.h" @implementation Party - (instancetype)init { self = [super init]; if (self) { _players = [[NSMutableArray alloc] init]; } return self; } @end
创建XML方法（创建三个Player这里没有给出，请读者直接写一下哈）
+ (void)saveParty:(Party *)aParty { GDataXMLElement *partyElement = [GDataXMLElement elementWithName:@"Party"]; //添加属性 [partyElement addAttribute:[GDataXMLNode elementWithName:@"attribute" stringValue:@"party's attribute"]]; //添加命名空间 [partyElement addNamespace:[GDataXMLNode namespaceWithName:@"name space" stringValue:@"http://www.baidu.com"]]; //添加缺省命名空间 [partyElement addNamespace:[GDataXMLNode namespaceWithName:@"" stringValue:@"http://www.google.com/hk"]]; for (Player *player in aParty.players) { GDataXMLElement *playerElement = [GDataXMLNode elementWithName:@"Player"]; // 创建元素 GDataXMLElement *nameElement = [GDataXMLNode elementWithName:@"Name" stringValue:player.name]; GDataXMLElement *levelElement = [GDataXMLNode elementWithName:@"Level" stringValue:[NSString stringWithFormat:@"%d", player.level]]; NSString *rpgClass = nil; if (player.rpgClass == RPGClassFighter) { rpgClass = @"Fighter"; } else if (player.rpgClass == RPGClassRogue) { rpgClass = @"Rogue"; }else if (player.rpgClass == RPGClassWizard) { rpgClass = @"Wizard"; } GDataXMLElement *rpgClassElement = [GDataXMLNode elementWithName:@"Class" stringValue:rpgClass]; [playerElement addChild:nameElement]; // 给player添加name元素 [playerElement addChild:levelElement]; // 给player添加level元素 [playerElement addChild:rpgClassElement]; // 给player添加rpgClass元素 [partyElement addChild:playerElement]; // 给party添加player元素 } GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithRootElement:partyElement]; NSData *xmlData = [doc XMLData]; NSString *filePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"makeXMLFile.xml"]; [xmlData writeToFile:filePath atomically:YES]; }
看完代码是不是觉得XML创建也不难吧（如有不合理地方请指正，谢谢！）