XML解析與建立（GDataXML），xmlgdataxml

XML解析與建立（GDataXML），xmlgdataxml

 一、XML解析

  對於JSON解析，iOS5之前有比較多的開源三方類（如JSONKit等）支援，一行代碼搞定；iOS5後JSON可以用原生API解析，不僅方便而且高效。但是XML解析原生的API不是很友好，解析也麻煩；還好可以用Google的GDataXML來解析，怎麼整合GDataXML到工程請查看我以前的隨筆，用GDataXML稍稍好解析一點，XML的解析原理可以理解成：脫衣模式，想要洗澡就要把衣服從外到裡依次脫掉，然後每件衣服都可以看做是一個GDataElement，每一個GDataElement都有自己的值與屬性，下面來解析以下XML資料。

XML檔案資料（檔案名稱位Attribute.xml）：

<list>    <OrderData 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解析代碼（所有element的值與屬性用log來列印）：

NSError *error = nil;    NSString *filePath0 = [[NSBundle mainBundle] pathForResource:@"Attribute" ofType:@"xml"];// 擷取工程內Attribute.xml檔案    NSData *xmldata0 = [[NSData alloc] initWithContentsOfFile:filePath0];    GDataXMLDocument *doc0 = [[GDataXMLDocument alloc] initWithData:xmldata0 options:0 error:&error];    GDataXMLElement *rootElement = doc0.rootElement;//擷取跟節點    NSLog(@"%@", rootElement);    NSArray *messages = [rootElement elementsForName:@"OrderData"];    if (messages.count > 0) {        for (GDataXMLElement *element in messages) {            //取OrderData的HASH屬性值            NSLog(@"attrute:%@", [[element attributeForName:@"HASH"] stringValue]);            //取OrderData的HASH屬性值，如果沒有值，取出來的則是所有子值的組合（這裡是：97cdbadaodd10odd11odd12l）            NSLog(@"OrderData:%@", [element stringValue]);            //擷取id子項目數組            NSArray *elementIDs = [element elementsForName:@"id"];            if (elementIDs.count > 0) {                for (GDataXMLElement *eID in elementIDs) {                    NSLog(@"id:%d", [[eID stringValue] intValue]);  // 擷取ID的值                }            }                        //擷取customer子項目數組            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]);  // 擷取customerData的值                            NSLog(@"customerData-attrute:%@", [[customerData attributeForName:@"HASH"] stringValue]);  // 擷取customerData的HASH屬性值                        }                    }                }            }                      //擷取billingAddress子項目數組            NSArray *elementBillingAddresses = [element elementsForName:@"billingAddress"];            if (elementBillingAddresses.count > 0) {                for (GDataXMLElement *eID in elementBillingAddresses) {                    NSLog(@"billingAddress:%@", [eID stringValue]);  // 擷取billingAddress的值                }            }                        //擷取deliveryAddress子項目數組            NSArray *elementDeliveryAddressses = [element elementsForName:@"deliveryAddress"];            if (elementDeliveryAddressses.count > 0) {                for (GDataXMLElement *eID in elementDeliveryAddressses) {                    NSLog(@"deliveryAddress:%@", [eID stringValue]);// 擷取deliveryAddress的值                }            }            //擷取orderDetail子項目數組            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]);                                }                            }                        }                    }                }            }            //擷取log子項目數組            NSArray *elementLogs = [element elementsForName:@"log"];            if (elementLogs.count > 0) {                for (GDataXMLElement *eID in elementLogs) {                    NSLog(@"log:%@", [eID stringValue]);// 擷取log的值                }            }        }    }

 

這樣一層一層的解析是不是很清楚，媽媽在也不用擔心我解不了複雜的XML了。在這裡分享一個小技巧，擷取節點的時候不用這樣擷取節點：GDataXMLElement *rootElement = doc.rootElement;

可以通過路徑直接擷取相應的節點：NSArray *nodes = [doc nodesForXPath:@"//Party/Player" error:&error];，這樣做得好處是在一個比較複雜的XML檔案中不用一層一層的遍曆，直接取到直接想要的那層。

 

二、XML建立

XML建立與解析是一個逆過程，可以理解為：穿衣模式，冬天起床，創衣服的順序依次是穿裡衣，毛衣，外套等。建立XML檔案也是一樣，先建立添加最裡層元素（GDataXMLElement），那麼下面我們來建立有以下資料的xml檔案

<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>

 

為了在簡化建立的代碼與邏輯，我們先建立Player與Party兩個OC類

//  Player.h檔案#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檔案#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檔案#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

 

建立XML方法（建立三個Player這裡沒有給出，請讀者直接寫一下哈）

+ (void)saveParty:(Party *)aParty {    GDataXMLElement *partyElement = [GDataXMLElement elementWithName:@"Party"];    //添加屬性    [partyElement addAttribute:[GDataXMLNode elementWithName:@"attribute" stringValue:@"party's attribute"]];    //添加命名空間    [partyElement addNamespace:[GDataXMLNode namespaceWithName:@"name space" stringValue:@"http://www.baidu.com"]];    //添加預設命名空間    [partyElement addNamespace:[GDataXMLNode namespaceWithName:@"" stringValue:@"http://www.google.com/hk"]];    for (Player *player in aParty.players) {        GDataXMLElement *playerElement = [GDataXMLNode elementWithName:@"Player"];   // 建立元素        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];       // 給player添加name元素        [playerElement addChild:levelElement];      // 給player添加level元素        [playerElement addChild:rpgClassElement];   // 給player添加rpgClass元素        [partyElement addChild:playerElement];      // 給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];}

 

看完代碼是不是覺得XML建立也不難吧（如有不合理地方請指正，謝謝！）