JSON处理

本文介绍了一种递归方法将自定义对象转换为JSON字符串的过程,支持NSString、NSArray及自定义类等成员变量类型,并讨论了如何处理空值和特殊类型如NSDecimalNumber。

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在进行JSON处理的时候,按照其数据结构的定义,对其对应的字典进行操作取值即可,

对于嵌套的结构,数组等,抽象出相应的方法,一层层的去处理(责任链模式)就可以,这样很清晰

以下是一个factory, 根据给定的对象生产出对应的JSON字符串

 

采用递归的方法访问一个对象,讲其内容写到一个字典中

支持的成员变量类型:

1,NSString *

2,NSArray *

3,由1,2,构成的自定义类



+ (NSMutableDictionary *) getDicFromObject: (id) theObject

{

if ([theObjectisKindOfClass:[NSStringclass]])

{

return theObject;

}


NSMutableDictionary * tmpDic = [[[NSMutableDictionaryalloc] init] autorelease];

if (theObject ==nil)

{

return tmpDic;

}

//get all the property fields names

NSString *className =NSStringFromClass([theObject class]);

    const char *cClassName = [className UTF8String];


    id theClass = objc_getClass(cClassName);

unsignedint outCount, i;


    objc_property_t *properties = class_copyPropertyList(theClass, &outCount);


    NSMutableArray *propertyNames = [[NSMutableArrayalloc] initWithCapacity:1];


    for (i = 0; i < outCount; i++) 

{

        objc_property_t property = properties[i];


        NSString *propertyNameString = [[NSStringalloc] initWithCString:property_getName(property) 

encoding:NSUTF8StringEncoding]; 


        [propertyNamesaddObject:propertyNameString];


        [propertyNameStringrelease];


       NSLog(@"%s %s\n",property_getName(property), property_getAttributes(property));


    }


for (NSString *keyin propertyNames)

    {

        SEL selector = NSSelectorFromString(key);

        id value = [theObject performSelector:selector];


        if (value == nil)

        {

            value = [NSNullnull];

[tmpDicsetObject:value forKey:key];

continue;

        }


       //[finalDict setObject:value forKey:key];

if ([valueisKindOfClass:[NSStringclass]])

{

[tmpDicsetObject:value forKey:key];

}

elseif ([value isKindOfClass:[NSArrayclass]])

{

NSMutableArray * valueArray = [[[NSMutableArrayalloc] init]autorelease];

NSArray * aArray = (NSArray *)value;

for (int i =0; i < [aArray count]; i++)

{

[valueArrayaddObject:[NetRequestManagergetDicFromObject:[aArray objectAtIndex:i]]];

//[tmpDic setObject:[NetRequestManager getDicFromObject:[aArray objectAtIndex:i]]

//  forKey:key];

}

[tmpDicsetObject:valueArray forKey:key];

}

else 

{

[tmpDicsetObject:[NetRequestManagergetDicFromObject:value] forKey:key];

}

    }


return tmpDic;

}

 

"PageSize":2  , 使用NSNumber类型来处理

NSNumber * 

{"RstMode":"1","AddrBookVersion":"5154812","PageStartIndex":"3","PageSize":2}




2012-06-27 09:57:59.364 appTest[20741:10a03] primaryEmail T@"NSString",&,N,VprimaryEmail

2012-06-27 09:57:59.365 appTest[20741:10a03] primaryMobile T@"NSString",&,N,VprimaryMobile

2012-06-27 09:57:59.365 appTest[20741:10a03] name T@"NameObj",&,N,Vname

2012-06-27 09:57:59.366 appTest[20741:10a03] lastName T@"NSString",&,N,VlastName

2012-06-27 09:57:59.367 appTest[20741:10a03] middleName T@"NSString",&,N,VmiddleName

2012-06-27 09:57:59.367 appTest[20741:10a03] firstName T@"NSString",&,N,VfirstName

2012-06-27 09:57:59.368 appTest[20741:10a03] {"primaryEmail":"America","primaryMobile":null,"name":{"firstName":null,"middleName":null,"lastName":null}}

2012-06-27 09:57:59.369 appTest[20741:10a03] contactListIDs T@"NSMutableArray",&,N,VcontactListIDs

2012-06-27 09:57:59.369 appTest[20741:10a03] contactID T@"NSString",&,N,VcontactID

2012-06-27 09:57:59.370 appTest[20741:10a03] contactBaseInfo T@"ContactBaseInfoObj",&,N,VcontactBaseInfo

2012-06-27 09:57:59.370 appTest[20741:10a03] primaryEmail T@"NSString",&,N,VprimaryEmail

2012-06-27 09:57:59.371 appTest[20741:10a03] primaryMobile T@"NSString",&,N,VprimaryMobile

2012-06-27 09:57:59.371 appTest[20741:10a03] name T@"NameObj",&,N,Vname

2012-06-27 09:57:59.372 appTest[20741:10a03] lastName T@"NSString",&,N,VlastName

2012-06-27 09:57:59.372 appTest[20741:10a03] middleName T@"NSString",&,N,VmiddleName

2012-06-27 09:57:59.373 appTest[20741:10a03] firstName T@"NSString",&,N,VfirstName

2012-06-27 09:57:59.373 appTest[20741:10a03] {"contactID":"123456","contactBaseInfo":{"primaryEmail":"America","primaryMobile":null,"name":{"firstName":null,"middleName":null,"lastName":null}},"contactListIDs":[]}

2012-06-27 09:57:59.374 appTest[20741:10a03] test ={"RstMode":1,"AddrBookVersion":"test","PageStartIndex":3,"PageSize":2}

2012-06-27 09:57:59.375 appTest[20741:10a03] the class is [NSDecimalNumber]

2012-06-27 09:57:59.375 appTest[20741:10a03] the int value is 2

2012-06-27 09:57:59.375 appTest[20741:10a03] tv is NSNumber class




{"RstMode":"1","AddrBookVersion":"5154812","PageStartIndex":"3","PageSize":2} 

通过解析得到的dic中,PageSizeNSDecimalNumber  NSNumber类型的,处理的时候需要注意




2012-06-27 13:36:51.393 appTest[23182:10a03] {"primaryEmail":"America","primaryMobile":null,"name":{"firstName":null,"middleName":null,"lastName":null}}

(gdb) po aDic

{

    name =     {

        firstName = "<null>";

        lastName = "<null>";

        middleName = "<null>";

    };

    primaryEmail = America;

    primaryMobile = "<null>";

}

(gdb) n

(gdb) po tnull

<null>

(gdb) po [tnull class]

NSNull



可以使用[NSNull null] 来处理空值



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