1.应用场景
接口传输数据时,有时需要用POST传一长串string数据,一般要求转为json格式方便服务器解析
- 解释：以接口参数的形式上传复杂日志的内容(字符串)，此复杂字符串做为接口参数值必须转成json字符串，否则接口上传失败。
2.需要转义的字符说明
- NSString转json时若包含以下字符,需要进行转义
" (双引号)
/ (正斜线)
\n (换行符)
\b (退格符)
\f (换页符)
\r (回车符)
\t (制表符,一个tab或按8下空格)
等
3. 普通字符串转json字符串的方法实现
方法一：直接根据特殊字符定制方法进行转换（不建议）
- 网上常见使用如下方法进行string转jsonstring，对于一些简单的转换需求这个可以实现，但是对于复杂情况并不能实现完全转换。
- (NSString *)string2JSONString:(NSString *)string {
NSMutableString *s = [NSMutableString stringWithString:string];
[s replaceOccurrencesOfString:@"\"" withString:@"\\\"" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@"/" withString:@"\\/" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@"\n" withString:@"\\n" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@"\b" withString:@"\\b" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@"\f" withString:@"\\f" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@"\r" withString:@"\\r" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@"\t" withString:@"\\t" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
return [NSString stringWithString:s];
}
方法二：先自定义字典存入string，使用自带的JSONSerialization把字典转成json后，删除key只保留value部分即可（推荐）
- 1.读取包含特殊字符的文本，存入字符串midiStr
NSString *midiPath = [[NSBundle mainBundle] pathForResource:@"test11" ofType:@"txt"];
NSFileHandle* readHandle = [NSFileHandle fileHandleForReadingAtPath:midiPath];
[readHandle seekToFileOffset:0];
NSData* data = [readHandle readDataToEndOfFile];
NSString *midiStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
- 2.midiStr存入自定义字典，并转成jsonString
- 3.拆分jsonDictString，仅取json键对应的value值部分，即midiStr转换为了json字符串。
oc写法
+ (NSString *)stringToJsonStrWithStr:(NSString *)str{
NSString *key = @"json";
NSDictionary *tempDict = @{key: str};
NSMutableString *tempJsonStr = [[NSMutableString alloc] initWithString:[NSString jsonStringFromDict:tempDict]];
NSString *valueJsonStr1 = [tempJsonStr substringFromIndex:key.length+5];
NSString *valueJsonStr2 = [[[NSMutableString alloc] initWithString:valueJsonStr1] substringToIndex:valueJsonStr1.length-2];
return valueJsonStr2;
}
swift写法
static func stringToJsonStr(str: String) -> String{
let key = "json"
let tempDict = [key: str]
if(!JSONSerialization.isValidJSONObject(tempDict)) {
print("无法解析出JSONString")
return ""
}
do {
let data = try JSONSerialization.data(withJSONObject: tempDict)
let jsonStr = String(data: data, encoding: .utf8) ?? ""
//去除键，只留转化的value
let json1 = jsonStr.dropFirst(key.count+4)//"{\"json\":
let json2 = json1.dropLast(1)
return String(json2)
} catch let error as NSError {
print(error)
return ""
}
}
4. 字典和json互转方法实现
4-1 字典转JSON
- OC 方法实现
- (NSString *)convert2JSONWithDictionary:(NSDictionary *)dic{
NSError *err;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dic options:0 error:&err];
NSString *jsonString;
if (!jsonData) {
NSLog(@"%@",err);
}else{
jsonString = [[NSString alloc]initWithData:jsonData encoding:NSUTF8StringEncoding];
}
NSLog(@"%@",jsonString);
return jsonString;
}
- swift方法实现
public static func convertDictionaryToString(dict:[String:AnyObject]) -> String {
var result:String = ""
do {
//如果设置options为JSONSerialization.WritingOptions.prettyPrinted，则打印格式更好阅读
let jsonData = try JSONSerialization.data(withJSONObject: dict, options: JSONSerialization.WritingOptions.init(rawValue: 0))
if let JSONString = String(data: jsonData, encoding: String.Encoding.utf8) {
result = JSONString
}
} catch {
result = ""
}
return result
}
4-2 JSON转字典
- OC 方法实现
- (NSDictionary *)convert2DictionaryWithJSONString:(NSString *)jsonString{
NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
NSError *err;
NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData
options:NSJSONReadingMutableContainers
error:&err];
if(err)
{
NSLog(@"%@",err);
return nil;
}
return dic;
}
- swift 实现方法
static func convertStringToDictionary(text: String) -> [String:AnyObject]? {
if let data = text.data(using: String.Encoding.utf8) {
do {
return try JSONSerialization.jsonObject(with: data, options: [JSONSerialization.ReadingOptions.init(rawValue: 0)]) as? [String:AnyObject]
} catch let error as NSError {
Log.error(error)
}
}
return nil
}
4-3 数组转json(同字典转json)
- swift
static func convertArrayToString(arr:[AnyObject]) -> String {
var result:String = ""
do {
let jsonData = try JSONSerialization.data(withJSONObject: arr, options: JSONSerialization.WritingOptions.init(rawValue: 0))
if let JSONString = String(data: jsonData, encoding: String.Encoding.utf8) {
result = JSONString
}
} catch {
result = ""
}
return result
}
5. 附场景应用：读取文本文件内容POST方法上传,参数放在body内
- (void)uploadJsonStringAsyn{
//读取txt文件内容(包含回车空格等特殊字符)转为jsonString
NSMutableDictionary *params = [[NSMutableDictionary alloc] init];
NSString *midiPath = [[NSBundle mainBundle] pathForResource:@"test" ofType:@"txt"];
NSFileHandle* readHandle = [NSFileHandle fileHandleForReadingAtPath:midiPath];
[readHandle seekToFileOffset:0];
NSData* data = [readHandle readDataToEndOfFile];
NSString *midiStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
params[@"jsonString"] = [self stringToJsonStr:midiStr];
//设置上传地址
NSString *urlString = [NSString stringWithFormat:@"http://"];
NSURL *url = [NSURL URLWithString:urlString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:@"POST"];
[request addValue:@"application/json;charset=UTF-8" forHTTPHeaderField:@"Content-Type"];
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:params options:NSJSONWritingPrettyPrinted error:nil];
//添加参数
[request setHTTPBody:jsonData];
//创建session对象
NSURLSession *session = [NSURLSession sharedSession];
//创建一个请求任务
NSURLSessionTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
NSString *result = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"POST%@",result);
}];
[task resume];
}