Network HTTP, JSON, XML parsing and other review

One basic elements of HTTP requests
1. Request URL: Which path the client uses to locate the server

2. Request parameters: Data sent by the client to the server
* such as user name and password to be sent at login

3. Return results: Data returned by the server to the client
* Typically JSON data or XML data

II. Basic HTTP request Steps (Mobile client)
1. Stitching "Request URL" + "?" + "Request parameter"
* Format of request parameter: Parameter name = argument value
* Multiple request parameters separated by &: Parameter name 1 = parameter value 1& argument Name 2 = parameter value 2
* For example: http://localhost:8080/MJServer/login?username=123&pwd=456

2. Sending the request

3. Parsing the data returned by the server

Third, JSON parsing
1. Using Nsjsonserialization class parsing
* JSON data (NSData)--Foundation-oc objects (Nsdictionary, Nsarray, NSString, NSNumber)

+ (ID) Jsonobjectwithdata: (NSData *) Data options: (nsjsonreadingoptions) opt error: (NSERROR *) error;

2.JSON Analytic law
* {}--nsdictionary @{}
* []--Nsarray @[]
* "--nsstring @" "
*---NSNumber @10

Iv. nsurlconnection
1. Publish an asynchronous request--block callback

+ (void) Sendasynchronousrequest: (nsurlrequest*) Requestqueue: (nsoperationqueue*) Queuecompletionhandler: (void (^) (nsurlresponse* response, nsdata* data, nserror* connectionerror)) Handler

* Request: Requests that need to be sent
* Queue: Generally with the home row, storage handler this task
* Handler: When the request is complete, the block is automatically called

2. Basic steps for sending requests using nsurlconnection

// 1> Creating URLs Nsurl *url = [Nsurl urlwithstring:@ "http://4234324/5345345"]; // 2> Creating a request Nsurlrequest *request = [Nsurlrequest requestwithurl:url]; // 3> Sending requests [nsurlconnection sendasynchronousrequest:request queue:queue Completionhandler:^ (Nsurlresponse * Response, NSData *data, Nserror *connectionerror) {//4> processing the data returned by the server }];

Five, XML
1. Syntax
1> Document Declaration
<?xml version= "1.0" encoding= "UTF-8"?>

2> elements
3> Property
<videos>
<video name= "Small yellow No. 01" length= "/>"
<video name= "Small yellow No. 01" length= "/>"
</videos>
* Videos and video are elements (nodes)
* Name and length are called attributes of the element
* The video element is a child element of the videos element

2. Parsing
1> Sax parsing: Parse-by-element down, for large files
* Nsxmlparser

2> Dom parsing: A breath of loading the entire XML document into memory, suitable for small files, using the simplest
* Gdataxml

VI. Communication Process for HTTP
1. Request
1> Request Line: Request method, request path, version of HTTP protocol
Get/mjserver/resources/images/1.jpg http/1.1

2> Request Header: Some descriptive information for the client
* User-agent: Client-side environment (software environment)

3> Request Body: Post request only this thing
* Request parameters, data sent to the server

2. Response
1> status line (response line): Version of HTTP protocol, response status Code, response status description
http/1.1 OK

2> response Header: Some descriptive information about the server
* Content-type: The content type returned to the client by the server
* Content-length: The length of the content returned to the client by the server (such as the size of the file)

3> Entity content (response body)
* The server returns specific data to the client, such as file data

Vii. Request method for HTTP
1.GET
1> Features
* All request parameters are stitched behind the URL

2> Disadvantages
* All request data is exposed in the URL, not too secure
* URL is limited in length and cannot send too many parameters

3> Use occasions
* If you only request data from the server, you typically use GET requests

4> How to send a GET request
* Default is GET request

// 1.URL Nsurl *url = [Nsurl urlwithstring:@ "http://www.baidu.com"]; // 2. Request Nsurlrequest *request = [Nsurlrequest requestwithurl:url]; // 3. Sending the request [Nsurlconnection sendasynchronousrequest:request queue:[nsoperationqueue Mainqueue] completionHandler:^ ( Nsurlresponse *response, NSData *data, Nserror *connectionerror) {}];

2.POST
1> Features
* Place all request parameters in the request body (httpbody)
* Theoretically, there is no limit to the size of the data sent to the server

2> Use occasions
* In addition to requesting data from the server, you can use the POST request
* If the data sent to the server is some privacy, sensitive data, you must use the POST request

3> How to send a POST request

//1. Create a URL: request pathNsurl *url = [Nsurl urlwithstring:@"Http://localhost:8080/MJServer/login"];//2. Create a requestNsmutableurlrequest *request =[Nsmutableurlrequest Requestwithurl:url];//Set Request MethodRequest. HttpMethod =@"POST";//Set Request body: Request ParametersNSString *param = [NSString stringWithFormat:@"username=%@&pwd=%@", Usernametext, Pwdtext];//NSString-NSDataRequest. Httpbody = [param datausingencoding:nsutf8stringencoding];

Eight, the common method of Nsmutableurlrequest
1. Set timeout

5;

Nsurlrequest is not able to set the timeout because the object is immutable

Nine, url transcoding
1.URL can not contain Chinese, you have to transcode the Chinese (plus a bunch of%)

NSString *urlstr = [NSString stringWithFormat:@ "http://localhost/login?username= drink &pwd=123 "  = [Urlstr stringbyaddingpercentescapesusingencoding:nsutf8stringencoding]; // Urlstr = = @ " Http://localhost/login?username=%E5%96%9D%E5%96%9D &pwd=123 "

X. Data security

1. Network Data encryption
1> Encrypted objects: Privacy data, such as passwords, bank information
2> Encryption Scheme
* Submit privacy data, must use POST request
* Encrypt private data using cryptographic algorithms, such as MD5
3> encryption Enhancement: In order to increase the difficulty of the crack
* 2 Md5:md5 for clear text (MD5 ($pass))
* Salt the plaintext before md5:md5 ($pass. $salt)

2. Local Storage encryption
1> Encrypted objects: Important data, such as game data

3. Code Security issues
1> now has tools and techniques to decompile source code: Reverse Engineering
* The anti-compilation is pure C language, the readability is not high
* At the very least, you can know which frames are used in the source code.

2> reference book: "Reverse engineering of iOS"

3> Solution: Confusing code before publishing

// * before confusing @interface hmperson:nsobject-(void) run; -(void) eat; @end // * After confusion @interface a:nsobject-(void) A; -(void) b; @end

Xi. monitoring the status of the network
1. Active monitoring and monitoring of network status

// whether WiFi+ (BOOL) Isenablewifi {return ([[Reachability Reachabilityforlocalwifi] Currentreachabilitystatus]! = notreachable);} // whether 3G+ (BOOL) isenable3g {return ([[Reachability reachabilityforinternetconnection] Currentreachabilitystatus]! = notreachable);}

2. Monitor network status
1> Monitoring Notifications

object: nil];

2> Start listening to network status

// get reachability object self.reachability = [reachability reachabilityforinternetconnection]; // Start monitoring the network [Self.reachability Startnotifier];

3> Remove Listener

[Self.reachability Stopnotifier]; [[Nsnotificationcenter Defaultcenter] removeobserver:self];

Network HTTP, JSON, XML parsing and other review