iOS開發-Get請求，Post請求，同步請求和非同步請求

標籤：

標題中的Get和Post是請求的兩種方式，同步和非同步屬於實現的方法，Get方式有同步和非同步兩種方法，Post同理也有兩種。稍微有點Web知識的，對Get和Post應該不會陌生，常說的請求處理響應，基本上請求的是都是這兩個哥們，Http最開始定義的與伺服器互動的方式有八種，不過隨著時間的進化，現在基本上使用的只剩下這兩種，有興趣的可以參考本人之前的部落格Http協議中Get和Post的淺談，iOS用戶端需要和服務端打交道，Get和Post是跑不了的，本文中包含iOS代碼和少量Java服務端代碼，開始正題吧.

Get和Post同步請求

Get和Post同步請求的時候最常見的是登入，輸入各種密碼才能看到的功能，必須是同步，非同步在Web上局部重新整理的時候用的比較多，比較耗時的時候執行非同步請求，可以讓客戶先看到一部分功能，然後慢慢重新整理，舉個例子就是餐館吃飯的時候點了十幾個菜，給你先上一兩個吃著，之後給別人上，剩下的慢慢上。大概就是這樣的。弄了幾個按鈕先:

先貼下同步請求的代碼:

     //設定URL路徑     NSString *urlStr=[NSString stringWithFormat:@"http://localhost:8080/MyWeb/Book?username=%@&password=%@&type=get",@"部落格園",@"keso"];     urlStr=[urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];     NSURL *url=[NSURL URLWithString:urlStr];        //通過URL設定網路請求    NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];    NSError *error=nil;    //擷取伺服器資料    NSData *requestData= [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:&error];    if (error) {        NSLog(@"錯誤資訊:%@",[error localizedDescription]);    }else{        NSString *result=[[NSString alloc]initWithData:requestData encoding:NSUTF8StringEncoding];        NSLog(@"返回結果:%@",result);    }

代碼很多，需要解釋一下:

①URL如果有中文無法傳遞，需要編碼一下:

[urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

②設定網路請求中的代碼，有兩個參數，最後一個佈建要求的時間，這個不用說什麼，重點說下緩衝策略cachePolicy，系統中的定義如下:

typedef NS_ENUM(NSUInteger, NSURLRequestCachePolicy){    NSURLRequestUseProtocolCachePolicy = 0,    NSURLRequestReloadIgnoringLocalCacheData = 1,    NSURLRequestReloadIgnoringLocalAndRemoteCacheData = 4, // Unimplemented    NSURLRequestReloadIgnoringCacheData = NSURLRequestReloadIgnoringLocalCacheData,    NSURLRequestReturnCacheDataElseLoad = 2,    NSURLRequestReturnCacheDataDontLoad = 3,    NSURLRequestReloadRevalidatingCacheData = 5, // Unimplemented};

 NSURLRequestUseProtocolCachePolicy（基礎策略）,NSURLRequestReloadIgnoringLocalCacheData（忽略本機快取）;

NSURLRequestReloadIgnoringLocalAndRemoteCacheData（無視任何緩衝策略，無論是本地的還是遠端，總是從原地址重新下載）;

NSURLRequestReturnCacheDataElseLoad（首先使用緩衝，如果沒有本機快取，才從原地址下載);

NSURLRequestReturnCacheDataDontLoad（使用本機快取，從不下載，如果本地沒有緩衝，則請求失敗，此策略多用於離線操作）;

NSURLRequestReloadRevalidatingCacheData（如果本機快取是有效則不下載，其他任何情況都從原地址重新下載）;

Java服務端代碼:

protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubresponse.setContentType("text/html;charset=utf-8;");PrintWriter out = response.getWriter();System.out.println(request.getParameter("username"));System.out.println(request.getParameter("password"));if (request.getParameter("type") == null) {out.print("預設測試");} else {if (request.getParameter("type").equals("async")) {out.print("非同步Get請求");} else {out.print("Get請求");}}}

 最終效果如下:

Post請求的代碼，基本跟Get類型，有注釋，就不多解釋了:

   //設定URL    NSURL *url=[NSURL URLWithString:@"http://localhost:8080/MyWeb/Book"];    //建立請求    NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];        [request setHTTPMethod:@"POST"];//佈建要求方式為POST，預設為GET        NSString *param= @"Name=部落格園&Address=http://www.cnblogs.com/xiaofeixiang&Type=post";//設定參數        NSData *data = [param dataUsingEncoding:NSUTF8StringEncoding];        [request setHTTPBody:data];        //串連伺服器    NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];    NSString *result= [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];    NSLog(@"%@",result);

　Java服務端代碼:

protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubrequest.setCharacterEncoding("utf-8");  response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter();System.out.println("姓名:" + request.getParameter("Name"));System.out.println("地址:" + request.getParameter("Address"));System.out.println("類型:" + request.getParameter("Type"));if (request.getParameter("Type").equals("async")) {out.print("非同步請求");} else {out.print("Post請求");}}

效果如下:

Get和Post非同步請求

非同步實現的時候需要實現協議NSURLConnectionDataDelegate，Get非同步代碼如下:

   //設定URL路徑    NSString *urlStr=[NSString stringWithFormat:@"http://localhost:8080/MyWeb/Book?username=%@&password=%s&type=async",@"FlyElephant","keso"];       urlStr=[urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];        NSURL *url=[NSURL URLWithString:urlStr];    //建立請求    NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];        //串連伺服器    NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];

 實現協議的串連過程的方法:

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{    NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;        NSLog(@"%@",[res allHeaderFields]);        self.myResult = [NSMutableData data];}////接收到伺服器傳輸資料的時候調用，此方法根據資料大小執行若干次-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{    [self.myResult appendData:data];    }//資料轉送完成之後執行方法-(void)connectionDidFinishLoading:(NSURLConnection *)connection{    NSString *receiveStr = [[NSString alloc]initWithData:self.myResult encoding:NSUTF8StringEncoding];        NSLog(@"%@",receiveStr);    }//網路請求時出現錯誤（斷網，連線逾時)執行方法-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{    NSLog(@"%@",[error localizedDescription]);}

非同步傳輸的過程資料需要拼接，所以這個時候需要設定一個屬性接收資料:

@property (strong,nonatomic) NSMutableData *myResult;

效果如下:

 

Post非同步傳遞代碼:

   //設定URL    NSURL *url=[NSURL URLWithString:@"http://localhost:8080/MyWeb/Book"];        //佈建要求    NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];        [request setHTTPMethod:@"POST"];//佈建要求方式為POST，預設為GET        NSString *param= @"Name=keso&Address=http://www.cnblogs.com/xiaofeixiang&Type=async";//設定參數        NSData *data = [param dataUsingEncoding:NSUTF8StringEncoding];        [request setHTTPBody:data];    //串連伺服器    NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];

效果如下:

非同步請求比較簡單，需要的方法都已經被封裝好了，需要注意資料是動態拼接的,請求的代碼都是在Java Servlet中實現的，Java項目中的目錄如下:

Book.java中代碼如下:

import java.io.IOException;import java.io.PrintWriter;import java.net.URLDecoder;import java.net.URLEncoder;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class Book */@WebServlet("/Book")public class Book extends HttpServlet {private static final long serialVersionUID = 1L;/** * @see HttpServlet#HttpServlet() */public Book() {super();// TODO Auto-generated constructor stub}/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse *      response) */protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubresponse.setContentType("text/html;charset=utf-8;");PrintWriter out = response.getWriter();System.out.println(request.getParameter("username"));System.out.println(request.getParameter("password"));if (request.getParameter("type") == null) {out.print("預設測試");} else {if (request.getParameter("type").equals("async")) {out.print("非同步Get請求");} else {out.print("Get請求");}}}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse *      response) */protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubrequest.setCharacterEncoding("utf-8");  response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter();System.out.println("姓名:" + request.getParameter("Name"));System.out.println("地址:" + request.getParameter("Address"));System.out.println("類型:" + request.getParameter("Type"));if (request.getParameter("Type").equals("async")) {out.print("非同步Post請求");} else {out.print("Post請求");}}}

Get和Post總結

①同步請求一旦發送，程式將停止使用者互動，直至伺服器返回資料完成，才可以進行下一步操作(例如登入驗證)；

②非同步請求不會阻塞主線程，會建立一個新的線程來操作，發出非同步請求後，依然可以對UI進行操作，程式可以繼續運行；

③Get請求，將參數直接寫在訪問路徑上，容易被外界看到，安全性不高，地址最多255位元組;

④Post請求，將參數放到body裡面，安全性高，不易被捕獲；

iOS開發-Get請求，Post請求，同步請求和非同步請求