iOS开发-Get请求,Post请求,同步请求和异步请求
标题中的Get和Post是请求的两种方式,同步和异步属于实现的方法,Get方式有同步和异步两种方法,Post同理也有两种。稍微有点Web知识的,对Get和Post应该不会陌生,常说的请求处理响应,基本上请求的是都是这两个哥们,Http最开始定义的与服务器交互的方式有八种,不过随着时间的进化,现在基本上使用的只剩下这两种,有兴趣的可以参考本人之前的博客Http协议中Get和Post的浅谈,iOS客户端需要和服务端打交道,Get和Post是跑不了的,本文中包含iOS代码和少量Java服务端代码,开始正题吧.
Get和Post同步请求
Get和Post同步请求的时候最常见的是登录,输入各种密码才能看到的功能,必须是同步,异步在Web上局部刷新的时候用的比较多,比较耗时的时候执行异步请求,可以让客户先看到一部分功能,然后慢慢刷新,举个例子就是餐馆吃饭的时候点了十几个菜,给你先上一两个吃着,之后给别人上,剩下的慢慢上。大概就是这样的。弄了几个按钮先上图:
先贴下同步请求的代码:
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//设置URL路径 NSString *urlStr=[ NSString stringWithFormat:@ "http://localhost:8080/MyWeb/Book?username=%@&password=%@&type=get" ,@ "博客园" ,@ "keso" ];
urlStr=[urlStr stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding ];
NSURL *url=[ NSURL URLWithString:urlStr];
//通过URL设置网络请求 NSURLRequest *request = [[ NSURLRequest alloc]initWithURL:url cachePolicy: NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
NSError *error= nil ;
//获取服务器数据 NSData *requestData= [ NSURLConnection sendSynchronousRequest:request returningResponse: nil error:&error];
if (error) {
NSLog (@ "错误信息:%@" ,[error localizedDescription]);
} else {
NSString *result=[[ NSString alloc]initWithData:requestData encoding: NSUTF8StringEncoding ];
NSLog (@ "返回结果:%@" ,result);
} |
代码很多,需要解释一下:
①URL如果有中文无法传递,需要编码一下:
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[urlStr stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding ];
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②设置网路请求中的代码,有两个参数,最后一个设置请求的时间,这个不用说什么,重点说下缓存策略cachePolicy,系统中的定义如下:
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typedef NS_ENUM ( NSUInteger , NSURLRequestCachePolicy )
{ NSURLRequestUseProtocolCachePolicy = 0,
NSURLRequestReloadIgnoringLocalCacheData = 1,
NSURLRequestReloadIgnoringLocalAndRemoteCacheData = 4, // Unimplemented
NSURLRequestReloadIgnoringCacheData = NSURLRequestReloadIgnoringLocalCacheData ,
NSURLRequestReturnCacheDataElseLoad = 2,
NSURLRequestReturnCacheDataDontLoad = 3,
NSURLRequestReloadRevalidatingCacheData = 5, // Unimplemented
}; |
NSURLRequestUseProtocolCachePolicy(基础策略),NSURLRequestReloadIgnoringLocalCacheData(忽略本地缓存);
NSURLRequestReloadIgnoringLocalAndRemoteCacheData(无视任何缓存策略,无论是本地的还是远程的,总是从原地址重新下载);
NSURLRequestReturnCacheDataElseLoad(首先使用缓存,如果没有本地缓存,才从原地址下载);
NSURLRequestReturnCacheDataDontLoad(使用本地缓存,从不下载,如果本地没有缓存,则请求失败,此策略多用于离线操作);
NSURLRequestReloadRevalidatingCacheData(如果本地缓存是有效的则不下载,其他任何情况都从原地址重新下载);
Java服务端代码:
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protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.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( "默认测试" );
} else {
if (request.getParameter( "type" ).equals( "async" )) {
out.print( "异步Get请求" );
} else {
out.print( "Get请求" );
}
}
} |
最终效果如下:
Post请求的代码,基本跟Get类型,有注释,就不多解释了:
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//设置URL NSURL *url=[ NSURL URLWithString:@ "http://localhost:8080/MyWeb/Book" ];
//创建请求
NSMutableURLRequest *request = [[ NSMutableURLRequest alloc]initWithURL:url cachePolicy: NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
[request setHTTPMethod:@ "POST" ]; //设置请求方式为POST,默认为GET
NSString *param= @ "Name=博客园&Address=http://www.cnblogs.com/xiaofeixiang&Type=post" ;//设置参数
NSData *data = [param dataUsingEncoding: NSUTF8StringEncoding ];
[request setHTTPBody:data];
//连接服务器
NSData *received = [ NSURLConnection sendSynchronousRequest:request returningResponse: nil error: nil ];
NSString *result= [[ NSString alloc]initWithData:received encoding: NSUTF8StringEncoding ];
NSLog (@ "%@" ,result);
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Java服务端代码:
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protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.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( "类型:" + request.getParameter( "Type" ));
if (request.getParameter( "Type" ).equals( "async" )) {
out.print( "异步请求" );
} else {
out.print( "Post请求" );
}
} |
效果如下:
Get和Post异步请求
异步实现的时候需要实现协议NSURLConnectionDataDelegate,Get异步代码如下:
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//设置URL路径 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];
//创建请求
NSURLRequest *request = [[ NSURLRequest alloc]initWithURL:url cachePolicy: NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
//连接服务器
NSURLConnection *connection = [[ NSURLConnection alloc]initWithRequest:request delegate: self ];
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实现协议的连接过程的方法:
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-( void )connection:( NSURLConnection *)connection didReceiveResponse:( NSURLResponse *)response{
NSHTTPURLResponse *res = ( NSHTTPURLResponse *)response;
NSLog (@ "%@" ,[res allHeaderFields]);
self .myResult = [ NSMutableData data];
} ////接收到服务器传输数据的时候调用,此方法根据数据大小执行若干次 -( void )connection:( NSURLConnection *)connection didReceiveData:( NSData *)data
{ [ self .myResult appendData:data];
} //数据传输完成之后执行方法 -( void )connectionDidFinishLoading:( NSURLConnection *)connection
{ NSString *receiveStr = [[ NSString alloc]initWithData: self .myResult encoding: NSUTF8StringEncoding ];
NSLog (@ "%@" ,receiveStr);
} //网络请求时出现错误(断网,连接超时)执行方法 -( void )connection:( NSURLConnection *)connection didFailWithError:( NSError *)error
{ NSLog (@ "%@" ,[error localizedDescription]);
} |
异步传输的过程数据需要拼接,所以这个时候需要设置一个属性接收数据:
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@property (strong, nonatomic ) NSMutableData *myResult;
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效果如下:
Post异步传递代码:
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//设置URL NSURL *url=[ NSURL URLWithString:@ "http://localhost:8080/MyWeb/Book" ];
//设置请求
NSMutableURLRequest *request = [[ NSMutableURLRequest alloc]initWithURL:url cachePolicy: NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
[request setHTTPMethod:@ "POST" ]; //设置请求方式为POST,默认为GET
NSString *param= @ "Name=keso&Address=http://www.cnblogs.com/xiaofeixiang&Type=async" ;//设置参数
NSData *data = [param dataUsingEncoding: NSUTF8StringEncoding ];
[request setHTTPBody:data];
//连接服务器
NSURLConnection *connection = [[ NSURLConnection alloc]initWithRequest:request delegate: self ];
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效果如下:
异步的请求比较简单,需要的方法都已经被封装好了,需要注意数据是动态拼接的,请求的代码都是在Java Servlet中实现的,Java项目中的目录如下:
Book.java中代码如下:
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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 stub
response.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( "默认测试" );
} else {
if (request.getParameter( "type" ).equals( "async" )) {
out.print( "异步Get请求" );
} else {
out.print( "Get请求" );
}
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.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( "类型:" + request.getParameter( "Type" ));
if (request.getParameter( "Type" ).equals( "async" )) {
out.print( "异步Post请求" );
} else {
out.print( "Post请求" );
}
}
} |
Get和Post总结
①同步请求一旦发送,程序将停止用户交互,直至服务器返回数据完成,才可以进行下一步操作(例如登录验证);
②异步请求不会阻塞主线程,会建立一个新的线程来操作,发出异步请求后,依然可以对UI进行操作,程序可以继续运行;
③Get请求,将参数直接写在访问路径上,容易被外界看到,安全性不高,地址最多255字节;
④Post请求,将参数放到body里面,安全性高,不易被捕获;
本文转自Fly_Elephant博客园博客,原文链接:http://www.cnblogs.com/xiaofeixiang/p/4306786.html,如需转载请自行联系原作者