ios中的http：get，post，同步，异步

            <?
            xml version="1.0" encoding="UTF-8"
            ?>
            <
            web-app 
            version
            ="2.5"
             
    xmlns
            ="http://java.sun.com/xml/ns/javaee"
             
    xmlns:xsi
            ="http://www.w3.org/2001/XMLSchema-instance"
             
    xsi:schemaLocation
            ="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
            >
            <
            welcome-file-list
            >
            <
            welcome-file
            >index.jsp</welcome-file></welcome-file-list><servlet><servlet-name>LoginServlet</servlet-name><!--lsdkalskdfjasdkfj--><servlet-class>com.wiscom.servlet.LoginServlet</servlet-class></servlet><servlet-mapping><servlet-name>LoginServlet</servlet-name><url-pattern>/LoginServlet</url-pattern></servlet-mapping></web-app>

            package
             com.wiscom.servlet;


            import
             java.io.IOException;

            import
             java.io.PrintWriter;


            import
             javax.servlet.ServletException;

            import
             javax.servlet.http.HttpServlet;

            import
             javax.servlet.http.HttpServletRequest;

            import
             javax.servlet.http.HttpServletResponse;


            public
            class LoginServlet extends HttpServlet {

  publicvoid doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    response.setContentType("text/html;charset=utf-8");
    
    request.setCharacterEncoding("utf-8");//设置参数解码类型，必须和页面中一致
    String sName=request.getParameter("name");
    String sPassword=request.getParameter("psw");
    
    PrintWriter out = response.getWriter();
    if(sName.equals("admin")&&sPassword.equals("admin")){
                out.print(sName+",您已成功登陆！！");
    }else{
            out.print(sName+",用户名密码有误！！");
    }
   }
  
  publicvoid doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
      this.doGet(request, response);
  }
}

            #import <Foundation/Foundation.h>

@interface NetCenter : NSObject

@property(nonatomic,retain) NSMutableData *receiveData;

@property(nonatomic,assign)int dataPackSerialNo;

- (void)httpGetSyn;

- (void)httpPostSyn;

- (void)httpGetNoSyn;

- (void)httpPostNoSyn;

@end

            #import
            "
            NetCenter.h
            "
            @implementation
             NetCenter


            @synthesize receiveData=_receiveData;
@synthesize dataPackSerialNo=_dataPackSerialNo;

- (void)httpGetSyn
{
    NSLog(@"httpGetSyn...");
    
    /*
    NSString *urlString =url;
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
    [request setURL:[NSURL URLWithString:urlString]];
    [request setHTTPMethod:@"GET"];
    NSHTTPURLResponse* urlResponse = nil;
    NSError *error = [[NSError alloc] init];
    NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&urlResponse error:&error];
    NSMutableString *result = [[NSMutableString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
    NSLog(@"The result string is :%@",result);
    *///第一步，创建URL
    NSURL *url = [NSURL URLWithString:@"http://10.0.0.96:8080/app_server/LoginServlet?name=admin&psw=admin"];
    
    //第二步，通过URL创建网络请求
    NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
    //NSURLRequest初始化方法第一个参数：请求访问路径，第二个参数：缓存协议，第三个参数：网络请求超时时间（秒）/*
    其中缓存协议是个枚举类型包含：
    NSURLRequestUseProtocolCachePolicy（基础策略）
    NSURLRequestReloadIgnoringLocalCacheData（忽略本地缓存）
    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）
    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）
    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）
    *///第三步，连接服务器
    NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
    NSString *str = [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];
    
    NSLog(@"%@",str);

}

- (void)httpPostSyn
{
    NSLog(@"httpPostSyn...");
    
    //第一步，创建URL
    NSURL *url = [NSURL URLWithString:@"http://10.0.0.96:8080/app_server/LoginServlet"];
    
    //第二步，创建请求
    NSString *postStr = [[NSString alloc] initWithFormat:@"name=%@&psw=%@",@"admin",@"admin"];
    NSData *postData = [postStr dataUsingEncoding:NSUTF8StringEncoding];
    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
    [request setHTTPBody:postData];//设置参数
    
    //第三步，连接服务器
    NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
    NSString *backStr = [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];
    
    NSLog(@"%@",backStr);
}

- (void)httpGetNoSyn
{
    NSLog(@"httpGetNoSyn...");
    
    //第一步，创建url
    NSURL *url = [NSURL URLWithString:@"http://10.0.0.96:8080/app_server/LoginServlet?name=admin&psw=admin"];
    
    //第二步，创建请求
    NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
    
    //第三步，连接服务器
    NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
    
}

- (void)httpPostNoSyn
{
    NSLog(@"httpPostNoSyn...");
    
    //第一步，创建url
    NSURL *url = [NSURL URLWithString:@"http://10.0.0.96:8080/app_server/LoginServlet"];
    
    //第二步，创建请求
    NSString *postStr = [[NSString alloc] initWithFormat:@"name=%@&psw=%@",@"admin",@"admin"];
    NSData *postData = [postStr dataUsingEncoding:NSUTF8StringEncoding];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
    [request setHTTPMethod:@"POST"];
    [request setHTTPBody:postData];
    
    //第三步，连接服务器
    NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
}

/*************5、异步请求的代理方法[start]****************///接收到服务器回应的时候调用此方法
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;
    NSLog(@"%@",[res allHeaderFields]);
    self.receiveData = [NSMutableData data];//数据存储对象的的初始化
    self.dataPackSerialNo=0;
    NSLog(@"收到服务器回应。。。");
}

//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
{
    NSLog(@"收到服务器传回的数据包,数据包序号：%d",self.dataPackSerialNo);
    [self.receiveData appendData:data];
    self.dataPackSerialNo+=1;
}

//数据传完之后调用此方法
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"数据传输完成，输出所有数据结果。。。");
    NSString *receiveStr = [[NSString alloc]initWithData:self.receiveData encoding:NSUTF8StringEncoding];
    NSLog(@"%@",receiveStr);
}

//网络请求过程中，出现任何错误（断网，连接超时等）会进入此方法
-(void)connection:(NSURLConnection *)connection
 didFailWithError:(NSError *)error
{
    NSLog(@"网络请求出错：%@",[error localizedDescription]);
}

/*************5、异步请求的代理方法[end]****************/@end

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    
    NetCenter *netCenter=[[NetCenter alloc]init];
    
    
    /*****************同步请求****************///[netCenter httpGetSyn];
    //[netCenter httpPostSyn];/*****************异步请求****************///[netCenter httpGetNoSyn];    [netCenter httpPostNoSyn];
    
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}