HTTP权威指南阅读笔记三：HTTP报文

　　报文的组成部分

　　报文由三部分组成：对报文进行描述的起始行(start line)、包含属性的首部(header)，以及可选的、包含数据的主体(body)部分。

　　请求报文格式

　　<method> <request-URL> <version>

　　<headers>

　　<entity-body>

　　响应报文格式

　　<version> <status> <reson-phrase>

　　<headers>

　　<entity-body>

　　HTTP方法

　　主要的HTTP方法有：

方法	描述	是否包含主体
GET	从服务器获取一份文档	否
HEAD	只从服务器获取文档的首部	否
POST	向服务器发送需要处理的数据	是
PUT	将请求的主体部分存储在服务器上	是
TRACE	对可能经过代理服务器传送到服务器上去的报文进行追踪	否
OPTIONS	决定可以在服务器上执行哪些方法	否
DELETE	从服务器上删除一份文档	否

　　另外，HTTP1.1允许扩展规范中没有的方法。

　　示例

　　js部分：

var httpMethodTest = (function () {
    "use strict";

    var _xhr = new XMLHttpRequest();

    var _sendXHR = function (method, url, callback) {
        _xhr.onreadystatechange = function () {
            if (_xhr.readyState === 4 && _xhr.status === 200) {
                callback(_xhr);
            }
        };

        _xhr.open(method, url, true);
        _xhr.send('');
    };

    var get = function (url, callback) {
        _sendXHR("GET", url, callback);
    };

    var put = function (url, callback) {
        _sendXHR("PUT", url, callback);
    };

    var post = function (url, callback) {
        _sendXHR("POST", url, callback);
    };

    var head = function (url, callback) {
        _sendXHR("HEAD", url, callback);
    };

    var trace = function (url, callback) {
        _sendXHR("TRACE", url, callback);
    };

    var options = function (url, callback) {
        _sendXHR("OPTIONS", url, callback);
    };

    var deleteMethod = function (url, callback) {
    };

    return {
        get: get,
        put: put,
        post: post,
        head: head,
        trace: trace,
        options: options,
        deleteMethod: deleteMethod
    };
})();

var btnGET = document.getElementById("btnGET"),
    btnPOST = document.getElementById("btnPOST"),
    btnPUT = document.getElementById("btnPUT"),
    btnHEAD = document.getElementById("btnHEAD"),
    btnOPTIONS = document.getElementById("btnOPTIONS"),
    btnTRACE = document.getElementById("btnTRACE"),
    headerResultNode = document.getElementById("headerResult"),
    bodyResultNode = document.getElementById("bodyResult"),
    headerTitleNode = document.getElementById("headerTitle"),
    bodyTitleNode = document.getElementById("bodyTitle");
btnGET.onclick = function () {
    headerTitleNode.innerHTML = "GET Response Headers:";
    bodyTitleNode.innerHTML = "GET Response Body:";
    httpMethodTest.get("/home/Test?t=" + Math.random(), methodResult);
}

btnPOST.onclick = function () {
    headerTitleNode.innerHTML = "POST Response Headers:";
    bodyTitleNode.innerHTML = "POST Response Body:";
    httpMethodTest.post("/home/Test?t=" + Math.random(), methodResult);
}

btnPUT.onclick = function () {
    headerTitleNode.innerHTML = "PUT Response Headers:";
    bodyTitleNode.innerHTML = "PUT Response Body:";
    httpMethodTest.put("/home/Test?t=" + Math.random(), methodResult);
}

btnHEAD.onclick = function () {
    headerTitleNode.innerHTML = "HEAD Response Headers:";
    bodyTitleNode.innerHTML = "HEAD Response Body:";
    httpMethodTest.head("/home/Test?t=" + Math.random(), methodResult);
}

//由于ajax中不可以直接发trace请求，所以这里改为发get请求，然后在controller中作代理发trace请求
btnTRACE.onclick = function () {
    headerTitleNode.innerHTML = "TRACE Response Headers:";
    bodyTitleNode.innerHTML = "TRACE Response Body:";
    httpMethodTest.get("/home/Trace?url=" + encodeURIComponent("http://xxxxx/test.php") + "&t" + Math.random(), methodResult);
}

btnOPTIONS.onclick = function () {
    headerTitleNode.innerHTML = "OPTIONS Response Headers:";
    bodyTitleNode.innerHTML = "OPTIONS Response Body:";
    httpMethodTest.options("/home/Test?t=" + Math.random(), methodResult);
}

//从XMLHttpRequest中取出Header及Body数据
function methodResult(xhr) {
    var header = {},
        response = "",
        results = [];
    header["status"] = xhr.status;
    header["statusText"] = xhr.statusText;
    header["Cache-Control"] = xhr.getResponseHeader("Cache-Control");
    header["Content-Type"] = xhr.getResponseHeader("Content-Type");
    header["Allow"] = xhr.getResponseHeader("Allow");
    header["Content-Encoding"] = xhr.getResponseHeader("Content-Encoding");
    header["Vary"] = xhr.getResponseHeader("Vary");
    header["Server"] = xhr.getResponseHeader("Server");
    header["Date"] = xhr.getResponseHeader("Date");
    header["Content-Length"] = xhr.getResponseHeader("Content-Length");
    for (var key in header) {
        if (header[key]) {
            results.push("<li>" + key + ": " + header[key] + "</li>");
        }
    }
    headerResultNode.innerHTML = results.join("");
    bodyResultNode.value = xhr.responseText;
}

　　页面部分：

<div>
    <input type="button" id="btnGET" value="GET" />
    <input type="button" id="btnPOST" value="POST" />
    <input type="button" id="btnPUT" value="PUT" />
    <input type="button" id="btnHEAD" value="HEAD" />
    <input type="button" id="btnTRACE" value="TRACE" />
    <input type="button" id="btnOPTIONS" value="OPTIONS" />
</div>
<h3 id="headerTitle">Response Headers:</h3>
<ul id="headerResult" class="list-txt">

</ul>
<h3 id="bodyTitle">Response Body:</h3>
<textarea id="bodyResult" class="list-txt" rows="5" disabled="disabled"></textarea>

　　controller中发送trace请求：　

public void Test()
{
    Response.ClearContent();
    if (Request.HttpMethod.Equals("OPTIONS"))
    {
        Response.AddHeader("Allow", "GET, POST, PUT, DELETE, TRACE, OPTIONS");
    }
    else
    {
        Response.Write("This is a " + Request.HttpMethod);
    }
    Response.End();
}

public void Trace(string url)
{
    HttpWebRequest httpWReq = (HttpWebRequest)WebRequest.Create(url);

    httpWReq.Method = "TRACE";
    httpWReq.ContentType = "application/x-www-form-urlencoded";

    HttpWebResponse response = (HttpWebResponse)httpWReq.GetResponse();

    string responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
    Response.ClearContent();
    Response.Write(responseString);
    Response.End();
}

　　运行结果：

　　get/put/post的header及body类似，也很常见，这里就不帖图了

　　

HEAD

TRACE

OPTIONS