简约之美Jodd-http--深入源码理解http协议-白红宇

简约之美Jodd-http--深入源码理解http协议

阅读量：6935 次

发布时间：2019-06-27

本文共 8716 字，大约阅读时间需要 29 分钟。

Jodd 是一个开源的 Java 工具集，包含一些实用的工具类和小型框架。简单，却很强大！

jodd-http是一个轻巧的HTTP客户端。现在我们以一个简单的示例从源码层看看是如何实现的？

　HttpRequest httpRequest = HttpRequest.get("http://jodd.org"); //1. 构建一个get请求    HttpResponse response = httpRequest.send(); //2.发送请求并接受响应信息    System.out.println(response);//3.打印响应信息

构建一个get请求

先复习一下http请求报文的格式：

下图展示一般请求所带有的属性

调用get方法构建http请求：

/**     * Builds a GET request.     */    public static HttpRequest get(String destination) {        return new HttpRequest()                .method("GET")                .set(destination);    }

method方法如下：

/**     * Specifies request method. It will be converted into uppercase.     */    public HttpRequest method(String method) {        this.method = method.toUpperCase();        return this;    }

set方法如下：

/**     * Sets the destination (method, host, port... ) at once.     */    public HttpRequest set(String destination) {        destination = destination.trim();        // http method        int ndx = destination.indexOf(' ');        if (ndx != -1) {            method = destination.substring(0, ndx).toUpperCase();            destination = destination.substring(ndx + 1);        }        // protocol        ndx = destination.indexOf("://");        if (ndx != -1) {            protocol = destination.substring(0, ndx);            destination = destination.substring(ndx + 3);        }        // host        ndx = destination.indexOf('/');        if (ndx == -1) {            ndx = destination.length();        }        if (ndx != 0) {            host = destination.substring(0, ndx);            destination = destination.substring(ndx);            // port            ndx = host.indexOf(':');            if (ndx == -1) {                port = DEFAULT_PORT;            } else {                port = Integer.parseInt(host.substring(ndx + 1));                host = host.substring(0, ndx);            }        }        // path + query        path(destination);        return this;    }

上述方法，根据destination解析出一下几个部分：

1. 方法：HTTP1.1支持7种请求方法:GET、POST、HEAD、OPTIONS、PUT、DELETE和TARCE。

2. 协议：http或者https

3. 主机：请求的服务器地址

4. 端口：请求的服务器端口

5. 路径+查询参数，其中参数以“?”开头，使用“&”连接

/**     * Sets request path. Query string is allowed.     * Adds a slash if path doesn't start with one.     * Query will be stripped out from the path.     * Previous query is discarded.     * @see #query()     */    public HttpRequest path(String path) {        // this must be the only place that sets the path        if (path.startsWith(StringPool.SLASH) == false) {            path = StringPool.SLASH + path;        }        int ndx = path.indexOf('?');        if (ndx != -1) {            String queryString = path.substring(ndx + 1);            path = path.substring(0, ndx);            query = HttpUtil.parseQuery(queryString, true);        } else {            query = HttpValuesMap.ofObjects();        }        this.path = path;        return this;    }

发送请求

先熟悉一下http响应报文的格式：

响应首部一般包含如下内容：

/**     * {
    @link #open() Opens connection} if not already open, sends request,     * reads response and closes the request. If keep-alive mode is enabled     * connection will not be closed.     */    public HttpResponse send() {        if (httpConnection == null) {            open();        }        // prepare http connection        if (timeout != -1) {            httpConnection.setTimeout(timeout);        }        // sends data        HttpResponse httpResponse;        try {            OutputStream outputStream = httpConnection.getOutputStream();            sendTo(outputStream);            InputStream inputStream = httpConnection.getInputStream();            httpResponse = HttpResponse.readFrom(inputStream);            httpResponse.assignHttpRequest(this);        } catch (IOException ioex) {            throw new HttpException(ioex);        }        boolean keepAlive = httpResponse.isConnectionPersistent();        if (keepAlive == false) {            // closes connection if keep alive is false, or if counter reached 0            httpConnection.close();            httpConnection = null;        }        return httpResponse;    }

1. 打开HttpConnection

/**     * Opens a new {
    @link HttpConnection connection} using     * {
    @link JoddHttp#httpConnectionProvider default connection provider}.     */    public HttpRequest open() {        return open(JoddHttp.httpConnectionProvider);    }    /**     * Opens a new {
    @link jodd.http.HttpConnection connection}     * using given {
    @link jodd.http.HttpConnectionProvider}.     */    public HttpRequest open(HttpConnectionProvider httpConnectionProvider) {        if (this.httpConnection != null) {            throw new HttpException("Connection already opened");        }        try {            this.httpConnectionProvider = httpConnectionProvider;            this.httpConnection = httpConnectionProvider.createHttpConnection(this);        } catch (IOException ioex) {            throw new HttpException(ioex);        }        return this;    }

判断是否有连接，若没有连接则创建一个新的连接。

2. 创建连接实现

/**     * Creates new connection from current {
    @link jodd.http.HttpRequest request}.     *     * @see #createSocket(String, int)     */    public HttpConnection createHttpConnection(HttpRequest httpRequest) throws IOException {        Socket socket;        if (httpRequest.protocol().equalsIgnoreCase("https")) {            SSLSocket sslSocket = createSSLSocket(httpRequest.host(), httpRequest.port());            sslSocket.startHandshake();            socket = sslSocket;        } else {            socket = createSocket(httpRequest.host(), httpRequest.port());        }        return new SocketHttpConnection(socket);    }

3. 创建socket

　　根据协议的不同，http使用SocketFactory创建socket，https使用SSLSocketFactory创建SSLSocket。最终使用SocketHttpConnection进行包装。

SocketHttpConnection继承自HttpConnection，实现了socket的输入输出流连接。注意：https创建完SSLSocket时需要进行握手。

public class SocketHttpConnection implements HttpConnection {    protected final Socket socket;    public SocketHttpConnection(Socket socket) {        this.socket = socket;    }    public OutputStream getOutputStream() throws IOException {        return socket.getOutputStream();    }    public InputStream getInputStream() throws IOException {        return socket.getInputStream();    }    public void close() {        try {            socket.close();        } catch (IOException ignore) {        }    }    public void setTimeout(int milliseconds) {        try {            socket.setSoTimeout(milliseconds);        } catch (SocketException sex) {            throw new HttpException(sex);        }    }    /**     * Returns Socket used by this connection.     */    public Socket getSocket() {        return socket;    }}

打开Connection的输出流发送信息，打开connection的输入流接受返回信息。

OutputStream outputStream = httpConnection.getOutputStream();            sendTo(outputStream);            InputStream inputStream = httpConnection.getInputStream();

发送过程：

protected HttpProgressListener httpProgressListener;    /**     * Sends request or response to output stream.     */    public void sendTo(OutputStream out) throws IOException {        Buffer buffer = buffer(true);        if (httpProgressListener == null) {            buffer.writeTo(out);        }        else {            buffer.writeTo(out, httpProgressListener);        }        out.flush();    }

将缓冲区的数据写入输出流，并发送。

接受数据并读取报文内容：

/**     * Reads response input stream and returns {
    @link HttpResponse response}.     * Supports both streamed and chunked response.     */    public static HttpResponse readFrom(InputStream in) {        InputStreamReader inputStreamReader;        try {            inputStreamReader = new InputStreamReader(in, StringPool.ISO_8859_1);        } catch (UnsupportedEncodingException ignore) {            return null;        }        BufferedReader reader = new BufferedReader(inputStreamReader);        HttpResponse httpResponse = new HttpResponse();        // the first line        String line;        try {            line = reader.readLine();        } catch (IOException ioex) {            throw new HttpException(ioex);        }        if (line != null) {            line = line.trim();            int ndx = line.indexOf(' ');            httpResponse.httpVersion(line.substring(0, ndx));            int ndx2 = line.indexOf(' ', ndx + 1);            if (ndx2 == -1) {                ndx2 = line.length();            }            httpResponse.statusCode(Integer.parseInt(line.substring(ndx, ndx2).trim()));            httpResponse.statusPhrase(line.substring(ndx2).trim());        }        httpResponse.readHeaders(reader);        httpResponse.readBody(reader);        return httpResponse;    }

小结

从上面的代码，我们可以看出http使用socket来建立和destination的连接，然后通过连接的输出流和输入流来进行通信。

参考文献：

【1】http://www.it165.net/admin/html/201403/2541.html

【2】http://jodd.org/doc/http.html

转载地址：http://thpjl.baihongyu.com/

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