tomcat简单实现（how tomcat work第一章内容）

来源：互联网发布：淘宝现在禁止好评返现编辑：程序博客网时间：2024/06/04 01:24

学习tomcat的时候，我们只是编写一个实现Servlet（间接实现）简单的java类。但是容器却能把他变成一个服务，在这之前他还是一个普通的类，并不能接受http请求。只有容器加载类并调用init方法才会把他变成一个真正的servlet，这时候他才能接受请求返回响应。

那么容器究竟是怎么实现的呢，从上一篇文章我们利用socket编程实现了远程操作文件夹，同样的。tomcat也是封装了socket从而实现将servlet类变成servlet服务。只是最终的业务逻辑传到我们编写的servlet类来处理。下面我们来实现一个简单的web服务器，效果就是可以接受http请求并响应,先看效果图：网址中输入http:\\localhost:8080

后台打印信息，也就是请求信息

下面是源代码，共有三个类

HttServer：提供服务

Resquest：得到请求信息并解析

Response：返回信息（需要加入http响应头部，不然浏览器无法解析）

import java.io.*;import java.net.*;/** *我们的服务类，当运行这个类时会监听指定的端口 */public class HttpServer {    // 关闭标识    private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";    // 是否关闭监听，根据URI判定    private boolean shutdown = false;    public static void main(String[] args) {        HttpServer server = new HttpServer();        server.await();    }    public void await() {        ServerSocket serverSocket = null;        int port = 8080;        try {            //监听本地8080端口            serverSocket =  new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));        }        catch (IOException e) {            e.printStackTrace();            System.exit(1);        }        //死循环，监听端口        while (!shutdown) {            Socket socket = null;            InputStream input = null;            OutputStream output = null;            try {                socket = serverSocket.accept();                input = socket.getInputStream();                output = socket.getOutputStream();                // 读取请求内容，包括http请求头，以及请求内容                Request request = new Request(input);                request.parse();                // 做出响应                Response response = new Response(output);                response.setRequest(request);                response.sendStaticResource();                // 关闭socket                socket.close();                //检查是否要关闭监听                shutdown = request.getUri().equals(SHUTDOWN_COMMAND);            }            catch (Exception e) {                e.printStackTrace();                continue;            }        }    }}

import java.io.*;/** * 解析请求内容 */public class Request {    private InputStream input;    private String uri;    public Request(InputStream input) {        this.input = input;    }    public void parse() {        StringBuffer request = new StringBuffer(2048);        int i;        byte[] buffer = new byte[2048];        try {            i = input.read(buffer);        }        catch (IOException e) {            e.printStackTrace();            i = -1;        }        for (int j=0; j<i; j++) {            request.append((char) buffer[j]);        }        System.out.println("请求信息"+request.toString());        uri = parseUri(request.toString());        System.out.println("URI"+uri);    }    private String parseUri(String requestString) {        int index1, index2;        index1 = requestString.indexOf(' ');        if (index1 != -1) {            index2 = requestString.indexOf(' ', index1 + 1);            if (index2 > index1)                return requestString.substring(index1 + 1, index2);        }        return null;    }    public String getUri() {        return uri;    }}

import java.io.*;/** * 响应类 */public class Response {    private static final int BUFFER_SIZE = 1024;    Request request;    OutputStream output;    public Response(OutputStream output) {        this.output = output;    }    public void setRequest(Request request) {        this.request = request;    }    public void sendStaticResource() throws IOException {        byte[] bytes = new byte[BUFFER_SIZE];        FileInputStream fis = null;        try {            //File file = new File(HttpServer.WEB_ROOT, request.getUri());            System.out.println(request.getUri());            File file = new File("F:\\howtomcatworks\\HowTomcatWorks\\webroot\\index.html");            System.out.println("文件已找到");            if (file.exists()) {                String errorMessage = "HTTP/1.1 200 File Found\r\n" +                        "Content-Type: text/html\r\n" +                        "\r\n"+                        "<h1>File Found</h1>";                output.write(errorMessage.getBytes());            }            else {                // file not found                String errorMessage = "HTTP/1.1 404 File Not Found\r\n" +                        "Content-Type: text/html\r\n" +                        "Content-Length: 23\r\n" +                        "\r\n" +                        "<h1>File Not Found</h1>";                output.write(errorMessage.getBytes());            }        }        catch (Exception e) {            // thrown if cannot instantiate a File object            System.out.println(e.toString() );        }        finally {            if (fis!=null)                fis.close();        }    }}

阅读全文

0 0