手写迷你版tomcat

Minicat

Minicat要做的事情：作为⼀个服务器软件提供服务的，也即我们可以通过浏览器客户端发送http请求，
Minicat可以接收到请求进⾏处理，处理之后的结果可以返回浏览器客户端。
1）提供服务，接收请求（Socket通信）
2）请求信息封装成Request对象（Response对象）
3）客户端请求资源，资源分为静态资源（html）和动态资源（Servlet）
4）资源返回给客户端浏览器
我们递进式完成以上需求，提出V1.0、V2.0、V3.0版本的需求
V1.0需求：浏览器请求http://localhost:8080,返回⼀个固定的字符串到⻚⾯"Hello Minicat!”
V2.0需求：封装Request和Response对象，返回html静态资源⽂件
V3.0需求：可以请求动态资源（Servlet）

具体代码

Bootstrap

package server;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.*;

/**
 * Minicat的主类
 */
public class Bootstrap {

    /**定义socket监听的端口号*/
    private int port = 8080;

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }


    /**
     * Minicat启动需要初始化展开的一些操作
     */
    public void start() throws Exception {

        // 加载解析相关的配置，web.xml
        loadServlet();


        // 定义一个线程池
        int corePoolSize = 10;
        int maximumPoolSize =50;
        long keepAliveTime = 100L;
        TimeUnit unit = TimeUnit.SECONDS;
        BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<>(50);
        ThreadFactory threadFactory = Executors.defaultThreadFactory();
        RejectedExecutionHandler handler = new ThreadPoolExecutor.AbortPolicy();


        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
                corePoolSize,
                maximumPoolSize,
                keepAliveTime,
                unit,
                workQueue,
                threadFactory,
                handler
        );





        /*
            完成Minicat 1.0版本
            需求：浏览器请求http://localhost:8080,返回一个固定的字符串到页面"Hello Minicat!"
         */
        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("=====>>>Minicat start on port：" + port);

        /*while(true) {
            Socket socket = serverSocket.accept();
            // 有了socket，接收到请求，获取输出流
            OutputStream outputStream = socket.getOutputStream();
            String data = "Hello Minicat!";
            String responseText = HttpProtocolUtil.getHttpHeader200(data.getBytes().length) + data;
            outputStream.write(responseText.getBytes());
            socket.close();
        }*/


        /**
         * 完成Minicat 2.0版本
         * 需求：封装Request和Response对象，返回html静态资源文件
         */
     /*   while(true) {
            Socket socket = serverSocket.accept();
            InputStream inputStream = socket.getInputStream();

            // 封装Request对象和Response对象
            Request request = new Request(inputStream);
            Response response = new Response(socket.getOutputStream());

            response.outputHtml(request.getUrl());
            socket.close();
        }*/


        /**
         * 完成Minicat 3.0版本
         * 需求：可以请求动态资源（Servlet）
         */
        while(true) {
            Socket socket = serverSocket.accept();
            InputStream inputStream = socket.getInputStream();

            // 封装Request对象和Response对象
            Request request = new Request(inputStream);
            Response response = new Response(socket.getOutputStream());

            // 静态资源处理
            if(servletMap.get(request.getUrl()) == null) {
                response.outputHtml(request.getUrl());
            }else{
                // 动态资源servlet请求
                HttpServlet httpServlet = servletMap.get(request.getUrl());
                httpServlet.service(request,response);
            }

            socket.close();

        }

        /*
            多线程改造（不使用线程池）
         */
        /*while(true) {
            Socket socket = serverSocket.accept();
            RequestProcessor requestProcessor = new RequestProcessor(socket,servletMap);
            requestProcessor.start();
        }*/



        /*System.out.println("=========>>>>>>使用线程池进行多线程改造");
        *//*
            多线程改造（使用线程池）
         *//*
        while(true) {

            Socket socket = serverSocket.accept();
            RequestProcessor requestProcessor = new RequestProcessor(socket,servletMap);
            //requestProcessor.start();
            threadPoolExecutor.execute(requestProcessor);
        }*/



    }


    private Map<String,HttpServlet> servletMap = new HashMap<String,HttpServlet>();

    /**
     * 加载解析web.xml，初始化Servlet
     */
    private void loadServlet() {
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream("web.xml");
        SAXReader saxReader = new SAXReader();

        try {
            Document document = saxReader.read(resourceAsStream);
            Element rootElement = document.getRootElement();

            List<Element> selectNodes = rootElement.selectNodes("//servlet");
            for (int i = 0; i < selectNodes.size(); i++) {
                Element element =  selectNodes.get(i);
                // <servlet-name>lagou</servlet-name>
                Element servletnameElement = (Element) element.selectSingleNode("servlet-name");
                String servletName = servletnameElement.getStringValue();
                // <servlet-class>server.LagouServlet</servlet-class>
                Element servletclassElement = (Element) element.selectSingleNode("servlet-class");
                String servletClass = servletclassElement.getStringValue();


                // 根据servlet-name的值找到url-pattern
                Element servletMapping = (Element) rootElement.selectSingleNode("/web-app/servlet-mapping[servlet-name='" + servletName + "']");
                // /lagou
                String urlPattern = servletMapping.selectSingleNode("url-pattern").getStringValue();
                servletMap.put(urlPattern, (HttpServlet) Class.forName(servletClass).newInstance());

            }



        } catch (DocumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

    }


    /**
     * Minicat 的程序启动入口
     * @param args
     */
    public static void main(String[] args) {
        Bootstrap bootstrap = new Bootstrap();
        try {
            // 启动Minicat
            bootstrap.start();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

HttpProtocolUtil

package server;

/**
 * http协议工具类，主要是提供响应头信息，这里我们只提供200和404的情况
 */
public class HttpProtocolUtil {

    /**
     * 为响应码200提供请求头信息
     * @return
     */
    public static String getHttpHeader200(long contentLength) {
        return "HTTP/1.1 200 OK \n" +
                "Content-Type: text/html \n" +
                "Content-Length: " + contentLength + " \n" +
                "\r\n";
    }

    /**
     * 为响应码404提供请求头信息(此处也包含了数据内容)
     * @return
     */
    public static String getHttpHeader404() {
        String str404 = "<h1>404 not found</h1>";
        return "HTTP/1.1 404 NOT Found \n" +
                "Content-Type: text/html \n" +
                "Content-Length: " + str404.getBytes().length + " \n" +
                "\r\n" + str404;
    }
}

HttpServlet

package server;

public abstract class HttpServlet implements Servlet{


    public abstract void doGet(Request request,Response response);

    public abstract void doPost(Request request,Response response);


    @Override
    public void service(Request request, Response response) throws Exception {
        if("GET".equalsIgnoreCase(request.getMethod())) {
            doGet(request,response);
        }else{
            doPost(request,response);
        }
    }
}

LagouServlet

package server;

import java.io.IOException;

public class LagouServlet extends HttpServlet {
    @Override
    public void doGet(Request request, Response response) {


        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        String content = "<h1>LagouServlet get</h1>";
        try {
            response.output((HttpProtocolUtil.getHttpHeader200(content.getBytes().length) + content));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void doPost(Request request, Response response) {
        String content = "<h1>LagouServlet post</h1>";
        try {
            response.output((HttpProtocolUtil.getHttpHeader200(content.getBytes().length) + content));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void init() throws Exception {

    }

    @Override
    public void destory() throws Exception {

    }
}

Request

package server;

import java.io.IOException;
import java.io.InputStream;

/**
 * 把请求信息封装为Request对象（根据InputSteam输入流封装）
 */
public class Request {

    private String method; // 请求方式，比如GET/POST
    private String url;  // 例如 /,/index.html

    private InputStream inputStream;  // 输入流，其他属性从输入流中解析出来


    public String getMethod() {
        return method;
    }

    public void setMethod(String method) {
        this.method = method;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public InputStream getInputStream() {
        return inputStream;
    }

    public void setInputStream(InputStream inputStream) {
        this.inputStream = inputStream;
    }

    public Request() {
    }


    // 构造器，输入流传入
    public Request(InputStream inputStream) throws IOException {
        this.inputStream = inputStream;

        // 从输入流中获取请求信息
        int count = 0;
        while (count == 0) {
            count = inputStream.available();
        }

        byte[] bytes = new byte[count];
        inputStream.read(bytes);

        String inputStr = new String(bytes);
        // 获取第一行请求头信息
        String firstLineStr = inputStr.split("\\n")[0];  // GET / HTTP/1.1

        String[] strings = firstLineStr.split(" ");

        this.method = strings[0];
        this.url = strings[1];

        System.out.println("=====>>method:" + method);
        System.out.println("=====>>url:" + url);


    }
}

RequestProcessor

package server;
import java.io.InputStream;
import java.net.Socket;
import java.util.Map;

public class RequestProcessor extends Thread {

    private Socket socket;
    private Map<String,HttpServlet> servletMap;

    public RequestProcessor(Socket socket, Map<String, HttpServlet> servletMap) {
        this.socket = socket;
        this.servletMap = servletMap;
    }

    @Override
    public void run() {
        try{
            InputStream inputStream = socket.getInputStream();

            // 封装Request对象和Response对象
            Request request = new Request(inputStream);
            Response response = new Response(socket.getOutputStream());

            // 静态资源处理
            if(servletMap.get(request.getUrl()) == null) {
                response.outputHtml(request.getUrl());
            }else{
                // 动态资源servlet请求
                HttpServlet httpServlet = servletMap.get(request.getUrl());
                httpServlet.service(request,response);
            }

            socket.close();

        }catch (Exception e) {
            e.printStackTrace();
        }

    }
}

Response

package server;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * 封装Response对象，需要依赖于OutputStream
 *
 * 该对象需要提供核心方法，输出html
 */
public class Response {

    private OutputStream outputStream;

    public Response() {
    }

    public Response(OutputStream outputStream) {
        this.outputStream = outputStream;
    }


    // 使用输出流输出指定字符串
    public void output(String content) throws IOException {
        outputStream.write(content.getBytes());
    }


    /**
     *
     * @param path  url，随后要根据url来获取到静态资源的绝对路径，进一步根据绝对路径读取该静态资源文件，最终通过
     *                  输出流输出
     *              /-----> classes
     */
    public void outputHtml(String path) throws IOException {
        // 获取静态资源文件的绝对路径
        String absoluteResourcePath = StaticResourceUtil.getAbsolutePath(path);

        // 输入静态资源文件
        File file = new File(absoluteResourcePath);

        if(file.exists() && file.isFile()) {
            // 读取静态资源文件，输出静态资源
            StaticResourceUtil.outputStaticResource(new FileInputStream(file),outputStream);
        }else{
            // 输出404
            output(HttpProtocolUtil.getHttpHeader404());
        }

    }

}

Servlet

package server;

public interface Servlet {

    void init() throws Exception;

    void destory() throws Exception;

    void service(Request request,Response response) throws Exception;
}

StaticResourceUtil

package server;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class StaticResourceUtil {

    /**
     * 获取静态资源文件的绝对路径
     * @param path
     * @return
     */
    public static String getAbsolutePath(String path) {
        String absolutePath = "";
        try {
            absolutePath = StaticResourceUtil.class.getResource(path).getPath().replaceAll("%20","");
            absolutePath = java.net.URLDecoder.decode(absolutePath,"utf-8"); //解决路径包含中文的情况
        } catch (Exception e) {

        }

        return absolutePath.replaceAll("\\\\","/");
    }


    /**
     * 读取静态资源文件输入流，通过输出流输出
     */
    public static void outputStaticResource(InputStream inputStream, OutputStream outputStream) throws IOException {

        int count = 0;
        while(count == 0) {
            count = inputStream.available();
        }

        int resourceSize = count;
        // 输出http请求头,然后再输出具体内容
        outputStream.write(HttpProtocolUtil.getHttpHeader200(resourceSize).getBytes());

        // 读取内容输出
        long written = 0 ;// 已经读取的内容长度
        int byteSize = 1024; // 计划每次缓冲的长度
        byte[] bytes = new byte[byteSize];

        while(written < resourceSize) {
            if(written  + byteSize > resourceSize) {  // 说明剩余未读取大小不足一个1024长度，那就按真实长度处理
                byteSize = (int) (resourceSize - written);  // 剩余的文件内容长度
                bytes = new byte[byteSize];
            }

            inputStream.read(bytes);
            outputStream.write(bytes);

            outputStream.flush();
            written+=byteSize;
        }
    }
}

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>static resouce</title>
</head>
<body>
Hello Minicat-static resouce!
</body>
</html>

<?xml version="1.0" encoding="UTF-8" ?>
<web-app>
    <servlet>
        <servlet-name>lagou</servlet-name>
        <servlet-class>server.LagouServlet</servlet-class>
    </servlet>


    <servlet-mapping>
        <servlet-name>lagou</servlet-name>
        <url-pattern>/lagou</url-pattern>
    </servlet-mapping>
</web-app>