【仿写tomcat】五、响应静态资源（访问html页面）、路由支持以及多线程改进

访问html页面

如果我们想访问html页面其实就是将本地的html文件以流的方式响应给前端即可，下面我们对HttpResponseServlet这个类做一些改造

package com.tomcatServer.domain;

import com.tomcatServer.utils.ScanUtil;

import java.io.IOException;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * http servlet响应
 *
 * @author ez4sterben
 * @date 2023/08/15
 */
public class HttpServletResponse {

    private final PrintWriter out;

    private static final String response;

    private static final String htmlResponse;

    public HttpServletResponse(PrintWriter out) {
        this.out = out;
    }

    static {
        response = "HTTP/1.1 200 OK\r\n" +
                "Content-Type: text/plain\r\n" +
                "\r\n";
        htmlResponse = "HTTP/1.1 200 OK\r\n" +
                "Content-Type: text/html\r\n" +
                "\r\n";
    }


    /**
     * 写
     *
     * @param content 内容
     */
    public void write(String content) {
        out.println(response + content);
    }

    /**
     * 编写html
     *
     * @param htmlFileName html文件名字
     * @throws IOException ioexception
     */
    public void writeHtml(String htmlFileName) throws IOException {
        Path path = Paths.get(ScanUtil.WEB_APP_PATH + "\\" + htmlFileName);
        byte[] bytes = Files.readAllBytes(path);
        out.println(htmlResponse + new String(bytes, StandardCharsets.UTF_8));
    }
}

writeHtml这个方法将会读取webApp下面的html文件，注意只读取下面一级文件中的html文件，然后将这个文件以二进制流的形式转换成字符串拼接到上面定义的html格式的响应头。

处理静态资源请求

当我们有了解析html文件的方法后，下面要做的就是处理静态资源，也就是判断一下请求路径中是否有.html这个字符串，有的话就把这次请求当做静态资源请求处理，没有的话再交给GET或者POST请求。这个逻辑将添加在SocketStore中，下面展示更改玩的SocketStore代码

package com.tomcatServer.socket;

import com.tomcatServer.domain.HttpServletRequest;
import com.tomcatServer.domain.HttpServletResponse;
import com.tomcatServer.utils.ScanUtil;
import com.tomcatServer.utils.ServletUtil;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Map;

/**
 * 套接字存储
 *
 * @author ez4sterben
 * @date 2023/08/15
 */
public class SocketStore {

    private static ServerSocket socket;

    public static void connect(Integer port) throws IOException {
        socket = new ServerSocket(port);
    }

    public static void close() throws IOException {
        socket.close();
    }

    public static ServerSocket getSocket() {
        return socket;
    }


    /**
     * 处理请求
     *
     * @throws IOException ioexception
     */
    public static void handleRequest(Socket accept) throws IOException {
        // 获取输入输出流
        BufferedReader in = new BufferedReader(new InputStreamReader(accept.getInputStream()));
        PrintWriter out = new PrintWriter(accept.getOutputStream(), true);
        // 定义字符串接收Http协议内容
        String inputLine;
        StringBuilder requestData = new StringBuilder();
        // 读取数据
        while ((inputLine = in.readLine()) != null && !inputLine.isEmpty()) {
            requestData.append(inputLine).append("\r\n");
        }
        // 解析request param
        String url = requestData.toString().split(" ")[1];
        // 处理静态资源
        if(url.contains(".html")){
            String staticSourceName = (url.split(".html")[0] + ".html").substring(1);
            HttpServletResponse response = new HttpServletResponse(out);
            response.writeHtml(staticSourceName);
        }else {
            // 处理GET与POST请求
            if (!requestData.toString().trim().equals("")){
                handleGetAndPostReuqest(in, out, String.valueOf(requestData));
            }
        }
        // 关闭资源
        accept.close();
    }

    /**
     * 处理post请求
     *
     * @param in          在
     * @param requestData 请求数据
     * @throws IOException ioexception
     */
    private static void handleGetAndPostReuqest(BufferedReader in,PrintWriter out, String requestData) throws IOException {
        // 解析request param
        String url = requestData.split(" ")[1];
        String[] urlContent = url.split("\\?");
        String requestPath = urlContent[0];
        String params = urlContent[1];
        String[] paramsKeyValue = params.split("=");

        // 设置请求参数
        HttpServletRequest request = new HttpServletRequest();
        Map<String, String> paramsMap = request.getParams();
        for (int i = 0; i < paramsKeyValue.length; i += 2) {
            paramsMap.put(paramsKeyValue[i],paramsKeyValue[i+1]);
        }
        if (requestData.contains("POST")) {
            // 解析request body
            int contentLength = Integer.parseInt(requestData.split("Content-Length: ")[1].split("\r\n")[0]);
            StringBuilder requestBody = new StringBuilder();
            for (int i = 0; i < contentLength; i++) {
                requestBody.append((char) in.read());
            }

            // 设置request body
            request.setRequestBody(String.valueOf(requestBody));

            // 设置响应内容
            HttpServletResponse response = new HttpServletResponse(out);
            ServletUtil.invokePost(requestPath,request,response);
        }
        if (requestData.contains("GET")){
            // 设置响应内容
            HttpServletResponse response = new HttpServletResponse(out);
            ServletUtil.invokeGet(requestPath,request,response);
        }
    }

}

访问测试

接下来我们在index.html里面写点东西并访问一下试试

http://localhost:8080/index.html

路由支持

其实刚才完成这个功能的时候就会发现，如何访问子目录里面的html呢？
这里其实就要写一个小方法来支持路由重定向了，下面编写一个HttpUtil

package com.tomcatServer.utils;

import com.tomcatServer.domain.HttpServletRequest;
import com.tomcatServer.domain.HttpServletResponse;

import java.io.IOException;

public class HttpUtil {

    private final String redirectPath;

    public HttpUtil(String redirectPath) {
        this.redirectPath = redirectPath;
    }
    public void forward(HttpServletRequest request, HttpServletResponse response) throws IOException {
        response.writeHtml(redirectPath);
    }
}

对HttpServletRequest做一些改进，提供一个加载静态资源的方法。

    public HttpUtil getStaticSource(String path){
        return new HttpUtil(path);
    }

其实这样我们的功能就完成了，写一个servlet以及html来测试一下

package tomcatProject.com.ez4sterben.servlet;

import com.tomcatServer.annotation.WebServlet;
import com.tomcatServer.domain.HttpServlet;
import com.tomcatServer.domain.HttpServletRequest;
import com.tomcatServer.domain.HttpServletResponse;

import java.io.IOException;

@WebServlet("/router")
public class RouterServlet extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        request.getStaticSource("WEB-INF/page/"+request.getParam("path")+".html").forward(request, response);
    }

    @Override
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
        doGet(request, response);
    }
}

多线程改进

为什么要在这里谈多线程改进呢，其实是因为我们最近本的接收请求，响应请求，响应页面以及完成了，接下来要考虑的就是如何支持并发处理请求，如何配置并发数，如何配置端口等优化问题。

如果想实现并发处理请求的话，实际上只需要预先定义一个线程池即可，把处理请求的方法交给一个任务类并且实现Runnable接口，当然我们后面会再优化这种方案。

package com.tomcatServer.task;

import com.tomcatServer.socket.SocketStore;

import java.io.IOException;
import java.net.Socket;

public class RequestTask implements Runnable{

    private final Socket accept;

    public RequestTask(Socket accept) {
        this.accept = accept;
    }

    @Override
    public void run() {
        try {
            SocketStore.handleRequest(accept);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

        ...
        public static ExecutorService threadPool;
        ...
		// 5.初始化线程池
        threadPool = Executors.newFixedThreadPool(10);

        // 6.处理http请求
        try {
            SocketStore.connect(PORT);
            while (true){
                Socket accept = SocketStore.getSocket().accept();
                if (accept != null){
                    threadPool.submit(new RequestTask(accept));
                }
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }finally {
            SocketStore.close();
        }