Web后端开发-SpringBootWeb入门、Http协议、Tomcat

Web后端开发简介

SpringBootWeb入门

package com.wuxuan.javaweb_wushuang.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

//请求处理类
@RestController
public class hello {

    @RequestMapping("/hello")
    public String hello(){
        System.out.println("Hello World~");
        return "Hello World~";
    }

}

package com.wuxuan.javaweb_wushuang.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

//请求处理类
@RestController
public class hello {

    @RequestMapping("/hello")
    public String hello(){
        System.out.println("Hello World~");
        return "Hello World~";
    }

}

HTTP协议

HTTP-概述

HTTP-请求协议

HTTP-响应协议

HTTP-协议解析

HTTP的解析和处理十分繁琐，如果要写代码，要写大量代码！非常麻烦，而Web服务器为我们解决了这个问题。Web服务器可以为我们解析和处理HTTP，使我们只需关注业务逻辑的实现。

package com.wuxuan.javabase_homework;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;

/*
 * 自定义web服务器
 */
public class Server {
    public static void main(String[] args) throws IOException {
        ServerSocket ss = new ServerSocket(8080); // 监听指定端口
        System.out.println("server is running...");

        while (true){
            Socket sock = ss.accept();
            System.out.println("connected from " + sock.getRemoteSocketAddress());

            //开启线程处理请求
            Thread t = new Handler(sock);
            t.start();
        }
    }
}

class Handler extends Thread {
    Socket sock;

    public Handler(Socket sock) {
        this.sock = sock;
    }

    @Override
    public void run() {
        try (InputStream input = this.sock.getInputStream(); OutputStream output = this.sock.getOutputStream()) {
                handle(input, output);
        } catch (Exception e) {
            try {
                this.sock.close();
            } catch (IOException ioe) {
            }
            System.out.println("client disconnected.");
        }
    }

    private void handle(InputStream input, OutputStream output) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(input, StandardCharsets.UTF_8));
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(output, StandardCharsets.UTF_8));

        // 读取HTTP请求:
        boolean requestOk = false;
        String first = reader.readLine();
        if (first.startsWith("GET / HTTP/1.")) {
            requestOk = true;
        }

        for (;;) {
            String header = reader.readLine();
            if (header.isEmpty()) { // 读取到空行时, HTTP Header读取完毕
                break;
            }
            System.out.println(header);
        }
        System.out.println(requestOk ? "Response OK" : "Response Error");

        if (!requestOk) {// 发送错误响应:
            writer.write("HTTP/1.0 404 Not Found\r\n");
            writer.write("Content-Length: 0\r\n");
            writer.write("\r\n");
            writer.flush();
        } else {  // 发送成功响应:
            //读取html文件，转换为字符串
            InputStream is = Server.class.getClassLoader().getResourceAsStream("html/a.html");
            BufferedReader br = new BufferedReader(new InputStreamReader(is));
            StringBuilder data = new StringBuilder();
            String line = null;
            while ((line = br.readLine()) != null){
                data.append(line);
            }
            br.close();
            int length = data.toString().getBytes(StandardCharsets.UTF_8).length;

            writer.write("HTTP/1.1 200 OK\r\n");
            writer.write("Connection: keep-alive\r\n");
            writer.write("Content-Type: text/html\r\n");
            writer.write("Content-Length: " + length + "\r\n");
            writer.write("\r\n"); // 空行标识Header和Body的分隔
            writer.write(data.toString());
            writer.flush();
        }
    }
}

Web服务器-Tomcat

简介

基本使用

SpringBootWeb入门程序解析