手写简易的WEB服务

环境:

• JDK 1.8
• Idea 工具
• 新建Java项目

前提需要具备的基础

• Socket
• IO

思路

写一个服务端即可，用浏览器做现成的客户端

• 启动Socket服务，循环接收浏览器的请求
• 接收请求之后，将流中的数据取出
• 判断目标是资源是否存在，若不存在，返回404页面
• 若存在，将目标资源通过输出流响应给客户端(浏览器)

需要使用到的类

• Server：开启Socket服务
• Request：封装请求，处理请求的业务
• Response：封装响应，处理响应的相关业务
• Test: 测试类

Server服务器中

public class SimpleHttpServer {
    //端口
    private int port=8080;
    //IP就是本地 不需要配置
    //接收请求的方法
    public void receiving(){
        try {
            //创建Socket服务
            ServerSocket serverSocket = new ServerSocket(port);
            //循环接收
            while (true){
                //每次请求就会拿到Socket对象就是接收一个请求
                Socket socket = serverSocket.accept();
                //System.out.println(socket);
                //获取连接对象的输入流
                InputStream inputStream = socket.getInputStream();
                //创建request对象
                SimpleHttpRequest simpleHttpRequest = new SimpleHttpRequest(inputStream);
                //解析请求
                simpleHttpRequest.parse();
                //获取连接对象的输出流
                OutputStream outputStream = socket.getOutputStream();
                //创建Response
                SimpleHttpResponse simpleHttpResponse = new SimpleHttpResponse(outputStream);
                //进行响应
                simpleHttpResponse.sendRedirect(simpleHttpRequest.getUri());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Request对象解析请求

public class SimpleHttpRequest {
    private InputStream inputStream;
    //返回请求头中的网页资源路径
    private String uri;
    public SimpleHttpRequest(InputStream inputStream) {
        this.inputStream = inputStream;
    }
    //进行解析
    public void parse() {
        try {
            byte[] bytes = new byte[1024];
            inputStream.read(bytes);
            String request=new String(bytes);
            System.out.println(request);
            parseUri(request);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    //解析
    public void parseUri(String request) {
        int index1 ,index2;
        //找到第一次的空格
        index1 = request.indexOf(32);
        index2 = request.indexOf(32, index1 + 1);
        //截取中间的资源
        uri = request.substring(index1 + 1, index2);
        System.out.println(uri);
    }
    public String getUri() {
        return this.uri;
    }
}

Response对象进行对请求信息的响应

public class SimpleHttpResponse {
    private OutputStream outputStream;
    public SimpleHttpResponse(OutputStream outputStream) {
        this.outputStream = outputStream;
    }
    public void sendRedirect(String uri) {
        try {
            //获取项目目录再拼接路径
            String path = System.getProperty("user.dir") + "/WebContent" + uri;
            //判断资源uri是否存在
            File file = new File(path);
            if (!file.exists()) {
                //不存在返回404
                String error = getResponseMessage("404", "404 File Not Found");
                System.out.println(error);
                this.outputStream.write(error.getBytes());
            } else {
                //存在就返回目标资源的数据
                FileInputStream inputStream = new FileInputStream(file);
                byte[] bytes = new byte[(int) file.length()];
                inputStream.read(bytes);
                String result = new String(bytes);
                String responseMessage = getResponseMessage("200", result);
                this.outputStream.write(responseMessage.getBytes());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    //响应的格式
    public String getResponseMessage(String code, String message) {
        return "HTTP/1.1" + code + "\r\n"
            + "Content-type: text/html\r\n"
            + "Content-Length: " + message.length()
            + "\r\n"
            + "\r\n"
            + message;
    }
}
 

测试服务

 public static void main(String[] args) {
        SimpleHttpServer server = new SimpleHttpServer();
        System.out.println("Server Startup Successfully");
        server.receiving();
    }

测试中的数据

• Socket[addr=/0:0:0:0:0:0:0:1,port=51572,localport=8080] 整个port是浏览器提供的接口

• 浏览器发送的请求消息

  GET /index.html HTTP/1.1
  Host: localhost:8080
  Connection: keep-alive
  Upgrade-Insecure-Requests: 1
  User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36
  Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3
  Accept-Encoding: gzip, deflate, br
  Accept-Language: zh-CN,zh;q=0.9,en;q=0.8

记录错误：

java.net.SocketException: Socket is not bound yet 创建服务时忘记把端口传入进去

记录新发现：

System.getProperty("user.dir") ==> 获取项目的路径 本次获取的 D:\..\SimpleWebServer