Web容器或许这样的

╰半橙微兮° 2022-02-28 05:42 94阅读 0赞

初学javaEE,对Tomcat的认识也一直是一个Web容器,今天先猜猜它是怎么工作的

一、自定义的Web容器  
根据servlet学习，推测Web容器功能应该有：

1.  建立SeverSocket，等待Socket连接
2.  给servlet提供Request、Response对象
3.  执行servlet GET、POST方法
4.  向socket发送响应信息

package com.cooooode.main;
    
    import java.io.IOException;
    import java.net.ServerSocket;
    import java.net.Socket;
    
    public class Container {
        private ServerSocket server;
        Container(){
            System.out.println("创建Container对象");
        }
        Container(int port) throws IOException {
            this();
            this.server=new ServerSocket(port);//1建立SeverSocket
        }
        public void start() throws IOException {
            System.out.println("启动容器");
            while(true) {
                Socket client = server.accept();//等待Socket连接
                HttpRequest httpRequest = getHttpRequest(client);//获取Request对象
                HttpResponse httpResponse = getHttpResponse(client);//获取Response对象
                String method=httpRequest.getRequestMethod();
                Servlet servlet=new Servlet();
                //2，3 提供Request、Response对象 执行servlet GET、POST方法
                if(method.toUpperCase().equals("GET"))
                    servlet.get(httpRequest,httpResponse);
                else
                    servlet.post(httpRequest,httpResponse);
                httpResponse.push();//4. 向socket发送响应信息
            }
        }
        public HttpRequest getHttpRequest(Socket client) throws IOException {
            return new HttpRequest(client);
        }
        public HttpResponse getHttpResponse(Socket client) {
            return new HttpResponse(client);
        }
        public static void main(String[] args) throws IOException {
            new Container(8000).start();
        }
    }

二、自定义Request  
便宜行事，只写了两个方法

1.  获取请求头信息
2.  获取请求方法（GET/POST）

package com.cooooode.main;
    
    import java.io.IOException;
    import java.net.Socket;
    
    public class HttpRequest {
        private Socket client;
        private String headinfo;
        HttpRequest(){
            System.out.println("创建HttpRequest对象");
        }
        HttpRequest(Socket client) throws IOException {
            this();
            this.client=client;
            byte[] bytes = new byte[20480];
            int len=client.getInputStream().read(bytes);
            headinfo=new String(bytes,0,len);
        }
        // 1. 获取请求头信息
        public String getHeadMessage() throws IOException {
            return headinfo;
        }
        // 2. 获取请求方法（GET/POST）
        public String getRequestMethod() throws IOException {
            return headinfo.split(" ")[0];
        }
    }

三、自定义Response  
定义了两个主要方法

1.  将servlet传递的响应内容添加到响应输出中
2.  推送响应信息

package com.cooooode.main;
    
    import java.io.BufferedWriter;
    import java.io.IOException;
    import java.io.OutputStreamWriter;
    import java.net.Socket;
    import java.util.Date;
    
    public class HttpResponse {
        private Socket client;
        private StringBuffer response=new StringBuffer();
        private StringBuffer headinfo=new StringBuffer();
        public static final String BLANK=" ";
        public static final String CRLF="\r\n";
        private BufferedWriter bw;
        private int len;
        private String charset="utf-8";
        private String contextType="text/html";
        private int code=200;
        HttpResponse(){
            System.out.println("创建HttpResponse对象");
        }
        HttpResponse(Socket client){
            this();
            this.client=client;
        }
    	public void setCode(int code){
            this.code=code;
        }
    	public void setCharset(String charset){
            this.charset=charset;
        }
        public void setContextType(String contextType){
            this.contextType=contextType;
        }
        // 1. 将servlet传递的响应内容添加到响应输出中
        public StringBuffer println(String context){
            len+=(context+CRLF).getBytes().length;
            return response.append(context).append(CRLF);
        }
        // 1. 将servlet传递的响应内容添加到响应输出中
        public StringBuffer print(String context){
            len+=context.getBytes().length;
            return response.append(context);
        }
    	// 2. 推送响应信息
        public void push() throws IOException {
            System.out.println(client);
            bw = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));
            headinfo.append("HTTP/1.1").append(BLANK).append(code).append(BLANK);
            switch (code) {
                case 200:
                    headinfo.append("OK");
                    break;
                case 404:
                    headinfo.append("NOT FOUND");
                    break;
                case 505:
                    headinfo.append("SERVER ERROR");
                    break;
            }
            headinfo.append(CRLF);
            headinfo.append("Content-Type:" + contextType).append(CRLF);
            headinfo.append("Content-Length:" + len).append(CRLF);
            headinfo.append("Date:" + new Date()).append(CRLF);
            headinfo.append(CRLF);
            headinfo.append(response);
            bw.write(headinfo.toString());
            bw.flush();
            bw.close();
        }
    }

四、自定义servlet

package com.cooooode.main;
    
    import java.io.IOException;
    
    public class Servlet{
    
        public void get(HttpRequest httpRequest,HttpResponse httpResponse) throws IOException {
            System.out.println(httpRequest.getHeadMessage());
            httpResponse.println("<h1>Cooooode HttpServer</h1>");
            httpResponse.println("<b>2019 03 24</b>");
        }
        public void post(HttpRequest httpRequest,HttpResponse httpResponse) throws IOException {
            this.get(httpRequest,httpResponse);
        }
    }

执行容器main方法，一个简陋的javaWeb应用就启动了