源码请移步->
reference:
1、http与tcp的关系
2、netty
1、基于bio实现的一个简易tomcat（部分代码）
package com.grayson.netty.tomcat.bio;
import com.grayson.netty.tomcat.bio.http.GraysonRequest;
import com.grayson.netty.tomcat.bio.http.GraysonResponse;
import com.grayson.netty.tomcat.bio.servlet.GraysonAbstarctServlet;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
/**
* 基于bio实现的一个简易tomcat
*/
public class GraysonTomcat {
//tomcat默认端口
private int port = 8080;
private ServerSocket server;
private Properties properties = new Properties();
private Map<String, GraysonAbstarctServlet> servletMapping = new ConcurrentHashMap<String, GraysonAbstarctServlet>(8);
//tomcat启动入口
public static void main(String[] args) {
new GraysonTomcat().start();
}
//1、初始化方法：加载web.properties参数,
//2、解析配置：将servlet.*.className与servlet.*.url建立映射关系，并缓存，
//3、解析浏览器请求的url映射到对应的servlet，通过反射创建servlet实例，访问对应的servlet的doget或dopost方法
private void start() {
//1、初始化方法：加载web.properties参数,
init();
try {
//2、启动服务端socket等待用户请求（java中操作tcp的方法：ServerSocket/Socket）
server = new ServerSocket(port);
System.out.println("启动中...，监听端口是：" + this.port);
//一直等待用户请求
while (true){
Socket client = server.accept();
//socket一般会携带两个对象InputStream/OutputStream.request和response就是对InputStream/OutputStream的封装。
//获得请求信息，解析http内容
process(client);
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void init(){
//获取resources文件路径
String WEB_INF = this.getClass().getResource("/").getPath();
//获取文件输入流
try {
FileInputStream is = new FileInputStream(WEB_INF + "web.properties");
//加载web.properties文件输入流
properties.load(is);
for(Object k : properties.keySet()){
String key = k.toString();
//是否key以url结尾
if(key.endsWith(".url")){
//获取servlet.*
String servletName = key.replaceAll("\\.url$", "");
//key -> servlet.*.className, value -> className
String className = properties.getProperty(servletName + ".className");
String url = properties.getProperty(key);
//通过className反射获取servlet对象, java9之后推荐的写法.getDeclaredConstructor()
GraysonAbstarctServlet obj = (GraysonAbstarctServlet)Class.forName(className).getDeclaredConstructor().newInstance();
//将url和对应的Servlet对象缓存(建立映射关系）
servletMapping.put(url, obj);
//根据j2ee规范，web.xml中还有<load-on-startup>值需要配置
//（大于等于1，表示sevlet在web容器启动时初始化，否则，在请求时初始化，这里直接默认启动时初始化，忽略了<load-on-startup>）
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void process(Socket client) throws Exception{
InputStream is = client.getInputStream();
OutputStream os = client.getOutputStream();
GraysonRequest request = new GraysonRequest(is);
GraysonResponse response = new GraysonResponse(os);
String url = request.getUrl();
if(servletMapping.containsKey(url)){
servletMapping.get(url).service(request, response);
} else {
response.write("404 - Not Found!!");
}
os.flush();
os.close();
is.close();
client.close();
}
}
二、基于netty实现的一个简易tomcat(部分代码)
netty最为基础的通信框架，封装了传输层（tcp&udp）相关的协议，在通信领域，适应范围广，几乎无所不能，性能高，详见netty官网。
package com.grayson.netty.tomcat.nio;
import com.grayson.netty.tomcat.nio.http.GraysonRequest;
import com.grayson.netty.tomcat.nio.http.GraysonResponse;
import com.grayson.netty.tomcat.nio.servlet.GraysonAbstarctServlet;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpRequestDecoder;
import io.netty.handler.codec.http.HttpResponseEncoder;
import java.io.FileInputStream;
import java.net.Socket;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
/**
* 前提：先了解bio
* 基于nio实现的一个简易tomcat
* netty封装了http解析的方法
*/
public class GraysonTomcat {
//tomcat默认端口
private int port = 8080;
private Properties properties = new Properties();
private Map<String, GraysonAbstarctServlet> servletMapping = new HashMap<String, GraysonAbstarctServlet>(8);
//tomcat启动入口
public static void main(String[] args) {
new GraysonTomcat().start();
}
//1、初始化方法：加载web.properties参数,
//2、解析配置：将servlet.*.className与servlet.*.url建立映射关系，并缓存，
//3、解析浏览器请求的url映射到对应的servlet，通过反射创建servlet实例，访问对应的servlet的doget或dopost方法
private void start() {
//1、初始化方法：加载web.properties参数,
init();
//Boss线程
EventLoopGroup boosGroup = new NioEventLoopGroup();
//Worker线程
EventLoopGroup workerGroup = new NioEventLoopGroup();
//2、创建Netty服务端对象(ServerBootstrap 这里作用类似于bio中ServerSocket)
ServerBootstrap server = new ServerBootstrap();
try {
//3、配置服务端参数
server.group(boosGroup, workerGroup)
//配置主线程的处理逻辑，基于nio的socket
.channel(NioServerSocketChannel.class)
//子线程的回调处理
.childHandler(new ChannelInitializer() {
@Override
protected void initChannel(Channel client) throws Exception {
//处理回调的逻辑
//netty内部逻辑处理是链式编程，每一个处理逻辑都是一个hander
//处理请求的encoder，即处理响应结果的封装
client.pipeline().addLast(new HttpResponseEncoder());
//处理请求的decoder，即按http格式解码
client.pipeline().addLast(new HttpRequestDecoder());
//用户自己的业务逻辑
client.pipeline().addLast(new GraysonTomcatHandler());
}
})
//配置主线程分配的最大的线程数
.option(ChannelOption.SO_BACKLOG, 128)
//保持长连接
.childOption(ChannelOption.SO_KEEPALIVE, true);
//启动服务
ChannelFuture f = server.bind(this.port).sync();
System.out.println("GraysonTomcat 已启动，监听端口：" + this.port);
f.channel().closeFuture().sync();
}catch (Exception e){
e.printStackTrace();
}finally {
boosGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public void init(){
//获取resources文件路径
String WEB_INF = this.getClass().getResource("/").getPath();
//获取文件输入流
try {
FileInputStream is = new FileInputStream(WEB_INF + "web-nio.properties");
//加载web.properties文件输入流
properties.load(is);
for(Object k : properties.keySet()){
String key = k.toString();
//是否key以url结尾
if(key.endsWith(".url")){
//获取servlet.*
String servletName = key.replaceAll("\\.url$", "");
//key -> servlet.*.className, value -> className
String className = properties.getProperty(servletName + ".className");
String url = properties.getProperty(key);
//通过className反射获取servlet对象, java9之后推荐的写法.getDeclaredConstructor()
GraysonAbstarctServlet obj = (GraysonAbstarctServlet)Class.forName(className).getDeclaredConstructor().newInstance();
//将url和对应的Servlet对象缓存(建立映射关系）
servletMapping.put(url, obj);
//根据j2ee规范，web.xml中还有<load-on-startup>值需要配置
//（大于等于1，表示sevlet在web容器启动时初始化，否则，在请求时初始化，这里直接默认启动时初始化，忽略了<load-on-startup>）
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void process(Socket client) throws Exception{
}
private class GraysonTomcatHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
if(msg instanceof HttpRequest){
HttpRequest req = (HttpRequest)msg;
GraysonRequest request = new GraysonRequest(ctx, req);
GraysonResponse response = new GraysonResponse(ctx, req);
String url = request.getUrl();
if(servletMapping.containsKey(url)){
servletMapping.get(url).service(request, response);
}else {
response.write("404 - not found");
}
}
}
}
}
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