技术栈

java.net.Socket

java.net.ServerSocket

执行流程

创建一个ServerSocket对象；

调用ServerSocket对象的accept方法，等待连接，连接成功会返回一个Socket对象，否则一直阻塞等待；

从Socket对象中获取InputStream和OutputStream字节流，这两个流分别对应request请求和response响应；

处理请求：读取InputStream字节流信息，转成字符串形式，并解析，这里的解析比较简单，仅仅获取uri(统一资源标识符)信息;

处理响应：根据解析出来的uri信息，从WEB_ROOT目录中寻找请求的资源资源文件, 读取资源文件，并将其写入到OutputStream字节流中；

关闭Socket对象；

转到步骤2，继续等待连接请求；

代码实现

服务器

package com.kunlinr.lifealien.servlet.server;

import java.io.File;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.InetAddress;

import java.net.ServerSocket;

import java.net.Socket;

public class HttpServer {

/**WEB_ROOT是HTML和其它文件存放的目录. 这里的WEB_ROOT为工作目录下的WebContent目录*/

public static final String WEB_ROOT = System.getProperty("user.dir")+File.separator+"WebContent";

//关闭服务命令

public static final String SHUTDOWN_COMMAND = "/SHUTDOWN";

public static void main(String[] args) {

HttpServer server = new HttpServer();

server.await();

}

/**

* 等待连接请求

*/

private void await() {

ServerSocket serverSocket = null;

int port = 8080;

try {

//服务器套接字对象

serverSocket = new ServerSocket(port,0,InetAddress.getByName("127.0.0.1"));

}catch (Exception e) {

e.printStackTrace();

System.exit(1);

}

//循环等待请求

while(true) {

Socket socket = null;

InputStream input = null;

OutputStream output = null;

try {

socket = serverSocket.accept();

input = socket.getInputStream();

output = socket.getOutputStream();

//创建Request

Request request = new Request(input);

//检查是否关闭服务命令

if(request.getUri().equals(SHUTDOWN_COMMAND)) {

break;

}

//创建Response

Response response = new Response(output);

response.setRequest(request);

response.sendStaticResource();

//关闭socket

socket.close();

}catch(Exception e) {

e.printStackTrace();

continue;

}

}

}

}

Request

package com.kunlinr.lifealien.servlet.server;

import java.io.ByteArrayOutputStream;

import java.io.InputStream;

@SuppressWarnings("unused")

public class Request {

private InputStream input;

private String uri;

public Request(InputStream input) {

this.input = input;

parse();

}

/**

* 从inputStream中读取request信息，获取uri值。

*/

public void parse() {

StringBuffer request = new StringBuffer(2048);

int i;

byte[] buffer = new byte[2048];

try {

i = input.read(buffer);

}catch (Exception e) {

e.printStackTrace();

i = -1;

}

for(int j=0;j

request.append((char)buffer[j]);

}

uri = parseUri(request.toString());

}

/**

* requestString形式如下：

* GET /index.html HTTP/1.1

* Host: localhost:8080

* Connection: keep-alive

* Cache-Control: max-age=0

* ...

* 获取/index.html字符串

* @param string

* @return

*/

private String parseUri(String string) {

int index1,index2;

index1 = string.indexOf(' ');

if (index1 != -1) {

index2 = string.indexOf(' ', index1 + 1);

if (index2 > index1)

return string.substring(index1 + 1, index2);

}

return "";

}

public String getUri() {

return uri;

}

}

Response

package com.kunlinr.lifealien.servlet.server;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.util.ArrayList;

import java.util.List;

public class Response {

private static final int BUFFER_SIZE = 1024;

private Request request;

private OutputStream output;

public Response(OutputStream output) {

this.output = output;

}

public void setRequest(Request request) {

this.request = request;

}

/**

* 发送静态资源

* @throws IOException

*/

public void sendStaticResource() throws IOException {

byte[] bytes = new byte[BUFFER_SIZE];

FileInputStream fis = null;

try {

//将web文件写入到OutputStream字节流中

File file = new File(HttpServer.WEB_ROOT, request.getUri());

if (file.exists()) {

fis = new FileInputStream(file);

List contentbytes = new ArrayList<>();

int ch = fis.read(bytes, 0, BUFFER_SIZE);

int size = 0;

while (ch != -1) {

contentbytes.add(bytes);

ch = fis.read(bytes, 0, BUFFER_SIZE);

size += BUFFER_SIZE;

}

String head = "HTTP/1.1 200 OK\r\n" + "Content-Type: text/html\r\n"

+ "Content-Length: "+size+"\r\n" + "\r\n";

byte[] headbytes = head.getBytes();

output.write(headbytes,0,headbytes.length);

for(byte[] contentbyte:contentbytes) {

output.write(contentbyte);

}

} else {

// file not found

String errorMessage = "HTTP/1.1 404 File Not Found\r\n" + "Content-Type: text/html\r\n"

+ "Content-Length: 23\r\n" + "\r\n" + "

File Not Found

";

output.write(errorMessage.getBytes());

}

} catch (Exception e) {

// thrown if cannot instantiate a File object

System.out.println(e.toString());

} finally {

if (fis != null)

fis.close();

}

}

}

简单页面

Hello,this is your own Page!

Everything is Simple!

效果

启动服务

发送请求

返回正文

Hello,this is your own Page!

Everything is Simple!

参考文档