简单实现Java web服务器

一个简单的java web服务器实现，比较简单，基于java.net.socket和java.net.serversocket实现；
一、程序执行步骤
 1.创建一个serversocket对象；
 2.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；
 3.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；
 4.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;
 5.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；
 6.关闭socket对象；
 7.转到步骤2，继续等待连接请求； 

二、代码实现

 服务器实现： 

package ex01.pyrmont;

import java.net.socket;
import java.net.serversocket;
import java.net.inetaddress;
import java.io.inputstream;
import java.io.outputstream;
import java.io.ioexception;
import java.io.file;

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webroot目录
 */
 public static final string web_root = system.getproperty("user.dir") + file.separator + "webroot";

 // 关闭服务命令
 private static final string shutdown_command = "/shutdown";

 public static void main(string[] args) {
 httpserver server = new httpserver();
 //等待连接请求
 server.await();
 }

 public void await() {
 serversocket serversocket = null;
 int port = 8080;
 try {
  //服务器套接字对象
  serversocket = new serversocket(port, 1, inetaddress.getbyname("127.0.0.1"));
 } catch (ioexception e) {
  e.printstacktrace();
  system.exit(1);
 }

 // 循环等待一个请求
 while (true) {
  socket socket = null;
  inputstream input = null;
  outputstream output = null;
  try {
  //等待连接，连接成功后，返回一个socket对象
  socket = serversocket.accept();
  input = socket.getinputstream();
  output = socket.getoutputstream();

  // 创建request对象并解析
  request request = new request(input);
  request.parse();
  // 检查是否是关闭服务命令
  if (request.geturi().equals(shutdown_command)) {
   break;
  }

  // 创建 response 对象
  response response = new response(output);
  response.setrequest(request);
  response.sendstaticresource();

  // 关闭 socket 对象
  socket.close();
  
  } catch (exception e) {
  e.printstacktrace();
  continue;
  }
 }
 }
}

request类： 

package ex01.pyrmont;

import java.io.inputstream;
import java.io.ioexception;

public class request {

 private inputstream input;
 private string uri;

 public request(inputstream input) {
 this.input = input;
 }

 //从inputstream中读取request信息，并从request中获取uri值
 public void parse() {
 stringbuffer request = new stringbuffer(2048);
 int i;
 byte[] buffer = new byte[2048];
 try {
  i = input.read(buffer);
 } catch (ioexception e) {
  e.printstacktrace();
  i = -1;
 }
 for (int j = 0; j < i; j++) {
  request.append((char) buffer[j]);
 }
 system.out.print(request.tostring());
 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
 * ...
 * 该函数目的就是为了获取/index.html字符串
 */
 private string parseuri(string requeststring) {
 int index1, index2;
 index1 = requeststring.indexof(' ');
 if (index1 != -1) {
  index2 = requeststring.indexof(' ', index1 + 1);
  if (index2 > index1)
  return requeststring.substring(index1 + 1, index2);
 }
 return null;
 }

 public string geturi() {
 return uri;
 }

}

response类：

 package ex01.pyrmont;

import java.io.outputstream;
import java.io.ioexception;
import java.io.fileinputstream;
import java.io.file;

/*
 http response = status-line
 *(( general-header | response-header | entity-header ) crlf)
 crlf
 [ message-body ]
 status-line = http-version sp status-code sp reason-phrase crlf
*/

public class response {

 private static final int buffer_size = 1024;
 request request;
 outputstream output;

 public response(outputstream output) {
 this.output = output;
 }

 public void setrequest(request request) {
 this.request = request;
 }

 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);
  int ch = fis.read(bytes, 0, buffer_size);
  while (ch != -1) {
   output.write(bytes, 0, ch);
   ch = fis.read(bytes, 0, buffer_size);
  }
  } 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" + "<h1>file not found</h1>";
  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();
 }
 }
}

三、结果测试

访问存在的资源文件(注意存放在工程目录的webroot文件夹里)：

访问不存在的资源文件：

关闭服务器：

参考资料：《深入剖析tomcat》

@author   风一样的码农

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