深入剖析Tomcat-实现简单的Web服务器

在深入剖析Tomcat中，用socket实现了一个简单的服务器，服务器监听80端口，接受浏览器的请求，如果请求了静态资源，比如index.html,那么会将webroot下的静态文件index.html通过socket发送给浏览器

HttpServer程序

public class HttpServer {
//静态资源目录为webroot
public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator +"webroot";
private  static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
private  boolean shutdown = false;

public static void main(String[] args) {
System.out.println(System.getProperty("user.dir"));
HttpServer server = new HttpServer();
server.await();
}
public void await(){
int port =80;
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(port, 1,InetAddress.getByName("127.0.0.1"));
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
while(!shutdown){
Socket socket  = null;
InputStream input = null;
OutputStream out = null;
try{
socket = serverSocket.accept();
input = socket.getInputStream();
out = socket.getOutputStream();

Request request  = new Request(input);
request.parse();;
Response response = new Response(out);
response.setRequest(request);
response.sendStaticResource();
socket.close();
}catch (Exception e){
e.printStackTrace();

}
}

}

}

Request类，解析请求的url

public class Request {
private InputStream input;
private String uri;
public Request(InputStream input){
this.input = input;
}
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<i;j++){
request.append((char)buffer[j]);
}
System.out.print(request.toString());
uri = parseUri(request.toString());
}
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 this.uri;
}
}

Response类，返回数据到浏览器

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{
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 {
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){
System.out.println(e.toString());
}finally {
if(fis !=null){
fis.close();
}
}
}
}

服务器截图



浏览器截图



从上面的程序来看，浏览器发送的数据最终也是通过socket发送的，服务器程序监听端口，然后收到浏览器发送的头信息。然后吧index.html的内容用outputstream流发送到浏览器