自己动手编写tomcat服务器(二)

上一篇博客《自己动手编写tomcat服务器(一)》并不完美，它只能支持请求静态文件，如hello.html,不能请求servlet文件，这篇将完善，同时支持这两种请求

应用包含以下文件：

HttpServer1

Request

Response

StaticResourceProcessor

ServletProcessor1

Constants

UML类图如下：



应用的入口是HttpServer1的main方法，它创建了一个HttpServer1的实例并调用它的await方法，这个方法等待HTTP请求，为每一个请求创建Request

对象和Response对象，然后根据请求的是静态文件还是一个servlet，把它们传给StaticResourceProcessor或ServletProcessor1的实例

如果请求的是静态文件，其路径为：http://machineName:port/staticResource

如果请求的是servlet，路径为：http://machineName:port/servlet/servletClass

HttpServer1的源码如下：

package ex02.pyrmont;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

public class HttpServer1 {
private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
private boolean shutdown = false;

public static void main(String[] args) {
HttpServer1 server = new HttpServer1();
server.await();
}

private void await() {
ServerSocket serverSocket = null;
int port = 8080;
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 output = null;
try{
socket = serverSocket.accept();
input = socket.getInputStream();
output = socket.getOutputStream();

Request request = new Request(input);
request.parse();

Response response = new Response(output);
response.setRequest(request);

if(request.getUri().startsWith("/servlet/")){
ServletProcessor1 processor = new ServletProcessor1();
processor.process(request,response);
}else{
StaticResourceProcessor processor = new StaticResourceProcessor();
processor.process(request,response);
}

socket.close();

shutdown = request.getUri().equals(SHUTDOWN_COMMAND);

}catch(IOException e){
e.printStackTrace();
System.exit(1);
}
}

}

}

Request类的源代码如下：

package ex02.pyrmont;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletRequest;

public class Request implements ServletRequest{

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(IOException e){
e.printStackTrace();
i = -1;
}
for(int j=0;j<i;j++){
request.append((char)buffer[j]);
}

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

uri = parseUri(request.toString());

}

public String getUri() {
return uri;
}

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 Object getAttribute(String arg0) {
// TODO Auto-generated method stub
return null;
}

public Enumeration getAttributeNames() {
// TODO Auto-generated method stub
return null;
}

public String getCharacterEncoding() {
// TODO Auto-generated method stub
return null;
}

public int getContentLength() {
// TODO Auto-generated method stub
return 0;
}

public String getContentType() {
// TODO Auto-generated method stub
return null;
}

public ServletInputStream getInputStream() throws IOException {
// TODO Auto-generated method stub
return null;
}

public String getLocalAddr() {
// TODO Auto-generated method stub
return null;
}

public String getLocalName() {
// TODO Auto-generated method stub
return null;
}

public int getLocalPort() {
// TODO Auto-generated method stub
return 0;
}

public Locale getLocale() {
// TODO Auto-generated method stub
return null;
}

public Enumeration getLocales() {
// TODO Auto-generated method stub
return null;
}

public String getParameter(String arg0) {
// TODO Auto-generated method stub
return null;
}

public Map getParameterMap() {
// TODO Auto-generated method stub
return null;
}

public Enumeration getParameterNames() {
// TODO Auto-generated method stub
return null;
}

public String[] getParameterValues(String arg0) {
// TODO Auto-generated method stub
return null;
}

public String getProtocol() {
// TODO Auto-generated method stub
return null;
}

public BufferedReader getReader() throws IOException {
// TODO Auto-generated method stub
return null;
}

public String getRealPath(String arg0) {
// TODO Auto-generated method stub
return null;
}

public String getRemoteAddr() {
// TODO Auto-generated method stub
return null;
}

public String getRemoteHost() {
// TODO Auto-generated method stub
return null;
}

public int getRemotePort() {
// TODO Auto-generated method stub
return 0;
}

public RequestDispatcher getRequestDispatcher(String arg0) {
// TODO Auto-generated method stub
return null;
}

public String getScheme() {
// TODO Auto-generated method stub
return null;
}

public String getServerName() {
// TODO Auto-generated method stub
return null;
}

public int getServerPort() {
// TODO Auto-generated method stub
return 0;
}

public boolean isSecure() {
// TODO Auto-generated method stub
return false;
}

public void removeAttribute(String arg0) {
// TODO Auto-generated method stub

}

public void setAttribute(String arg0, Object arg1) {
// TODO Auto-generated method stub

}

public void setCharacterEncoding(String arg0)
throws UnsupportedEncodingException {
// TODO Auto-generated method stub

}

}

Request类代表传递给Servlet的service方法的request对象，它实现了javax.servlet.ServletRequest接口

Response类的源代码如下：

package ex02.pyrmont;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Locale;

import javax.servlet.ServletOutputStream;
import javax.servlet.ServletResponse;

public class Response implements ServletResponse{
private static final int BUFFER_SIZE = 1024;
private OutputStream output;
private Request request;
private PrintWriter writer;

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 {
/* request.getUri has been replaced by request.getRequestURI */
File file = new File(Constants.WEB_ROOT, request.getUri());
fis = new FileInputStream(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
*/
int ch = fis.read(bytes, 0, BUFFER_SIZE);
while (ch != -1) {
output.write(bytes, 0, ch);
ch = fis.read(bytes, 0, BUFFER_SIZE);
}
} catch (FileNotFoundException e) {
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());
} finally {
if (fis != null)
fis.close();
}
}

public void flushBuffer() throws IOException {
// TODO Auto-generated method stub

}

public int getBufferSize() {
// TODO Auto-generated method stub
return 0;
}

public String getCharacterEncoding() {
// TODO Auto-generated method stub
return null;
}

public String getContentType() {
// TODO Auto-generated method stub
return null;
}

public Locale getLocale() {
// TODO Auto-generated method stub
return null;
}

public ServletOutputStream getOutputStream() throws IOException {
// TODO Auto-generated method stub
return null;
}

public PrintWriter getWriter() throws IOException {
writer = new PrintWriter(output,true);
return writer;
}

public boolean isCommitted() {
// TODO Auto-generated method stub
return false;
}

public void reset() {
// TODO Auto-generated method stub

}

public void resetBuffer() {
// TODO Auto-generated method stub

}

public void setBufferSize(int arg0) {
// TODO Auto-generated method stub

}

public void setCharacterEncoding(String arg0) {
// TODO Auto-generated method stub

}

public void setContentLength(int arg0) {
// TODO Auto-generated method stub

}

public void setContentType(String arg0) {
// TODO Auto-generated method stub

}

public void setLocale(Locale arg0) {
// TODO Auto-generated method stub

}

}

它实现了javax.servlet.ServletResponse接口，代表传递给servlet的service方法的response对象

StaticResourceProcessor的源代码如下：

package ex02.pyrmont;

import java.io.IOException;

public class StaticResourceProcessor {

public void process(Request request, Response response) {
try{
response.sendStaticResource();
}catch(IOException e){
e.printStackTrace();
}

}

}

它用来处理对静态资源的请求

ServletProcessor1的源码如下：

package ex02.pyrmont;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLStreamHandler;

import javax.servlet.Servlet;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class ServletProcessor1 {

public void process(Request request, Response response) {
String uri = request.getUri();
String servletName = uri.substring(uri.lastIndexOf("/") + 1);
URLClassLoader loader = null;
try{
URL[] urls = new URL[1];
URLStreamHandler streamHandler = null;
File classPath = new File(Constants.WEB_ROOT);
String repository = new URL("file",null,classPath.getCanonicalPath()+ File.separator).toString();
urls[0] = new URL(null,repository,streamHandler);
loader = new URLClassLoader(urls);
}catch(IOException e){
System.out.println(e.toString());
}

Class myClass = null;
try{
myClass = loader.loadClass(servletName);
}catch(ClassNotFoundException e){
System.out.println(e.toString());
}

Servlet servlet = null;
try{
servlet = (Servlet) myClass.newInstance();
servlet.service((ServletRequest)request, (ServletResponse)response);
}catch(Exception e){
System.out.println(e.toString());
}catch(Throwable e){
System.out.println(e.toString());
}

}

}

它用来处理对servlet的请求

Constants的源代码如下：

package ex02.pyrmont;

import java.io.File;

public class Constants {
public static final String WEB_ROOT =
System.getProperty("user.dir") + File.separator  + "webroot";
}

再写一个简单的servlet测试一下

PrimitiveServlet

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class PrimitiveServlet implements Servlet {

public void destroy() {
System.out.println("destroy");

}

public ServletConfig getServletConfig() {
// TODO Auto-generated method stub
return null;
}

public String getServletInfo() {
// TODO Auto-generated method stub
return null;
}

public void init(ServletConfig arg0) throws ServletException {
System.out.println("init");

}

public void service(ServletRequest arg0, ServletResponse arg1)
throws ServletException, IOException {
System.out.println("form service");
PrintWriter out = arg1.getWriter();
out.println("Hello,roses are red");
out.println("violets are blues");

}

}

将index.html和PrimitiveServlet编译后的class文件放入到webroot目录中，运行HttpServer1程序，在浏览器中输入：http://localhost:8080/index.html

或http://localhost:8080/servlet/PrimitiveServlet，将会看到结果