?HttpServer
package com.whatsmars.tomcat.servlet;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
/**
* Created by shenhongxi on 16/3/21.
*/
public class HttpServer {
private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
private boolean shutdown = false;
public static void main(String[] args) {
HttpServer server = new HttpServer();
server.await();
}
private void await() {
ServerSocket serverSocket = null;
int port = 8080;
try {
serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));
System.out.println("Server started!");
} 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);
// check if this is a request for a servlet or a static resource
if (request.getUri().startsWith("/servlet/")) {
ServletProcessor processor = new ServletProcessor();
processor.process(request, response);
} else {
StaticResourceProcessor processor = new StaticResourceProcessor();
processor.process(request, response);
}
socket.close();
shutdown = request.getUri().equals(SHUTDOWN_COMMAND);
} catch (Exception e) {
e.printStackTrace();
continue;
}
}
}
}
? Request
package com.whatsmars.tomcat.servlet;
import javax.servlet.*;
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;
/**
* Created by shenhongxi on 16/3/21.
*/
public class Request implements ServletRequest {
private InputStream input;
private String uri; // 性能考虑，用byte[]
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());
}
private String parseUri(String requestStr) {
// GET /index.html HTTP/1.1
// Accept: text/plain; text/html
// ...
int index1 = requestStr.indexOf(‘ ‘);
int index2;
if (index1 != -1) {
index2 = requestStr.indexOf(‘ ‘, index1 + 1);
if (index2 > index1) {
return requestStr.substring(index1 + 1, index2);
}
}
return null;
}
public String getUri() {
return uri;
}
public Object getAttribute(String name) {
return null;
}
public Enumeration<String> getAttributeNames() {
return null;
}
public String getCharacterEncoding() {
return null;
}
public void setCharacterEncoding(String env) throws UnsupportedEncodingException {
}
public int getContentLength() {
return 0;
}
}
?Response
package com.whatsmars.tomcat.servlet;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletResponse;
import java.io.*;
import java.util.Locale;
/**
* Created by shenhongxi on 16/3/21.
*/
public class Response implements ServletResponse {
private static final int BUFFER_SIZE = 1024;
Request request;
OutputStream output;
PrintWriter writer;
public void sendStaticResource() throws IOException {
byte[] bytes = new byte[BUFFER_SIZE];
FileInputStream fis = null;
try {
File file = new File(Constants.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 errorMsg = "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(errorMsg.getBytes());
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (fis != null) {
fis.close();
}
}
}
public Response(OutputStream output) {
this.output = output;
}
public void setRequest(Request request) {
this.request = request;
}
public String getCharacterEncoding() {
return null;
}
public String getContentType() {
return null;
}
public ServletOutputStream getOutputStream() throws IOException {
return null;
}
public PrintWriter getWriter() throws IOException {
// autoflush is true, println() will flush, but print() will not
writer = new PrintWriter(output, true);
return writer;
}
}
?RequestFacade
package com.whatsmars.tomcat.servlet;
import javax.servlet.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;
/**
* Created by shenhongxi on 2016/4/12.
*/
public class RequestFacade implements ServletRequest {
private ServletRequest request;
public RequestFacade(Request request) {
this.request = request;
}
public Object getAttribute(String name) {
return request.getAttribute(name);
}
public Enumeration<String> getAttributeNames() {
return request.getAttributeNames();
}
}
?ResponseFacade
package com.whatsmars.tomcat.servlet;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Locale;
/**
* Created by shenhongxi on 2016/4/12.
*/
public class ResponseFacade implements ServletResponse {
private ServletResponse response;
public ResponseFacade(Response response) {
this.response = response;
}
public String getCharacterEncoding() {
return response.getCharacterEncoding();
}
public String getContentType() {
return null;
}
public ServletOutputStream getOutputStream() throws IOException {
return null;
}
public PrintWriter getWriter() throws IOException {
return response.getWriter();
}
}
?ServletProcessor
package com.whatsmars.tomcat.servlet;
import javax.servlet.Servlet;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLStreamHandler;
/**
* Created by shenhongxi on 2016/4/12.
*/
public class ServletProcessor {
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) {
E.printStackTrace();
}
Class myClass = null;
try {
myClass = loader.loadClass(servletName);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
Servlet servlet = null;
try {
servlet = (Servlet) myClass.newInstance();
RequestFacade requestFacade = new RequestFacade(request);
ResponseFacade responseFacade = new ResponseFacade(response);
// 为了安全考虑，除了实现ServletRequest/ServletResponse的方法，
// Request/Response中的其他公共方法需对servlet隐藏，所以用外观类
servlet.service((ServletRequest) requestFacade, (ServletResponse) responseFacade);
} catch (Exception e) {
e.printStackTrace();
} catch (Throwable e) {
e.printStackTrace();
}
}
}
?StaticResourceProcessor
package com.whatsmars.tomcat.servlet;
import java.io.IOException;
/**
* Created by shenhongxi on 2016/4/12.
*/
public class StaticResourceProcessor {
public void process(Request request, Response response) {
try {
response.sendStaticResource();
} catch (IOException e) {
e.printStackTrace();
}
}
}
? PrimitiveServlet
package com.whatsmars.tomcat.servlet;
import javax.servlet.*;
import java.io.IOException;
import java.io.PrintWriter;
/**
* Created by shenhongxi on 2016/4/12.
*/
public class PrimitiveServlet implements Servlet {
public void init(ServletConfig config) throws ServletException {
System.out.println("init");
}
public ServletConfig getServletConfig() {
return null;
}
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
System.out.println("from service");
PrintWriter out = res.getWriter();
out.println("Hello. Roses are red.");
out.print("Violets are blue");
}
public String getServletInfo() {
return null;
}
public void destroy() {
System.out.println("destroy");
}
}
? Constants
package com.whatsmars.tomcat.servlet;
import java.io.File;
/**
* Created by shenhongxi on 2016/4/12.
*/
public class Constants {
public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "whatsmars-tomcat/src/main/webapp"; // 资源文件，class文件等
}
?
原文：http://wely.iteye.com/blog/2290575