深入剖析Tomcat-第二章：一个简单的servlet容器（1）
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内容：在上一章的基础上多了对servlet的处理，重点是ServletProcessor1这个类，利用到了URL、URLClassLoader(可以参看文档)和java反射机制。
webroot：
public class HttpServer1 {
private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
private boolean shutdown = false;
public 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 (Exception e) {
e.printStackTrace();
System.exit(1);
}
}
}
public static void main(String[] args) {
HttpServer1 server = new HttpServer1();
System.out.println("start");
server.await();
}
}
public class Request implements ServletRequest{
private InputStream input;
private String uri;
public Request(InputStream inputStream) {
this.input = inputStream;
}
public String getUri() {
return this.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 void parse() {
StringBuffer request = new StringBuffer(2048);
int i;
byte bytes[] = new byte[2048];
try {
i = input.read(bytes);
} catch (IOException e) {
e.printStackTrace();
i = -1;
}
for (int j = 0; j < i; j++)
request.append((char) bytes[j]);
System.out.print(request.toString());
uri = parseUri(request.toString());
}
@Override
public AsyncContext getAsyncContext() {
return null;
}
@Override
public Object getAttribute(String arg0) {
return null;
}
@Override
public Enumeration<String> getAttributeNames() {
return null;
}
@Override
public String getCharacterEncoding() {
return null;
}
@Override
public int getContentLength() {
return 0;
}
@Override
public long getContentLengthLong() {
return 0;
}
@Override
public String getContentType() {
return null;
}
@Override
public DispatcherType getDispatcherType() {
return null;
}
@Override
public ServletInputStream getInputStream() throws IOException {
return null;
}
@Override
public String getLocalAddr() {
return null;
}
@Override
public String getLocalName() {
return null;
}
@Override
public int getLocalPort() {
return 0;
}
@Override
public Locale getLocale() {
return null;
}
@Override
public Enumeration<Locale> getLocales() {
return null;
}
@Override
public String getParameter(String arg0) {
return null;
}
@Override
public Map<String, String[]> getParameterMap() {
return null;
}
@Override
public Enumeration<String> getParameterNames() {
return null;
}
@Override
public String[] getParameterValues(String arg0) {
return null;
}
@Override
public String getProtocol() {
return null;
}
@Override
public BufferedReader getReader() throws IOException {
return null;
}
@Override
public String getRealPath(String arg0) {
return null;
}
@Override
public String getRemoteAddr() {
return null;
}
@Override
public String getRemoteHost() {
return null;
}
@Override
public int getRemotePort() {
return 0;
}
@Override
public RequestDispatcher getRequestDispatcher(String arg0) {
return null;
}
@Override
public String getScheme() {
return null;
}
@Override
public String getServerName() {
return null;
}
@Override
public int getServerPort() {
return 0;
}
@Override
public ServletContext getServletContext() {
return null;
}
@Override
public boolean isAsyncStarted() {
return false;
}
@Override
public boolean isAsyncSupported() {
return false;
}
@Override
public boolean isSecure() {
return false;
}
@Override
public void removeAttribute(String arg0) {
}
@Override
public void setAttribute(String arg0, Object arg1) {
}
@Override
public void setCharacterEncoding(String arg0)
throws UnsupportedEncodingException {
}
@Override
public AsyncContext startAsync() throws IllegalStateException {
return null;
}
@Override
public AsyncContext startAsync(ServletRequest arg0, ServletResponse arg1)
throws IllegalStateException {
return null;
}
}
public class Response implements ServletResponse {
private static final int BUFFER_SIZE = 1024;
private Request request;
private OutputStream output;
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 {
File file = new File(Constants.WEB_ROOT, request.getUri());
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);
}
} 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();
}
}
@Override
public void flushBuffer() throws IOException {
// TODO Auto-generated method stub
}
@Override
public int getBufferSize() {
// TODO Auto-generated method stub
return 0;
}
@Override
public String getCharacterEncoding() {
// TODO Auto-generated method stub
return null;
}
@Override
public String getContentType() {
// TODO Auto-generated method stub
return null;
}
@Override
public Locale getLocale() {
// TODO Auto-generated method stub
return null;
}
@Override
public ServletOutputStream getOutputStream() throws IOException {
// TODO Auto-generated method stub
return null;
}
@Override
public PrintWriter getWriter() throws IOException {
writer = new PrintWriter(output, true);
return writer;
}
@Override
public boolean isCommitted() {
// TODO Auto-generated method stub
return false;
}
@Override
public void reset() {
// TODO Auto-generated method stub
}
@Override
public void resetBuffer() {
// TODO Auto-generated method stub
}
@Override
public void setBufferSize(int arg0) {
// TODO Auto-generated method stub
}
@Override
public void setCharacterEncoding(String arg0) {
// TODO Auto-generated method stub
}
@Override
public void setContentLength(int arg0) {
// TODO Auto-generated method stub
}
@Override
public void setContentLengthLong(long arg0) {
// TODO Auto-generated method stub
}
@Override
public void setContentType(String arg0) {
// TODO Auto-generated method stub
}
@Override
public void setLocale(Locale arg0) {
// TODO Auto-generated method stub
}
}
public class Constants {
public static final String WEB_ROOT =
System.getProperty("user.dir") + File.separator + "webroot";
}
public class StaticResourceProcessor {
public void process(Request request, Response response) {
try {
response.sendStaticResource();
} catch(IOException e) {
e.printStackTrace();
}
}
}
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());
}
}
}
原文：http://blog.csdn.net/u011345136/article/details/45268701
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