ほんの数行のコードでJDKとサーブレットapiだけでJ2EEサーブレットの基本的なサポートを提供するhttpserverを作成することが可能です。
これは、他の軽量コンテナよりも起動が速いため、サーブレットの単体テストに非常に役立つことがわかりました（生産には突堤を使用します）。
ほとんどの非常に軽量なhttpserverはサーブレットをサポートしていませんが、必要なので、共有したいと思いました。
以下の例は、基本的なサーブレットのサポート、またはまだ実装されていないものに対するスローとUnsupportedOperationExceptionを示しています。基本的なhttpサポートにcom.sun.net.httpserver.HttpServerを使用します。
import java.io.*;
import java.lang.reflect.*;
import java.net.InetSocketAddress;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;
@SuppressWarnings("deprecation")
public class VerySimpleServletHttpServer {
HttpServer server;
private String contextPath;
private HttpHandler httpHandler;
public VerySimpleServletHttpServer(String contextPath, HttpServlet servlet) {
this.contextPath = contextPath;
httpHandler = new HttpHandlerWithServletSupport(servlet);
}
public void start(int port) throws IOException {
InetSocketAddress inetSocketAddress = new InetSocketAddress(port);
server = HttpServer.create(inetSocketAddress, 0);
server.createContext(contextPath, httpHandler);
server.setExecutor(null);
server.start();
}
public void stop(int secondsDelay) {
server.stop(secondsDelay);
}
public int getServerPort() {
return server.getAddress().getPort();
}
}
final class HttpHandlerWithServletSupport implements HttpHandler {
private HttpServlet servlet;
private final class RequestWrapper extends HttpServletRequestWrapper {
private final HttpExchange ex;
private final Map<String, String[]> postData;
private final ServletInputStream is;
private final Map<String, Object> attributes = new HashMap<>();
private RequestWrapper(HttpServletRequest request, HttpExchange ex, Map<String, String[]> postData, ServletInputStream is) {
super(request);
this.ex = ex;
this.postData = postData;
this.is = is;
}
@Override
public String getHeader(String name) {
return ex.getRequestHeaders().getFirst(name);
}
@Override
public Enumeration<String> getHeaders(String name) {
return new Vector<String>(ex.getRequestHeaders().get(name)).elements();
}
@Override
public Enumeration<String> getHeaderNames() {
return new Vector<String>(ex.getRequestHeaders().keySet()).elements();
}
@Override
public Object getAttribute(String name) {
return attributes.get(name);
}
@Override
public void setAttribute(String name, Object o) {
this.attributes.put(name, o);
}
@Override
public Enumeration<String> getAttributeNames() {
return new Vector<String>(attributes.keySet()).elements();
}
@Override
public String getMethod() {
return ex.getRequestMethod();
}
@Override
public ServletInputStream getInputStream() throws IOException {
return is;
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(getInputStream()));
}
@Override
public String getPathInfo() {
return ex.getRequestURI().getPath();
}
@Override
public String getParameter(String name) {
String[] arr = postData.get(name);
return arr != null ? (arr.length > 1 ? Arrays.toString(arr) : arr[0]) : null;
}
@Override
public Map<String, String[]> getParameterMap() {
return postData;
}
@Override
public Enumeration<String> getParameterNames() {
return new Vector<String>(postData.keySet()).elements();
}
}
private final class ResponseWrapper extends HttpServletResponseWrapper {
final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
final ServletOutputStream servletOutputStream = new ServletOutputStream() {
@Override
public void write(int b) throws IOException {
outputStream.write(b);
}
};
private final HttpExchange ex;
private final PrintWriter printWriter;
private int status = HttpServletResponse.SC_OK;
private ResponseWrapper(HttpServletResponse response, HttpExchange ex) {
super(response);
this.ex = ex;
printWriter = new PrintWriter(servletOutputStream);
}
@Override
public void setContentType(String type) {
ex.getResponseHeaders().add("Content-Type", type);
}
@Override
public void setHeader(String name, String value) {
ex.getResponseHeaders().add(name, value);
}
@Override
public javax.servlet.ServletOutputStream getOutputStream() throws IOException {
return servletOutputStream;
}
@Override
public void setContentLength(int len) {
ex.getResponseHeaders().add("Content-Length", len + "");
}
@Override
public void setStatus(int status) {
this.status = status;
}
@Override
public void sendError(int sc, String msg) throws IOException {
this.status = sc;
if (msg != null) {
printWriter.write(msg);
}
}
@Override
public void sendError(int sc) throws IOException {
sendError(sc, null);
}
@Override
public PrintWriter getWriter() throws IOException {
return printWriter;
}
public void complete() throws IOException {
try {
printWriter.flush();
ex.sendResponseHeaders(status, outputStream.size());
if (outputStream.size() > 0) {
ex.getResponseBody().write(outputStream.toByteArray());
}
ex.getResponseBody().flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
ex.close();
}
}
}
public HttpHandlerWithServletSupport(HttpServlet servlet) {
this.servlet = servlet;
}
@SuppressWarnings("deprecation")
@Override
public void handle(final HttpExchange ex) throws IOException {
byte[] inBytes = getBytes(ex.getRequestBody());
ex.getRequestBody().close();
final ByteArrayInputStream newInput = new ByteArrayInputStream(inBytes);
final ServletInputStream is = new ServletInputStream() {
@Override
public int read() throws IOException {
return newInput.read();
}
};
Map<String, String[]> parsePostData = new HashMap<>();
try {
parsePostData.putAll(HttpUtils.parseQueryString(ex.getRequestURI().getQuery()));
// check if any postdata to parse
parsePostData.putAll(HttpUtils.parsePostData(inBytes.length, is));
} catch (IllegalArgumentException e) {
// no postData - just reset inputstream
newInput.reset();
}
final Map<String, String[]> postData = parsePostData;
RequestWrapper req = new RequestWrapper(createUnimplementAdapter(HttpServletRequest.class), ex, postData, is);
ResponseWrapper resp = new ResponseWrapper(createUnimplementAdapter(HttpServletResponse.class), ex);
try {
servlet.service(req, resp);
resp.complete();
} catch (ServletException e) {
throw new IOException(e);
}
}
private static byte[] getBytes(InputStream in) throws IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
while (true) {
int r = in.read(buffer);
if (r == -1)
break;
out.write(buffer, 0, r);
}
return out.toByteArray();
}
@SuppressWarnings("unchecked")
private static <T> T createUnimplementAdapter(Class<T> httpServletApi) {
class UnimplementedHandler implements InvocationHandler {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
throw new UnsupportedOperationException("Not implemented: " + method + ", args=" + Arrays.toString(args));
}
}
return (T) Proxy.newProxyInstance(UnimplementedHandler.class.getClassLoader(),
new Class<?>[] { httpServletApi },
new UnimplementedHandler());
}
}