Java tutorial
/* This file is part of Cyclos (www.cyclos.org). A project of the Social Trade Organisation (www.socialtrade.org). Cyclos is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. Cyclos is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Cyclos; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ package nl.strohalm.cyclos.http; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.FileReader; import java.io.IOException; import java.io.OutputStream; import java.io.PrintWriter; import java.util.ArrayList; import java.util.HashSet; import java.util.List; import java.util.Locale; import java.util.Set; import javax.servlet.ServletOutputStream; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServletResponse; import org.apache.commons.io.IOUtils; import org.apache.commons.lang.exception.NestableRuntimeException; /** * An {@link HttpServletResponse} which wraps another response, keeping track of changes. Any changes can be applied or reset. * @author luis */ @SuppressWarnings("deprecation") public class ResettableHttpServletResponse implements HttpServletResponse, Resettable { private interface ResponseOperation { void apply(); } private HttpServletResponse wrapped; private List<ResponseOperation> operations; private Locale locale; private int bufferSize; private String contentType; private String charset; private PrintWriter writer; private OutputStream outputStream; private ServletOutputStream servletOutputStream; private File contents; private Set<String> headerNames; private Integer status; private boolean stateApplied; public ResettableHttpServletResponse(final HttpServletResponse response) { wrapped = response; operations = new ArrayList<ResponseOperation>(); headerNames = new HashSet<String>(); resetState(); } @Override public void addCookie(final Cookie cookie) { operations.add(new ResponseOperation() { @Override public void apply() { wrapped.addCookie(cookie); } }); } @Override public void addDateHeader(final String name, final long date) { operations.add(new ResponseOperation() { @Override public void apply() { wrapped.addDateHeader(name, date); } }); } @Override public void addHeader(final String name, final String value) { operations.add(new ResponseOperation() { @Override public void apply() { wrapped.addHeader(name, value); } }); } @Override public void addIntHeader(final String name, final int value) { operations.add(new ResponseOperation() { @Override public void apply() { wrapped.addIntHeader(name, value); } }); } @Override public void applyState() { try { // Apply all operations for (final ResponseOperation operation : operations) { operation.apply(); } // Copy the response contents, if any if (outputStream != null) { try { outputStream.flush(); IOUtils.copy(new FileInputStream(contents), wrapped.getOutputStream()); } catch (final Exception e) { throw new NestableRuntimeException(e); } } else if (writer != null) { try { writer.flush(); IOUtils.copy(new FileReader(contents), wrapped.getWriter()); } catch (final Exception e) { throw new NestableRuntimeException(e); } } stateApplied = true; } finally { reset(); } } @Override public boolean containsHeader(final String name) { return headerNames.contains(name); } @Override public String encodeRedirectUrl(final String url) { return wrapped.encodeRedirectUrl(url); } @Override public String encodeRedirectURL(final String url) { return wrapped.encodeRedirectURL(url); } @Override public String encodeUrl(final String url) { return wrapped.encodeUrl(url); } @Override public String encodeURL(final String url) { return wrapped.encodeURL(url); } @Override public void flushBuffer() throws IOException { // No-op, as nothing has been done in the real response } @Override public int getBufferSize() { return bufferSize; } @Override public String getCharacterEncoding() { return charset; } @Override public String getContentType() { return contentType; } @Override public Locale getLocale() { return locale; } @Override public ServletOutputStream getOutputStream() throws IOException { if (writer != null) { throw new IllegalStateException("getWriter() was already invoked in this response"); } if (servletOutputStream == null) { contents = File.createTempFile("cyclos_", "_response"); outputStream = new FileOutputStream(contents); servletOutputStream = new ServletOutputStream() { @Override public void close() throws IOException { outputStream.close(); } @Override public void flush() throws IOException { outputStream.flush(); } @Override public void write(final byte[] b) throws IOException { outputStream.write(b); } @Override public void write(final byte[] b, final int off, final int len) throws IOException { outputStream.write(b, off, len); } @Override public void write(final int b) throws IOException { outputStream.write(b); } }; } return servletOutputStream; } public Integer getStatus() { return status; } @Override public PrintWriter getWriter() throws IOException { if (outputStream != null) { throw new IllegalStateException("getOutputStream() was already invoked"); } if (writer == null) { contents = File.createTempFile("cyclos_", "_response"); writer = new PrintWriter(contents); } return writer; } @Override public boolean isCommitted() { if (!stateApplied) { return false; } return wrapped.isCommitted(); } @Override public void reset() { resetState(); } @Override public void resetBuffer() { IOUtils.closeQuietly(outputStream); IOUtils.closeQuietly(writer); outputStream = null; servletOutputStream = null; writer = null; if (contents != null) { contents.delete(); contents = null; } } @Override public void resetState() { status = null; operations.clear(); headerNames.clear(); charset = wrapped.getCharacterEncoding(); bufferSize = wrapped.getBufferSize(); contentType = wrapped.getContentType(); locale = wrapped.getLocale(); resetBuffer(); } @Override public void sendError(final int sc) { status = sc; operations.add(new ResponseOperation() { @Override public void apply() { try { wrapped.sendError(sc); } catch (final IOException e) { throw new NestableRuntimeException(e); } } }); } @Override public void sendError(final int sc, final String msg) throws IOException { status = sc; operations.add(new ResponseOperation() { @Override public void apply() { try { wrapped.sendError(sc, msg); } catch (final IOException e) { throw new NestableRuntimeException(e); } } }); } @Override public void sendRedirect(final String location) throws IOException { operations.add(new ResponseOperation() { @Override public void apply() { try { wrapped.sendRedirect(location); } catch (final IOException e) { throw new NestableRuntimeException(e); } } }); } @Override public void setBufferSize(final int bufferSize) { this.bufferSize = bufferSize; operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setBufferSize(bufferSize); } }); } @Override public void setCharacterEncoding(final String charset) { this.charset = charset; operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setCharacterEncoding(charset); } }); } @Override public void setContentLength(final int len) { operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setContentLength(len); } }); } @Override public void setContentType(final String contentType) { this.contentType = contentType; operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setContentType(contentType); } }); } @Override public void setDateHeader(final String name, final long date) { operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setDateHeader(name, date); } }); } @Override public void setHeader(final String name, final String value) { operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setHeader(name, value); } }); } @Override public void setIntHeader(final String name, final int value) { operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setIntHeader(name, value); } }); } @Override public void setLocale(final Locale locale) { this.locale = locale; operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setLocale(locale); } }); } @Override public void setStatus(final int sc) { status = sc; operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setStatus(sc); } }); } @Override public void setStatus(final int sc, final String sm) { status = sc; operations.add(new ResponseOperation() { @Override public void apply() { wrapped.setStatus(sc, sm); } }); } }