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EE4J Compatible Implementation for Jakarta Faces API
/*
* Copyright (c) 1997, 2021 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package com.sun.faces.application.view;
import static jakarta.faces.application.StateManager.IS_SAVING_STATE;
import static java.lang.Boolean.TRUE;
import java.io.IOException;
import java.io.Writer;
import java.util.Map;
import com.sun.faces.RIConstants;
import com.sun.faces.io.FastStringWriter;
import com.sun.faces.util.Util;
import jakarta.faces.application.StateManager;
import jakarta.faces.context.FacesContext;
import jakarta.faces.context.ResponseWriter;
import jakarta.faces.view.ViewDeclarationLanguage;
/**
* Custom {@link Writer} to efficiently handle the state manager replacement marker written out by
* {@link MultiViewHandler#writeState(jakarta.faces.context.FacesContext)}.
*/
final class WriteBehindStateWriter extends Writer {
// length of the state marker
private static final int STATE_MARKER_LEN = RIConstants.SAVESTATE_FIELD_MARKER.length();
private static final ThreadLocal CUR_WRITER = new ThreadLocal<>();
private Writer out;
private Writer orig;
private FastStringWriter fWriter;
private boolean stateWritten;
private int bufSize;
private char[] buf;
private FacesContext context;
private Object state;
// -------------------------------------------------------- Constructors
/**
* Constructs a new WriteBehindStateWriter instance.
*
* @param out the writer we write non-buffered content to
* @param context the {@link FacesContext} for the current request
* @param bufSize the buffer size for post-processing buffered content
*/
public WriteBehindStateWriter(Writer out, FacesContext context, int bufSize) {
this.out = out;
orig = out;
this.context = context;
this.bufSize = bufSize;
buf = new char[bufSize];
CUR_WRITER.set(this);
}
// ------------------------------------------------- Methods from Writer
/**
* Writes directly to the current out.
*
* @see Writer#write(int)
*/
@Override
public void write(int c) throws IOException {
out.write(c);
}
/**
* Writes directly to the current out.
*
* @see Writer#write(char[])
*/
@Override
public void write(char cbuf[]) throws IOException {
out.write(cbuf);
}
/**
* Writes directly to the current out.
*
* @see Writer#write(String)
*/
@Override
public void write(String str) throws IOException {
out.write(str);
}
/**
* Writes directly to the current out.
*
* @see Writer#write(String, int, int)
*/
@Override
public void write(String str, int off, int len) throws IOException {
out.write(str, off, len);
}
/**
* Writes directly to the current out.
*
* @see Writer#write(char[], int, int)
*/
@Override
public void write(char cbuf[], int off, int len) throws IOException {
out.write(cbuf, off, len);
}
/**
* This is a no-op.
*/
@Override
public void flush() throws IOException {
// no-op
}
/**
* This is a no-op.
*/
@Override
public void close() throws IOException {
// no-op
}
// ------------------------------------------------------ Public Methods
/**
* @return the WriteBehindStateWriter being used for processing this request
*/
public static WriteBehindStateWriter getCurrentInstance() {
return CUR_WRITER.get();
}
/**
* Clear the ThreadLocal state.
*/
public void release() {
CUR_WRITER.remove();
}
/**
* When called, the original writer is backed up and replaced with a new FastStringWriter. All content written after
* this method is called will then be buffered and written out later after the entire view has been rendered.
*/
public void writingState() {
if (!stateWritten) {
stateWritten = true;
out = fWriter = new FastStringWriter(1024);
}
}
/**
* @return true if {@link #writingState()} has been called, otherwise returns false
*/
public boolean stateWritten() {
return stateWritten;
}
/**
*
* Write directly from our FastStringWriter to the provided writer.
*
*
* @throws IOException if an error occurs
*/
public void flushToWriter() throws IOException {
// Save the state to a new instance of StringWriter to
// avoid multiple serialization steps if the view contains
// multiple forms.
StateManager stateManager = Util.getStateManager(context);
ResponseWriter origWriter = context.getResponseWriter();
StringBuilder stateBuilder = getState(stateManager, origWriter);
StringBuilder builder = fWriter.getBuffer();
// Begin writing...
int totalLen = builder.length();
int stateLen = stateBuilder.length();
int pos = 0;
int tildeIdx = getNextDelimiterIndex(builder, pos);
while (pos < totalLen) {
if (tildeIdx != -1) {
if (tildeIdx > pos && tildeIdx - pos > bufSize) {
// There's enough content before the first ~
// to fill the entire buffer
builder.getChars(pos, pos + bufSize, buf, 0);
orig.write(buf);
pos += bufSize;
} else {
// Write all content up to the first '~'
builder.getChars(pos, tildeIdx, buf, 0);
int len = tildeIdx - pos;
orig.write(buf, 0, len);
// Now check to see if the state saving string is
// at the begining of pos, if so, write our
// state out.
if (builder.indexOf(RIConstants.SAVESTATE_FIELD_MARKER, pos) == tildeIdx) {
// buf is effectively zero'd out at this point
int statePos = 0;
while (statePos < stateLen) {
if (stateLen - statePos > bufSize) {
// enough state to fill the buffer
stateBuilder.getChars(statePos, statePos + bufSize, buf, 0);
orig.write(buf);
statePos += bufSize;
} else {
int slen = stateLen - statePos;
stateBuilder.getChars(statePos, stateLen, buf, 0);
orig.write(buf, 0, slen);
statePos += slen;
}
}
// Push us past the last '~' at the end of the marker
pos += len + STATE_MARKER_LEN;
tildeIdx = getNextDelimiterIndex(builder, pos);
stateBuilder = getState(stateManager, origWriter);
stateLen = stateBuilder.length();
} else {
pos = tildeIdx;
tildeIdx = getNextDelimiterIndex(builder, tildeIdx + 1);
}
}
} else {
// We've written all of the state field markers.
// finish writing content
if (totalLen - pos > bufSize) {
// There's enough content to fill the buffer
builder.getChars(pos, pos + bufSize, buf, 0);
orig.write(buf);
pos += bufSize;
} else {
// We're near the end of the response
builder.getChars(pos, totalLen, buf, 0);
int len = totalLen - pos;
orig.write(buf, 0, len);
pos += len + 1;
}
}
}
// all state has been written. Have 'out' point to the
// response so that all subsequent writes will make it to the
// browser.
out = orig;
}
/**
* Get the state.
*
*
* In Faces it is required by the specification that the view state hidden input in each h:form has a unique id. So we
* have to call this method multiple times as each h:form needs to generate the element id for itself.
*
*
* @param stateManager the state manager.
* @param origWriter the original response writer.
* @return the state.
* @throws IOException when an I/O error occurs.
*/
private StringBuilder getState(StateManager stateManager, ResponseWriter origWriter) throws IOException {
FastStringWriter stateWriter = new FastStringWriter(stateManager.isSavingStateInClient(context) ? bufSize : 128);
context.setResponseWriter(origWriter.cloneWithWriter(stateWriter));
if (state == null) {
String viewId = context.getViewRoot().getViewId();
ViewDeclarationLanguage vdl = context.getApplication().getViewHandler().getViewDeclarationLanguage(context, viewId);
if (vdl != null) {
Map contextAttributes = context.getAttributes();
try {
contextAttributes.put(IS_SAVING_STATE, TRUE);
state = vdl.getStateManagementStrategy(context, viewId)
.saveView(context);
} finally {
contextAttributes.remove(IS_SAVING_STATE);
}
}
}
stateManager.writeState(context, state);
context.setResponseWriter(origWriter);
return stateWriter.getBuffer();
}
/**
* @param builder buffered content
* @param offset the offset to start the search from
* @return the index of the next delimiter, if any
*/
private static int getNextDelimiterIndex(StringBuilder builder, int offset) {
return builder.indexOf(RIConstants.SAVESTATE_FIELD_DELIMITER, offset);
}
}