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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.bcel.classfile;
import java.io.DataInput;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import org.apache.bcel.Const;
/**
* This class is derived from the abstract {@link Constant}
* and represents a reference to a Utf8 encoded string.
*
* @version $Id$
* @see Constant
*/
public final class ConstantUtf8 extends Constant {
private final String bytes;
// TODO these should perhaps be AtomicInt?
private static volatile int considered = 0;
private static volatile int hits = 0;
private static volatile int skipped = 0;
private static volatile int created = 0;
// Set the size to 0 or below to skip caching entirely
private static final int MAX_CACHED_SIZE =
Integer.getInteger("bcel.maxcached.size", 200).intValue();// CHECKSTYLE IGNORE MagicNumber
private static final boolean BCEL_STATISTICS = Boolean.getBoolean("bcel.statistics");
private static class CACHE_HOLDER {
private static final int MAX_CACHE_ENTRIES = 20000;
private static final int INITIAL_CACHE_CAPACITY = (int)(MAX_CACHE_ENTRIES/0.75);
private static final HashMap<String, ConstantUtf8> CACHE =
new LinkedHashMap<String, ConstantUtf8>(INITIAL_CACHE_CAPACITY, 0.75f, true) {
private static final long serialVersionUID = -8506975356158971766L;
@Override
protected boolean removeEldestEntry(final Map.Entry<String, ConstantUtf8> eldest) {
return size() > MAX_CACHE_ENTRIES;
}
};
}
// for accesss by test code
static void printStats() {
System.err.println("Cache hit " + hits + "/" + considered +", " + skipped + " skipped");
System.err.println("Total of " + created + " ConstantUtf8 objects created");
}
// for accesss by test code
static void clearStats() {
hits = considered = skipped = created = 0;
}
static {
if (BCEL_STATISTICS) {
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
printStats();
}
});
}
}
/**
* @since 6.0
*/
public static ConstantUtf8 getCachedInstance(final String s) {
if (s.length() > MAX_CACHED_SIZE) {
skipped++;
return new ConstantUtf8(s);
}
considered++;
synchronized (ConstantUtf8.class) { // might be better with a specific lock object
ConstantUtf8 result = CACHE_HOLDER.CACHE.get(s);
if (result != null) {
hits++;
return result;
}
result = new ConstantUtf8(s);
CACHE_HOLDER.CACHE.put(s, result);
return result;
}
}
/**
* @since 6.0
*/
public static ConstantUtf8 getInstance(final String s) {
return new ConstantUtf8(s);
}
/**
* @since 6.0
*/
public static ConstantUtf8 getInstance (final DataInput input) throws IOException {
return getInstance(input.readUTF());
}
/**
* Initialize from another object.
*/
public ConstantUtf8(final ConstantUtf8 c) {
this(c.getBytes());
}
/**
* Initialize instance from file data.
*
* @param file Input stream
* @throws IOException
*/
ConstantUtf8(final DataInput file) throws IOException {
super(Const.CONSTANT_Utf8);
bytes = file.readUTF();
created++;
}
/**
* @param bytes Data
*/
public ConstantUtf8(final String bytes) {
super(Const.CONSTANT_Utf8);
if (bytes == null) {
throw new IllegalArgumentException("bytes must not be null!");
}
this.bytes = bytes;
created++;
}
/**
* Called by objects that are traversing the nodes of the tree implicitely
* defined by the contents of a Java class. I.e., the hierarchy of methods,
* fields, attributes, etc. spawns a tree of objects.
*
* @param v Visitor object
*/
@Override
public void accept( final Visitor v ) {
v.visitConstantUtf8(this);
}
/**
* Dump String in Utf8 format to file stream.
*
* @param file Output file stream
* @throws IOException
*/
@Override
public final void dump( final DataOutputStream file ) throws IOException {
file.writeByte(super.getTag());
file.writeUTF(bytes);
}
/**
* @return Data converted to string.
*/
public final String getBytes() {
return bytes;
}
/**
* @param bytes the raw bytes of this Utf-8
* @deprecated (since 6.0)
*/
@java.lang.Deprecated
public final void setBytes( final String bytes ) {
throw new UnsupportedOperationException();
}
/**
* @return String representation
*/
@Override
public final String toString() {
return super.toString() + "(\"" + Utility.replace(bytes, "\n", "\\n") + "\")";
}
}
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