org.apache.tomcat.util.bcel.classfile.ConstantUtf8 Maven / Gradle / Ivy
/*
* 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.tomcat.util.bcel.classfile;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import org.apache.tomcat.util.bcel.Constants;
/**
* This class is derived from the abstract
* Constant class
* and represents a reference to a Utf8 encoded string.
*
* @author M. Dahm
* @see Constant
*/
public final class ConstantUtf8 extends Constant {
private static final long serialVersionUID = 8119001312020421976L;
private final String bytes;
private static final int MAX_CACHE_ENTRIES = 20000;
private static final int INITIAL_CACHE_CAPACITY = (int)(MAX_CACHE_ENTRIES/0.75);
private static HashMap cache;
private static synchronized ConstantUtf8 getCachedInstance(String s) {
if (s.length() > 200) {
return new ConstantUtf8(s);
}
if (cache == null) {
cache = new LinkedHashMap(INITIAL_CACHE_CAPACITY, 0.75f, true) {
private static final long serialVersionUID = 1L;
@Override
protected boolean removeEldestEntry(Map.Entry eldest) {
return size() > MAX_CACHE_ENTRIES;
}
};
}
ConstantUtf8 result = cache.get(s);
if (result != null) {
return result;
}
result = new ConstantUtf8(s);
cache.put(s, result);
return result;
}
private static ConstantUtf8 getInstance(String s) {
return getCachedInstance(s);
}
static ConstantUtf8 getInstance(DataInputStream file) throws IOException {
return getInstance(file.readUTF());
}
/**
* Initialize instance from file data.
*
* @param file Input stream
* @throws IOException
*/
ConstantUtf8(DataInput file) throws IOException {
super(Constants.CONSTANT_Utf8);
bytes = file.readUTF();
}
/**
* @param bytes Data
*/
private ConstantUtf8(String bytes) {
super(Constants.CONSTANT_Utf8);
if (bytes == null) {
throw new IllegalArgumentException("bytes must not be null!");
}
this.bytes = bytes;
}
/**
* @return Data converted to string.
*/
public final String getBytes() {
return bytes;
}
}