/*
* Copyright (c) 2002-2012 Alibaba Group Holding Limited.
* All rights reserved.
*
* Licensed 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 com.alibaba.citrus.service.pull.support;
import static com.alibaba.citrus.util.Assert.*;
import static com.alibaba.citrus.util.CollectionUtil.*;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Map;
import com.alibaba.citrus.service.pull.ToolFactory;
import com.alibaba.citrus.util.ObjectUtil;
import com.alibaba.citrus.util.ToStringBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* 在模板中使用constant的tool。
* <p>
* 例如：<code>$myconstant.MY_CONSTANT</code>。
* </p>
*
* @author Michael Zhou
*/
public class ConstantTool implements ToolFactory {
private static final Logger log = LoggerFactory.getLogger(ConstantTool.class);
private Class<?> constantClass;
protected Map<String, Object> constants = createHashMap();
public Class<?> getConstantClass() {
return constantClass;
}
public void setConstantClass(Class<?> constantClass) {
this.constantClass = assertNotNull(constantClass, "constantClass");
log.trace("Introspecting constants in class {}", constantClass.getName());
Field[] fields = constantClass.getFields();
Map<String, Field> fieldsMap = createHashMap();
for (Field field : fields) {
int modifier = field.getModifiers();
// 取得public static final的常量。
if (Modifier.isPublic(modifier) && Modifier.isFinal(modifier) && Modifier.isStatic(modifier)) {
// 处理名称冲突，确保子类覆盖父类的常量。
if (fieldsMap.containsKey(field.getName())) {
Field existField = fieldsMap.get(field.getName());
if (existField.getDeclaringClass().isAssignableFrom(field.getDeclaringClass())) {
fieldsMap.put(field.getName(), field);
}
} else {
fieldsMap.put(field.getName(), field);
}
}
}
for (Field field : fieldsMap.values()) {
try {
Object value = field.get(null);
constants.put(field.getName(), field.get(null));
if (log.isTraceEnabled()) {
log.trace("Found constant: {}.{} = {}",
new Object[] { constantClass.getSimpleName(), field.getName(), ObjectUtil.toString(value) });
}
} catch (Exception e) {
unexpectedException(e, "failed to get constant: %s", field.getName());
}
}
}
public boolean isSingleton() {
return true;
}
public Object createTool() {
return this;
}
public Object get(String name) {
return constants.get(name);
}
@Override
public String toString() {
return new ToStringBuilder().append("Constant[")
.append(constantClass == null ? "" : constantClass.getSimpleName()).append("]").append(constants)
.toString();
}
}