/*
* Copyright 2009-2012 the original author or authors.
*
* 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 i 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 net.paoding.rose.jade.statement.cached;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import net.paoding.rose.jade.annotation.Cache;
import net.paoding.rose.jade.annotation.CacheDelete;
import net.paoding.rose.jade.annotation.SQLType;
import net.paoding.rose.jade.statement.Statement;
import net.paoding.rose.jade.statement.StatementMetaData;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanWrapperImpl;
/**
* {@link CachedStatement} 封装了支持Cache的逻辑
*
* @author qieqie.wang
*
*/
public class CachedStatement implements Statement {
/**
* 实际底层Statemenet，比如就是数据库操作的实际执行语句
*/
private final Statement realStatement;
/**
* 注解在DAO方法上的 {@link Cache}，如果没有则为null
* <p>
* 仅在该语句为查询语句时侯此有效，即如果某个更新语句的DAO方法上也注解了 {@link Cache} 在这里也仍保留null
*/
private final Cache cacheAnnotation;
/**
* 注解在该语句上的 {@link CacheDelete}，如果没有则为null
* <p>
*
* 可使用在各种语句上，甚至事查询语句上(很悲剧的：我也不知道为何有这种用法，执行一次查询还会附带删除神马Cache的啊？真的有吗？)
*/
private final CacheDelete cacheDeleteAnnotation;
/**
* cache服务接口
*/
private final CacheProvider cacheProvider;
/**
*
* @param cacheProvider
* @param realStatement
*/
public CachedStatement(CacheProvider cacheProvider, Statement realStatement) {
this.realStatement = realStatement;
this.cacheProvider = cacheProvider;
StatementMetaData metaData = realStatement.getMetaData();
SQLType sqlType = metaData.getSQLType();
cacheDeleteAnnotation = metaData.getMethod().getAnnotation(CacheDelete.class);
Cache cacheAnnotation = metaData.getMethod().getAnnotation(Cache.class);
if (sqlType == SQLType.READ) {
this.cacheAnnotation = cacheAnnotation;
} else {
this.cacheAnnotation = null;
if (cacheAnnotation != null) {
Log logger = LogFactory.getLog(CachedStatement.class);
logger.warn("@" + Cache.class.getName() + " is invalid for a " //
+ sqlType + " SQL:" + metaData.getSQL());
}
}
}
@Override
public StatementMetaData getMetaData() {
return realStatement.getMetaData();
}
@Override
public Object execute(Map<String, Object> parameters) {
Object value = null;
if (cacheAnnotation == null) {
value = realStatement.execute(parameters);
} else {
CacheInterface cache = cacheProvider.getCacheByPool(//
getMetaData(), cacheAnnotation.pool());
String cacheKey = buildKey(cacheAnnotation.key(), parameters);
value = cache.get(cacheKey);
if (value == null) {
value = realStatement.execute(parameters);
cache.set(cacheKey, value, cacheAnnotation.expiry());
}
}
if (cacheDeleteAnnotation != null) {
CacheInterface cache = cacheProvider.getCacheByPool(//
getMetaData(), cacheDeleteAnnotation.pool());
for (String key : cacheDeleteAnnotation.key()) {
String cacheKey = buildKey(key, parameters);
cache.delete(cacheKey);
}
}
return value;
}
// 参数的模板
private static final Pattern PATTERN = Pattern.compile("\\:([a-zA-Z0-9_\\.]*)");
/**
* 查找模板 KEY 中所有的 :name, :name.property 参数替换成实际值。
*
* @param key - 作为模板的 KEY
* @param parameters - 传入的参数
*
* @return 最终的缓存 KEY
* @author 廖涵 in355hz@gmail.com
*/
private static String buildKey(String key, Map<String, Object> parameters) {
// 匹配符合 :name 格式的参数
Matcher matcher = PATTERN.matcher(key);
if (matcher.find()) {
StringBuilder builder = new StringBuilder();
int index = 0;
do {
// 提取参数名称
final String name = matcher.group(1).trim();
Object value = null;
// 解析 a.b.c 类型的名称
int find = name.indexOf('.');
if (find >= 0) {
// 用 BeanWrapper 获取属性值
Object bean = parameters.get(name.substring(0, find));
if (bean != null) {
value = new BeanWrapperImpl(bean)
.getPropertyValue(name.substring(find + 1));
}
} else {
// 获取参数值
value = parameters.get(name);
}
// 拼装参数值
builder.append(key.substring(index, matcher.start()));
builder.append(value);
index = matcher.end();
} while (matcher.find());
// 拼装最后一段
builder.append(key.substring(index));
return builder.toString();
}
return key;
}
}