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Comprehensive Java common library (Java7+)
/*
* Copyright (C) 2015-2018 S.Violet
*
* 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.
*
* Project GitHub: https://github.com/shepherdviolet/thistle
* Email: [email protected]
*/
package sviolet.thistle.x.common.thistlespi;
import sviolet.thistle.util.judge.CheckUtils;
import java.lang.reflect.Constructor;
import java.net.URL;
import java.util.Enumeration;
import java.util.Properties;
import static sviolet.thistle.x.common.thistlespi.Constants.*;
import static sviolet.thistle.x.common.thistlespi.ThistleSpi.PROPERTIES_URL;
class InstantiationUtils {
/**
* 类型实例化, 可包含一个String构造参数
* @param clazz 需要实例化的类
* @param arg 构造参数, null / String参数 / Properties文件名
* @param classLoader (用于加载构造参数应用的配置文件)类加载器
* @param configPath (用于加载构造参数应用的配置文件)配置文件根路径
* @param configUrl (用于加载构造参数应用的配置文件)服务/插件的配置文件URL
* @param logger (日志相关)日志打印器
* @param loaderId (日志相关)加载器ID
*/
static Object newInstance(Class clazz, String arg, ClassLoader classLoader, String configPath, URL configUrl, SpiLogger logger, int loaderId) throws Exception {
//constructors
Constructor[] constructors = clazz.getConstructors();
if (constructors.length != 1) {
throw new RuntimeException("ThistleSpi: Illegal Service/Plugin implementation " + clazz.getName() +
", the implementation must have one and only one public constructor, now it has " + constructors.length +
", definitions:" + configUrl);
}
//constructor
Constructor constructor = constructors[0];
//constructor parameter types
Class[] paramTypes = constructor.getParameterTypes();
if (paramTypes.length > 1) {
//invalid
throw new RuntimeException("ThistleSpi: Illegal Service/Plugin implementation " + clazz.getName() +
", the constructor can only have 0 or 1 parameter, now it has " + paramTypes.length +
", definitions:" + configUrl);
} else if (paramTypes.length == 0) {
//no parameter
return constructor.newInstance();
} else if (String.class.isAssignableFrom(paramTypes[0])){
//paramType length == 1 and is instance of String
return constructor.newInstance(arg);
} else if (Properties.class.isAssignableFrom(paramTypes[0])) {
//paramType length == 1 and is instance of Properties
if (CheckUtils.isEmptyOrBlank(arg)) {
//input empty Properties
if (LOG_LV >= DEBUG) {
logger.print(loaderId + LOG_PREFIX_LOADER + "The parameter type of constructor is java.util.Properties in " +
clazz.getName() + ", But no constructor arg defined in definitions:" + configPath);
}
return constructor.newInstance(new Properties());
}
return newInstanceForPropConstructor(clazz, arg, classLoader, configPath, configUrl, logger, loaderId, constructor);
} else {
//invalid
throw new RuntimeException("ThistleSpi: Illegal Service/Plugin implementation " + clazz.getName() +
", the parameter type of constructor must be java.lang.String or java.util.Properties, now it it " +
paramTypes[0].getName() + ", definitions:" + configUrl);
}
}
/**
* @param clazz 需要实例化的类
* @param arg 构造参数, null / String参数 / Properties文件名
* @param classLoader (用于加载构造参数应用的配置文件)类加载器
* @param configPath (用于加载构造参数应用的配置文件)配置文件根路径
* @param configUrl (用于加载构造参数应用的配置文件)服务/插件的配置文件URL
* @param logger (日志相关)日志打印器
* @param loaderId (日志相关)加载器ID
* @param constructor 构造器
*/
private static Object newInstanceForPropConstructor(Class clazz, String arg, ClassLoader classLoader, String configPath, URL configUrl, SpiLogger logger, int loaderId, Constructor constructor) throws Exception {
//find properties in the same package
//properties file path, e.g. parameter/hello.properties
String propertiesPath = CONFIG_PATH_PARAMETER + arg;
//config file url prefix
String urlPrefix = String.valueOf(configUrl);
urlPrefix = urlPrefix.substring(0, urlPrefix.lastIndexOf('/') + 1);
//find in classpath
Enumeration urls;
try {
urls = classLoader.getResources(configPath + propertiesPath);
} catch (Exception e) {
throw new RuntimeException("ThistleSpi: Error while finding properties for constructor of " + clazz.getName() +
", seeking " + propertiesPath + " in " + urlPrefix + ", definitions:" + configUrl, e);
}
if (urls == null || !urls.hasMoreElements()) {
throw new RuntimeException("ThistleSpi: Illegal Service/Plugin definition, the parameter type of constructor is java.util.Properties in " +
clazz.getName() + ", so you have to define a properties file at " + urlPrefix + propertiesPath + ", definitions:" + configUrl);
}
//find url starts with specified prefix
while (urls.hasMoreElements()) {
URL url = urls.nextElement();
if (String.valueOf(url).startsWith(urlPrefix)) {
//found
Properties properties;
try {
properties = new Properties();
properties.load(url.openStream());
} catch (Exception e) {
throw new RuntimeException("ThistleSpi: Error while loading properties for constructor of " + clazz.getName() +
", properties path:" + url + ", definitions:" + configUrl, e);
}
//set url to properties (key only)
properties.setProperty(PROPERTIES_URL, "...");
if (LOG_LV >= INFO) {
logger.print(loaderId + LOG_PREFIX_LOADER + "Parameters load successfully: " + clazz.getName() + "(" + arg + ") params:" + properties + (LOG_LV >= DEBUG ? " definitions:" + url : ""));
}
//set url to properties (with value)
properties.setProperty(PROPERTIES_URL, String.valueOf(url));
return constructor.newInstance(properties);
}
}
//not found
throw new RuntimeException("ThistleSpi: Illegal definition, the param type of constructor is Properties in " + clazz.getName() +
", you have to define a properties file at " + urlPrefix + propertiesPath +
", NOTICE!!! MUST BE in the SAME project as the definition file (See https://github.com/shepherdviolet/thistle/blob/master/docs/thistlespi/guide.md)" +
", definition file:" + configUrl);
}
}