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feilong is a suite of core and expanded libraries that include utility classes, http, excel,cvs, io classes, and much much more.
/*
* Copyright (C) 2008 feilong
*
* 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.feilong.core.lang;
import static com.feilong.core.bean.ConvertUtil.toList;
import static com.feilong.core.util.MapUtil.newLinkedHashMap;
import java.io.InputStream;
import java.net.URL;
import java.util.List;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.feilong.core.Validate;
import com.feilong.core.net.URLUtil;
import com.feilong.tools.slf4j.Slf4jUtil;
/**
* {@link java.lang.ClassLoader ClassLoader}工具类.
*
* 关于查找资源:
*
*
*
*
* - {@link #getResource(String)}
* - {@link #getResourceInAllClassLoader(String, Class)}
*
*
*
*
* 关于 {@link java.lang.Class#getResourceAsStream(String) Class#getResourceAsStream(String)} VS
* {@link java.lang.ClassLoader#getResourceAsStream(String) ClassLoader#getResourceAsStream(String)}
*
*
*
*
* 基本上,两个都可以用于从 classpath 里面进行资源读取,classpath包含classpath中的路径和classpath中的jar
*
*
*
* 假设配置文件在 src/main/resources下面,比如 messages/feilong-core-message_en_US.properties,
*
*
*
* - {@link java.lang.Class#getResourceAsStream(String) Class#getResourceAsStream(String)} 需要这么写
* "/messages/feilong-core-message_en_US.properties",
* 路径可以写成相对路径或者绝对路径; 以 / 开头,则这样的路径是指定绝对路径, 如果不以 / 开头, 则路径是相对与这个class所在的包的
* - {@link java.lang.ClassLoader#getResourceAsStream(String) ClassLoader#getResourceAsStream(String)} 需要这么写
* "messages/feilong-core-message_en_US.properties",
* {@link ClassLoader} JVM会使用BootstrapLoader去加载资源文件.
* 所以路径还是这种相对于工程的根目录即"messages/feilong-core-message_en_US.properties" 不需要"/"
* - 如果你的项目使用了spring,建议条件允许的话,使用
org.springframework.core.io.ClassPathResource,这个类是基于{@link ClassLoader}的,同时会
* org.springframework.util.StringUtils#cleanPath(String),并且如果发现首字符是/斜杆, 会去掉,这样使用起来很方便
*
*
*
*
* @author feilong
* @see java.lang.ClassLoader
* @see java.net.URLClassLoader
* @see "org.springframework.core.io.ClassPathResource#ClassPathResource(String, ClassLoader)"
* @since 1.0.0
*/
public final class ClassLoaderUtil{
/** The Constant LOGGER. */
private static final Logger LOGGER = LoggerFactory.getLogger(ClassLoaderUtil.class);
/** Don't let anyone instantiate this class. */
private ClassLoaderUtil(){
//AssertionError不是必须的. 但它可以避免不小心在类的内部调用构造器. 保证该类在任何情况下都不会被实例化.
//see 《Effective Java》 2nd
throw new AssertionError("No " + getClass().getName() + " instances for you!");
}
//---------------------------------------------------------------
/**
* 获得给定名称 resourceName 的资源.
*
* 示例:
*
*
*
*
* 比如,在 src/test/resources 目录下面有 messages/feilong-core-test.properties 资源文件,编译之后,地址会出现在
* target/test-classes/messages/feilong-core-test.properties
*
*
*
* ClassLoaderUtil.getResource("/messages/feilong-core-test.properties")
* 或者 ClassLoaderUtil.getResource("messages/feilong-core-test.properties")
*
*
* 返回相同的结果
*
*
* file:/E:/Workspaces/feilong/feilong-core/target/test-classes/messages/feilong-core-test.properties
*
*
*
*
* 注意:
*
*
* - 如果
resourceName 是以斜杆 "/" 开头,那么会被截取,因为 {@link ClassLoader} 解析方式不需要开头的斜杆, 请参见
* org.springframework.core.io.ClassPathResource#ClassPathResource(String, ClassLoader)
* - "",表示classes 的根目录
*
*
*
* 不同环境结果不一样:
*
*
*
*
*
* 示例
* (maven)测试
* 在web环境中,(即使打成jar的情形)
*
*
*
* getResource("")file:/E:/Workspaces/feilong/feilong-platform/feilong-core/target/test-classes/
* file:/E:/Workspaces/feilong/feilong-platform/feilong-web-test/src/main/webapp/WEB-INF/classes/
*
*
*
* getResource("com")file:/E:/Workspaces/feilong/feilong-platform/feilong-core/target/test-classes/com
* file:/E:/Workspaces/feilong/feilong-platform/feilong-web-test/src/main/webapp/WEB-INF/classes/com/
*
*
*
*
* @param resourceName
* the resource name
* @return 如果 resourceName 是null,抛出 {@link NullPointerException}
* 如果找不到该资源,或者调用者没有足够的权限获取该资源,则返回 null
* @see "org.apache.commons.lang3.ClassPathUtils#toFullyQualifiedPath(Package, String)"
* @see #getResource(ClassLoader, String)
* @see #getClassLoaderByClass(Class)
*/
public static URL getResource(String resourceName){
return getResource(getClassLoaderByClass(ClassLoaderUtil.class), resourceName);
}
/**
* 查找具有给定名称的资源,资源是可以通过类代码以与代码基无关的方式访问的一些数据(图像、声音、文本等).
*
* 注意:
*
*
* - 如果
resourceName 是以 斜杆 "/" 开头,那么会被截取, 因为 ClassLoader解析方式不需要 开头的斜杆, 请参见
* org.springframework.core.io.ClassPathResource#ClassPathResource(String, ClassLoader)
* - "",表示classes 的根目录
*
*
*
* @param classLoader
* the class loader
* @param resourceName
* the resource name
* @return 如果 classLoader 是null,抛出 {@link NullPointerException}
* 如果 resourceName 是null,抛出 {@link NullPointerException}
* 如果找不到该资源,或者调用者没有足够的权限获取该资源,则返回 null
* @since 1.2.1
*/
private static URL getResource(ClassLoader classLoader,String resourceName){
Validate.notNull(classLoader, "classLoader can't be null!");
Validate.notNull(resourceName, "resourceName can't be null!");
boolean startsWithSlash = resourceName.startsWith("/");
String usePath = startsWithSlash ? StringUtil.substring(resourceName, 1) : resourceName;
URL result = classLoader.getResource(usePath);
LOGGER.trace("search resource:[\"{}\"] in [{}],result:[{}]", resourceName, classLoader, result);
return result;
}
//---------------------------------------------------------------
/**
* 加载资源 resourceName为 InputStream.
*
* 注意:
*
*
* - 如果
resourceName 是以 斜杆 "/" 开头,那么会被截取, 因为 ClassLoader解析方式不需要 开头的斜杆, 请参见
* org.springframework.core.io.ClassPathResource#ClassPathResource(String, ClassLoader)
* - "",表示classes 的根目录
*
*
*
* @param resourceName
* The name of the resource to load
* @param callingClass
* The Class object of the calling object
* @return 如果 resourceName 是null,抛出 {@link NullPointerException}
* 如果查找不到资源,那么返回 null
* @see #getResourceInAllClassLoader(String, Class)
* @see "org.apache.velocity.util.ClassUtils#getResourceAsStream(Class, String)"
*/
public static InputStream getResourceAsStream(String resourceName,Class callingClass){
URL url = getResourceInAllClassLoader(resourceName, callingClass);
return URLUtil.openStream(url);
}
/**
* Load a given resource.
*
* 注意:
*
*
* - 如果
resourceName 是以 斜杆 "/" 开头,那么会被截取,因为 ClassLoader解析方式不需要开头的斜杆, 请参见
* org.springframework.core.io.ClassPathResource#ClassPathResource(String, ClassLoader)
* - "",表示classes 的根目录
* -
*
* This method will try to load the resource using the following methods (in order):
*
*
* - From {@link Thread#getContextClassLoader() Thread.currentThread().getContextClassLoader()}
*
- From {@link Class#getClassLoader() ClassLoaderUtil.class.getClassLoader()}
*
- From {@link Class#getClassLoader() callingClass.getClassLoader() } (如果 callingClass 不是null)
*
*
*
*
*
* @param resourceName
* The name of the resource to load
* @param callingClass
* The Class object of the calling object
* @return 如果 resourceName 是null,抛出 {@link NullPointerException}
* 如果 callingClass 是null,将会忽略此参数
* 如果在所有的{@link ClassLoader}里面都查不到资源,那么返回null
* @since 1.6.2
*/
public static URL getResourceInAllClassLoader(String resourceName,Class callingClass){
Validate.notNull(resourceName, "resourceName can't be null!");
List classLoaderList = getAllClassLoaderList(callingClass);
for (ClassLoader classLoader : classLoaderList){
URL url = getResource(classLoader, resourceName);
if (null == url){
LOGGER.trace(getLogInfo(resourceName, classLoader, false));
}else{
if (LOGGER.isTraceEnabled()){
LOGGER.trace(getLogInfo(resourceName, classLoader, true));
}
return url;
}
}
LOGGER.debug("not found:[{}] in all ClassLoader,return null", resourceName);
return null;
}
//---------------------------------------------------------------
/**
* 获得 all class loader list.
*
*
* This method will try to get ClassLoader list using the following methods (in order):
*
*
* - From {@link Thread#getContextClassLoader() Thread.currentThread().getContextClassLoader()}
*
- From {@link Class#getClassLoader() ClassLoaderUtil.class.getClassLoader()}
*
- From {@link Class#getClassLoader() callingClass.getClassLoader() } (如果
callingClass 不是null)
*
*
* @param callingClass
* the calling class
* @return the all class loader
* @since 1.6.2
*/
private static List getAllClassLoaderList(Class callingClass){
List list = toList(//
getClassLoaderByCurrentThread(),
getClassLoaderByClass(ClassLoaderUtil.class));
if (null != callingClass){
list.add(getClassLoaderByClass(callingClass));
}
return list;
}
/**
* 通过 {@link Thread#getContextClassLoader()} 获得 {@link ClassLoader}.
*
* @return the class loader by current thread
*/
private static ClassLoader getClassLoaderByCurrentThread(){
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
if (LOGGER.isTraceEnabled()){
LOGGER.trace("[Thread.currentThread()].getContextClassLoader:{}", formatClassLoader(classLoader));
}
return classLoader;
}
/**
* 通过类来获得 {@link ClassLoader}.
*
* @param callingClass
* the calling class
* @return 如果 callingClass 是null,抛出 {@link NullPointerException}
* @see java.lang.Class#getClassLoader()
*/
private static ClassLoader getClassLoaderByClass(Class callingClass){
Validate.notNull(callingClass, "callingClass can't be null!");
ClassLoader classLoader = callingClass.getClassLoader();
if (LOGGER.isTraceEnabled()){
LOGGER.trace("[{}].getClassLoader():{}", callingClass.getSimpleName(), formatClassLoader(classLoader));
}
return classLoader;
}
//---------------------------------------------------------------
/**
* 获得 log info.
*
* @param resourceName
* the resource name
* @param classLoader
* the class loader
* @param isFouned
* the is founed
* @return the log info
* @since 1.6.2
*/
private static String getLogInfo(String resourceName,ClassLoader classLoader,boolean isFouned){
String message = "{}found [{}],in ClassLoader:[{}]";
return Slf4jUtil.format(message, isFouned ? "" : "not ", resourceName, formatClassLoader(classLoader));
}
/**
* Format class loader.
*
* @param classLoader
* the class loader
* @return the string
* @since 1.6.2
*/
private static String formatClassLoader(ClassLoader classLoader){
Map map = newLinkedHashMap(2);
map.put("classLoader[CanonicalName]", classLoader.getClass().getCanonicalName());
map.put("classLoader[Root Classpath]", "" + getResource(classLoader, ""));
return map.toString();
}
}