Spring boot的ClasssLoader加载和卸载jar/class

ゝ一世哀愁。 2023-06-20 11:59 4阅读 0赞

# 一.前言 #

在开发过程中，有时候需要动态加载各种jar/class到程序中，然而又只使用一次，或者加载的jar/class中有改动需要持续升级。程序一直在运行，每次加载进去的jar/class如果过多，对系统会造成很大的压力，而且已经加载进去的jar/class不能覆盖，从而造成得不到想要的结果。此时就需要考虑对加载进去的jar/class进行卸载。

# 二.思路 #

我们知道，当一个java类的完整的生命周期会经历 ***加载、连接、初始化、使用、和卸*载** 五个阶段，当该类的class对象不再被引用之后，该类的生命周期也就结束了，那么该类会被GC回收，从而达到卸载的功能。

![20191210151250715.png][]

# 三.案例编写 #

编写一个简单的自定义classLoad，继承 URLClassLoader 。

此处特别注意 MyClassLoad 构造函数中调用父级构造的第二个参数

package com.vae.classLoader.loader;
    
    import com.vae.classLoader.Application;
    
    import java.io.File;
    import java.net.MalformedURLException;
    import java.net.URL;
    import java.net.URLClassLoader;
    
    /**
     * 自定义的ClassLader
     */
    public class MyClassLoad extends URLClassLoader {
    
        public MyClassLoad(String pathName) {
            /**
             * 第一个参数为jar/class地址
             * 第二个参数是父级classLoader，此处是spring boot 的classLoader，意味着继承了spring boot
             * 的classLoader，在MyClassLoad中可使用到spring boot的jvm
             */
            super(getMyURLs(pathName), Application.class.getClassLoader());
        }
    
        private static URL[] getMyURLs(String pathName) {
            URL url = null;
            try {
                url = new File(pathName).toURI().toURL();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            }
            return new URL[]{url};
        }
    
        @Override
        protected Class<?> findClass(String name) throws ClassNotFoundException {
            return super.findClass(name);
        }
    
        @Override
        public Class<?> loadClass(String name) throws ClassNotFoundException {
            return super.loadClass(name, false);
        }
    
        @Override
        public URL[] getURLs() {
            return super.getURLs();
        }
    
        @Override
        public void addURL(URL url) {
            super.addURL(url);
        }
    }

# 四、测试 #

> 新建一个简单的project工程，只编写一个main方法，代码结构如下图，打成jar包后放在 F:/v/test.jar，修改打印部分数字为2再打一个jar包放在 F:/v/v/test.jar（注意目录层次）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhYnlsb3Zld2Vp_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhYnlsb3Zld2Vp_size_16_color_FFFFFF_t_70 1][]

###  编写测试方法 ###

package com.vae.classLoader.loader;
    
    import com.vae.classLoader.Application;
    
    import java.lang.reflect.Method;
    import java.net.URL;
    import java.net.URLClassLoader;
    
    public class ClassUnLoadTest {
    
    	/**
    	 * 测试class的加载与卸载情况。
    	 * @param args
    	 * @throws Exception
    	 */
    	public static void main(String[] args) throws Exception {
    
                printSupJvm();
    
    	    MyClassLoad loader1 = new MyClassLoad("f:/v/test.jar");
    	    Class<?> clazz1 = loader1.loadClass("com.vae.Test");
    	    Object a1 = clazz1.newInstance();
                Method method = clazz1.getMethod("main", String[].class);
                method.invoke(null, (Object) new String[]{"2019"});
                for (URL url : loader1.getURLs()){
                    System.out.println(url.toString());
                }
    	    // 清除相关引用，等待gc回收
    	    a1 = null;
    	    clazz1 = null;
    	    loader1 = null;
    
                printSupJvm();
    
                MyClassLoad loader2 = new MyClassLoad("f:/v/v/test.jar");
                Class<?> clazz2 = loader2.loadClass("com.vae.Test");
                Object a2 = clazz2.newInstance();
                Method method2 = clazz2.getMethod("main", String[].class);
                method2.invoke(null, (Object) new String[]{"2019"});
                for (URL url : loader2.getURLs()){
                System.out.println(url.toString());
                }
                a2 = null;
                clazz2 = null;
                loader2 = null;
        
                printSupJvm();
    	}
    
        /**
         * 打印输出父级SpringBoot中的className
         */
        private static void printSupJvm(){
            URLClassLoader load = (URLClassLoader)Application.class.getClassLoader();
            System.out.println(load.getClass().getName() + "===================================");
            for (URL url : load.getURLs()){
                System.out.println(url.toString());
            }
            System.out.println("================================================================");
        }
    }

###  运行输出打印结果如下 ###

> **打印输出结构：**
> 
> "C:\\Program Files\\Java\\jdk1.8.0\_144\\bin\\java.exe" ...
> 
> sun.misc.Launcher$AppClassLoader===================================
> 
>  Application的classLoad中所有的jar/class列表......  
> ================================================================  
> **Hello World!\_\_ 1 \_\_**  
> **file:/f:/v/test.jar**  
> sun.misc.Launcher$AppClassLoader===================================  
>  Application的classLoad中所有的jar/class列表......  
> ================================================================  
> **Hello World!\_\_ 2 \_\_**  
> **file:/f:/v/v/test.jar**  
> sun.misc.Launcher$AppClassLoader===================================  
>  Application的classLoad中所有的jar/class列表......  
> ================================================================
> 
> Process finished with exit code 0

"C:\Program Files\Java\jdk1.8.0_144\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2018.3.6\lib\idea_rt.jar=52595:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2018.3.6\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_144\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_144\jre\lib\rt.jar;D:\workRepository\example\case-classLoader\target\classes;D:\maven\repository\idea\org\springframework\boot\spring-boot-starter\2.0.1.RELEASE\spring-boot-starter-2.0.1.RELEASE.jar;D:\maven\repository\idea\org\springframework\boot\spring-boot\2.0.1.RELEASE\spring-boot-2.0.1.RELEASE.jar;D:\maven\repository\idea\org\springframework\spring-context\5.0.5.RELEASE\spring-context-5.0.5.RELEASE.jar;D:\maven\repository\idea\org\springframework\spring-aop\5.0.5.RELEASE\spring-aop-5.0.5.RELEASE.jar;D:\maven\repository\idea\org\springframework\spring-beans\5.0.5.RELEASE\spring-beans-5.0.5.RELEASE.jar;D:\maven\repository\idea\org\springframework\spring-expression\5.0.5.RELEASE\spring-expression-5.0.5.RELEASE.jar;D:\maven\repository\idea\org\springframework\boot\spring-boot-autoconfigure\2.0.1.RELEASE\spring-boot-autoconfigure-2.0.1.RELEASE.jar;D:\maven\repository\idea\org\springframework\boot\spring-boot-starter-logging\2.0.1.RELEASE\spring-boot-starter-logging-2.0.1.RELEASE.jar;D:\maven\repository\idea\ch\qos\logback\logback-classic\1.2.3\logback-classic-1.2.3.jar;D:\maven\repository\idea\ch\qos\logback\logback-core\1.2.3\logback-core-1.2.3.jar;D:\maven\repository\idea\org\apache\logging\log4j\log4j-to-slf4j\2.10.0\log4j-to-slf4j-2.10.0.jar;D:\maven\repository\idea\org\apache\logging\log4j\log4j-api\2.10.0\log4j-api-2.10.0.jar;D:\maven\repository\idea\org\slf4j\jul-to-slf4j\1.7.25\jul-to-slf4j-1.7.25.jar;D:\maven\repository\idea\javax\annotation\javax.annotation-api\1.3.2\javax.annotation-api-1.3.2.jar;D:\maven\repository\idea\org\springframework\spring-core\5.0.5.RELEASE\spring-core-5.0.5.RELEASE.jar;D:\maven\repository\idea\org\springframework\spring-jcl\5.0.5.RELEASE\spring-jcl-5.0.5.RELEASE.jar;D:\maven\repository\idea\org\yaml\snakeyaml\1.19\snakeyaml-1.19.jar;D:\maven\repository\idea\org\apache\commons\commons-lang3\3.5\commons-lang3-3.5.jar;D:\maven\repository\idea\org\apache\tomcat\embed\tomcat-embed-core\8.5.29\tomcat-embed-core-8.5.29.jar;D:\maven\repository\idea\org\apache\tomcat\tomcat-annotations-api\8.5.29\tomcat-annotations-api-8.5.29.jar;D:\maven\repository\idea\org\slf4j\slf4j-api\1.7.25\slf4j-api-1.7.25.jar;D:\maven\repository\idea\log4j\log4j\1.2.17\log4j-1.2.17.jar" com.vae.classLoader.loader.ClassUnLoadTest
    sun.misc.Launcher$AppClassLoader===================================
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/charsets.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/deploy.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/access-bridge-64.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/cldrdata.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/dnsns.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/jaccess.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/jfxrt.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/localedata.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/nashorn.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunec.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunjce_provider.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunmscapi.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunpkcs11.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/zipfs.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/javaws.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jce.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jfr.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jfxswt.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jsse.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/management-agent.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/plugin.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/resources.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/rt.jar
    file:/D:/workRepository/example/case-classLoader/target/classes/
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-starter/2.0.1.RELEASE/spring-boot-starter-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot/2.0.1.RELEASE/spring-boot-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-context/5.0.5.RELEASE/spring-context-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-aop/5.0.5.RELEASE/spring-aop-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-beans/5.0.5.RELEASE/spring-beans-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-expression/5.0.5.RELEASE/spring-expression-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-autoconfigure/2.0.1.RELEASE/spring-boot-autoconfigure-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-starter-logging/2.0.1.RELEASE/spring-boot-starter-logging-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
    file:/D:/maven/repository/idea/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar
    file:/D:/maven/repository/idea/org/apache/logging/log4j/log4j-to-slf4j/2.10.0/log4j-to-slf4j-2.10.0.jar
    file:/D:/maven/repository/idea/org/apache/logging/log4j/log4j-api/2.10.0/log4j-api-2.10.0.jar
    file:/D:/maven/repository/idea/org/slf4j/jul-to-slf4j/1.7.25/jul-to-slf4j-1.7.25.jar
    file:/D:/maven/repository/idea/javax/annotation/javax.annotation-api/1.3.2/javax.annotation-api-1.3.2.jar
    file:/D:/maven/repository/idea/org/springframework/spring-core/5.0.5.RELEASE/spring-core-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-jcl/5.0.5.RELEASE/spring-jcl-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/yaml/snakeyaml/1.19/snakeyaml-1.19.jar
    file:/D:/maven/repository/idea/org/apache/commons/commons-lang3/3.5/commons-lang3-3.5.jar
    file:/D:/maven/repository/idea/org/apache/tomcat/embed/tomcat-embed-core/8.5.29/tomcat-embed-core-8.5.29.jar
    file:/D:/maven/repository/idea/org/apache/tomcat/tomcat-annotations-api/8.5.29/tomcat-annotations-api-8.5.29.jar
    file:/D:/maven/repository/idea/org/slf4j/slf4j-api/1.7.25/slf4j-api-1.7.25.jar
    file:/D:/maven/repository/idea/log4j/log4j/1.2.17/log4j-1.2.17.jar
    file:/D:/Program%20Files/JetBrains/IntelliJ%20IDEA%20Community%20Edition%202018.3.6/lib/idea_rt.jar
    ================================================================
    Hello World!__ 1 __
    file:/f:/v/test.jar
    sun.misc.Launcher$AppClassLoader===================================
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/charsets.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/deploy.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/access-bridge-64.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/cldrdata.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/dnsns.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/jaccess.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/jfxrt.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/localedata.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/nashorn.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunec.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunjce_provider.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunmscapi.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunpkcs11.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/zipfs.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/javaws.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jce.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jfr.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jfxswt.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jsse.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/management-agent.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/plugin.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/resources.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/rt.jar
    file:/D:/workRepository/example/case-classLoader/target/classes/
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-starter/2.0.1.RELEASE/spring-boot-starter-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot/2.0.1.RELEASE/spring-boot-2.0.1.RELEASE.jar
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    file:/D:/maven/repository/idea/org/springframework/spring-aop/5.0.5.RELEASE/spring-aop-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-beans/5.0.5.RELEASE/spring-beans-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-expression/5.0.5.RELEASE/spring-expression-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-autoconfigure/2.0.1.RELEASE/spring-boot-autoconfigure-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-starter-logging/2.0.1.RELEASE/spring-boot-starter-logging-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
    file:/D:/maven/repository/idea/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar
    file:/D:/maven/repository/idea/org/apache/logging/log4j/log4j-to-slf4j/2.10.0/log4j-to-slf4j-2.10.0.jar
    file:/D:/maven/repository/idea/org/apache/logging/log4j/log4j-api/2.10.0/log4j-api-2.10.0.jar
    file:/D:/maven/repository/idea/org/slf4j/jul-to-slf4j/1.7.25/jul-to-slf4j-1.7.25.jar
    file:/D:/maven/repository/idea/javax/annotation/javax.annotation-api/1.3.2/javax.annotation-api-1.3.2.jar
    file:/D:/maven/repository/idea/org/springframework/spring-core/5.0.5.RELEASE/spring-core-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-jcl/5.0.5.RELEASE/spring-jcl-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/yaml/snakeyaml/1.19/snakeyaml-1.19.jar
    file:/D:/maven/repository/idea/org/apache/commons/commons-lang3/3.5/commons-lang3-3.5.jar
    file:/D:/maven/repository/idea/org/apache/tomcat/embed/tomcat-embed-core/8.5.29/tomcat-embed-core-8.5.29.jar
    file:/D:/maven/repository/idea/org/apache/tomcat/tomcat-annotations-api/8.5.29/tomcat-annotations-api-8.5.29.jar
    file:/D:/maven/repository/idea/org/slf4j/slf4j-api/1.7.25/slf4j-api-1.7.25.jar
    file:/D:/maven/repository/idea/log4j/log4j/1.2.17/log4j-1.2.17.jar
    file:/D:/Program%20Files/JetBrains/IntelliJ%20IDEA%20Community%20Edition%202018.3.6/lib/idea_rt.jar
    ================================================================
    Hello World!__ 2 __
    file:/f:/v/v/test.jar
    sun.misc.Launcher$AppClassLoader===================================
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/charsets.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/deploy.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/access-bridge-64.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/cldrdata.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/dnsns.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/jaccess.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/jfxrt.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/localedata.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/nashorn.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunec.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunjce_provider.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunmscapi.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/sunpkcs11.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/ext/zipfs.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/javaws.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jce.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jfr.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jfxswt.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/jsse.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/management-agent.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/plugin.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/resources.jar
    file:/C:/Program%20Files/Java/jdk1.8.0_144/jre/lib/rt.jar
    file:/D:/workRepository/example/case-classLoader/target/classes/
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-starter/2.0.1.RELEASE/spring-boot-starter-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot/2.0.1.RELEASE/spring-boot-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-context/5.0.5.RELEASE/spring-context-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-aop/5.0.5.RELEASE/spring-aop-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-beans/5.0.5.RELEASE/spring-beans-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-expression/5.0.5.RELEASE/spring-expression-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-autoconfigure/2.0.1.RELEASE/spring-boot-autoconfigure-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/boot/spring-boot-starter-logging/2.0.1.RELEASE/spring-boot-starter-logging-2.0.1.RELEASE.jar
    file:/D:/maven/repository/idea/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
    file:/D:/maven/repository/idea/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar
    file:/D:/maven/repository/idea/org/apache/logging/log4j/log4j-to-slf4j/2.10.0/log4j-to-slf4j-2.10.0.jar
    file:/D:/maven/repository/idea/org/apache/logging/log4j/log4j-api/2.10.0/log4j-api-2.10.0.jar
    file:/D:/maven/repository/idea/org/slf4j/jul-to-slf4j/1.7.25/jul-to-slf4j-1.7.25.jar
    file:/D:/maven/repository/idea/javax/annotation/javax.annotation-api/1.3.2/javax.annotation-api-1.3.2.jar
    file:/D:/maven/repository/idea/org/springframework/spring-core/5.0.5.RELEASE/spring-core-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/springframework/spring-jcl/5.0.5.RELEASE/spring-jcl-5.0.5.RELEASE.jar
    file:/D:/maven/repository/idea/org/yaml/snakeyaml/1.19/snakeyaml-1.19.jar
    file:/D:/maven/repository/idea/org/apache/commons/commons-lang3/3.5/commons-lang3-3.5.jar
    file:/D:/maven/repository/idea/org/apache/tomcat/embed/tomcat-embed-core/8.5.29/tomcat-embed-core-8.5.29.jar
    file:/D:/maven/repository/idea/org/apache/tomcat/tomcat-annotations-api/8.5.29/tomcat-annotations-api-8.5.29.jar
    file:/D:/maven/repository/idea/org/slf4j/slf4j-api/1.7.25/slf4j-api-1.7.25.jar
    file:/D:/maven/repository/idea/log4j/log4j/1.2.17/log4j-1.2.17.jar
    file:/D:/Program%20Files/JetBrains/IntelliJ%20IDEA%20Community%20Edition%202018.3.6/lib/idea_rt.jar
    ================================================================
    
    Process finished with exit code 0

> 由上述可以看出，每次加载进去的jar，与父级SpringBoot的Application的classLoad中的jar是隔离的，每次new出来的MyClassLaoder都是一个新的classLoad，把每次new出来的自定义的classLoad置为null，等待GC回收，实现卸载jar/class功能。

[20191210151250715.png]: https://img-blog.csdnimg.cn/20191210151250715.png
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