什麼是OOM？常見有哪些OOM？

​OOM：OutOfMemory (內存溢出)

/**
 * Thrown when the Java Virtual Machine cannot allocate an object
 * because it is out of memory, and no more memory could be made
 * available by the garbage collector.
 *
 * {@code OutOfMemoryError} objects may be constructed by the virtual
 * machine as if {@linkplain Throwable#Throwable(String, Throwable,
 * boolean, boolean) suppression were disabled and/or the stack trace was not
 * writable}.
 *
 * @author  unascribed
 * @since   JDK1.0
 */
public class OutOfMemoryError extends VirtualMachineError {
}

 

 

 

開發常見異常

1 StackOverFlowError

示例：遞歸調用後方法特別多，將棧空間撐爆

 

public class StackOverFlowErrorDemo {
​
    public static void main(String[] args) {
        test();
    }
​
    private static void test() {
        //遞歸調用
        test();
    }
}

結果

Exception in thread "main" java.lang.StackOverflowError
	at com.coolcoding.boot.oom.StackOverFlowErrorDemo.test(StackOverFlowErrorDemo.java:13)
	at com.coolcoding.boot.oom.StackOverFlowErrorDemo.test(StackOverFlowErrorDemo.java:13)
	at com.coolcoding.boot.oom.StackOverFlowErrorDemo.test(StackOverFlowErrorDemo.java:13)

2 java.lang.OutOfMemoryError: Java heap space

爲了調試方便先設置最大堆內存和初始堆內存大小

JVM調試參數設置和說明

-Xms	初始堆內存	一般爲內存的1/16
-Xmx	最大堆內存	一般爲內存的1/4

設置：-Xms10m -Xmx10m

 

 

案例：

public class JavaHeapSpaceDemo {
​
    public static void main(String[] args) {
        String str = "xxxxxxxxxdddddddddddd";
​
        while (true){
        //循環創建字符串對象
            str += str + new Random().nextInt(1111111111) + new Random().nextInt(222222222);
            //從常量池中獲取字符串，若不存在，則創建一個字符串放到常量池中
            str.intern();
        }
    }
}

結果：

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
  at java.util.Arrays.copyOf(Arrays.java:3332)
  at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:124)
  at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:674)
  at java.lang.StringBuilder.append(StringBuilder.java:208)
  at com.coolcoding.boot.oom.JavaHeapSpaceDemo.main(JavaHeapSpaceDemo.java:14)

 

 

3 java.lang.OutOfMemoryError: GC overhead limit exceeded

簡單理解：GC回收時間過長，時間過多耗費在GC中，但是回收效果不佳。

原理：

• 回收過長指的是超過98%的時間用來做GC，並且回收了不到2%的堆內存，

• 連續多次GC，都只回收了不到2%的極端情況下才會拋出異常，

• 如不拋出異常，GC清理後的內存也會很快再次填滿，迫使GC再次執行，

• 就此形成惡性循環

 

JVM參數設置：

-Xms10m -Xmx10m -XX:+PrintGCDetails -XX:MaxDirectMemory=5m

案例

public class GCOverheadDemo {
​
    public static void main(String[] args) {
        int i = 0;
        List<String> list = new ArrayList<>();
        try {
            while (true){
                list.add(String.valueOf(++i).intern());
            }
        }catch (Throwable e){
            e.printStackTrace();
            throw e;
        }
​
    }
}

結果：

[Full GC (Ergonomics) [PSYoungGen: 2048K->2048K(2560K)] [ParOldGen: 7049K->7046K(7168K)] 9097K->9094K(9728K), [Metaspace: 3886K->3886K(1056768K)], 0.0530256 secs] [Times: user=0.14 sys=0.00, real=0.05 secs] 
[Full GC (Ergonomics) java.lang.OutOfMemoryError: GC overhead limit exceeded
[PSYoungGen: 2048K->2048K(2560K)] [ParOldGen: 7050K->7046K(7168K)] 9098K->9094K(9728K), [Metaspace: 3886K->3886K(1056768K)], 0.0493460 secs] [Times: user=0.13 sys=0.00, real=0.05 secs] 
[Full GC (Ergonomics)   at java.lang.Integer.toString(Integer.java:401)
             //回收前2048k -> 回收後2048k 可見GC回收效果不佳
[PSYoungGen: 2048K->2048K(2560K)
[Full GC (Ergonomics) [PSYoungGen: 2048K->0K(2560K)] [ParOldGen: 7020K->1119K(7168K)] 9068K->1119K(9728K), [Metaspace: 3892K->3892K(1056768K)], 0.0176793 secs] [Times: user=0.02 sys=0.00, real=0.02 secs] 
  at java.lang.String.valueOf(String.java:3099)
  at com.coolcoding.boot.oom.GCOverheadDemo.main(GCOverheadDemo.java:16)
Exception in thread "main" java.lang.OutOfMemoryError: GC overhead limit exceeded
  at java.lang.Integer.toString(Integer.java:401)
  at java.lang.String.valueOf(String.java:3099)
  at com.coolcoding.boot.oom.GCOverheadDemo.main(GCOverheadDemo.java:16)
Heap

4 java.lang.OutOfMemoryError: Direct buffer memory

直接內存溢出

原因分析：

直接內存崩潰，此處元空間並不在虛擬機中，而是使用本地內存，與GC無關。

常見於NIO程序中，使用ByteBuffer來讀取和寫入數據，這是基於通道channel和緩衝區buffer的IO方式，可以使用Native函數直接分配堆外內存，通過存儲在JAVA堆裏面的DirectByteBuffer對象作爲這塊內存的引用進行操作。該方式在某些常見中能提高性能，因爲避免了java堆和native堆中來回拷貝數據

例如

ByteBuffer.allocate(capability)	堆內內存	屬於GC管轄，由於需要拷貝所以速度相對較慢
ByteBuffer.allocateDirect(capability)	本地內存	不屬於GC管轄，由於不需要拷貝所以速度較快

如果不斷分配本地內存，堆內存很少使用，那麼JVM就不需要執行GC，DirectByteBuffer對象們就不會被回收，此時堆內存充足，但是本地內存即將耗盡，那麼再次嘗試分配本地內存就會出現OOM

配置參數：

-Xms10m -Xmx10m -XX:+PrintGCDetails -XX:MaxDirectMemorySize=5m

示例：

public class DirectBufferMemoryDemo {
​
    public static void main(String[] args) {
        System.out.println("本地內存 = " + (VM.maxDirectMemory() / 1024 / 1024) + "MB");
        try{
            TimeUnit.SECONDS.sleep(3);}catch (InterruptedException e){e.printStackTrace();}
        //allocateDirect 分配直接內存
        ByteBuffer.allocateDirect(6 * 1024 * 1024);
    }
}

結果：

"D:\Program Files\Java\jdk1.8.0_144\bin\java.exe" -Xms10m -Xmx10m -XX:+PrintGCDetails -XX:MaxDirectMemorySize=5m "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA 2019.3\lib\idea_rt.jar=49710:D:\Program Files\JetBrains\IntelliJ IDEA 2019.3\bin" -Dfile.encoding=UTF-8 -classpath "D:\Program Files\Java\jdk1.8.0_144\jre\lib\charsets.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\deploy.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\access-bridge-64.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\cldrdata.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\dnsns.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\jaccess.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\jfxrt.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\localedata.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\nashorn.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\student.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\sunec.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\sunjce_provider.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\sunmscapi.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\sunpkcs11.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\ext\zipfs.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\javaws.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\jce.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\jfr.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\jfxswt.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\jsse.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\management-agent.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\plugin.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\resources.jar;D:\Program Files\Java\jdk1.8.0_144\jre\lib\rt.jar;E:\workspace\springboot-demo\target\classes;D:\mavenRepository\org\springframework\boot\spring-boot-starter-web\2.2.6.RELEASE\spring-boot-starter-web-2.2.6.RELEASE.jar;D:\mavenRepository\org\springframework\boot\spring-boot-starter\2.2.6.RELEASE\spring-boot-starter-2.2.6.RELEASE.jar;D:\mavenRepository\org\springframework\boot\spring-boot-starter-logging\2.2.6.RELEASE\spring-boot-starter-logging-2.2.6.RELEASE.jar;D:\mavenRepository\ch\qos\logback\logback-classic\1.2.3\logback-classic-1.2.3.jar;D:\mavenRepository\ch\qos\logback\logback-core\1.2.3\logback-core-1.2.3.jar;D:\mavenRepository\org\apache\logging\log4j\log4j-to-slf4j\2.12.1\log4j-to-slf4j-2.12.1.jar;D:\mavenRepository\org\apache\logging\log4j\log4j-api\2.12.1\log4j-api-2.12.1.jar;D:\mavenRepository\org\slf4j\jul-to-slf4j\1.7.30\jul-to-slf4j-1.7.30.jar;D:\mavenRepository\org\yaml\snakeyaml\1.25\snakeyaml-1.25.jar;D:\mavenRepository\org\springframework\boot\spring-boot-starter-json\2.2.6.RELEASE\spring-boot-starter-json-2.2.6.RELEASE.jar;D:\mavenRepository\com\fasterxml\jackson\core\jackson-databind\2.10.3\jackson-databind-2.10.3.jar;D:\mavenRepository\com\fasterxml\jackson\core\jackson-annotations\2.10.3\jackson-annotations-2.10.3.jar;D:\mavenRepository\com\fasterxml\jackson\core\jackson-core\2.10.3\jackson-core-2.10.3.jar;D:\mavenRepository\com\fasterxml\jackson\datatype\jackson-datatype-jdk8\2.10.3\jackson-datatype-jdk8-2.10.3.jar;D:\mavenRepository\com\fasterxml\jackson\datatype\jackson-datatype-jsr310\2.10.3\jackson-datatype-jsr310-2.10.3.jar;D:\mavenRepository\com\fasterxml\jackson\module\jackson-module-parameter-names\2.10.3\jackson-module-parameter-names-2.10.3.jar;D:\mavenRepository\org\springframework\boot\spring-boot-starter-validation\2.2.6.RELEASE\spring-boot-starter-validation-2.2.6.RELEASE.jar;D:\mavenRepository\jakarta\validation\jakarta.validation-api\2.0.2\jakarta.validation-api-2.0.2.jar;D:\mavenRepository\org\hibernate\validator\hibernate-validator\6.0.18.Final\hibernate-validator-6.0.18.Final.jar;D:\mavenRepository\org\jboss\logging\jboss-logging\3.4.1.Final\jboss-logging-3.4.1.Final.jar;D:\mavenRepository\com\fasterxml\classmate\1.5.1\classmate-1.5.1.jar;D:\mavenRepository\org\springframework\spring-web\5.2.5.RELEASE\spring-web-5.2.5.RELEASE.jar;D:\mavenRepository\org\springframework\spring-beans\5.2.5.RELEASE\spring-beans-5.2.5.RELEASE.jar;D:\mavenRepository\org\springframework\spring-webmvc\5.2.5.RELEASE\spring-webmvc-5.2.5.RELEASE.jar;D:\mavenRepository\org\springframework\spring-aop\5.2.5.RELEASE\spring-aop-5.2.5.RELEASE.jar;D:\mavenRepository\org\springframework\spring-context\5.2.5.RELEASE\spring-context-5.2.5.RELEASE.jar;D:\mavenRepository\org\springframework\spring-expression\5.2.5.RELEASE\spring-expression-5.2.5.RELEASE.jar;D:\mavenRepository\org\springframework\boot\spring-boot-devtools\2.2.6.RELEASE\spring-boot-devtools-2.2.6.RELEASE.jar;D:\mavenRepository\org\springframework\boot\spring-boot\2.2.6.RELEASE\spring-boot-2.2.6.RELEASE.jar;D:\mavenRepository\org\springframework\boot\spring-boot-autoconfigure\2.2.6.RELEASE\spring-boot-autoconfigure-2.2.6.RELEASE.jar;D:\mavenRepository\org\projectlombok\lombok\1.18.12\lombok-1.18.12.jar;D:\mavenRepository\jakarta\annotation\jakarta.annotation-api\1.3.5\jakarta.annotation-api-1.3.5.jar;D:\mavenRepository\org\springframework\spring-core\5.2.5.RELEASE\spring-core-5.2.5.RELEASE.jar;D:\mavenRepository\org\springframework\spring-jcl\5.2.5.RELEASE\spring-jcl-5.2.5.RELEASE.jar;D:\mavenRepository\cn\hutool\hutool-all\5.1.0\hutool-all-5.1.0.jar;D:\mavenRepository\org\apache\poi\poi-ooxml\4.1.2\poi-ooxml-4.1.2.jar;D:\mavenRepository\org\apache\poi\poi\4.1.2\poi-4.1.2.jar;D:\mavenRepository\commons-codec\commons-codec\1.13\commons-codec-1.13.jar;D:\mavenRepository\org\apache\commons\commons-collections4\4.4\commons-collections4-4.4.jar;D:\mavenRepository\org\apache\commons\commons-math3\3.6.1\commons-math3-3.6.1.jar;D:\mavenRepository\com\zaxxer\SparseBitSet\1.2\SparseBitSet-1.2.jar;D:\mavenRepository\org\apache\poi\poi-ooxml-schemas\4.1.2\poi-ooxml-schemas-4.1.2.jar;D:\mavenRepository\org\apache\xmlbeans\xmlbeans\3.1.0\xmlbeans-3.1.0.jar;D:\mavenRepository\org\apache\commons\commons-compress\1.19\commons-compress-1.19.jar;D:\mavenRepository\com\github\virtuald\curvesapi\1.06\curvesapi-1.06.jar;D:\mavenRepository\com\101tec\zkclient\0.11\zkclient-0.11.jar;D:\mavenRepository\org\apache\zookeeper\zookeeper\3.4.13\zookeeper-3.4.13.jar;D:\mavenRepository\org\slf4j\slf4j-log4j12\1.7.30\slf4j-log4j12-1.7.30.jar;D:\mavenRepository\log4j\log4j\1.2.17\log4j-1.2.17.jar;D:\mavenRepository\jline\jline\0.9.94\jline-0.9.94.jar;D:\mavenRepository\org\apache\yetus\audience-annotations\0.5.0\audience-annotations-0.5.0.jar;D:\mavenRepository\io\netty\netty\3.10.6.Final\netty-3.10.6.Final.jar;D:\mavenRepository\org\slf4j\slf4j-api\1.7.30\slf4j-api-1.7.30.jar;D:\mavenRepository\com\google\guava\guava\29.0-jre\guava-29.0-jre.jar;D:\mavenRepository\com\google\guava\failureaccess\1.0.1\failureaccess-1.0.1.jar;D:\mavenRepository\com\google\guava\listenablefuture\9999.0-empty-to-avoid-conflict-with-guava\listenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar;D:\mavenRepository\com\google\code\findbugs\jsr305\3.0.2\jsr305-3.0.2.jar;D:\mavenRepository\org\checkerframework\checker-qual\2.11.1\checker-qual-2.11.1.jar;D:\mavenRepository\com\google\errorprone\error_prone_annotations\2.3.4\error_prone_annotations-2.3.4.jar;D:\mavenRepository\com\google\j2objc\j2objc-annotations\1.3\j2objc-annotations-1.3.jar;D:\mavenRepository\com\baomidou\dynamic-datasource-spring-boot-starter\3.0.0\dynamic-datasource-spring-boot-starter-3.0.0.jar;D:\mavenRepository\org\springframework\boot\spring-boot-starter-aop\2.2.6.RELEASE\spring-boot-starter-aop-2.2.6.RELEASE.jar;D:\mavenRepository\org\aspectj\aspectjweaver\1.9.5\aspectjweaver-1.9.5.jar;D:\mavenRepository\mysql\mysql-connector-java\8.0.19\mysql-connector-java-8.0.19.jar;D:\mavenRepository\org\springframework\boot\spring-boot-starter-jdbc\2.2.6.RELEASE\spring-boot-starter-jdbc-2.2.6.RELEASE.jar;D:\mavenRepository\com\zaxxer\HikariCP\3.4.2\HikariCP-3.4.2.jar;D:\mavenRepository\org\springframework\spring-jdbc\5.2.5.RELEASE\spring-jdbc-5.2.5.RELEASE.jar;D:\mavenRepository\org\springframework\spring-tx\5.2.5.RELEASE\spring-tx-5.2.5.RELEASE.jar;D:\mavenRepository\org\mybatis\spring\boot\mybatis-spring-boot-starter\1.3.5\mybatis-spring-boot-starter-1.3.5.jar;D:\mavenRepository\org\mybatis\spring\boot\mybatis-spring-boot-autoconfigure\1.3.5\mybatis-spring-boot-autoconfigure-1.3.5.jar;D:\mavenRepository\org\mybatis\mybatis\3.4.6\mybatis-3.4.6.jar;D:\mavenRepository\org\mybatis\mybatis-spring\1.3.3\mybatis-spring-1.3.3.jar" com.coolcoding.boot.oom.DirectBufferMemoryDemo
[GC (Allocation Failure) [PSYoungGen: 2048K->504K(2560K)] 2048K->983K(9728K), 0.0023899 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 
本地內存 = 5MB
[GC (Allocation Failure) [PSYoungGen: 2552K->504K(2560K)] 3031K->1543K(9728K), 0.0035927 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 
[GC (System.gc()) [PSYoungGen: 781K->504K(2560K)] 1820K->1591K(9728K), 0.0013692 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 
[Full GC (System.gc()) [PSYoungGen: 504K->0K(2560K)] [ParOldGen: 1087K->1333K(7168K)] 1591K->1333K(9728K), [Metaspace: 4029K->4029K(1056768K)], 0.0155318 secs] [Times: user=0.03 sys=0.00, real=0.02 secs] 
Exception in thread "main" java.lang.OutOfMemoryError: Direct buffer memory
  at java.nio.Bits.reserveMemory(Bits.java:694)
  at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:123)
  at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:311)
  at com.coolcoding.boot.oom.DirectBufferMemoryDemo.main(DirectBufferMemoryDemo.java:17)
Heap
 PSYoungGen      total 2560K, used 53K [0x00000000ffd00000, 0x0000000100000000, 0x0000000100000000)
  eden space 2048K, 2% used [0x00000000ffd00000,0x00000000ffd0d748,0x00000000fff00000)
  from space 512K, 0% used [0x00000000fff00000,0x00000000fff00000,0x00000000fff80000)
  to   space 512K, 0% used [0x00000000fff80000,0x00000000fff80000,0x0000000100000000)
 ParOldGen       total 7168K, used 1333K [0x00000000ff600000, 0x00000000ffd00000, 0x00000000ffd00000)
  object space 7168K, 18% used [0x00000000ff600000,0x00000000ff74d618,0x00000000ffd00000)
 Metaspace       used 4061K, capacity 4568K, committed 4864K, reserved 1056768K
  class space    used 450K, capacity 460K, committed 512K, reserved 1048576K

5 java.lang.OutOfMemoryError: unable to create new native thread

高併發情況下會出現該異常，該異常與對應的平臺有關

原因分析

一個應用進程創建太多的線程，超過系統承載極限。如Linux默認允許單個進程可以創建的線程數是1024個。

解決方法

• 降低應用程序創建線程的數量，分析應用是否真的需要創建那麼多線程，將線程數降到最低

• 修改服務器配置，如修改Linux服務器配置，擴大Linux默認限制

案例：

public class UnableCreateNewThreadDemo {
​
    public static void main(String[] args) {
        //不斷for循環創建線程
        for (int i = 0; ; i++) {
            new Thread(()->{
                //設置Integer.MAX_VALUE 以保持線程還在運行中
                try{ TimeUnit.SECONDS.sleep(Integer.MAX_VALUE);}catch (InterruptedException e){e.printStackTrace();}
            }).start();
        }
    }
}

試驗

將該文件上傳放到linux下

執行javac -d 文件名

執行java 包名.文件名 啓動測試應用

 

達到系統負載後則會拋出java.lang.OutOfMemoryError: unable to create new native thread

若要修改系統配置可以先查看對應用戶的線程限制

linux下查看對應用戶的線程限制個數

//查看限制個數
ulimit -u//編輯修改vim /etc/security/limits.d/90-nproc.conf

如修改對z3用戶的配置

 

6 java.lang.OutOfMemoryError: Metaspace

在cmd中執行 以下命令可以查看默認的JVM參數基本配置，可以查看metaspaceSize的大小

java -XX:+PrintFlagsInitial

 

metaspace存放數據：（永久代 JAVA8之後被metaspace取代了）

• 虛擬機加載的類信息

• 常量池

• 靜態變量

• 即時編譯後的代碼

JVM參數配置

-XX:MetaspaceSize=8m -XX:MaxMetaspaceSize=8m

案例：

public class MetaspaceOOMTest {
    //準備一個靜態類
    static class OOMTest {
    }
​
    ;
​
    public static void main(String[] args) {
        int i = 0;
        try {
            while (true) {
                //循環不斷創建靜態類來填充metaspace的空間
                i++;
                Enhancer enhancer = new Enhancer();
                enhancer.setSuperclass(OOMTest.class);
                enhancer.setUseCache(false);
                enhancer.setCallback(new MethodInterceptor() {
                    @Override
                    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                        return methodProxy.invoke(o, args);
                    }
                });
                enhancer.create();
            }
        } catch (Exception e) {
        //記錄查看創建了多少個靜態類OOMTest
            System.out.println(i + "次後發生異常");
            e.printStackTrace();
        }
    }
}

結果

279次後發生異常
org.springframework.cglib.core.CodeGenerationException: java.lang.OutOfMemoryError-->Metaspace
  at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:538)
  at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:363)
  at org.springframework.cglib.proxy.Enhancer.generate(Enhancer.java:582)
  at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:131)
  at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:319)
  at org.springframework.cglib.proxy.Enhancer.createHelper(Enhancer.java:569)
  at org.springframework.cglib.proxy.Enhancer.create(Enhancer.java:384)
  at com.coolcoding.boot.oom.MetaspaceOOMTest.main(MetaspaceOOMTest.java:34)
Caused by: java.lang.OutOfMemoryError: Metaspace
  at java.lang.ClassLoader.defineClass1(Native Method)
  at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
  at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:498)
  at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:535)
  ... 7 more

有不夠細緻的地方或者想探討的可以評論區留言