一、JVM基本常識
1.程式的執行方式
主要為以下三種：靜態編譯執行、動態編譯執行、動態解釋執行 2.為什么使用JVM
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解釋
解釋
機器碼
機器碼
java程式
java位元組碼
windows Java虛擬機
Linux Java虛擬機
windows作業系統
Linux作業系統
查看JDK的版本
java - version
(1)如果是SUN/OracleJDK,顯示資訊為
java version "1.8.0_241"
Java(TM) SE Runtime Environment (build 1.8.0_241-b07)
Java HotSpot(TM) 64-Bit Server VM (build 25.241-b07, mixed mode)
說明：Java HotSpot(TM) 64-Bit Server VM表明，此JDK的JVM是Oracle的64位HotSpot虛擬機 ，運行在Server模式下（虛擬機有Server和Client兩種運行模式） Java(TM) SE Runtime Environment (build 1.8.0_241-b07)是java運行時環境（JRE）的版本資訊
(2)如果是OpenJDK，顯示資訊為
[root@localhost ~]# java -version
openjdk version "1.8.0_144"
OpenJDK Runtime Environment (build 1.8.0_144-b01)
OpenJDK 64-Bit Server VM (build 25.144-b01, mixed mode)
OpenJDK
OpenJDK根據許可證GPL v2發布;
(2) Oracle JDK的來歷
OpenJDK使用的是開源免費的FreeType, 可以按照GPL v2許可證使用.GPL V2允許在商業上使用;
JRockit是Oracle的JVM, 從Java SE 7開始, HotSpot和JRockit合并為一個JVM.
JVM是《JVM虛擬機規范》中提出來的規范
JVM的client運行模式和server運行模式的區別
JVM有兩種運行模式Server與Client，
學習java必不可少的環節—JVM決議（1.2）
