Java Command Practice

1. jar打包命令，制作可运行的jar包

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> 编写好java文件之后,编译成class文件
> jar命令打包，注意包路径: jar -cvf myname.jar package1.package2/ 
> 打开jar包,修改manifest文件，在其中加入一行：Main-Class: package.MainClassName
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或者-e指定主属性：jar -cfev GumballServer.jar  proxy.gumball.GumballServer proxy/gumball/*

2. 查询运行的java进程

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jps -l

3. 使用import static

4. 虚拟机常用命令

jstat

jinfo

jvisualvm

jconsole

5. 查看字节码文件

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$ javap -verbose TestDatabase.class 

Classfile /home/jay/workspace/UnderstandJVM/bin/TestDatabase.class
  Last modified 2017-5-3; size 2171 bytes
  MD5 checksum 79e36bc0f72e63279222fa350470d5a5
  Compiled from "TestDatabase.java"
public class TestDatabase
  minor version: 0
  major version: 52
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
    #1 = Class              #2            // TestDatabase
    #2 = Utf8               TestDatabase
    #3 = Class              #4            // java/lang/Object
    #4 = Utf8               java/lang/Object
    #5 = Utf8               url
    #6 = Utf8               Ljava/lang/String;