cmd.md

java program in cmd

• 编译
• 解释
• class文件查看
• 压缩
• 解压
• 生成注释文档
• 编码转换
• 打包
• Java性能分析工具

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The first program in Java

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//Source file
public class HelloJava {
	public static void main(String args[]){
		System.out.println("Hello Java!");
	}
}

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• 编译HelloJava.java文件

javac HelloJava.java

• 解释HelloJava.class文件

java HelloJava

• 查看HelloJava.class内容

javap -verbose HelloJava.class

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Classfile /F:/HelloJava.class
  Last modified 2017-10-26; size 423 bytes
  MD5 checksum bc9c1481256a513db9ca781accdeb234
  Compiled from "HelloJava.java"
public class HelloJava
  minor version: 0
  major version: 52
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
   #1 = Methodref          #6.#15         // java/lang/Object."<init>":()V
   #2 = Fieldref           #16.#17        // java/lang/System.out:Ljava/io/PrintStream;
   #3 = String             #18            // Hello Java!
   #4 = Methodref          #19.#20        // java/io/PrintStream.println:(Ljava/lang/String;)V
   #5 = Class              #21            // HelloJava
   #6 = Class              #22            // java/lang/Object
   #7 = Utf8               <init>
   #8 = Utf8               ()V
   #9 = Utf8               Code
  #10 = Utf8               LineNumberTable
  #11 = Utf8               main
  #12 = Utf8               ([Ljava/lang/String;)V
  #13 = Utf8               SourceFile
  #14 = Utf8               HelloJava.java
  #15 = NameAndType        #7:#8          // "<init>":()V
  #16 = Class              #23            // java/lang/System
  #17 = NameAndType        #24:#25        // out:Ljava/io/PrintStream;
  #18 = Utf8               Hello Java!
  #19 = Class              #26            // java/io/PrintStream
  #20 = NameAndType        #27:#28        // println:(Ljava/lang/String;)V
  #21 = Utf8               HelloJava
  #22 = Utf8               java/lang/Object
  #23 = Utf8               java/lang/System
  #24 = Utf8               out
  #25 = Utf8               Ljava/io/PrintStream;
  #26 = Utf8               java/io/PrintStream
  #27 = Utf8               println
  #28 = Utf8               (Ljava/lang/String;)V
{
  public HelloJava();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 1: 0

  public static void main(java.lang.String[]);
    descriptor: ([Ljava/lang/String;)V
    flags: ACC_PUBLIC, ACC_STATIC
    Code:
      stack=2, locals=1, args_size=1
         0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
         3: ldc           #3                  // String Hello Java!
         5: invokevirtual #4                  // Method java/io/PrintStream.println:(Ljava/lang/String;)V
         8: return
      LineNumberTable:
        line 3: 0
        line 4: 8
}
SourceFile: "HelloJava.java"

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• 将Hello.java压缩为myjar.jar

• • jar cf myjar.jar Hello.jar(不显示处理信息)
  • jar cvf myjar.jar Hello.jar(显示打包详细信息)
  • jar tf myjar.jar Hello.jar(显示jar文件目录和文件列表信息)
  • jar tvf myjar.jar Hello.jar(显示jar文件目录和文件列表信息和文件大小，创建时间详细信息)

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• 解压myjar.jar文件

• • jar xf myjar.jar(不显示解压信息)
  • jar xf myjar.jar(显示解压详细信息)

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• 带参执行

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//source file
public class Param {
	public static void main(String[] args) {
		int len=args.length;
		for(int i=0;i<len;i++){
			System.out.printf("args[%d]=%s%n",i,args[i]);
		}
	}
}

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• 生成注释文档

javadoc HelloJava.java

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源文件text.txt

//text.txt
我是唐龙

• 编码转换

• • native2ascii text.txt test.txt 将text.txt的内容转为本地编码并存储到test.txt文件中

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   //test.txt
   \u6211\u662f\u5510\u9f99
  

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  • native2ascii -encoding gbk text.txt test.txt 将text.txt的内容转换为gbk编码并存储到test.txt文件中(此时本地编码是gbk)

   //test.txt
   \u6211\u662f\u5510\u9f99
  

• 打包

  ：jar cvf 目标文件名.jar 需要打包的文件

将tree.txt 打包为tree.jar的命令，jar cvf tree.jar tree.txt

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• Java性能分析

• • 配置好JAVA_HOME/bin，在cmd输入jconsole，点击‘本地连接’，选择一个连接进程，点击连接。
    
  • Jconsole 官方文档

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