各种语言运行原理浅析

c/c++

C语言运行

编写源代码

编写.c/.cpp文件包含相应的业务逻辑
编译代码

初步校验代码

生成编译文件 *.obj 和 *.o
链接

生成可执行文件 .exe 和 .sh

Java

Java语言运行原理

编写源代码

编写 .java 文件
编译

javac 命令编译.java源文件编译成 .class文件
- 分析和输入到符号表
- 注解处理
- 语义分析和生成class文件
java -verbose **.java 表示会输出编译器正在执行的操作的消息

javap 是jdk自带的反解析工具。

它的作用就是根据class字节码文件，反解析出当前类对应的code区（汇编指令）、本地变量表、异常表和代码行偏移量映射表、常量池等等信息。

Java编译输出简单测试

python

javascript

Go

调试过程

Java编译输出简单测试

编写源代码

  //HelloWord.java file
  public class HelloWord{
      public static void main(String[] args) {
          //test [javac HelloWord.java] command and  [javac -verbose HelloWord.java]
          System.out.println("test");
      }
  }

在类所在目录下执行编译过程简单查看方式

提前配置环境变量 java -version 有输出

javac HelloWord.java 生成HelloWord.class文件

javac -verbose HelloWord.java

  PS D:\test\java> javac -verbose .\HelloWord.java
  [解析开始时间 RegularFileObject[.\HelloWord.java]]
  [解析已完成, 用时 22 毫秒]
  [源文件的搜索路径: .]
  [类文件的搜索路径: C:\Program Files\Java\jdk1.8.0_131\jre\lib\resources.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\rt.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\sunrsasign.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\jsse.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\jce.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\charsets.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\jfr.jar,C:\Program Files\Java\jdk1.8.0_131\jre\classes,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\access-bridge-64.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\cldrdata.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\dnsns.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\jaccess.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\jfxrt.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\localedata.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\nashorn.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunec.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunjce_provider.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunmscapi.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunpkcs11.jar,C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\zipfs.jar,.]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Object.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/String.class)]]
  [正在检查HelloWord]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/io/Serializable.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/AutoCloseable.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Byte.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Character.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Short.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Long.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Float.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Integer.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Double.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Boolean.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Void.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/System.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/io/PrintStream.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Appendable.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/io/Closeable.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/io/FilterOutputStream.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/io/OutputStream.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/io/Flushable.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/Comparable.class)]]
  [正在加载ZipFileIndexFileObject[C:\Program Files\Java\jdk1.8.0_131\lib\ct.sym(META-INF/sym/rt.jar/java/lang/CharSequence.class)]]
  [已写入RegularFileObject[.\HelloWord.class]]
  [共 249 毫秒]

Java class 反解析查看

javap 命令

java -c -l HelloWord.class 查看更清晰

javap -c .\HelloWord.class 反汇编代码查看

  Compiled from "HelloWord.java"
  public class HelloWord {
  public HelloWord();
      Code:
      0: aload_0
      1: invokespecial #1                  // Method java/lang/Object."<init>":()V
      4: return

  public static void main(java.lang.String[]);
      Code:
      0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
      3: ldc           #3                  // String test
      5: invokevirtual #4                  // Method java/io/PrintStream.println:(Ljava/lang/String;)V
      8: return
  }

java代码执行顺序父子类静态代码块执行分析
1. 静态属性 > 静态代码块 > 构造方法
2. 父类 > 子类
3. 按顺序执行