07.SpringShell内置命令详解

r囧r小猫 2022-03-22 07:58 337阅读 0赞

> SpringShell 除了允许我们自定义命令之外, 还提供了一些内置命令, 用于辅助我们操作. 笔者使用的是SpringShell 2.0版本, 内置命令只提供了五个:**help, clear, stacktrace, script, exit/quite.**

## 1.help命令-查看帮助 ##

### 1.1 查看所有内置命令 ###

help 本身就是内置命令, 不跟参数的help命令会打印所有内置命令.

shell:>help
    AVAILABLE COMMANDS
    
    Built-In Commands
            clear: Clear the shell screen.
            exit, quit: Exit the shell.
            help: Display help about available commands.
            script: Read and execute commands from a file.
            stacktrace: Display the full stacktrace of the last error.

### 1.2 查看命令详情 ###

可通过help + 命令方式, 查看命令详情.

shell:>help add
    NAME
    	add - 计算两个整数的加法
    SYNOPSYS
    	add [-a] int  [-b] int
    OPTIONS
    	-a  int
    		[Mandatory]
    	-b  int
    		[Mandatory]
    ALSO KNOWN AS
    	sum

## 2. clear命令-清屏 ##

SpringShell 也提供了类似于linux shell的清屏方式, 输入clear 或使用Ctrl+L快捷键.

shell:>clear

## 3. stacktrace命令-查看异常堆栈信息 ##

默认情况下, 命令执行抛出的异常, 只会输出异常的内容, 不会输出异常的堆栈信息. 当命令发生异常时, 我们可以通过stacktrace 来查看异常的堆栈信息. 需要注意的是, stacktrace 永远只保存上一次的异常的堆栈信息.

shell:>div 2 0
    / by zero
    Details of the error have been omitted. You can use the stacktrace command to print the full stacktrace.
    
    shell:>stacktrace
    java.lang.ArithmeticException: / by zero
    	at org.zongf.learn.spring.shell.cmd.CalculatorCommands.div(CalculatorCommands.java:32)
    	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)
    	at org.springframework.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:246)
    	at org.springframework.shell.Shell.evaluate(Shell.java:169)
    	at org.springframework.shell.Shell.run(Shell.java:134)
    	at org.springframework.shell.jline.InteractiveShellApplicationRunner.run(InteractiveShellApplicationRunner.java:84)
    	at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:804)
    	at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:794)
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:324)
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
    	at org.zongf.learn.spring.shell.SpringShellApplication.main(SpringShellApplication.java:10)
    	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)
    	at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
    	at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
    	at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)
    	at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)

## 4. script命令-执行脚本 ##

script命令使批量执行命令成了可能, 我们可以将一组命令存入文件, 然后批量执行. 需要注意的时, 文件名需要使用绝对路径.

### 4.1 创建批量脚本文件 ###

脚本存放在 /tmp/zongf/cmds

add 1 2
    add 2 3
    add 3 4
    div 4 2
    div 9 3

### 4.2 执行脚本 ###

shell:>script /tmp/zongf/cmds
    3
    5
    7
    2
    3

## 5. exit/quit命令-退出应用 ##

exit和quite命令互为别名, 使用哪个都可以退出应用.

shell:>exit