jshell is a repl (read-evaluate-print-loop) tool used to execute simple statements, evaluates it, and displays the result without a main() method. we can start it by simply type jshell in command-line prompt.
we need to get the system properties by using system.getproperty() and system.getproperties() methods.
in the below code snippet, we can able to display the system properties in the jshell tool by using static method property() of system class.
snippet-1jshell> system.getproperty("java.class.path")$1 ==> "c:\program files\java\jdk-9.0.4\lib;c:\json-jars\json.jar;.;c:\json-jars\json-simple.jar;.;c:\json-jars\gson.jar;.;c:\json-jars\commons-io.jar;.;c:\json-jars\jackson-core.jar;.;c:\json-jars\jackson-databind.jar;.;c:\json-jars\jackson-annotations.jar;.;c:\json jars\flexjson.jar;.;c:\json-jars\jackson-dataformat-xml.jar;.;c:\json-jars\stax2-api.jar;.;c:\json-jars\jackson-dataformat-csv.jar;.;c:\json-jars\javax.json.jar;.;c:\json jars\javax.json-api.jar;.;c:\json-jars\jackson-module-jsonschema.jar;.;c:\json-jars\json-lib.jar;.;c:\json-jars\commons-lang.jar;.;c:\json-jars\commons-logging.jar;.;"
在下面的代码片段中，我们必须使用扩展了hashtable的“properties”对象。因此，可以通过在jshell工具中使用“system.getproperties().foreach((k, v)”来列出所有属性作为键/值对.
snippet-2jshell> system.getproperties().foreach((k, v) -> { system.out.printf("%s: %s\n", k, v); })sun.desktop: windowsawt.toolkit: sun.awt.windows.wtoolkitjava.specification.version: 9file.encoding.pkg: sun.iosun.cpu.isalist: amd64sun.jnu.encoding: cp1252java.class.path: c:\program files\java\jdk-9.0.4\lib;c:\json jars\json.jar;.;c:\json jars\json-simple.jar;.;c:\json jars\gson.jar;.;c:\json jars\commons-io.jar;.;c:\json jars\jackson-core.jar;.;c:\json jars\jackson-databind.jar;.;c:\json jars\jackson-annotations.jar;.;c:\json jars\flexjson.jar;.;c:\json jars\jackson-dataformat-xml.jar;.;c:\json jars\stax2-api.jar;.;c:\json jars\jackson-dataformat-csv.jar;.;c:\json jars\javax.json.jar;.;c:\json jars\javax.json-api.jar;.;c:\json jars\jackson-module-jsonschema.jar;.;c:\json jars\json-lib.jar;.;c:\json jars\commons-lang.jar;.;c:\json jars\commons-logging.jar;.;java.vm.vendor: oracle corporationsun.arch.data.model: 64user.variant:java.vendor.url: http://java.oracle.com/user.timezone:os.name: windows 8.1java.vm.specification.version: 9sun.java.launcher: sun_standarduser.country: ussun.boot.library.path: c:\program files\java\jdk-9.0.4\binsun.java.command: jdk.jshell.execution.remoteexecutioncontrol 54984jdk.debug: releasesun.cpu.endian: littleuser.home: c:\users\useruser.language: enjava.specification.vendor: oracle corporationjava.home: c:\program files\java\jdk-9.0.4file.separator: \java.vm.compressedoopsmode: 32-bitline.separator:java.vm.specification.vendor: oracle corporationjava.specification.name: java platform api specificationjava.awt.graphicsenv: sun.awt.win32graphicsenvironmentuser.script:sun.management.compiler: hotspot 64-bit tiered compilersjava.runtime.version: 9.0.4+11user.name: userpath.separator: ;os.version: 6.3java.runtime.name: java(tm) se runtime environmentfile.encoding: cp1252java.vm.name: java hotspot(tm) 64-bit server vmjava.vendor.url.bug: http://bugreport.java.com/bugreport/java.io.tmpdir: c:\users\user\appdata\local\temp\java.version: 9.0.4user.dir: c:\users\user\desktop\java 9 qnaos.arch: amd64java.vm.specification.name: java virtual machine specificationjava.awt.printerjob: sun.awt.windows.wprinterjobsun.os.patch.level:java.library.path: c:\program files\java\jdk-9.0.4\bin;c:\windows\sun\java\bin;c:\windows\system32;c:\windows;c:\program files\java\jdk-9.0.4\bin;.;;.java.vm.info: mixed modejava.vendor: oracle corporationjava.vm.version: 9.0.4+11sun.io.unicode.encoding: unicodelittlejava.class.version: 53.0
以上就是如何在java 9的jshell中获取系统属性？的详细内容。