我们一直希望我们的开发/测试环境像生产环境一样，但是经常会陷入使用JDK函数的陷阱中，这些函数没有非常明确地暴露环境依赖性(例如必需的方法参数)，或者可能难以发现和察觉。例如:
public String(byte bytes[])使用默认编码new Date()/Instant.now()使用系统时区System.out.printf("%n")使用平台行结尾其中一些可以由JVM参数(如
-Dfile.encoding=UTF-8)驱动。但是如何找到所有这些陷阱呢？
最佳答案
陷阱的类型取决于您的应用程序的类型。
对于几乎完整的列表，您可以运行此检查，该检查同时列出了操作系统环境变量和java系统属性:
import java.awt.GraphicsEnvironment;
import java.util.Map;
import java.util.Properties;
public class Sof39189179 {
public static void main(String[] args) {
Map<String, String> sysenv = System.getenv();
for(String key: sysenv.keySet())
System.out.println( key + ": " + sysenv.get(key));
Properties properties = System.getProperties();
for(Object key: properties.keySet())
System.out.println(key + ": " + properties.get(key));
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
System.out.println("headless: " + ge.isHeadless());
}
}
在我的计算机上，我得到以下输出(我省略了一些行):
M2: $M2_HOME/bin
JAVA_HOME: /opt/local/jdk-1.8.0_51
LANG: en_US.UTF-8
CATALINA_HOME: /opt/local/tomcat-8.0.24
...
---------------------
java.runtime.name: Java(TM) SE Runtime Environment
sun.boot.library.path: /opt/local/jdk-1.8.0_51/jre/lib/amd64
java.vm.version: 25.51-b03
java.vm.vendor: Oracle Corporation
java.vendor.url: http://java.oracle.com/
path.separator: :
java.vm.name: Java HotSpot(TM) 64-Bit Server VM
file.encoding.pkg: sun.io
user.country: US
sun.java.launcher: SUN_STANDARD
sun.os.patch.level: unknown
java.vm.specification.name: Java Virtual Machine Specification
user.dir: /home/rudolf/workspace/neon/sof39189179
java.runtime.version: 1.8.0_51-b16
java.awt.graphicsenv: sun.awt.X11GraphicsEnvironment
java.endorsed.dirs: /opt/local/jdk-1.8.0_51/jre/lib/endorsed
os.arch: amd64
java.io.tmpdir: /tmp
line.separator:
java.vm.specification.vendor: Oracle Corporation
os.name: Linux
...
java.awt.printerjob: sun.print.PSPrinterJob
file.encoding: UTF-8
java.specification.version: 1.8
java.class.path: /home/rudolf/workspace/neon/sof39189179/bin
user.name: rudolf
java.vm.specification.version: 1.8
java.home: /opt/local/jdk-1.8.0_51/jre
sun.arch.data.model: 64
user.language: en
java.specification.vendor: Oracle Corporation
awt.toolkit: sun.awt.X11.XToolkit
java.vm.info: mixed mode
java.version: 1.8.0_51
java.ext.dirs: /opt/local/jdk-1.8.0_51/jre/lib/ext:/usr/java/packages/lib/ext
sun.boot.class.path: /opt/local/jdk-1.8.0_51/jre/lib/resources.jar:/opt/local/jdk-1.8.0_51/jre/lib/rt.jar:/opt/local/jdk-1.8.0_51/jre/lib/sunrsasign.jar:/opt/local/jdk-1.8.0_51/jre/lib/jsse.jar:/opt/local/jdk-1.8.0_51/jre/lib/jce.jar:/opt/local/jdk-1.8.0_51/jre/lib/charsets.jar:/opt/local/jdk-1.8.0_51/jre/lib/jfr.jar:/opt/local/jdk-1.8.0_51/jre/classes
java.vendor: Oracle Corporation
file.separator: /
java.vendor.url.bug: http://bugreport.sun.com/bugreport/
sun.io.unicode.encoding: UnicodeLittle
sun.cpu.endian: little
sun.cpu.isalist:
headless: false
您可以从此列表中确定与您的情况相关的属性，然后检查代码。或者，最好在编写代码时要牢记这些属性。
我更喜欢使用上面列出的属性，即为了打印换行符，我使用类似以下内容:
String newline = (String) System.getProperties().get("line.separator");
System.out.println("newline: " + newline);
关于java - 如何在JDK中找到平台相关陷阱的完整列表，例如时区，编码，行尾等？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/39189179/