JAVA基础之java简单命令 javajava基础

java -cp命令
存在两个路径，其中psdir下com/test/training/路径下有Main.class和Student.class
另外路径，libdir下com/newtest/support/路径下有Other.class
在mydir下执行命令

//Windows java -cp \psdir; \libdir com.test.training.Main //Unix platforms java -cp /psdir:/libdir com.test.training.Main

如果在psdir路径下，是training.jar包，包内com/test/training/路径下有Main.class和Student.class
另外路径，libdir下com/newtest/support/路径下有Other.class
在mydir下执行命令

//Windows java -cp \psdir\training.jar; \libdir com.test.training.Main //Unix platforms java -cp /psdir/training.jar:/libdir com.test.training.Main

mydir路径下ourapp.jar，jar包内包含Manifest文件，以及com/test/training/路径下有Main.class和Student.class，com/newtest/support/路径下有Other.class

Manifest-Version: 1.0 Main-Class: com.test.training.Main

此时才可以执行

java -jar ourapp.jar

环境变量

//设置变量以及取出 Properties props = new Properties(); props.setProperty("displayName","Bu Xuesong"); String name = props.getProperty("displayName"); System.out.println("name:"+name); String acctNum = props.getProperty("accountNumber"); System.out.println("acctNum:"+acctNum); String nextPosition = props.getProperty("accountNumber","1"); System.out.println("nextPosition:"+nextPosition); //获取系统变量 String username = System.getProperty("user.name"); System.out.println(username); String userHome = System.getProperty("user.home"); System.out.println(userHome); String osArchitecture = System.getProperty("os.arch"); System.out.println(osArchitecture); String javaVendor = System.getProperty("java.vendor"); System.out.println(javaVendor); Map map = System.getenv(); for (String key:map.keySet()) { System.out.println("key:"+key+"; value="https://www.it610.com/article/+map.get(key)); }String logName = System.getenv("LOGNAME"); System.out.println(logName);

将properties变量存入xml中

public static void XMLtest() { Properties prop = new Properties(); prop.setProperty("displayName","Xuesong Bu"); prop.setProperty("accountNumber","1-234-567"); try(OutputStream out = Files.newOutputStream(Paths.get("/Users/buxuesong/Documents/svn_code/demo/prop.xml"))){ prop.storeToXML(out,"My account"); }catch (Exception e){ System.out.println(e.getClass().getSimpleName()+" | "+e.getMessage()); }Properties inProp = new Properties(); try(InputStream in = Files.newInputStream(Paths.get("/Users/buxuesong/Documents/svn_code/demo/prop.xml"))){ inProp.loadFromXML(in); }catch(Exception e){ System.out.println(e.getClass().getSimpleName()+" | "+e.getMessage()); } String displayName = inProp.getProperty("displayName"); System.out.println("displayName:"+displayName); String accountNumber = inProp.getProperty("accountNumber"); System.out.println("accountNumber:"+accountNumber); }

生成的xml

My account Xuesong Bu 1-234-567 输出的日志： displayName:Xuesong Bu accountNumber:1-234-567

默认Properties方式，当创建Properties的时候不必每次都去重新读区，可以通过之前的Properties构造方法来默认创建

public static void defaultProperties() { Properties defaults = new Properties(); defaults.setProperty("position","1"); Properties props = new Properties(defaults); String nextPos = props.getProperty("position"); int pos = Integer.parseInt(nextPos); System.out.println("pos:"+pos); props.setProperty("position",Integer.toString(++pos)); nextPos = props.getProperty("position"); System.out.println("nextPos:"+nextPos); } 输出： pos:1 nextPos:2

通过读取默认的Properties以及将期存储为xml，后期可以再次取出。
以下程序在第一次执行时从默认MyDefaultValues.xml取出内容，放入userProps中，然后再将userProps存储到文件userValues.xml中，第二次执行就可以从userValues取出上一次存储的值

public class Main {public static void main(String[] args) { try{ Properties defaultProps = new Properties(); try(InputStream inputStream = Main.class.getClassLoader().getResourceAsStream("MyDefaultValues.xml")){ defaultProps.loadFromXML(inputStream); } Properties userProps = new Properties(defaultProps); loadUserProps(userProps); String welcomeMessage = userProps.getProperty("welcomeMessage"); String farewellMessage = userProps.getProperty("farewellMessage"); System.out.println("welcomeMessage:"+welcomeMessage); System.out.println("farewellMessage:"+farewellMessage); if(userProps.getProperty("isFirstRun").equalsIgnoreCase("Y")){ userProps.setProperty("welcomeMessage","Welcome back"); userProps.setProperty("farewellMessage","Things will be familiar now"); userProps.setProperty("isFirstRun","N"); saveUserProps(userProps); }}catch (Exception e){ System.out.println(e.getClass().getSimpleName()+" | "+e.getMessage()); } } private static Properties loadUserProps(Properties userProps){ Path userFile = Paths.get("/Users/buxuesong/Documents/svn_code/demo/userValues.xml"); if(Files.exists(userFile)){ try(InputStream inputStream = Files.newInputStream(userFile)){ userProps.loadFromXML(inputStream); }catch (Exception e){ System.out.println(e.getClass().getSimpleName()+" | "+e.getMessage()); } } return userProps; } private static void saveUserProps(Properties userProps){ try(OutputStream outputStream = Files.newOutputStream(Paths.get("/Users/buxuesong/Documents/svn_code/demo/userValues.xml"))){ userProps.storeToXML(outputStream,null); }catch (Exception e){ System.out.println(e.getClass().getSimpleName()+" | "+e.getMessage()); } } }

MyDefaultValues.xml内容为：