Java技能树-System类

1 需求

2 接口

Class System
java.lang.Object 
        java.lang.System 

• Field Detail
  • public static final InputStream in
  • public static final PrintStream out
  • public static final PrintStream err
• Method Detail
  • public static void setIn(InputStream in)
  • public static void setOut(PrintStream out)
  • public static void setErr(PrintStream err)
  • public static Console console()
  • public static Channel inheritedChannel() throws IOException
  • public static void setSecurityManager(SecurityManager s)
  • public static SecurityManager getSecurityManager()
  • public static long currentTimeMillis()
  • public static long nanoTime()
  • public static void arraycopy(Object src, int srcPos, Object dest, int destPos, int length)
  • public static int identityHashCode(Object x)
  • public static Properties getProperties()
  • public static String lineSeparator()
  • public static void setProperties(Properties props)
  • public static String getProperty(String key)
  • public static String getProperty(String key, String def)
  • public static String setProperty(String key, String value)
  • public static String clearProperty(String key)
  • public static String getenv(String name)
  • public static Map getenv()
  • public static void exit(int status)
  • public static void gc()
  • public static void runFinalization()
  • public static void load(String filename)
  • public static void loadLibrary(String libname)
  • public static String mapLibraryName(String libname)

3 示例代码

public class SystemDemo {
    public static void main(String[] args) {
        // 错误信息
        System.err.println("error information");

        // 操作系统名称
        System.out.println("os.name: " + System.getProperty("os.name"));
        // 操作系统架构
        System.out.println("os.arch: " + System.getProperty("os.arch"));
        // 操作系统版本
        System.out.println("os.version: " + System.getProperty("os.version"));

        // 毫秒
        System.out.println("currentTimeMillis: " + System.currentTimeMillis());
        //纳秒
        System.out.println("nanoTime: " + System.nanoTime());

        // 用户名
        System.out.println("user.name: " + System.getProperty("user.name"));

        // 当前用户工作根目录
        System.out.println("user.home: " + System.getProperty("user.home"));

        // 当前目录
        System.out.println("user.dir: " + System.getProperty("user.dir"));

        // 字符编码
        System.out.println("file.encoding: " + System.getProperty("file.encoding"));

        // 文件分隔符
        System.out.println("file.separator: " + System.getProperty("file.separator"));
        // 路径分隔符
        System.out.println("path.separator: " + System.getProperty("path.separator"));

        // 换行。On UNIX systems, it returns "n"; on Microsoft Windows systems it returns "rn".
        System.out.println("line.separator: " + System.getProperty("line.separator"));

        // 手动执行垃圾回收
        System.gc();

        // 中止应用执行
        System.exit(0);

        // System.arraycopy();
    }
}

4 参考资料