JAVA中擷取安裝路徑、運作路徑、執行路徑的辦法

　　這些路徑意思聽起來很糊塗，對不對？這很正常，大家都這樣。怎麼辦？開發中把下列參數進行修改，看結果是不是自己期望的那個：

/**
     * <dt>java.version         <dd>Java version number
     * <dt>java.vendor          <dd>Java vendor specific string
     * <dt>java.vendor.url      <dd>Java vendor URL
     * <dt>java.home            <dd>Java installation directory
     * <dt>java.class.version   <dd>Java class version number
     * <dt>java.class.path      <dd>Java classpath
     * <dt>os.name              <dd>Operating System Name
     * <dt>os.arch              <dd>Operating System Architecture
     * <dt>os.version           <dd>Operating System Version
     * <dt>file.separator       <dd>File separator ("/" on Unix)
     * <dt>path.separator       <dd>Path separator (":" on Unix)
     * <dt>line.separator       <dd>Line separator ("\n" on Unix)
     * <dt>user.name            <dd>User account name
     * <dt>user.home            <dd>User home directory
     * <dt>user.dir             <dd>User's current working directory
     */
System.out.println("java.home="+System.getProperty("java.home"));