Java获取heap信息heapSize, heapMaxSiz

    public static void main(String[] args) {
        long heapSize = Runtime.getRuntime().totalMemory();
        System.out.println(readableFileSize(heapSize)); //245.5 MB
        long heapMaxSize = Runtime.getRuntime().maxMemory();
        System.out.println(readableFileSize(heapMaxSize)); //3.6 GB
        long heapFreeSize = Runtime.getRuntime().freeMemory();
        System.out.println(readableFileSize(heapFreeSize)); //239.1 MB
    }