如何在java中获取java进程使用的内存

public class MemoryUsage {
    public static void main(String[] args) {
        Runtime runtime = Runtime.getRuntime();
        long totalMemory = runtime.totalMemory();
        long freeMemory = runtime.freeMemory();
        long usedMemory = totalMemory - freeMemory;
        System.out.println("Total memory: " + totalMemory + " bytes");
        System.out.println("Free memory: " + freeMemory + " bytes");
        System.out.println("Used memory: " + usedMemory + " bytes");
    }
}