java--通过java获取系统cpu及内存负载情况

代码如下

package com.haierpip.util;

import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.lang.management.ManagementFactory;

import com.sun.management.OperatingSystemMXBean;

public class SystemUtil {
	private static final int CPUTIME = 500;
	private static final int PERCENT = 100;
	private static final int FAULTLENGTH = 10;

	// 获得cpu使用率
	public static double getCpuRatioForWindows() {
		try {
			String procCmd = System.getenv(windir)
					+ \system32\wbem\wmic.exe process get Caption,CommandLine,KernelModeTime,ReadOperationCount,ThreadCount,UserModeTime,WriteOperationCount;

			// 取进程信息
			long[] c0 = readCpu(Runtime.getRuntime().exec(procCmd));
			Thread.sleep(CPUTIME);

			long[] c1 = readCpu(Runtime.getRuntime().exec(procCmd));

			if ((c0 != null) && (c1 != null)) {
				long idletime = c1[0] - c0[0];
				long busytime = c1[1] - c0[1];

				return Double.valueOf(
						(PERCENT * (busytime) * 1.0) / (busytime + idletime))
						.intValue();
			} else {
				return 0;
			}
		} catch (Exception ex) {
			ex.printStackTrace();

			return 0;
		}
	}

	// 读取cpu相关信息
	private static long[] readCpu(final Process proc) {
		long[] retn = new long[2];

		try {
			proc.getOutputStream().close();

			InputStreamReader ir = new InputStreamReader(proc.getInputStream());
			LineNumberReader input = new LineNumberReader(ir);
			String line = input.readLine();

			if ((line == null) || (line.length() < FAULTLENGTH)) {
				return null;
			}

			int capidx = line.indexOf(Caption);
			int cmdidx = line.indexOf(CommandLine);
			int rocidx = line.indexOf(ReadOperationCount);
			int umtidx = line.indexOf(UserModeTime);
			int kmtidx = line.indexOf(KernelModeTime);
			int wocidx = line.indexOf(WriteOperationCount);
			long idletime = 0;
			long kneltime = 0;
			long usertime = 0;

			while ((line = input.readLine()) != null) {
				if (line.length() < wocidx) {
					continue;
				}

				// 字段出现顺序：Caption,CommandLine,KernelModeTime,ReadOperationCount,
				// ThreadCount,UserModeTime,WriteOperation
				String caption = substring(line, capidx, cmdidx - 1).trim();
				String cmd = substring(line, cmdidx, kmtidx - 1).trim();

				if (cmd.indexOf(wmic.exe) >= 0) {
					continue;
				}

				String s1 = substring(line, kmtidx, rocidx - 1).trim();
				String s2 = substring(line, umtidx, wocidx - 1).trim();

				if (caption.equals(System Idle Process)
						|| caption.equals(System)) {
					if (s1.length() > 0) {
						idletime += Long.valueOf(s1).longValue();
					}

					if (s2.length() > 0) {
						idletime += Long.valueOf(s2).longValue();
					}

					continue;
				}

				if (s1.length() > 0) {
					kneltime += Long.valueOf(s1).longValue();
				}

				if (s2.length() > 0) {
					usertime += Long.valueOf(s2).longValue();
				}
			}

			retn[0] = idletime;
			retn[1] = kneltime + usertime;

			return retn;
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			try {
				proc.getInputStream().close();
			} catch (Exception e) {
				e.printStackTrace();
			}
		}

		return null;
	}

	/**
	 * 由于String.subString对汉字处理存在问题（把一个汉字视为一个字节)，因此在 包含汉字的字符串时存在隐患，现调整如下：
	 * 
	 * @param src
	 *            要截取的字符串
	 * @param start_idx
	 *            开始坐标（包括该坐标)
	 * @param end_idx
	 *            截止坐标（包括该坐标）
	 * @return
	 */
	private static String substring(String src, int start_idx, int end_idx) {
		byte[] b = src.getBytes();
		String tgt = ;

		for (int i = start_idx; i <= end_idx; i++) {
			tgt += (char) b[i];
		}

		return tgt;
	}
	
	// 获取内存使用率
	public static double getMemery() {
		OperatingSystemMXBean osmxb = (OperatingSystemMXBean) ManagementFactory
				.getOperatingSystemMXBean();
		// 总的物理内存+虚拟内存
		long totalvirtualMemory = osmxb.getTotalSwapSpaceSize();
		// 剩余的物理内存
		long freePhysicalMemorySize = osmxb.getFreePhysicalMemorySize();
		Double compare = (Double) (1 - freePhysicalMemorySize * 1.0
				/ totalvirtualMemory) * 100;
		return compare.intValue();
	}
}