这是一个工具类，获取的内容：

CPU使用率：得到的是当前CPU的使用情况，这是算出的是两次500毫秒时间差的CPU使用率

内存使用率：[1 -  剩余的物理内存/(总的物理内存+虚拟内存) ] * 100

磁盘总使用率：[1 -  磁盘空余大小/磁盘总大小 ] * 100

下面开始贴代码：使用暂时没有发现什么问题，如果有问题，咱们可以一起讨论

package com.util;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.lang.management.ManagementFactory;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

import org.apache.log4j.Logger;

import com.sun.management.OperatingSystemMXBean;

public class ComputerMonitorUtil {

private static String osName = System.getProperty("os.name");
private static final int CPUTIME = 500;
private static final int PERCENT = 100;
private static final int FAULTLENGTH = 10;
private static final Logger logger = Logger.getLogger(ComputerMonitorUtil.class);

/**
* 功能：获取Linux和Window系统cpu使用率
* */
public static double getCpuUsage() {
// 如果是window系统
if (osName.toLowerCase().contains("windows")
|| osName.toLowerCase().contains("win")) {
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));//第一次读取CPU信息
Thread.sleep(CPUTIME);//睡500ms
long[] c1 = readCpu(Runtime.getRuntime().exec(procCmd));//第二次读取CPU信息
if (c0 != null && c1 != null) {
long idletime = c1[0] - c0[0];//空闲时间
long busytime = c1[1] - c0[1];//使用时间
Double cpusage = Double.valueOf(PERCENT * (busytime) * 1.0 / (busytime + idletime));
BigDecimal b1 = new BigDecimal(cpusage);
double cpuUsage = b1.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
return cpuUsage;
} else {
return 0.0;
}
} catch (Exception ex) {
logger.debug(ex);
return 0.0;
}

} else {

try {
Map<?, ?> map1 = ComputerMonitorUtil.cpuinfo();
Thread.sleep(CPUTIME);
Map<?, ?> map2 = ComputerMonitorUtil.cpuinfo();

long user1 = Long.parseLong(map1.get("user").toString());
long nice1 = Long.parseLong(map1.get("nice").toString());
long system1 = Long.parseLong(map1.get("system").toString());
long idle1 = Long.parseLong(map1.get("idle").toString());

long user2 = Long.parseLong(map2.get("user").toString());
long nice2 = Long.parseLong(map2.get("nice").toString());
long system2 = Long.parseLong(map2.get("system").toString());
long idle2 = Long.parseLong(map2.get("idle").toString());

long total1 = user1 + system1 + nice1;
long total2 = user2 + system2 + nice2;
float total = total2 - total1;

long totalIdle1 = user1 + nice1 + system1 + idle1;
long totalIdle2 = user2 + nice2 + system2 + idle2;
float totalidle = totalIdle2 - totalIdle1;

float cpusage = (total / totalidle) * 100;

BigDecimal b1 = new BigDecimal(cpusage);
double cpuUsage = b1.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
return cpuUsage;
} catch (InterruptedException e) {
logger.debug(e);
}
}
return 0;
}

/**
* 功能：Linux CPU使用信息
* */
public static Map<?, ?> cpuinfo() {
InputStreamReader inputs = null;
BufferedReader buffer = null;
Map<String, Object> map = new HashMap<String, Object>();
try {
inputs = new InputStreamReader(new FileInputStream("/proc/stat"));
buffer = new BufferedReader(inputs);
String line = "";
while (true) {
line = buffer.readLine();
if (line == null) {
break;
}
if (line.startsWith("cpu")) {
StringTokenizer tokenizer = new StringTokenizer(line);
List<String> temp = new ArrayList<String>();
while (tokenizer.hasMoreElements()) {
String value = tokenizer.nextToken();
temp.add(value);
}
map.put("user", temp.get(1));
map.put("nice", temp.get(2));
map.put("system", temp.get(3));
map.put("idle", temp.get(4));
map.put("iowait", temp.get(5));
map.put("irq", temp.get(6));
map.put("softirq", temp.get(7));
map.put("stealstolen", temp.get(8));
break;
}
}
} catch (Exception e) {
logger.debug(e);
} finally {
try {
buffer.close();
inputs.close();
} catch (Exception e2) {
logger.debug(e2);
}
}
return map;
}

/**
* 功能：Linux 和 Window 内存使用率
* */
public static double getMemUsage() {
if (osName.toLowerCase().contains("windows")
|| osName.toLowerCase().contains("win")) {

try {
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 usage = (Double) (1 - freePhysicalMemorySize * 1.0 / totalvirtualMemory) * 100;
BigDecimal b1 = new BigDecimal(usage);
double memoryUsage = b1.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
return memoryUsage;
} catch (Exception e) {
logger.debug(e);
}
} else {
Map<String, Object> map = new HashMap<String, Object>();
InputStreamReader inputs = null;
BufferedReader buffer = null;
try {
inputs = new InputStreamReader(new FileInputStream("/proc/meminfo"));
buffer = new BufferedReader(inputs);
String line = "";
while (true) {
line = buffer.readLine();
if (line == null)
break;
int beginIndex = 0;
int endIndex = line.indexOf(":");
if (endIndex != -1) {
String key = line.substring(beginIndex, endIndex);
beginIndex = endIndex + 1;
endIndex = line.length();
String memory = line.substring(beginIndex, endIndex);
String value = memory.replace("kB", "").trim();
map.put(key, value);
}
}

long memTotal = Long.parseLong(map.get("MemTotal").toString());
long memFree = Long.parseLong(map.get("MemFree").toString());
long memused = memTotal - memFree;
long buffers = Long.parseLong(map.get("Buffers").toString());
long cached = Long.parseLong(map.get("Cached").toString());

double usage = (double) (memused - buffers - cached) / memTotal * 100;
BigDecimal b1 = new BigDecimal(usage);
double memoryUsage = b1.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
return memoryUsage;
} catch (Exception e) {
logger.debug(e);
} finally {
try {
buffer.close();
inputs.close();
} catch (Exception e2) {
logger.debug(e2);
}
}

}
return 0.0;
}

/**
* Window 和Linux 得到磁盘的使用率
*
* @return
* @throws Exception
*/
public static double getDiskUsage() throws Exception {
double totalHD = 0;
double usedHD = 0;
if (osName.toLowerCase().contains("windows")
|| osName.toLowerCase().contains("win")) {
long allTotal = 0;
long allFree = 0;
for (char c = 'A'; c <= 'Z'; c++) {
String dirName = c + ":/";
File win = new File(dirName);
if (win.exists()) {
long total = (long) win.getTotalSpace();
long free = (long) win.getFreeSpace();
allTotal = allTotal + total;
allFree = allFree + free;
}
}
Double precent = (Double) (1 - allFree * 1.0 / allTotal) * 100;
BigDecimal b1 = new BigDecimal(precent);
precent = b1.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
return precent;
} else {
Runtime rt = Runtime.getRuntime();
Process p = rt.exec("df -hl");// df -hl 查看硬盘空间
BufferedReader in = null;
try {
in = new BufferedReader(new InputStreamReader(p.getInputStream()));
String str = null;
String[] strArray = null;
while ((str = in.readLine()) != null) {
int m = 0;
strArray = str.split(" ");
for (String tmp : strArray) {
if (tmp.trim().length() == 0)
continue;
++m;
if (tmp.indexOf("G") != -1) {
if (m == 2) {
if (!tmp.equals("") && !tmp.equals("0"))
totalHD += Double.parseDouble(tmp.substring(0, tmp.length() - 1)) * 1024;
}
if (m == 3) {
if (!tmp.equals("none") && !tmp.equals("0"))
usedHD += Double.parseDouble(tmp.substring(0, tmp.length() - 1)) * 1024;
}
}
if (tmp.indexOf("M") != -1) {
if (m == 2) {
if (!tmp.equals("") && !tmp.equals("0"))
totalHD += Double.parseDouble(tmp.substring(0, tmp.length() - 1));
}
if (m == 3) {
if (!tmp.equals("none") && !tmp.equals("0"))
usedHD += Double.parseDouble(tmp.substring(0, tmp.length() - 1));
}
}
}
}
} catch (Exception e) {
logger.debug(e);
} finally {
in.close();
}
// 保留2位小数
double precent = (usedHD / totalHD) * 100;
BigDecimal b1 = new BigDecimal(precent);
precent = b1.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
return precent;
}

}

// window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;//读取物理设备时间
long usertime = 0;//执行代码占用时间
while ((line = input.readLine()) != null) {
if (line.length() < wocidx) {
continue;
}
// 字段出现顺序：Caption,CommandLine,KernelModeTime,ReadOperationCount
String caption = substring(line, capidx, cmdidx - 1).trim();
// System.out.println("caption:"+caption);
String cmd = substring(line, cmdidx, kmtidx - 1).trim();
// System.out.println("cmd:"+cmd);
if (cmd.indexOf("wmic.exe") >= 0) {
continue;
}
String s1 = substring(line, kmtidx, rocidx - 1).trim();
String s2 = substring(line, umtidx, wocidx - 1).trim();
List<String> digitS1 = getDigit(s1);
List<String> digitS2 = getDigit(s2);

// System.out.println("s1:"+digitS1.get(0));
// System.out.println("s2:"+digitS2.get(0));

if (caption.equals("System Idle Process") || caption.equals("System")) {
if (s1.length() > 0) {
if (!digitS1.get(0).equals("") && digitS1.get(0) != null) {
idletime += Long.valueOf(digitS1.get(0)).longValue();
}
}
if (s2.length() > 0) {
if (!digitS2.get(0).equals("") && digitS2.get(0) != null) {
idletime += Long.valueOf(digitS2.get(0)).longValue();
}
}
continue;
}
if (s1.length() > 0) {
if (!digitS1.get(0).equals("") && digitS1.get(0) != null) {
kneltime += Long.valueOf(digitS1.get(0)).longValue();
}
}

if (s2.length() > 0) {
if (!digitS2.get(0).equals("") && digitS2.get(0) != null) {
kneltime += Long.valueOf(digitS2.get(0)).longValue();
}
}
}
retn[0] = idletime;
retn[1] = kneltime + usertime;

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

/**
* 从字符串文本中获得数字
*
* @param text
* @return
*/
private static List<String> getDigit(String text) {
List<String> digitList = new ArrayList<String>();
digitList.add(text.replaceAll("\\D", ""));
return digitList;
}

/**
* 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;
}

public static void main(String[] args) throws Exception {

double cpuUsage = ComputerMonitorUtil .getCpuUsage();
//当前系统的内存使用率
double memUsage = ComputerMonitorUtil .getMemUsage();
//当前系统的硬盘使用率
double diskUsage = ComputerMonitorUtil .getDiskUsage();

System.out.println("cpuUsage:"+cpuUsage);
System.out.println("memUsage:"+memUsage);
System.out.println("diskUsage:"+diskUsage);

}

}