如何利用Java获取系统的信息（CPU、内存、各盘符使用情况）

/**

* 增加用于监控系统cpu,memory的工具类

*/

package com.hhf.test;

import java.io.File;

import java.io.InputStreamReader;

import java.io.LineNumberReader;

import java.lang.management.ManagementFactory;

import java.util.ArrayList;

import java.util.List;

import javax.management.MBeanServerConnection;

import javax.management.remote.JMXConnector;

import javax.management.remote.JMXConnectorFactory;

import javax.management.remote.JMXServiceURL;

import com.sun.management.OperatingSystemMXBean;

public class WindowsInfoUtil {

private static final int CPUTIME = 500;
private static final int PERCENT = 100;
private static final int FAULTLENGTH = 10;

// 获取内存使用率
public static String getMemery() {

OperatingSystemMXBean osmxb = ManagementFactory.getPlatformMXBean(OperatingSystemMXBean.class);
long totalvirtualMemory = osmxb.getTotalSwapSpaceSize(); // 剩余的物理内存
long freePhysicalMemorySize = osmxb.getFreePhysicalMemorySize();
Double compare = (Double) (1 - freePhysicalMemorySize * 1.0 / totalvirtualMemory) * 100;

String str = compare.intValue() + "%";
return str;

}

// 获取
4000
文件系统使用率
public static List<String> getDisk() {

// 操作系统
List<String> list = new ArrayList<String>();

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();
Double compare = (Double) (1 - free * 1.0 / total) * 100;
String str = c + ":盘已使用" + compare.intValue() + "%";
list.add(str);
}
}
return list;

}

// 获得cpu使用率
public static String 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 + "%";
}
}

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 = Bytes.substring(line, capidx, cmdidx - 1).trim();
String cmd = Bytes.substring(line, cmdidx, kmtidx - 1).trim();
if (cmd.indexOf("wmic.exe") >= 0) {
continue;
}
String s1 = Bytes.substring(line, kmtidx, rocidx - 1).trim();
String s2 = Bytes.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;

}
static class Bytes {
public 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 {

System.out.println("cpu占有率=" + WindowsInfoUtil.getCpuRatioForWindows());
System.out.println("可使用内存=" + WindowsInfoUtil.getMemery());
System.out.println("各盘占用情况：" + WindowsInfoUtil.getDisk());

}

}

这时就会出现com.sun.management.OperatingSystemMXBean这个类找不到！



这里的工程需要用到rt.jar，当我们额外下载导入rt.jar就可以解决这个问题，但是对于jdk来说本身是具有jar包的，原因是eclipse将这些访问受限制的API设置成了错误，导致不能import。