java怎样获取CPU占用率和硬盘占用率

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class T {

private static final int DRIVE_TYPE_HARD = 3;

private static final String CHARSET = "GBK";

private static final String CAP_LOAD_PERCENTAGE = "LoadPercentage";

private static final String CAP_CAPACITY = "Capacity";
private static final String CAP_CAPTION = "Caption";
private static final String CAP_DRIVE_LETTER = "DriveLetter";
private static final String CAP_DRIVE_TYPE = "DriveType";
private static final String CAP_FREE_SPACE = "FreeSpace";

private static final List CAPS_VOLUME = Arrays.asList(CAP_CAPACITY,
CAP_CAPTION, CAP_DRIVE_LETTER, CAP_DRIVE_TYPE, CAP_FREE_SPACE);

private static final String CMD_CPU = "wmic cpu get " + CAP_LOAD_PERCENTAGE;
private static final String CMD_VOLUME = "wmic volume get " + CAP_CAPACITY
+ "," + CAP_CAPTION + "," + CAP_DRIVE_LETTER + "," + CAP_DRIVE_TYPE + ","
+ CAP_FREE_SPACE;

public static void main(String[] args) throws IOException {
printDiskUsages(getDiskUsages());
printCpuUsage(getCpuLoadPercentage());
}

private static void printDiskUsages(List diskUsages) {
for (DiskUsage diskUsage : diskUsages) {
System.out.printf("%s占用率：%.2f%%\n", diskUsage.caption, diskUsage.usage);
}
}

private static void printCpuUsage(double cpuLoadPercentage) {
System.out.printf("CPU占用率：%.2f%%\n", cpuLoadPercentage);
}

/**
* 取得 CPU 占用率。
*
* @return
* @throws IOException
*/
private static double getCpuLoadPercentage() throws IOException {
Process process = Runtime.getRuntime().exec(CMD_CPU);
InputStream is = process.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is, CHARSET));
br.readLine(); // 舍弃标题行
br.readLine(); // 舍弃标题行下空行
String percentageLine = br.readLine();
if (percentageLine == null) {
return 0;
}
return Double.parseDouble(percentageLine.trim());
}

/**
* 取得硬盘占用率。
*
* @return
* @throws IOException
*/
private static List getDiskUsages() throws IOException {
Process process = Runtime.getRuntime().exec(CMD_VOLUME);
InputStream is = process.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is, CHARSET));
String captionLine = br.readLine(); // 舍弃标题行
br.readLine(); // 舍弃标题行下空行
Map captionToIndex = parseVolumeCaptionLine(captionLine);
String line;
List result = new ArrayList();
while ((line = br.readLine()) != null) {
if (line.length() == 0) {
// 舍弃空行
continue;
}
DiskUsage diskUsage = parseVolumeLine(line, captionToIndex);
if (diskUsage != null) {
result.add(diskUsage);
}
}
Collections.sort(result, new DiskUsageComparator());
return result;
}

private static Map parseVolumeCaptionLine(String captionLine) {
Map captionToIndex = new HashMap();
for (String caption : CAPS_VOLUME) {
captionToIndex.put(caption, captionLine.indexOf(caption));
}
return captionToIndex;
}

private static DiskUsage parseVolumeLine(String line,
Map captionToIndex) {
int driveType = parseVolumeDriveType(line, captionToIndex);
if (driveType != DRIVE_TYPE_HARD) {
return null;
}
String driveLetter = parseVolumeDriveLetter(line, captionToIndex);
if (!isValidDriveLetter(driveLetter)) {
return null;
}

String caption = parseVolumeCaption(line, captionToIndex);
long capacity = parseVolumeCapacity(line, captionToIndex);
long freeSpace = parseVolumeFreeSpace(line, captionToIndex);
return new DiskUsage(caption,
((capacity - freeSpace) / (double) capacity) * 100);
}

private static boolean isValidDriveLetter(String driveLetter) {
if (driveLetter.length() != 2) {
return false;
}
return Character.isUpperCase(driveLetter.charAt(0));
}

private static int parseVolumeDriveType(String line,
Map captionToIndex) {
String str = line.substring(captionToIndex.get(CAP_DRIVE_TYPE),
captionToIndex.get(CAP_FREE_SPACE));
return Integer.parseInt(str.trim());
}

private static String parseVolumeDriveLetter(String line,
Map captionToIndex) {
String str = line.substring(captionToIndex.get(CAP_DRIVE_LETTER),
captionToIndex.get(CAP_DRIVE_TYPE));
return str.trim();
}

private static String parseVolumeCaption(String line,
Map captionToIndex) {
String str = line.substring(captionToIndex.get(CAP_CAPTION),
captionToIndex.get(CAP_DRIVE_LETTER));
return str.trim();
}

private static long parseVolumeCapacity(String line,
Map captionToIndex) {
String str = line.substring(captionToIndex.get(CAP_CAPACITY),
captionToIndex.get(CAP_CAPTION));
return Long.parseLong(str.trim());
}

private static long parseVolumeFreeSpace(String line,
Map captionToIndex) {
String str = line.substring(captionToIndex.get(CAP_FREE_SPACE));
return Long.parseLong(str.trim());
}

private static class DiskUsageComparator implements Comparator {

@Override
public int compare(DiskUsage o1, DiskUsage o2) {
return o1.caption.compareTo(o2.caption);
}

}

private static class DiskUsage {
public String caption;
public double usage;

public DiskUsage(String caption, Double usage) {
this.caption = caption;
this.usage = usage;
}
}
}