Java获取Linux系统cpu使用率

原文：http://www.open-open.com/code/view/1426152165201

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

import org.apache.commons.io.FileSystemUtils;

public class OSUtils {

    /**
     * 功能：可用磁盘
     * */
    public static int disk() {
        try {
            long total = FileSystemUtils.freeSpaceKb("/home");
            double disk = (double) total / 1024 / 1024;
            return (int) disk;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return 0;
    }

    /**
     * 功能：获取Linux系统cpu使用率
     * */
    public static int cpuUsage() {
        try {
            Map<?, ?> map1 = OSUtils.cpuinfo();
            Thread.sleep(5 * 1000);
            Map<?, ?> map2 = OSUtils.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;
            return (int) cpusage;
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return 0;
    }

    /**
     * 功能：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) {
            e.printStackTrace();
        } finally {
            try {
                buffer.close();
                inputs.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return map;
    }

    /**
     * 功能：内存使用率
     * */
    public static int memoryUsage() {
        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;
            return (int) usage;
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                buffer.close();
                inputs.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return 0;
    }
}