如何获取android上每个cpu核心的使用情况

我在 Android 上开发了一个小部件，它显示许多有用的信息。

我正在尝试修改此方法以返回一个 cpu 核心的使用百分比，以便获得每个核心的使用百分比！

在我的 HTC One X 上，我在“ /proc/stat ”中有：

cpu  183549 10728 236016 3754379 7530 41 1013 0 0 0
cpu0 141962 5990 196956 720894 3333 41 970 0 0 0
cpu1 23400 2550 23158 980901 2211 0 23 0 0 0
cpu2 13602 1637 12561 1019126 1216 0 18 0 0 0
cpu3 4585 551 3341 1033458 770 0 2 0 0 0

我使用此方法返回所有 cpu 核心的使用百分比。

public float readUsage() {
    try {

        RandomAccessFile reader = new RandomAccessFile("/proc/stat", "r");
        String load = reader.readLine();


        String[] toks = load.split(" ");

        long idle1 = Long.parseLong(toks[5]);
        long cpu1 = Long.parseLong(toks[2]) + Long.parseLong(toks[3]) + Long.parseLong(toks[4])
              + Long.parseLong(toks[6]) + Long.parseLong(toks[7]) + Long.parseLong(toks[8]);

        try {
            Thread.sleep(800);
        } catch (Exception e) {}

        reader.seek(0);
        load = reader.readLine();
        reader.close();

        toks = load.split(" ");

        long idle2 = Long.parseLong(toks[5]);
        long cpu2 = Long.parseLong(toks[2]) + Long.parseLong(toks[3]) + Long.parseLong(toks[4])
            + Long.parseLong(toks[6]) + Long.parseLong(toks[7]) + Long.parseLong(toks[8]);

        return (float)(cpu2 - cpu1) / ((cpu2 + idle2) - (cpu1 + idle1));

    } catch (IOException ex) {
        ex.printStackTrace();
    }

    return 0;
} 

我正在尝试使用 cpu1，但它不起作用：

public float readUsageCPU0() {
    try {

        RandomAccessFile reader = new RandomAccessFile("/proc/stat", "r");
        reader.seek(0);
        String load = reader.readLine();
        load = reader.readLine();
        load = reader.readLine();


        String[] toks = load.split(" ");

        long idle1 = Long.parseLong(toks[5]);
        long cpu1 = Long.parseLong(toks[2]) + Long.parseLong(toks[3]) + Long.parseLong(toks[4])
              + Long.parseLong(toks[6]) + Long.parseLong(toks[7]) + Long.parseLong(toks[8]);

        try {
            Thread.sleep(500);
        } catch (Exception e) {}

        reader.seek(0);
        load = reader.readLine();
        load = reader.readLine();
        load = reader.readLine();
        reader.close();

        toks = load.split(" ");

        long idle2 = Long.parseLong(toks[5]);
        long cpu2 = Long.parseLong(toks[2]) + Long.parseLong(toks[3]) + Long.parseLong(toks[4])
            + Long.parseLong(toks[6]) + Long.parseLong(toks[7]) + Long.parseLong(toks[8]);

        return (float)(cpu2 - cpu1) / ((cpu2 + idle2) - (cpu1 + idle1));

    } catch (IOException ex) {
        ex.printStackTrace();
    }

    return 0;
}

这允许读取一行并且光标停留在该行的末尾：

String load = reader.readLine();

因此，我尝试使用它两次以获得 CPU0 的使用权，第三次尝试使用它来获得 CPU1 的使用权。 但结果总是0或100...我不明白！

我使用的方法正确吗？ 我使用的文件正确吗？ 这个结果正常吗？

请帮忙 ！！！

public class CpuStat {
    private static final String TAG = "CpuUsage";
    private RandomAccessFile statFile;
    private CpuInfo mCpuInfoTotal;
    private ArrayList<CpuInfo> mCpuInfoList;

    public CpuStat() {
    }

    public void update() {
        try {           
            createFile();
            parseFile();
            closeFile();
        } catch (FileNotFoundException e) {
            statFile = null;
            Log.e(TAG, "cannot open /proc/stat: " + e);
        } catch (IOException e) {
            Log.e(TAG, "cannot close /proc/stat: " + e);
        }
    }

    private void createFile() throws FileNotFoundException {
        statFile = new RandomAccessFile("/proc/stat", "r");
    }

    public void closeFile() throws IOException {
        if (statFile != null)
            statFile.close();
    }

    private void parseFile() {
        if (statFile != null) {
            try {
                statFile.seek(0);
                String cpuLine = "";
                int cpuId = -1;
                do { 
                    cpuLine = statFile.readLine();
                    parseCpuLine(cpuId, cpuLine);
                    cpuId++;
                } while (cpuLine != null);
            } catch (IOException e) {
                Log.e(TAG, "Ops: " + e);
            }
        }
    }

    private void parseCpuLine(int cpuId, String cpuLine) {
        if (cpuLine != null && cpuLine.length() > 0) { 
            String[] parts = cpuLine.split("[ ]+");
            String cpuLabel = "cpu";
            if ( parts[0].indexOf(cpuLabel) != -1) {
                createCpuInfo(cpuId, parts);
            }
        } else {
            Log.e(TAG, "unable to get cpu line");
        }
    }

    private void createCpuInfo(int cpuId, String[] parts) {
        if (cpuId == -1) {                      
            if (mCpuInfoTotal == null)
                mCpuInfoTotal = new CpuInfo();
            mCpuInfoTotal.update(parts);
        } else {
            if (mCpuInfoList == null)
                mCpuInfoList = new ArrayList<CpuInfo>();
            if (cpuId < mCpuInfoList.size())
                mCpuInfoList.get(cpuId).update(parts);
            else {
                CpuInfo info = new CpuInfo();
                info.update(parts);
                mCpuInfoList.add(info);
            }                               
        }
    }

    public int getCpuUsage(int cpuId) {
        update();
        int usage = 0;
        if (mCpuInfoList != null) {
            int cpuCount = mCpuInfoList.size();
            if (cpuCount > 0) {
                cpuCount--;
                if (cpuId == cpuCount) { // -1 total cpu usage
                    usage = mCpuInfoList.get(0).getUsage(); 
                } else {
                    if (cpuId <= cpuCount)
                        usage = mCpuInfoList.get(cpuId).getUsage();
                    else
                        usage = -1;
                }
            }
        }
        return usage;
    }


    public int getTotalCpuUsage() {
        update();           
        int usage = 0;
        if (mCpuInfoTotal != null)
            usage = mCpuInfoTotal.getUsage();
        return usage;
    }


    public String toString() {
        update();
        StringBuffer buf = new StringBuffer();
        if (mCpuInfoTotal != null) {
            buf.append("Cpu Total : ");
            buf.append(mCpuInfoTotal.getUsage());
            buf.append("%");
        }   
        if (mCpuInfoList != null) {
            for (int i=0; i < mCpuInfoList.size(); i++) {
                CpuInfo info = mCpuInfoList.get(i); 
                buf.append(" Cpu Core(" + i + ") : ");
                buf.append(info.getUsage());
                buf.append("%");
                info.getUsage();
            }
        }           
        return buf.toString();
    }

    public class CpuInfo {
        private int  mUsage;            
        private long mLastTotal;
        private long mLastIdle;

        public CpuInfo() {
            mUsage = 0;
            mLastTotal = 0;
            mLastIdle = 0;  
        }

        private int  getUsage() {
            return mUsage;
        }

        public void update(String[] parts) {
            // the columns are:
            //
            //      0 "cpu": the string "cpu" that identifies the line
            //      1 user: normal processes executing in user mode
            //      2 nice: niced processes executing in user mode
            //      3 system: processes executing in kernel mode
            //      4 idle: twiddling thumbs
            //      5 iowait: waiting for I/O to complete
            //      6 irq: servicing interrupts
            //      7 softirq: servicing softirqs
            //
            long idle = Long.parseLong(parts[4], 10);
            long total = 0;
            boolean head = true;
            for (String part : parts) {
                if (head) {
                    head = false;
                    continue;
                }
                total += Long.parseLong(part, 10);
            }
            long diffIdle   =   idle - mLastIdle;
            long diffTotal  =   total - mLastTotal;
            mUsage = (int)((float)(diffTotal - diffIdle) / diffTotal * 100);
            mLastTotal = total;
            mLastIdle = idle;
            Log.i(TAG, "CPU total=" + total + "; idle=" + idle + "; usage=" + mUsage);
        }
    }
}