获取系统内存，CPU使用率以及状态栏高度

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Field;
import java.util.List;

import android.app.ActivityManager;
import android.app.ActivityManager.RunningTaskInfo;
import android.content.Context;

public class DeviceInfoManager {

//  private static final String TAG = "DeviceInfoManager";
private static ActivityManager mActivityManager;

public synchronized static ActivityManager getActivityManager(Context context) {
if (mActivityManager == null) {
mActivityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
}
return mActivityManager;
}

/**
* 用于获取状态栏的高度。
*
* @return 返回状态栏高度的像素值。
*/
public static int getStatusBarHeight(Context context) {

int statusBarHeight = 0;
try {
Class<?> c = Class.forName("com.android.internal.R$dimen");
Object o = c.newInstance();
Field field = c.getField("status_bar_height");
int x = (Integer) field.get(o);
statusBarHeight = context.getResources().getDimensionPixelSize(x);
} catch (Exception e) {
e.printStackTrace();
}
return statusBarHeight;
}

/**
* 计算已使用内存的百分比，并返回。
*
* @param context
*            可传入应用程序上下文。
* @return 已使用内存的百分比，以字符串形式返回。
*/
public static String getUsedPercentValue(Context context) {
long totalMemorySize = getTotalMemory();
long availableSize = getAvailableMemory(context) / 1024;
int percent = (int) ((totalMemorySize - availableSize) / (float) totalMemorySize * 100);
return percent + "%";
}

/**
* 获取当前可用内存，返回数据以字节为单位。
*
* @param context 可传入应用程序上下文。
* @return 当前可用内存。
*/
public static long getAvailableMemory(Context context) {
ActivityManager.MemoryInfo mi = new ActivityManager.MemoryInfo();
getActivityManager(context).getMemoryInfo(mi);
return mi.availMem;
}

/**
* 获取系统总内存,返回字节单位为KB
* @return 系统总内存
*/
public static long getTotalMemory() {
long totalMemorySize = 0;
String dir = "/proc/meminfo";
try {
FileReader fr = new FileReader(dir);
BufferedReader br = new BufferedReader(fr, 2048);
String memoryLine = br.readLine();
String subMemoryLine = memoryLine.substring(memoryLine.indexOf("MemTotal:"));
br.close();

//将非数字的字符替换为空
totalMemorySize = Integer.parseInt(subMemoryLine.replaceAll("\\D+", ""));
} catch (IOException e) {
e.printStackTrace();
}

return totalMemorySize;
}

/**
* 获取顶层activity的包名
* @param context
* @return activity的包名
*/
public static String getTopActivityPackageName(Context context) {
ActivityManager activityManager = getActivityManager(context);
List<RunningTaskInfo> runningTasks = activityManager.getRunningTasks(1);
return runningTasks.get(0).topActivity.getPackageName();
}

/**
* 以下CPU使用时间，使用率方法参考自
* Android获取cpu使用率  (http://www.51testing.com/html/84/65284-822811.html)
* [Android]获取cpu使用率 (http://my.oschina.net/u/1429862/blog/223371)
* Android中获取CPU负载和进程cpu时间  (http://my.oschina.net/u/262208/blog/378660)
*/

/**
* 获取当前进程的CPU使用率
* @return CPU的使用率
*/
public static float getCurProcessCpuRate()
{

float totalCpuTime1 = getTotalCpuTime();
float processCpuTime1 = getAppCpuTime();
try
{
Thread.sleep(360);
}
catch (Exception e)
{
}

float totalCpuTime2 = getTotalCpuTime();
float processCpuTime2 = getAppCpuTime();

float cpuRate = 100 * (processCpuTime2 - processCpuTime1)
/ (totalCpuTime2 - totalCpuTime1);

return cpuRate;
}

/**
* 获取总的CPU使用率
* @return CPU使用率
*/
public static float getTotalCpuRate() {
float totalCpuTime1 = getTotalCpuTime();
float totalUsedCpuTime1 = totalCpuTime1 - sStatus.idletime;

try {
Thread.sleep(360);
} catch (InterruptedException e) {
e.printStackTrace();
}

float totalCpuTime2 = getTotalCpuTime();
float totalUsedCpuTime2 = totalCpuTime2 - sStatus.idletime;

float cpuRate = 100 * (totalUsedCpuTime2 - totalUsedCpuTime1)
/ (totalCpuTime2 - totalCpuTime1);

return cpuRate;
}

/**
* 获取系统总CPU使用时间
* @return 系统CPU总的使用时间
*/
public static long getTotalCpuTime()
{

String[] cpuInfos = null;
try
{
BufferedReader reader = new BufferedReader(new InputStreamReader(
new FileInputStream("/proc/stat")), 1000);
String load = reader.readLine();
reader.close();
cpuInfos = load.split(" ");
}
catch (IOException ex)
{
ex.printStackTrace();
}
//      long totalCpu = Long.parseLong(cpuInfos[2])
//              + Long.parseLong(cpuInfos[3]) + Long.parseLong(cpuInfos[4])
//              + Long.parseLong(cpuInfos[6]) + Long.parseLong(cpuInfos[5])
//              + Long.parseLong(cpuInfos[7]) + Long.parseLong(cpuInfos[8]);

sStatus.usertime = Long.parseLong(cpuInfos[2]);
sStatus.nicetime = Long.parseLong(cpuInfos[3]);
sStatus.systemtime = Long.parseLong(cpuInfos[4]);
sStatus.idletime = Long.parseLong(cpuInfos[5]);
sStatus.iowaittime = Long.parseLong(cpuInfos[6]);
sStatus.irqtime = Long.parseLong(cpuInfos[7]);
sStatus.softirqtime = Long.parseLong(cpuInfos[8]);

return sStatus.getTotalTime();
}

/**
* 获取当前进程的CPU使用时间
* @return 当前进程的CPU使用时间
*/
public static long getAppCpuTime()
{
// 获取应用占用的CPU时间
String[] cpuInfos = null;

try
{
int pid = android.os.Process.myPid();
BufferedReader reader = new BufferedReader(new InputStreamReader(
new FileInputStream("/proc/" + pid + "/stat")), 1000);
String load = reader.readLine();
reader.close();
cpuInfos = load.split(" ");
}

catch (IOException ex)
{
ex.printStackTrace();
}
long appCpuTime = Long.parseLong(cpuInfos[13])
+ Long.parseLong(cpuInfos[14]) + Long.parseLong(cpuInfos[15])
+ Long.parseLong(cpuInfos[16]);
return appCpuTime;
}

static Status sStatus = new Status();

static class Status {
public long usertime;
public long nicetime;
public long systemtime;
public long idletime;
public long iowaittime;
public long irqtime;
public long softirqtime;

public long getTotalTime() {
return (usertime + nicetime + systemtime + idletime + iowaittime
+ irqtime + softirqtime);
}
}
}