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最近做个项目，就是要取得cpu占有率等等的系统信息，一开始以为要用动态链接库了，但后来发现可以像下面这样做，不去调用jni，这样省去了很多看新技术的时间o(∩_∩)o...
在Java中，可以获得总的物理内存、剩余的物理内存、已使用的物理内存等信息，下面例子可以取得这些信息，并且获得在Windows下的内存使用率。
首先编写一个MonitorInfoBean类，用来装载监控的一些信息，包括物理内存、剩余的物理内存、已使用的物理内存、内存使用率等字段，该类的代码如下：
package com.amgkaka.performance;
/** */ /**
* 监视信息的JavaBean类.
* @author amg
* @version 1.0
* Creation date: 2008-4-25 - 上午10:37:00
*/
public class MonitorInfoBean {
/** */ /** 可使用内存. */
private long totalMemory;
/** */ /** 剩余内存. */
private long freeMemory;
/** */ /** 最大可使用内存. */
private long maxMemory;
/** */ /** 操作系统. */
private String osName;
/** */ /** 总的物理内存. */
private long totalMemorySize;
/** */ /** 剩余的物理内存. */
private long freePhysicalMemorySize;
/** */ /** 已使用的物理内存. */
private long usedMemory;
/** */ /** 线程总数. */
private int totalThread;
/** */ /** cpu使用率. */
private double cpuRatio;
public long getFreeMemory() {
return freeMemory;
}
public void setFreeMemory( long freeMemory) {
this .freeMemory = freeMemory;
}
public long getFreePhysicalMemorySize() {
return freePhysicalMemorySize;
}
public void setFreePhysicalMemorySize( long freePhysicalMemorySize) {
this .freePhysicalMemorySize = freePhysicalMemorySize;
}
public long getMaxMemory() {
return maxMemory;
}
public void setMaxMemory( long maxMemory) {
this .maxMemory = maxMemory;
}
public String getOsName() {
return osName;
}
public void setOsName(String osName) {
this .osName = osName;
}
public long getTotalMemory() {
return totalMemory;
}
public void setTotalMemory( long totalMemory) {
this .totalMemory = totalMemory;
}
public long getTotalMemorySize() {
return totalMemorySize;
}
public void setTotalMemorySize( long totalMemorySize) {
this .totalMemorySize = totalMemorySize;
}
public int getTotalThread() {
return totalThread;
}
public void setTotalThread( int totalThread) {
this .totalThread = totalThread;
}
public long getUsedMemory() {
return usedMemory;
}
public void setUsedMemory( long usedMemory) {
this .usedMemory = usedMemory;
}
public double getCpuRatio() {
return cpuRatio;
}
public void setCpuRatio( double cpuRatio) {
this .cpuRatio = cpuRatio;
}
}
接着编写一个获得当前的监控信息的接口，该类的代码如下所示：
package com.amgkaka.performance;
/** */ /**
* 获取系统信息的业务逻辑类接口.
* @author amg * @version 1.0
* Creation date: 2008-3-11 - 上午10:06:06
*/
public interface IMonitorService {
/** */ /**
* 获得当前的监控对象.
* @return 返回构造好的监控对象
* @throws Exception
* @author amgkaka
* Creation date: 2008-4-25 - 上午10:45:08
*/
public MonitorInfoBean getMonitorInfoBean() throws Exception;
}
该类的实现类MonitorServiceImpl如下所示：
package com.amgkaka.performance;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import sun.management.ManagementFactory;
import com.sun.management.OperatingSystemMXBean;
/** */ /**
* 获取系统信息的业务逻辑实现类.
* @author amg * @version 1.0 Creation date: 2008-3-11 - 上午10:06:06
*/
public class MonitorServiceImpl implements IMonitorService {
//可以设置长些，防止读到运行此次系统检查时的cpu占用率，就不准了
private static final int CPUTIME = 5000 ;
private static final int PERCENT = 100 ;
private static final int FAULTLENGTH = 10 ;
/** */ /**
* 获得当前的监控对象.
* @return 返回构造好的监控对象
* @throws Exception
* @author amg * Creation date: 2008-4-25 - 上午10:45:08
*/
public MonitorInfoBean getMonitorInfoBean() throws Exception {
int kb = 1024 ;
// 可使用内存
long totalMemory = Runtime.getRuntime().totalMemory() / kb;
// 剩余内存
long freeMemory = Runtime.getRuntime().freeMemory() / kb;
// 最大可使用内存
long maxMemory = Runtime.getRuntime().maxMemory() / kb;
OperatingSystemMXBean osmxb = (OperatingSystemMXBean) ManagementFactory
.getOperatingSystemMXBean();
// 操作系统
String osName = System.getProperty("os.name" );
// 总的物理内存
long totalMemorySize = osmxb.getTotalPhysicalMemorySize() / kb;
// 剩余的物理内存
long freePhysicalMemorySize = osmxb.getFreePhysicalMemorySize() / kb;
// 已使用的物理内存
long usedMemory = (osmxb.getTotalPhysicalMemorySize() - osmxb
.getFreePhysicalMemorySize())
/ kb;
// 获得线程总数
ThreadGroup parentThread;
for (parentThread = Thread.currentThread().getThreadGroup(); parentThread
.getParent() != null ; parentThread = parentThread.getParent())
;
int totalThread = parentThread.activeCount();
double cpuRatio = 0 ;
if (osName.toLowerCase().startsWith( "windows" )) {
cpuRatio = this .getCpuRatioForWindows();
}
// 构造返回对象
MonitorInfoBean infoBean = new MonitorInfoBean();
infoBean.setFreeMemory(freeMemory);
infoBean.setFreePhysicalMemorySize(freePhysicalMemorySize);
infoBean.setMaxMemory(maxMemory);
infoBean.setOsName(osName);
infoBean.setTotalMemory(totalMemory);
infoBean.setTotalMemorySize(totalMemorySize);
infoBean.setTotalThread(totalThread);
infoBean.setUsedMemory(usedMemory);
infoBean.setCpuRatio(cpuRatio);
return infoBean;
}
/** */ /**
* 获得CPU使用率.
* @return 返回cpu使用率
* @author amg * Creation date: 2008-4-25 - 下午06:05:11
*/
private double 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) / (busytime + idletime))
.doubleValue();
} else {
return 0.0 ;
}
} catch (Exception ex) {
ex.printStackTrace();
return 0.0 ;
}
}
/** */ /**
* 读取CPU信息.
* @param proc
* @return
* @author amg * Creation date: 2008-4-25 - 下午06:10:14
*/
private 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 ;
}
// log.info("line="+line);
if (caption.equals( "System Idle Process" )
|| caption.equals("System" )) {
idletime += Long.valueOf(
Bytes.substring(line, kmtidx, rocidx - 1 ).trim())
.longValue();
idletime += Long.valueOf(
Bytes.substring(line, umtidx, wocidx - 1 ).trim())
.longValue();
continue ;
}
kneltime += Long.valueOf(
Bytes.substring(line, kmtidx, rocidx - 1 ).trim())
.longValue();
usertime += Long.valueOf(
Bytes.substring(line, umtidx, wocidx - 1 ).trim())
.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 ;
}
/** */ /**
* 测试方法.
* @param args
* @throws Exception
* @author amg * Creation date: 2008-4-30 - 下午04:47:29
*/
public static void main(String[] args) throws Exception {
IMonitorService service = new MonitorServiceImpl();
MonitorInfoBean monitorInfo = service.getMonitorInfoBean();
System.out.println("cpu占有率=" + monitorInfo.getCpuRatio());
System.out.println("可使用内存=" + monitorInfo.getTotalMemory());
System.out.println("剩余内存=" + monitorInfo.getFreeMemory());
System.out.println("最大可使用内存=" + monitorInfo.getMaxMemory());
System.out.println("操作系统=" + monitorInfo.getOsName());
System.out.println("总的物理内存=" + monitorInfo.getTotalMemorySize() + "kb" );
System.out.println("剩余的物理内存=" + monitorInfo.getFreeMemory() + "kb" );
System.out.println("已使用的物理内存=" + monitorInfo.getUsedMemory() + "kb" );
System.out.println("线程总数=" + monitorInfo.getTotalThread() + "kb" );
}
}
该实现类中需要用到一个自己编写byte的工具类，该类的代码如下所示：
package com.amgkaka.performance;
/** */ /**
* byte操作类.
* @author amg * @version 1.0
* Creation date: 2008-4-30 - 下午04:57:23
*/
public class Bytes {
/** */ /**
* 由于String.subString对汉字处理存在问题(把一个汉字视为一个字节)，因此在
* 包含汉字的字符串时存在隐患，现调整如下：
* @param src 要截取的字符串
* @param start_idx 开始坐标(包括该坐标)
* @param end_idx 截止坐标(包括该坐标)
* @return
*/
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;
}
}
运行下MonitorBeanImpl类，读者将会看到当前的内存、cpu利用率等信息。
PS：得到局域网内所有主机名的方法
import java.net.InetAddress;
import java.net.UnknownHostException;
public class A {
static public void main(String[] args) {
try {
//通过主机名称得到IP地址
InetAddress address = InetAddress.getByName("192.168.9.148");
System.out.println("192.168.9.148"+": "+address.getHostAddress());
// 通过IP得到主机名称
String ips="192.168.9.",ip;
InetAddress addip;
for(int i=148;i<255;i++){
ip=ips+i;
addip=InetAddress.getByName(ip);
System.out.println(ip+": "+addip.getHostName());
}
}
catch(UnknownHostException uhe) {
System.err.println("Unable to find: "+"192.168.9.148");
}
}
}
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