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：
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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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