Java如何获取系统cpu、内存、硬盘信息

　　1 概述
　　前段时间摸索在Java中怎么获取系统信息包括cpu、内存、硬盘信息等，刚开始使用Java自带的包进行获取，但这样获取的内存信息不够准确并且容易出现找不到相应包等错误，所以后面使用sigar插件进行获取。下面列举出了这两种方式获取系统信息的方式及代码。
　　2 使用Java自带包获取系统信息
　　2.1 使用Java自带包获取系统信息代码如下：
　　2.1.1 Bytes.java
public class Bytes {
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;
}
}
　　2.1.2 IMonitorService.java
　　public interface IMonitorService {
　　public MonitorInfoBean getMonitorInfoBean() throws Exception;
　　}
　　2.1.3 MonitorInfoBean.java
public class MonitorInfoBean {
private long totalMemory;
private long freeMemory;
private long maxMemory;
private String osName;
private long totalMemorySize;
private long freePhysicalMemorySize;
private long usedMemory;
private int totalThread;
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;
}
}