1.需求場景

利用java程式監控Linux伺服器記憶體變化，根據設定的記憶體閾值發報警郵件

2.專案環境

 普通java專案，jar形式

3.解決方法

(1)讀取Linux 記憶體監控檔案(/proc/meminfo)，獲取記憶體資訊。

public  static  int [] getLinuxMemInfo() throws IOException, InterruptedException  
	{  
	File file = new File("/proc/meminfo" );  
	BufferedReader br = new BufferedReader( new InputStreamReader(new FileInputStream(file)));  
	int [] result = new  int [ 4 ];  
	String str = null ;  
	StringTokenizer token = null ;  
	while ((str = br.readLine()) != null )  
	{  
	token = new StringTokenizer(str);  
	if (!token.hasMoreTokens())  
	continue ;  
	str = token.nextToken();  
	if (!token.hasMoreTokens())  
	continue ;  
	if (str.equalsIgnoreCase("MemTotal:" ))  
	result[0 ] = Integer.parseInt(token.nextToken());  
	else  if (str.equalsIgnoreCase("MemFree:" ))  
	result[1 ] = Integer.parseInt(token.nextToken());  
	else  if (str.equalsIgnoreCase("SwapTotal:" ))  
	result[2 ] = Integer.parseInt(token.nextToken());  
	else  if (str.equalsIgnoreCase("SwapFree:" ))  
	result[3 ] = Integer.parseInt(token.nextToken());  
	}
	return result;
	}
 

(2)根據設定閾值，是否發郵件預警

    int [] mem = LinuxSystemTool.getMemInfo();
    double rate = (float)mem[1]/(float)mem[0];
		String content ="比值:"+new java.text.DecimalFormat("#0.00").format(rate)+"\t總記憶體:"+mem[0]+"KB\t空閒實體記憶體:"+mem[1]+"KB\t交換分割槽總記憶體:"+mem[2]+"KB\t交換分割槽空閒記憶體:"+mem[3]+"KB";
		if(rate<=0.2){
		content+="\t系統有些累了！o(╥﹏╥)o";
		EmailUtil.sendEmail("[email protected]", "記憶體預警", content);
		}else{
			System.out.println("系統充滿活力！^_^)";
		}
 

#!/bin/sh
export LANG=en_US.UTF-8
cd  /test/demo
/opt/jdk/bin/java -jar /test/demo/memmonitor.jar

(4)設定定時任務

crontab -e
*/10 * * * * /test/demo/memmonitor.sh