java开发中的异常捕获的重要性

   今天发现主机监控的内存采集不采集了，查看一下发现原来局方把sar的权限给取消了，导致采集方法报错，但是内存的采集是利用的vmstat 2 10 这个命令，为什么会导致内存采集不上来呢？
    查看源代码发现

	public Vector getMemory(HashMap params) {
		logger.info("begin getMemory");
		init(params);
		// 得到unit_id中使用的主机名称
		String neat_host_name = rpctarget.getNeat_host_name();
		if (neat_host_name == null || neat_host_name.equals("")) {
			// 获取主机名称
			String host_name = this.getHostName();
			// 得到unit_id中使用的主机名称
			neat_host_name = Formater.neatenunitid(host_name);
		}
		// 保存采集结果，并返回值
		CollBase collResult = new CollBase();
		// 本方法得到的kpi值的unit_id,均以PRE_UNITID + "-12"开头
		String memory_PRE_UNITID = PRE_UNITID + "-12";
		// 增加采集时间指标
		String pattern = "yyyy-MM-dd-HH-mm-ss";
		SimpleDateFormat dateFormat = new SimpleDateFormat(pattern);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "",
				"CM-00-01-001-22", dateFormat.format(new java.util.Date()));
		Vector memoryout = rpctarget.getKPISet("vmstat 2 10");
		String memoryrun = (String) memoryout.elementAt(memoryout.size() - 1);
		try {
			// PM-00-01-002-01 内存的使用率 主机内存的使用量与内存总量的比值
			Vector mem_num = rpctarget
					.getKPISet("prtconf |grep 'Good Memory Size:'");
			String memory = (String) mem_num.elementAt(0);
			int free_mem = Integer.parseInt(split(memoryrun, 3)) * 4 / 1024; // 空余内存
			// 单位：M
			int total_mem = Integer.parseInt(split(memory, 3)); // 总内存 单位：M
			double use_per = 100.0 - (free_mem * 100.0) / total_mem; // 内存使用率
			String mem_use_per = this
					.getByScale(new Double(use_per).toString());
			collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
					+ "-memory", "PM-00-01-002-01", Formater
					.formatDecimalKpivalue(mem_use_per));

			// 系统内存使用率
			// 用户内存使用率
			String sys_user_rate = Float.parseFloat(mem_use_per) * 0.7 + "";
			String sys_use_rate = Float.parseFloat(mem_use_per) * 0.3 + "";
			collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
					+ "-memory", "PM-00-01-002-07", Formater
					.formatDecimalKpivalue(sys_user_rate));
			collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
					+ "-memory", "PM-00-01-002-06", Formater
					.formatDecimalKpivalue(sys_use_rate));

		} catch (Exception e) {
			e.printStackTrace();
		}
		String value = "";
		// M-00-01-002-02 内存交换请求数
		value = split(memoryrun, 7);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "-memory",
				"PM-00-01-002-02", Formater.formatDecimalKpivalue(value));
		// PM-00-01-002-03 内存交换页换进率
		value = split(memoryrun, 5);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "-memory",
				"PM-00-01-002-03", Formater.formatDecimalKpivalue(value));
		// PM-00-01-002-04 内存交换页换出率
		value = split(memoryrun, 6);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "-memory",
				"PM-00-01-002-04", Formater.formatDecimalKpivalue(value));
		// PM-00-01-002-05 内存队列数
		value = split(memoryrun, 0);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "-memory",
				"PM-00-01-002-05", Formater.formatDecimalKpivalue(value));
		// PM-00-01-002-08 文件系统数据缓冲命中率
		// Vector filerate_result = rpctarget.getKPISet("sar -b 2 2");
		// if (filerate_result != null && filerate_result.size() > 0) {
		// String filerate_string = (String) filerate_result
		// .elementAt(filerate_result.size() - 1);
		// int r_rate = Integer.parseInt(split(filerate_string, 3));
		// int w_rate = Integer.parseInt(split(filerate_string, 6));
		// value = String.valueOf((r_rate + w_rate) / 2);
		// collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
		// + "-memory", "PM-00-01-002-08",
		// Formater.formatDecimalKpivalue(value));
		// } else {
		// logger.error("error when exe 'sar -b 2 2' , null or nothing return");
		// }
		// Vector filerate_result = rpctarget.getKPISet("sar -b 2 2");
		String commond = "sh ibmaix/cachehitrate.sh";
		Vector filerate_result = this.execute(commond);
			if (filerate_result != null && filerate_result.size() > 0) {
				String filerate_string = (String) filerate_result.elementAt(0);
				float fault = Float.parseFloat(split(filerate_string, 3));
				float odio = Float.parseFloat(split(filerate_string, 4));
				value = Formater.formatDecimalKpivalue(String.valueOf(fault
						* 100 / (fault + odio)));
				collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
						+ "-memory", "PM-00-01-002-08", Formater
						.formatDecimalKpivalue(value));
			} else {
				logger
						.error("error when exe 'sar -b 2 2' , null or nothing return");
			}

		logger.info("end getMemory");
		return collResult.getKPISet();
	}

出现问题的原因就是在下面的代码编程当中没有捕获异常，导致整个方法都采集不到值，真是城池失火殃及鱼池呀。做程序员一定要注意。
修改后的代码为：

	public Vector getMemory(HashMap params) {
		logger.info("begin getMemory");
		init(params);
		// 得到unit_id中使用的主机名称
		String neat_host_name = rpctarget.getNeat_host_name();
		if (neat_host_name == null || neat_host_name.equals("")) {
			// 获取主机名称
			String host_name = this.getHostName();
			// 得到unit_id中使用的主机名称
			neat_host_name = Formater.neatenunitid(host_name);
		}
		// 保存采集结果，并返回值
		CollBase collResult = new CollBase();
		// 本方法得到的kpi值的unit_id,均以PRE_UNITID + "-12"开头
		String memory_PRE_UNITID = PRE_UNITID + "-12";
		// 增加采集时间指标
		String pattern = "yyyy-MM-dd-HH-mm-ss";
		SimpleDateFormat dateFormat = new SimpleDateFormat(pattern);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "",
				"CM-00-01-001-22", dateFormat.format(new java.util.Date()));
		Vector memoryout = rpctarget.getKPISet("vmstat 2 10");
		String memoryrun = (String) memoryout.elementAt(memoryout.size() - 1);
		try {
			// PM-00-01-002-01 内存的使用率 主机内存的使用量与内存总量的比值
			Vector mem_num = rpctarget
					.getKPISet("prtconf |grep 'Good Memory Size:'");
			String memory = (String) mem_num.elementAt(0);
			int free_mem = Integer.parseInt(split(memoryrun, 3)) * 4 / 1024; // 空余内存
			// 单位：M
			int total_mem = Integer.parseInt(split(memory, 3)); // 总内存 单位：M
			double use_per = 100.0 - (free_mem * 100.0) / total_mem; // 内存使用率
			String mem_use_per = this
					.getByScale(new Double(use_per).toString());
			collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
					+ "-memory", "PM-00-01-002-01", Formater
					.formatDecimalKpivalue(mem_use_per));

			// 系统内存使用率
			// 用户内存使用率
			String sys_user_rate = Float.parseFloat(mem_use_per) * 0.7 + "";
			String sys_use_rate = Float.parseFloat(mem_use_per) * 0.3 + "";
			collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
					+ "-memory", "PM-00-01-002-07", Formater
					.formatDecimalKpivalue(sys_user_rate));
			collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
					+ "-memory", "PM-00-01-002-06", Formater
					.formatDecimalKpivalue(sys_use_rate));

		} catch (Exception e) {
			e.printStackTrace();
		}
		String value = "";
		// M-00-01-002-02 内存交换请求数
		value = split(memoryrun, 7);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "-memory",
				"PM-00-01-002-02", Formater.formatDecimalKpivalue(value));
		// PM-00-01-002-03 内存交换页换进率
		value = split(memoryrun, 5);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "-memory",
				"PM-00-01-002-03", Formater.formatDecimalKpivalue(value));
		// PM-00-01-002-04 内存交换页换出率
		value = split(memoryrun, 6);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "-memory",
				"PM-00-01-002-04", Formater.formatDecimalKpivalue(value));
		// PM-00-01-002-05 内存队列数
		value = split(memoryrun, 0);
		collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name + "-memory",
				"PM-00-01-002-05", Formater.formatDecimalKpivalue(value));
		// PM-00-01-002-08 文件系统数据缓冲命中率
		// Vector filerate_result = rpctarget.getKPISet("sar -b 2 2");
		// if (filerate_result != null && filerate_result.size() > 0) {
		// String filerate_string = (String) filerate_result
		// .elementAt(filerate_result.size() - 1);
		// int r_rate = Integer.parseInt(split(filerate_string, 3));
		// int w_rate = Integer.parseInt(split(filerate_string, 6));
		// value = String.valueOf((r_rate + w_rate) / 2);
		// collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
		// + "-memory", "PM-00-01-002-08",
		// Formater.formatDecimalKpivalue(value));
		// } else {
		// logger.error("error when exe 'sar -b 2 2' , null or nothing return");
		// }
		// Vector filerate_result = rpctarget.getKPISet("sar -b 2 2");
		String commond = "sh ibmaix/cachehitrate.sh";
		Vector filerate_result = this.execute(commond);
			if (filerate_result != null && filerate_result.size() > 0) {
				try{
				String filerate_string = (String) filerate_result.elementAt(0);
				float fault = Float.parseFloat(split(filerate_string, 3));
				float odio = Float.parseFloat(split(filerate_string, 4));
				value = Formater.formatDecimalKpivalue(String.valueOf(fault
						* 100 / (fault + odio)));
				collResult.addKPI(memory_PRE_UNITID + ":" + neat_host_name
						+ "-memory", "PM-00-01-002-08", Formater
						.formatDecimalKpivalue(value));
				}catch(Exception e){
					e.printStackTrace();
				}
			} else {
				logger
						.error("error when exe 'sar -b 2 2' , null or nothing return");
			}

		logger.info("end getMemory");
		return collResult.getKPISet();
	}

这样就把内存的利用率采集到了。