java获取linux服务器cpu，内存使用率

可以使用Java代码调用Linux命令获取CPU和内存使用率。

获取CPU使用率：

public static double getCpuUsage() throws IOException {
    double cpuUsage = 0.0;
    Process process = Runtime.getRuntime().exec("top -b -n1");
    try(BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()))) {
        String line;
        while((line = reader.readLine()) != null) {
            if(line.startsWith("Cpu(s)")) {
                String[] cpuInfo = line.split("\\s+");
                double user = Double.parseDouble(cpuInfo[1].replace("%",""));
                double sys = Double.parseDouble(cpuInfo[3].replace("%",""));
                double idle = Double.parseDouble(cpuInfo[7].replace("%",""));
                cpuUsage = (user + sys) / (user + sys + idle) * 100.0;
            }
        }
    }
    return cpuUsage;
}

获取内存使用率：

public static double getMemoryUsage() throws IOException {
    double memoryUsage = 0.0;
    Process process = Runtime.getRuntime().exec("free -m");
    try(BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()))) {
        String line;
        while((line = reader.readLine()) != null) {
            if(line.startsWith("Mem:")) {
                String[] memoryInfo = line.split("\\s+");
                double used = Double.parseDouble(memoryInfo[2]);
                double total = Double.parseDouble(memoryInfo[1]);
                memoryUsage = used / total * 100.0;
            }
        }
    }
    return memoryUsage;
}

这里使用了Linux命令`top -b -n1`和`free -m`来获取CPU和内存使用率。`-b`表示以批处理模式运行，不需要交互式输入。`-n1`表示只执行一次。获取到命令输出后，使用Java代码解析命令输出并计算出使用率。