Java中直接使用System.getProperty和通过安全控制器获取属性值有什么区别吗？

Question

static {
    String altThreshold = java.security.AccessController.doPrivileged(
        new sun.security.action.GetPropertyAction(
            "jdk.map.althashing.threshold"));

    int threshold;
    try {
        threshold = (null != altThreshold)
                ? Integer.parseInt(altThreshold)
                : ALTERNATIVE_HASHING_THRESHOLD_DEFAULT;

        // disable alternative hashing if -1
        if (threshold == -1) {
            threshold = Integer.MAX_VALUE;
        }

        if (threshold < 0) {
            throw new IllegalArgumentException("value must be positive integer.");
        }
    } catch(IllegalArgumentException failed) {
        throw new Error("Illegal value for 'jdk.map.althashing.threshold'", failed);
    }

    ALTERNATIVE_HASHING_THRESHOLD = threshold;
}

Answer 1

Java安全：SecurityManager与AccessController - 掘金