Java獲取請求IP的方法

一、使用HttpServletRequest對象獲取IP地址

Java Web中可以使用HttpServletRequest對象來獲取客戶端的IP地址。使用以下代碼可以獲取IP地址：

public String getIpAddress(HttpServletRequest request) {
    String ip = request.getHeader("x-forwarded-for");
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("Proxy-Client-IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("WL-Proxy-Client-IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("HTTP_CLIENT_IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("HTTP_X_FORWARDED_FOR");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getRemoteAddr();
    }
    return ip;
}

以上代碼從request的頭部信息中獲取IP地址，如果沒有則返回request的遠程地址。

二、使用Java Web容器的方法獲取IP地址

有些Java Web容器（如Tomcat）提供了獲取IP的方法，可以直接調用該方法來獲取IP地址。以Tomcat為例，可以使用下面的代碼獲取IP地址：

public String getIpAddress(HttpServletRequest request) {
    String ip = request.getHeader("x-forwarded-for");
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("Proxy-Client-IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("WL-Proxy-Client-IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("HTTP_CLIENT_IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("HTTP_X_FORWARDED_FOR");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getRemoteAddr();
    }
    return ip;
}

以上代碼從request的頭部信息中獲取IP地址，如果沒有則返回request的遠程地址。

三、使用第三方庫獲取IP地址

除了使用HttpServletRequest對象和Java Web容器提供的獲取IP地址的方法外，還可以使用第三方庫來獲取IP地址。

常用的第三方庫包括：

• Apache Commons工具包
• Google Guava工具包
• Spring Framework工具包

以下是使用Apache Commons工具包獲取IP地址的代碼：

public String getIpAddress(HttpServletRequest request) {
    String ip = request.getHeader("x-forwarded-for");
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("Proxy-Client-IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("WL-Proxy-Client-IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("HTTP_CLIENT_IP");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getHeader("HTTP_X_FORWARDED_FOR");
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
        ip = request.getRemoteAddr();
    }
    if (ip != null) {
        ip = org.apache.commons.lang.StringUtils.stripToNull(ip.split(",")[0]);
    }
    return ip;
}

以上代碼使用了Apache Commons工具包中的StringUtils類來處理獲取到的IP地址。

四、總結

Java可以通過HttpServletRequest對象、Java Web容器提供的方法、第三方庫來獲取請求IP地址。其中，HttpServletRequest對象是常用的獲取IP地址的方法，同時Apache Commons工具包也是很常用的第三方庫。