RequestUtils.java

package message.utils;

import message.base.Constants;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import java.util.*;

/**
 * HttpServletRequest的工具类
 *
 * @author sunhao(sunhao.java@gmail.com)
 * @version V1.0
 * @createTime 2012-2-15 下午10:12:52
 */
public class RequestUtils {

    /**
     * 私有化构造器
     */
    private RequestUtils() {
    }

    /**
     * 判断是否是AJAX请求
     *
     * @param request
     * @return
     */
    public static boolean isAjaxRequest(HttpServletRequest request) {
        String header = request.getHeader("X-Requested-With");
        return StringUtils.isNotEmpty(header) && "XMLHttpRequest".equals(header);
    }

    /**
     * 获取此次请求的url(不带contextPath)
     *
     * @param request    此次请求
     * @param needParams 是否需要参数
     * @return URL(未encoding)
     */
    public static String getRequestUrl(HttpServletRequest request, boolean needParams) {
        StringBuffer requestUrl = new StringBuffer(request.getServletPath());
        if (!needParams) {
            return requestUrl.toString();
        }

        //所带参数的MAP
        Map params = request.getParameterMap();
        Iterator it = params.keySet().iterator();
        if (it.hasNext())
            requestUrl.append("?");
        while (it.hasNext()) {
            String key = (String) it.next();
            String[] values = (String[]) params.get(key);
            String value = StringUtils.EMPTY;
            if (values != null && values.length > 0) {
                value = values[0];
            } else {
                value = StringUtils.EMPTY;
            }

            if (StringUtils.isNotEmpty(key)) {
                //key必须不为空，value可以为空
                requestUrl.append(key).append("=").append(value).append("&");
            }
        }

        if (requestUrl.toString().endsWith("&")) {
            return requestUrl.substring(0, requestUrl.length() - 1);
        }

        return requestUrl.toString();
    }

    /**
     * 获得请求中所带的参数
     *
     * @param request
     * @return
     */
    public static List<String> getRequestParam(HttpServletRequest request) {
        List<String> urlParams = new ArrayList<String>();
        Map params = request.getParameterMap();
        Iterator it = params.keySet().iterator();
        while (it.hasNext()) {
            String key = (String) it.next();
            String[] values = (String[]) params.get(key);
            if (values != null && values.length > 0) {
                urlParams.add(values[0]);
            } else {

            }
        }

        return urlParams;
    }

    /**
     * 获取contextPath
     *
     * @param request
     * @return
     */
    public static String getContextPath(HttpServletRequest request) {
        String contextPath = (String) request.getAttribute(Constants.DEFAULT_CONTEXT_PATH);
        if (StringUtils.isEmpty(contextPath)) {
            contextPath = request.getContextPath();

            if ((contextPath != null) && (contextPath.length() > 0)) {
                if ("/".equals(StringUtils.right(contextPath, 1))) {
                    contextPath = StringUtils.substringBeforeLast(contextPath, "/");
                }
            } else {
                contextPath = "";
            }

            request.setAttribute(Constants.DEFAULT_CONTEXT_PATH, contextPath);
        }

        return contextPath;
    }

    /**
     * get referer page from request object
     *
     * @param request HttpServletRequest object.
     * @return url of referer page.
     */
    public static String getReferer(final HttpServletRequest request) {
        String url = request.getParameter("referer");
        if (StringUtils.isBlank(url)) {
            url = request.getHeader("referer");
        }
        return url;
    }

    /**
     * 将一个对象同步到session中
     *
     * @param request request
     * @param key     key
     * @param object  对象
     */
    public static void syncToSession(HttpServletRequest request, String key, Object object) {
        HttpSession session = request.getSession();
        session.setAttribute(key, object);
    }

    /**
     * 将一个对象同步到session中
     *
     * @param request request
     * @param key     key
     * @param object  对象
     * @param life    存活时间
     */
    public static void syncToSession(HttpServletRequest request, String key, Object object, Integer life) {
        HttpSession session = request.getSession();
        session.setAttribute(key, object);
        session.setMaxInactiveInterval(life);
    }

    /**
     * 给定一段URL后面的参数,返回参数的map集合
     *
     * @param params 参数
     * @return
     */
    public static Map<String, Object> getParams(String params) {
        if (StringUtils.isEmpty(params)) {
            return Collections.EMPTY_MAP;
        }

        String[] ps = params.split("&");
        Map<String, Object> paramsMap = new HashMap<String, Object>();
        for (String p : ps) {
            String[] tmp = p.split("=");
            if (tmp == null || tmp.length <= 0)
                continue;

            if (tmp.length == 1)
                paramsMap.put(tmp[0], StringUtils.EMPTY);
            else
                paramsMap.put(tmp[0], tmp[1]);
        }

        return paramsMap;
    }

    /**
     * 给定一段URL后面的参数和一个key,返回key对应的值
     *
     * @param params 参数
     * @param key    key
     * @return
     */
    public static String getParam(String params, String key) {
        if (StringUtils.isEmpty(params) || StringUtils.isEmpty(key)) {
            return StringUtils.EMPTY;
        }

        String[] ps = params.split("&");
        for (String p : ps) {
            String[] tmp = p.split("=");
            if (tmp == null || tmp.length <= 0)
                continue;

            if (key.equals(tmp[0])) {
                if (tmp.length == 1)
                    return StringUtils.EMPTY;
                else
                    return tmp[1];
            }
        }

        return StringUtils.EMPTY;
    }

    /**
     * 给定一段URL和一个key,返回key对应的值
     *
     * @param url url
     * @param key key
     * @return
     */
    public static String getParamFromUrl(String url, String key) {
        if (StringUtils.isEmpty(url) || StringUtils.isEmpty(key)) {
            return StringUtils.EMPTY;
        }

        if (url.indexOf("?") == -1)
            return StringUtils.EMPTY;

        String params = url.substring(url.indexOf("?") + 1);
        return getParam(params, key);
    }

    /**
     * 从request中获取模块名
     *
     * @param request
     * @return
     * @throws Exception
     */
    public static String getModuleName(HttpServletRequest request) throws Exception {
        if (ObjectUtils.isEmpty(request)) {
            return StringUtils.EMPTY;
        }

        String href = request.getRequestURI();
        if (StringUtils.isNotEmpty(href)) {
            String[] args = href.split("/");

            if (args != null && args.length == 4) {
                return args[2];
            } else if (args != null && args.length == 3) {
                return args[1];
            } else {
                return StringUtils.EMPTY;
            }
        }

        return StringUtils.EMPTY;
    }
}