Http與Servlet工具類

Http與Servlet工具類

 

/**對用戶請求和響應作必定處理的工具方法。*/

package com.web;

import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.StringTokenizer;
import java.util.TreeMap;

import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang3.Validate;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import com.google.common.net.HttpHeaders;
import com.security.SystemAuthorizingRealm.Principal;
import com.utils.Encodes;
import com.utils.Global;
import com.utils.StringUtils;
import com.utils.UserUtils;

/**
 * Http與Servlet工具類.
 * @author calvin/thinkgem
 * @version 2014-8-19
 */
public class Servlets {

	// -- 經常使用數值定義 --//
	public static final long ONE_YEAR_SECONDS = 60 * 60 * 24 * 365;
	
	// 靜態文件後綴
	private final static String[] staticFiles = StringUtils.split(Global.getConfig("web.staticFile"), ",");
	
	// 動態映射URL後綴
	private final static String urlSuffix = Global.getUrlSuffix();

	/**
	 * 設置客戶端緩存過時時間 的Header.
	 */
	public static void setExpiresHeader(HttpServletResponse response, long expiresSeconds) {
		// Http 1.0 header, set a fix expires date.
		response.setDateHeader(HttpHeaders.EXPIRES, System.currentTimeMillis() + expiresSeconds * 1000);
		// Http 1.1 header, set a time after now.
		response.setHeader(HttpHeaders.CACHE_CONTROL, "private, max-age=" + expiresSeconds);
	}

	/**
	 * 設置禁止客戶端緩存的Header.
	 */
	public static void setNoCacheHeader(HttpServletResponse response) {
		// Http 1.0 header
		response.setDateHeader(HttpHeaders.EXPIRES, 1L);
		response.addHeader(HttpHeaders.PRAGMA, "no-cache");
		// Http 1.1 header
		response.setHeader(HttpHeaders.CACHE_CONTROL, "no-cache, no-store, max-age=0");
	}

	/**
	 * 設置LastModified Header.
	 */
	public static void setLastModifiedHeader(HttpServletResponse response, long lastModifiedDate) {
		response.setDateHeader(HttpHeaders.LAST_MODIFIED, lastModifiedDate);
	}

	/**
	 * 設置Etag Header.
	 */
	public static void setEtag(HttpServletResponse response, String etag) {
		response.setHeader(HttpHeaders.ETAG, etag);
	}

	/**
	 * 根據瀏覽器If-Modified-Since Header, 計算文件是否已被修改.
	 * 
	 * 若是無修改, checkIfModify返回false ,設置304 not modify status.
	 * 
	 * @param lastModified 內容的最後修改時間.
	 */
	public static boolean checkIfModifiedSince(HttpServletRequest request, HttpServletResponse response,
			long lastModified) {
		long ifModifiedSince = request.getDateHeader(HttpHeaders.IF_MODIFIED_SINCE);
		if ((ifModifiedSince != -1) && (lastModified < ifModifiedSince + 1000)) {
			response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
			return false;
		}
		return true;
	}

	/**
	 * 根據瀏覽器 If-None-Match Header, 計算Etag是否已無效.
	 * 
	 * 若是Etag有效, checkIfNoneMatch返回false, 設置304 not modify status.
	 * 
	 * @param etag 內容的ETag.
	 */
	public static boolean checkIfNoneMatchEtag(HttpServletRequest request, HttpServletResponse response, String etag) {
		String headerValue = request.getHeader(HttpHeaders.IF_NONE_MATCH);
		if (headerValue != null) {
			boolean conditionSatisfied = false;
			if (!"*".equals(headerValue)) {
				StringTokenizer commaTokenizer = new StringTokenizer(headerValue, ",");

				while (!conditionSatisfied && commaTokenizer.hasMoreTokens()) {
					String currentToken = commaTokenizer.nextToken();
					if (currentToken.trim().equals(etag)) {
						conditionSatisfied = true;
					}
				}
			} else {
				conditionSatisfied = true;
			}

			if (conditionSatisfied) {
				response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
				response.setHeader(HttpHeaders.ETAG, etag);
				return false;
			}
		}
		return true;
	}

	/**
	 * 設置讓瀏覽器彈出下載對話框的Header.
	 * 
	 * @param fileName 下載後的文件名.
	 */
	public static void setFileDownloadHeader(HttpServletResponse response, String fileName) {
		try {
			// 中文文件名支持
			String encodedfileName = new String(fileName.getBytes(), "ISO8859-1");
			response.setHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + encodedfileName + "\"");
		} catch (UnsupportedEncodingException e) {
			e.getMessage();
		}
	}

	/**
	 * 取得帶相同前綴的Request Parameters, copy from spring WebUtils.
	 * 
	 * 返回的結果的Parameter名已去除前綴.
	 */
	@SuppressWarnings("rawtypes")
	public static Map<String, Object> getParametersStartingWith(ServletRequest request, String prefix) {
		Validate.notNull(request, "Request must not be null");
		Enumeration paramNames = request.getParameterNames();
		Map<String, Object> params = new TreeMap<String, Object>();
		String pre = prefix;
		if (pre == null) {
			pre = "";
		}
		while (paramNames != null && paramNames.hasMoreElements()) {
			String paramName = (String) paramNames.nextElement();
			if ("".equals(pre) || paramName.startsWith(pre)) {
				String unprefixed = paramName.substring(pre.length());
				String[] values = request.getParameterValues(paramName);
				if (values == null || values.length == 0) {
					values = new String[]{};
					// Do nothing, no values found at all.
				} else if (values.length > 1) {
					params.put(unprefixed, values);
				} else {
					params.put(unprefixed, values[0]);
				}
			}
		}
		return params;
	}

	/**
	 * 組合Parameters生成Query String的Parameter部分,並在paramter name上加上prefix.
	 * 
	 */
	public static String encodeParameterStringWithPrefix(Map<String, Object> params, String prefix) {
		StringBuilder queryStringBuilder = new StringBuilder();

		String pre = prefix;
		if (pre == null) {
			pre = "";
		}
		Iterator<Entry<String, Object>> it = params.entrySet().iterator();
		while (it.hasNext()) {
			Entry<String, Object> entry = it.next();
			queryStringBuilder.append(pre).append(entry.getKey()).append("=").append(entry.getValue());
			if (it.hasNext()) {
				queryStringBuilder.append("&");
			}
		}
		return queryStringBuilder.toString();
	}

	/**
	 * 客戶端對Http Basic驗證的 Header進行編碼.
	 */
	public static String encodeHttpBasic(String userName, String password) {
		String encode = userName + ":" + password;
		return "Basic " + Encodes.encodeBase64(encode.getBytes());
	}
	
	/**
	 * 是不是Ajax異步請求
	 * @param request
	 */
	public static boolean isAjaxRequest(HttpServletRequest request){
		
		String accept = request.getHeader("accept");
		String xRequestedWith = request.getHeader("X-Requested-With");
		Principal principal = UserUtils.getPrincipal();

		// 若是是異步請求或是手機端，則直接返回信息
		return ((accept != null && accept.indexOf("application/json") != -1 
			|| (xRequestedWith != null && xRequestedWith.indexOf("XMLHttpRequest") != -1)
			|| (principal != null && principal.isMobileLogin())));
	}
	
	/**
	 * 獲取當前請求對象
	 * @return
	 */
	public static HttpServletRequest getRequest(){
		try{
			return ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();
		}catch(Exception e){
			return null;
		}
	}

	/**
     * 判斷訪問URI是不是靜態文件請求
	 * @throws Exception 
     */
    public static boolean isStaticFile(String uri){
		if (staticFiles == null){
			try {
				throw new Exception("檢測到「app.properties」中沒有配置「web.staticFile」屬性。配置示例：\n#靜態文件後綴\n"
					+"web.staticFile=.css,.js,.png,.jpg,.gif,.jpeg,.bmp,.ico,.swf,.psd,.htc,.crx,.xpi,.exe,.ipa,.apk");
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		if (StringUtils.endsWithAny(uri, staticFiles) && !StringUtils.endsWithAny(uri, urlSuffix)
				&& !StringUtils.endsWithAny(uri, ".jsp") && !StringUtils.endsWithAny(uri, ".java")){
			return true;
		}
		return false;
    }
}