ServletUtils - 封裝的工具類

package com.hanyong.utils;

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

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;


/**
 * 用戶端工具類
 *
 * @Author: hanYong
 * @CreateTime: 2019
 */
public class ServletUtils {
    /**
     * 請求格式為json
     */
    private static final String APPLICATION_JSON = "application/json";
    /**
     * 請求格式為xml
     */
    private static final String XML_HTTP_REQUEST = "XMLHttpRequest";
    /**
     * json字尾
     */
    private static final String JSON_SUFFIX = ".json";
    /**
     * xml字尾
     */
    private static final String XML_SUFFIX = ".xml";
    /**
     * 索引越界
     */
    private static final int INDEX_NOT_FOUND = -1;


    /**
     * 擷取String參數
     *
     * @param name 參數名
     * @return String 參數值
     */
    public static String getParameter(String name) {
        return getRequest().getParameter(name);
    }

    /**
     * 擷取String參數
     *
     * @param name         參數名
     * @param defaultValue 預設值
     * @return String 參數值
     */
    public static String getParameter(String name, String defaultValue) {
        return toStr(getRequest().getParameter(name), defaultValue);
    }

    /**
     * 擷取Integer參數
     *
     * @param name 參數名
     * @return Integer 參數值
     */
    public static Integer getParameterToInt(String name) {
        return toInt(getRequest().getParameter(name), null);
    }

    /**
     * 擷取Integer參數
     *
     * @param name         參數名
     * @param defaultValue 預設值
     * @return Integer 參數值
     */
    public static Integer getParameterToInt(String name, Integer defaultValue) {
        return toInt(getRequest().getParameter(name), defaultValue);
    }

    /**
     * 擷取request
     *
     * @return HttpServletRequest
     */
    public static HttpServletRequest getRequest() {
        return getRequestAttributes().getRequest();
    }

    /**
     * 擷取response
     *
     * @return HttpServletResponse
     */
    public static HttpServletResponse getResponse() {
        return getRequestAttributes().getResponse();
    }

    /**
     * 擷取session
     *
     * @return HttpSession
     */
    public static HttpSession getSession() {
        return getRequest().getSession();
    }

    /**
     * 擷取Attributes
     *
     * @return ServletRequestAttributes
     */
    public static ServletRequestAttributes getRequestAttributes() {
        RequestAttributes attributes = RequestContextHolder.getRequestAttributes();
        return (ServletRequestAttributes) attributes;
    }

    /**
     * 将字元串渲染到用戶端
     *
     * @param response 渲染對象
     * @param string   待渲染的字元串
     * @return null
     */
    public static String renderString(HttpServletResponse response, String string) {
        try {
            response.setContentType(APPLICATION_JSON);
            response.setCharacterEncoding("utf-8");
            response.getWriter().print(string);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 是否是Ajax異步請求
     *
     * @param request 用戶端請求
     * @return boolean
     */
    public static boolean isAjaxRequest(HttpServletRequest request) {
        String accept = request.getHeader("accept");
        if (accept != null && accept.contains(APPLICATION_JSON)) {
            return true;
        }

        String xRequestedWith = request.getHeader("X-Requested-With");
        if (xRequestedWith != null && xRequestedWith.contains(XML_HTTP_REQUEST)) {
            return true;
        }

        String uri = request.getRequestURI();
        if (inStringIgnoreCase(uri, JSON_SUFFIX, XML_SUFFIX)) {
            return true;
        }

        String ajax = request.getParameter("__ajax");
        return inStringIgnoreCase(ajax, "json", "xml");
    }

    /**
     * 轉換為int<br>
     * 如果給定的值為空，或者轉換失敗，傳回預設值<br>
     * 轉換失敗不會報錯
     *
     * @param value        被轉換的值
     * @param defaultValue 轉換錯誤時的預設值
     * @return Integer
     */
    public static Integer toInt(Object value, Integer defaultValue) {
        if (value == null) {
            return defaultValue;
        }

        if (value instanceof Integer) {
            return (Integer) value;
        }

        if (value instanceof Number) {
            return ((Number) value).intValue();
        }

        final String valueStr = toStr(value, null);
        if (StringUtils.isEmpty(valueStr)) {
            return defaultValue;
        }

        try {
            return Integer.parseInt(valueStr.trim());
        } catch (Exception e) {
            return defaultValue;
        }
    }

    /**
     * 轉換為字元串<br>
     * 如果給定的值為null，或者轉換失敗，傳回預設值<br>
     * 轉換失敗不會報錯
     *
     * @param value        被轉換的值
     * @param defaultValue 轉換錯誤時的預設值
     * @return String
     */
    public static String toStr(Object value, String defaultValue) {
        if (null == value) {
            return defaultValue;
        }

        if (value instanceof String) {
            return (String) value;
        }

        return value.toString();
    }

    /**
     * 是否包含字元串(不區分大小寫)
     *
     * @param str           驗證字元串
     * @param searchStrings 字元串組
     * @return boolean
     */
    public static boolean inStringIgnoreCase(String str, String... searchStrings) {
        if (str != null && searchStrings != null) {
            for (String s : searchStrings) {
                if (str.equalsIgnoreCase(StringUtils.trim(s))) {
                    return true;
                }
            }
        }
        return false;
    }
}