package com.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

/**
 * 
 * @author 黄路飞
 *
 * @data 2016年6月16日19:23:00
 */

public class SignUtil {
    
    //微信接口配置时填写的Token
    private static String token = "weixin";
    
    /**
     * 
     * 校验签名
     * @param signature 微信加密签名
     * @param timestamp 时间戳
     * @param nonce 随机数
     * @return true/false
     */
    public static boolean checkSignature(String signature, String timestamp, String nonce) {
        //字典排序
        String[] paramArr = new String[] { token, timestamp, nonce };
        Arrays.sort(paramArr);
        
        String content = paramArr[0].concat(paramArr[1]).concat(paramArr[2]);
        
        String ciphertext = null;
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-1");
            // 对接后的字符串进行sha1加密
            byte[] digest = md.digest(content.toString().getBytes());
            ciphertext = byteToStr(digest);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return ciphertext != null ? ciphertext.equals(signature.toUpperCase()) : false;
    }
    
    
    /**
     *  将字节转换为十六进制字符串
     * @param byteArray
     * @return 
     */
    private static String byteToStr(byte[] byteArray) {
        String strDigest = "";
        for (int i = 0; i < byteArray.length; i++) {
            strDigest += byteToHexStr(byteArray[i]);
        }
        return strDigest;
    }
    
    
    /**
     * 将字节转换为十六进制字符串
     * 
     * @param mByte
     * @return
     */
    private static String byteToHexStr(byte mByte) {
        char[] Digit = { ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘, ‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ };
        char[] tempArr = new char[2];
        tempArr[0] = Digit[(mByte >>> 4) & 0X0F];
        tempArr[1] = Digit[mByte & 0X0F];
        String s = new String(tempArr);
        return s;
    }

}

package com.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.util.SignUtil;

/**
 * 
 * @author 黄路飞
 *
 * @data 2016年6月16日19:34:37
 */
public class CoreServlet extends HttpServlet {

    
    
    private static final long serialVersionUID = 2168408682288701938L;
    
    /**
     * 请求校验（确认请求来自微信服务器）
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
        
        String signature = request.getParameter("signature");
        String timestamp = request.getParameter("timestamp");
        String nonce = request.getParameter("nonce");
        String echostr = request.getParameter("echostr");
        
        PrintWriter out = response.getWriter();
        if (SignUtil.checkSignature(signature, timestamp, nonce)) {
            out.print(echostr);
        }
        out.close();
        out = null;

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

    }

}