Introduction to graphic code in the preparation stage of WeChat development

package com.vlive.action.connector;  
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.vlive.utils.SignUtil;  
public class URlresponse extends HttpServlet{  
    @Override  
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)  
            throws ServletException, IOException {  
         // 微信加密签名    
        String signature = req.getParameter("signature");    
        // 时间戳    
        String timestamp = req.getParameter("timestamp");    
        // 随机数    
        String nonce = req.getParameter("nonce");    
        // 随机字符串    
        String echostr = req.getParameter("echostr");    
        PrintWriter out = resp.getWriter();    
        // 通过检验signature对请求进行校验，若校验成功则原样返回echostr，表示接入成功，否则接入失败    
        if (SignUtil.checkSignature(signature, timestamp, nonce)) {    
            out.print(echostr);    
        }    
        out.close();    
        out = null;    
    }  
}

package com.vlive.utils;  
import java.security.MessageDigest;  
import java.security.NoSuchAlgorithmException;  
import java.util.Arrays;  
public class SignUtil {  
    private static String token="vlive";  
    public static boolean checkSignature(String signature, String timestamp, String nonce) {    
        String[] arr = new String[] { token, timestamp, nonce };    
        // 将token、timestamp、nonce三个参数进行字典序排序    
        Arrays.sort(arr);    
        StringBuilder content = new StringBuilder();    
        for (int i = 0; i < arr.length; i++) {    
            content.append(arr[i]);    
        }    
        MessageDigest md = null;    
        String tmpStr = null;    
        try {    
            md = MessageDigest.getInstance("SHA-1");    
            // 将三个参数字符串拼接成一个字符串进行sha1加密    
            byte[] digest = md.digest(content.toString().getBytes());    
            tmpStr = byteToStr(digest);    
        } catch (NoSuchAlgorithmException e) {    
            e.printStackTrace();    
        }    
        content = null;    
        // 将sha1加密后的字符串可与signature对比，标识该请求来源于微信    
        return tmpStr != null ? tmpStr.equals(signature.toUpperCase()) : false;    
    }    
     /**  
     * 将字节数组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 = { &#39;0&#39;, &#39;1&#39;, &#39;2&#39;, &#39;3&#39;, &#39;4&#39;, &#39;5&#39;, &#39;6&#39;, &#39;7&#39;, &#39;8&#39;, &#39;9&#39;, &#39;A&#39;, &#39;B&#39;, &#39;C&#39;, &#39;D&#39;, &#39;E&#39;, &#39;F&#39; };    
        char[] tempArr = new char[2];    
        tempArr[0] = Digit[(mByte >>> 4) & 0X0F];    
        tempArr[1] = Digit[mByte & 0X0F];    
        String s = new String(tempArr);    
        return s;    
    }    
}