java 后台服务：

@Controller
public class LoginController {
    @RequestMapping(value = "/weixin/auth",method=RequestMethod.GET)
    public void login(HttpServletRequest request,HttpServletResponse response){
        System.out.println("success");
        String signature = request.getParameter("signature");
        String timestamp = request.getParameter("timestamp");
        String nonce = request.getParameter("nonce");
        String echostr = request.getParameter("echostr");
        PrintWriter out = null;
        try {
              out = response.getWriter();
            if(CheckUtil.checkSignature(signature, timestamp, nonce)){
                out.write(echostr);
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            out.close();
        }
        
    }
}

import java.util.Arrays;
/**
 * 
 * 类名称: CheckUtil
 * 类描述: 请求校验
 * @author yuanjun
 * 创建时间:2017年12月8日上午10:54:16
 */
public class CheckUtil {

    private static final String token = "自己设置,要与微信页面设置的一致";
    public static boolean checkSignature(String signature,String timestamp,String nonce){
        String[] str = new String[]{token,timestamp,nonce};
        //排序
        Arrays.sort(str);
        //拼接字符串
        StringBuffer buffer = new StringBuffer();
        for(int i =0 ;i<str.length;i++){
            buffer.append(str[i]);
        }
        //进行sha1加密
        String temp = SHA1.encode(buffer.toString());
        //与微信提供的signature进行匹对
        return signature.equals(temp);
    }
}

import java.security.MessageDigest;

/**
 * 
 * 类名称: SHA1
 * 类描述: sha1加密
 * @author yuanjun
 * 创建时间:2017年12月5日上午11:10:01
 */
public final  class SHA1 {
     private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5',  
         '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};  
    
    /** 
    * Takes the raw bytes from the digest and formats them correct. 
    * 
    * @param bytes the raw bytes from the digest. 
    * @return the formatted bytes. 
    */  
    private static String getFormattedText(byte[] bytes) {  
        int len = bytes.length;  
        StringBuilder buf = new StringBuilder(len * 2);  
        // 把密文转换成十六进制的字符串形式  
        for (int j = 0; j < len; j++) {  
        buf.append(HEX_DIGITS[(bytes[j] >> 4) & 0x0f]);  
        buf.append(HEX_DIGITS[bytes[j] & 0x0f]);  
        }  
        return buf.toString();  
    }  
    
    public static String encode(String str) {  
        if (str == null) {  
        return null;  
        }  
        try {  
        MessageDigest messageDigest = MessageDigest.getInstance("SHA1");  
        messageDigest.update(str.getBytes());  
        return getFormattedText(messageDigest.digest());  
        } catch (Exception e) {  
        throw new RuntimeException(e);  
        }  
    }  
}