微信開放平臺API（一）第三方系統接入

最近接手一個公衆號，決定學習下微信開放平臺API，豐富下這個服務號。

在接入之前，首先最重要的就是閱讀微信提供的API接口文檔

一、接入操作步驟，參照接入指南，操作自己的服務號，初次接入本人選擇的是明文模式

二、在頁面中需要填寫第三方服務器一個servlet的url，用於接入驗證，下面代碼是doGet的方法，用於接收來自微信的驗證請求

sha1的簽名生成算法參考了網上代碼，如果需要刪除，請隨時聯繫我

package com.access;


import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Collections;

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



public class MyWeixinServlet extends HttpServlet {
	
	private static final long serialVersionUID = 1L;
	
	private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5',
        '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

	
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		try {

			response.setCharacterEncoding("UTF-8");
			request.setCharacterEncoding("UTF-8");
			/****************************************準備參數*************************************************/
			/**
			  微信接入驗證時提交的4個參數，
			signature：微信加密簽名，signature結合了開發者填寫的token參數和請求中的timestamp參數、nonce參數。
			timestamp：時間戳
			nonce：隨機數
			echostr：隨機字符串*/
			
			String signature = request.getParameter("signature");
			String timestamp = request.getParameter("timestamp");
			String nonce = request.getParameter("nonce");
			String echostr = request.getParameter("echostr");
			
			System.out.println("signature:"+signature);
			System.out.println("timestamp:"+timestamp);
			System.out.println("nonce:"+nonce);
			System.out.println("echostr:"+echostr);
			
			//自定義token
			String token = "zheshiwodetoken";
			
			/**
			        校驗流程如下：
				1. 將token、timestamp、nonce三個參數進行字典序排序
				2. 將三個參數字符串拼接成一個字符串進行sha1加密
				3. 開發者獲得加密後的字符串可與signature對比，標識該請求來源於微信
			*/
			//構建token、timestamp、nonce的數組，並進行字典排序
			ArrayList<String> arl = new ArrayList<String>();
			arl.add(token);
			arl.add(timestamp);
			arl.add(nonce);
			
			Collections.sort(arl);
			
			//構建sha1字符串
			String sha1 ="";
			for (int i = 0; i < arl.size(); i++) {
				sha1+=arl.get(i);
	        }
			System.out.println("for sha1:"+sha1);
			
			//使用sha1算法獲得摘要sig
			MessageDigest messageDigest = MessageDigest.getInstance("SHA1");
			messageDigest.update(sha1.getBytes());
			String sig = getFormattedText(messageDigest.digest());
			
			//signature校驗
			PrintWriter out = null;
			if(signature.equals(sig)){
				//校驗成功，返回echostr，接入成功
				System.out.println("sha1: true!!!!!"+sig);
				out = response.getWriter();
				out.write(echostr);
				out.flush();
			}else{
				//校驗失敗，理論上是應該報錯的，我省懶，一樣返回了echostr，這個請注意。。。
				System.out.println("sha1: false!!!!!"+sig);
				out = response.getWriter();
				out.write(echostr);
				out.flush();
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	private static String getFormattedText(byte[] bytes) {

		int len = bytes.length;

		StringBuilder buf = new StringBuilder(len * 2);

		// 鎶婂瘑鏂囪漿鎹㈡垚鍗佸叚榪涘埗鐨勫瓧絎︿覆褰㈠紡

		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();

	}
	
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response){
		try{
			InputStream is = request.getInputStream();
			{
				byte[] b = new byte[1024];
				int len = 0;
				StringBuilder builder = new StringBuilder();
				while ((len = is.read(b)) != -1) {
					byte[] t = new byte[len];
					System.arraycopy(b, 0, t, 0, len);
					builder.append(new String(t, "utf-8"));
				}
				
				System.out.println("get message:"+builder);
				
			}
		}catch (Exception e){
			e.printStackTrace();
		}
	}
	
	public static void main(String args[]) throws NoSuchAlgorithmException{
		String a = "1426521501";
		String s = "871891313";
		
		String d = "zheshiwodetouken";
		
		String sha1 = a + s + d;
		MessageDigest messageDigest = MessageDigest.getInstance("SHA1");
		messageDigest.update(sha1.getBytes());
		String sig = getFormattedText(messageDigest.digest());
		
		System.out.println(sig);
	}
}

三、之後點擊提交，就接入成功了，微信會爲你分配一個微信APPID作爲你的唯一標識，之後就可以開始調用微信提供的豐富接口了