前言：
在做小程序的开发时需要获取用户的openId用来做唯一标识，来获取对应用户的相关数据
官方的文档说明上有四个必须传的参数
其中appId和appSecret可在自己的微信公众号平台上获取，同时这些也是属于私密信息，应该妥善保管的，因为微信手机客户端是很容易反编译获取到这些信息的，所以在前端的ajax请求将这些参数传到后台是不可取的，最好的方式是将这两个参数在后台传入，然后发送请求至官方接口
1.模拟Http请求
package com.btw.util;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.ProtocolException;
import java.net.URL;
import java.util.Map;
public class HttpUtil {
/**
* 请求类型： GET
*/
public final static String GET = "GET";
/**
* 请求类型： POST
*/
public final static String POST = "POST";
/**
* 模拟Http Get请求
* @param urlStr
* 请求路径
* @param paramMap
* 请求参数
* @return
* @throws Exception
*/
public static String get(String urlStr, Map<String, String> paramMap) throws Exception{
urlStr = urlStr + "?" + getParamString(paramMap);
HttpURLConnection conn = null;
try{
//创建URL对象
URL url = new URL(urlStr);
//获取URL连接
conn = (HttpURLConnection) url.openConnection();
//设置通用的请求属性
setHttpUrlConnection(conn, GET);
//建立实际的连接
conn.connect();
//获取响应的内容
return readResponseContent(conn.getInputStream());
}finally{
if(null!=conn) conn.disconnect();
}
}
/**
* 模拟Http Post请求
* @param urlStr
* 请求路径
* @param paramMap
* 请求参数
* @return
* @throws Exception
*/
public static String post(String urlStr, Map<String, String> paramMap) throws Exception{
HttpURLConnection conn = null;
PrintWriter writer = null;
try{
//创建URL对象
URL url = new URL(urlStr);
//获取请求参数
String param = getParamString(paramMap);
//获取URL连接
conn = (HttpURLConnection) url.openConnection();
//设置通用请求属性
setHttpUrlConnection(conn, POST);
//建立实际的连接
conn.connect();
//将请求参数写入请求字符流中
writer = new PrintWriter(conn.getOutputStream());
writer.print(param);
writer.flush();
//读取响应的内容
return readResponseContent(conn.getInputStream());
}finally{
if(null!=conn) conn.disconnect();
if(null!=writer) writer.close();
}
}
/**
* 读取响应字节流并将之转为字符串
* @param in
* 要读取的字节流
* @return
* @throws IOException
*/
private static String readResponseContent(InputStream in) throws IOException{
Reader reader = null;
StringBuilder content = new StringBuilder();
try{
reader = new InputStreamReader(in);
char[] buffer = new char[1024];
int head = 0;
while( (head=reader.read(buffer))>0 ){
content.append(new String(buffer, 0, head));
}
return content.toString();
}finally{
if(null!=in) in.close();
if(null!=reader) reader.close();
}
}
/**
* 设置Http连接属性
* @param conn
* http连接
* @return
* @throws ProtocolException
* @throws Exception
*/
private static void setHttpUrlConnection(HttpURLConnection conn, String requestMethod) throws ProtocolException{
conn.setRequestMethod(requestMethod);
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("Accept-Language", "zh-CN");
conn.setRequestProperty("User-Agent", "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)");
conn.setRequestProperty("Proxy-Connection", "Keep-Alive");
if(null!=requestMethod && POST.equals(requestMethod)){
conn.setDoOutput(true);
conn.setDoInput(true);
}
}
/**
* 将参数转为路径字符串
* @param paramMap
* 参数
* @return
*/
private static String getParamString(Map<String, String> paramMap){
if(null==paramMap || paramMap.isEmpty()){
return "";
}
StringBuilder builder = new StringBuilder();
for(String key : paramMap.keySet() ){
builder.append("&")
.append(key).append("=").append(paramMap.get(key));
}
return builder.deleteCharAt(0).toString();
}
}
其中请求参数已经封装成map的形式，非常方便
2.请求接口
在这个接口我们只需要接收一个code的参数，然后用String类型接收Util类返回的数据即可，其中的url为官方接口地址
package com.btw.controller;
import com.btw.util.AppConstant;
import com.btw.util.HttpUtil;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;
@RestController
@RequestMapping("/system")
public class SecretController {
@RequestMapping(value = "/getOpenId",method = RequestMethod.GET)
public String getOpenid(HttpServletRequest request,HttpServletResponse response, @RequestParam String code){
Map<String,String> paramMap=new HashMap<>();
paramMap.put("appid", AppConstant.AppId);
paramMap.put("secret",AppConstant.AppSecret);
paramMap.put("js_code",code);
paramMap.put("grant_type","authorization_code");
String url="https://api.weixin.qq.com/sns/jscode2session";
String res=null;
try {
res=HttpUtil.post(url,paramMap);
} catch (Exception e) {
e.printStackTrace();
}
return res;
}
}
3.前端Ajax请求
