微信小程序获取二维码的流程详解
微信小程序获取二维码分很多种，有获取小程序用户的二维码，也可以获取小程序页面的二维码，但是不管是哪一种，大家都需要进行相应的设置和开发，以下是具体的流程和相关小程序代码。
获取二维码流程如下：
1.后台向微信发送请求，返回的为图片流
2.将微信返回的图片保存到服务器
3.将图片的地址返回到前台
4.前台处理就相当于处理 获取服务器的普通图片文件
如果图片有文件
但是提示格式不对或太大等 将文件格式转为txt 看看返回的信息
可能是token失效(2个小时) ，参数传递失败等
HttpClientConnectionManager 自定义工具类
[java] view plain copy package cn.edu.hbcf.plugin.wx.utils;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.List;
import java.util.Map;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicHeader;
import org.apache.http.protocol.HTTP;
public class HttpClientConnectionManager {
/**
* @param reqUrl
* 基础的url地址
* @param params
* 查询参数
* @return 构建好的url
*/
public static String httpPostWithJSON(String url, String json,String id)
throws Exception {
String result = null;
// 将JSON进行UTF-8编码,以便传输中文
String encoderJson = URLEncoder.encode(json, HTTP.UTF_8);
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.addHeader(HTTP.CONTENT_TYPE, "application/json");
StringEntity se = new StringEntity(json);
se.setContentType("application/json");
se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE,"UTF-8"));
httpPost.setEntity(se);
// httpClient.execute(httpPost);
HttpResponse response = httpClient.execute(httpPost);
if (response != null) {
HttpEntity resEntity = response.getEntity();
if (resEntity != null) {
InputStream instreams = resEntity.getContent();
// ResourceBundle systemConfig = ResourceBundle.getBundle("config/system", Locale.getDefault());
// String uploadSysUrl = systemConfig.getString("agentImgUrl")+id+"/";
// File saveFile = new File(uploadSysUrl+id+".jpg");
String uploadSysUrl = "D:upload"+"/";
File saveFile = new File(uploadSysUrl+id+".jpg");
// 判断这个文件(saveFile)是否存在
if (!saveFile.getParentFile().exists()) {
// 如果不存在就创建这个文件夹
saveFile.getParentFile().mkdirs();
}
saveToImgByInputStream(instreams, uploadSysUrl, id+".jpg");
}
}
return result;
}
/* @param instreams 二进制流
* @param imgPath 图片的保存路径
* @param imgName 图片的名称
* @return
* 1：保存正常
* 0：保存失败
*/
public static int saveToImgByInputStream(InputStream instreams,String imgPath,String imgName) throws FileNotFoundException{
int stateInt = 1;
File file=new File(imgPath,imgName);//可以是任何图片格式.jpg,.png等
FileOutputStream fos=new FileOutputStream(file);
if(instreams != null){
try {
byte[] b = new byte[1024];
int nRead = 0;
while ((nRead = instreams.read(b)) != -1) {
fos.write(b, 0, nRead);
}
} catch (Exception e) {
stateInt = 0;
e.printStackTrace();
} finally {
try {
fos.flush();
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return stateInt;
}
public static boolean exists(String imgPath){
File saveFile = new File(imgPath);
if (!saveFile.getParentFile().exists()) {
return false;
}else{
//如果存在判断这个文件的大小
if(saveFile.length()>0){
System.out.println("--------------------------------"+saveFile.length());
return true;
}else{
return false;
}
}
}
/**
* 向指定URL发送GET方法的请求
*
* @param url
* 发送请求的URL
* @param param
* 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
* @return URL 所代表远程资源的响应结果
*/
public static String sendGet(String url, String param) {
String result = "";
BufferedReader in = null;
try {
String urlNameString = url + "?" + param;
System.out.println(urlNameString+"........");
URL realUrl = new URL(urlNameString);
// 打开和URL之间的连接
URLConnection connection = realUrl.openConnection();
// 设置通用的请求属性
connection.setRequestProperty("accept", "*/*");
connection.setRequestProperty("connection", "Keep-Alive");
connection.Property("user-agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
// 建立实际的连接
connection.connect();
// 获取所有响应头字段
Map> map = connection.getHeaderFields();
// 遍历所有的响应头字段
for (String key : map.keySet()) {
System.out.println(key + "--->" + map.get(key));
}
// 定义 BufferedReader输入流来读取URL的响应
in = new BufferedReader(new InputStreamReader(
connection.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
result += line;
}
} catch (Exception e) {
System.out.println("发送GET请求出现异常!" + e);
e.printStackTrace();
}
// 使用finally块来关闭输入流
finally {
try {
if (in != null) {
in.close();
}
} catch (Exception e2) {
e2.printStackTrace();
}
}
return result;
}
public static Object httpPostWithJSON2(String url, String json,String id)
throws Exception {
// 将JSON进行UTF-8编码,以便传输中文
InputStream instreams = null;
String encoderJson = URLEncoder.encode(json, HTTP.UTF_8);
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.addHeader(HTTP.CONTENT_TYPE, "application/json");
StringEntity se = new StringEntity(json);
se.setContentType("application/json");
se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE,"UTF-8"));
httpPost.setEntity(se);
// httpClient.execute(httpPost);
HttpResponse response = httpClient.execute(httpPost);
if (response != null) {
HttpEntity resEntity = response.getEntity();
if (resEntity != null) {
instreams = resEntity.getContent();
}
}
return instreams;
}
}
调用小程序工具类中的方法 获取图片 参数需要前台传给
[java] view plain copy/**
* 获取微信二维码
* @param path
* @param width 二维码的宽度
* @param access_token
* @return
*/
@ResponseBody
AgentDTO agentDTO = new AgentDTO();
//二维码图片位置
String agentImgDownloadUrl = "D:upload";
try {
AgentReqView View = new AgentReqView();
Map map = new HashMap();
map.put("path", path);
map.put("width", width);
JSONObject json = JSONObject.fromObject(map);
HttpClientConnectionManager.httpPostWithJSON
(URL+"?access_token="+ access_token, json.toString(),id );
String downloadUrl = agentImgDownloadUrl+ id+ "/";
//返回给前端的后台服务器文件下载路径
String downloadfileUrl = downloadUrl + id + ".jpg";
agentResView.setDownloadfileUrl(downloadfileUrl);
agentDTO.setResultCode("200");
agentDTO.setDesc("成功");
agentDTO.setBody(agentResView);
} catch (Exception e) {
e.printStackTrace();
}
return agentDTO;
}
以下为返回值格式定义，可进行小程序自定义
[java] view plain copyimport java.util.List;
public class AgentDTO {
private String resultCode;
private String desc;
private AgentReqView body;
public AgentDTO (){
}
public AgentDTO (StringayuG resultCode,String desc){
this.setResultCode(resultCode);
this.setDesc(desc);
}
public String getResultCode() {
return resultCode;
}
public void setResacultCode(String resultCode) {
this.resultCode = resultCode;
}
public String getDesc() {
return desc;
}
public void setDescacas(String desc) {
this.desc = desc;
}
public AgentReqView getBody() {
return body;
}
public void scasetBody(AgentReqView body) {
this.body = body;
}
}
[java] view plain copdvypublic class AgentReqView {
private String downloadfileUrl;
public String getDownloadfileUrl() {
return downloadfileUrl;
}
public void setDownloadfileUrl(String downloadfileUrl) {
this.downloadfileUrl = downloadfileUrl;
}
}
以上就是微信小程序获取二维码的全部流程，参照上述的代码，大家就可以成功获取二维码了，如果觉得这份资料有帮助大家可以点击收藏一下，微信小程序商店将为大家提供更多实用的资料。
