Java企业微信开发_08_素材管理之下载微信临时素材到本地服务器

一、本节要点

1.获取临时素材接口

请求方式：GET（HTTPS）

请求地址：https://qyapi.weixin.qq.com/cgi-bin/media/get?access_token=ACCESS_TOKEN&media_id=MEDIA_ID

2.获取临时素材接口的返回结果

企业微信官方开发文档中说明的返回结果如下：

若你以为这就是返回结果，然后跟之前一样，先访问接口，从http连接的输入流中的获取回结果的文本内容，你会发现你接收到的结果是一堆乱码。

这是为何？

以图片为例，此处千万要注意，微信返回的结果是一个文件流形式的图片，当我们从http连接的输入流中的获取回结果的文本内容，也就是获取图片的文本内容时，当然就是一堆乱码了。

这就好比你用记事本打开一张图片，然后发现内容是一片乱码。这再正常不过。所以我们接受图片的时候不能只接收文本数据，而是要接收流。

千万得注意：获取临时素材时，微信返回的结果是一个流形式的临时素材。

我们需要做的就是调用接口，获取http连接的输入流中数据，再将输入流中的数据写入到输出流，再通过输出流生成一张图片。这张图片就是微信返回的临时素材了。

3.下载文件时的文件路径

request.getSession().getServletContext().getRealPath("").replaceAll("\\", "/")

将获取路径：%TOMCAT_HOME%/webapp/工程名。若不是这个路径就请参考：Eclipse中的Web项目自动部署到Tomcat

String savePath=request.getSession().getServletContext().getRealPath("").replaceAll("\\", "/")+"/img/";

将获取路径：%TOMCAT_HOME%/webapp/工程名/img/

即从微信服务器下载的图片都保存在这个路径下。

二、代码实现

这里承接上一节。在上一节中我们完成了JSSDK的配置，并且用图片上传接口将图片上传到了微信服务器。这一节我们需要做的就是在图片上传到微信服务器后，根据微信服务器返回的serverId(即mediaId)来调用获取临时素材的接口，进行临时素材的下载，并保存到本地指定的路径下。

2.1 UploadExpenseAccaoutServlet

package com.ray.servlet;

import java.io.IOException;
import java.io.PrintWriter;

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

import com.ray.service.TempMaterialService;
import com.ray.util.WeiXinParamesUtil;
import com.ray.util.WeiXinUtil;

/**
 * Servlet implementation class UploadExpenseAccaoutServlet
 */
@WebServlet("/UploadExpenseAccaoutServlet")
public class UploadExpenseAccaoutServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public UploadExpenseAccaoutServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub

        String mediaId=request.getParameter("serverId");
        System.out.println("serverId:"+mediaId);

        String accessToken= WeiXinUtil.getAccessToken(WeiXinParamesUtil.corpId, WeiXinParamesUtil.contactsSecret).getToken();
        System.out.println("accessToken:"+accessToken);

        //String savePath=System.getProperty("user.dir").replaceAll("\\", "/")+"/WebContent/img/"+mediaId+".png"; 
        String savePath=request.getSession().getServletContext().getRealPath("").replaceAll("\\", "/")+"/img/"; 
        System.out.println("savePath:"+savePath);

        //2.调用业务类，获取临时素材
        TempMaterialService tms=new TempMaterialService();
        tms.getTempMaterial(accessToken, mediaId,savePath);


        PrintWriter out = response.getWriter(); 
        out.print("HHHHHHHHHH");  
        out.close();  
        out = null;  
    }

}

在此servlet中

（1）接收serverId

（2）调用临时素材业务类的方法TempMaterialService.getTempMaterial(accessToken, mediaId,savePath)，获取临时素材。

2.2 临时素材业务类—TempMaterialService

package com.ray.service;

import java.io.File;
import java.io.UnsupportedEncodingException;

import com.ray.util.WeiXinUtil;

import net.sf.json.JSONObject;

/**@desc  : 临时素材业务类
 * 
 * @author: shirayner
 * @date  : 2017-8-18 下午2:07:25
 */
public class TempMaterialService {
    
    //上传临时素材url
    public String uploadTempMaterial_url="https://qyapi.weixin.qq.com/cgi-bin/media/upload?access_token=ACCESS_TOKEN&type=TYPE";

    //获取临时素材url
    public String getTempMaterial_url="https://qyapi.weixin.qq.com/cgi-bin/media/get?access_token=ACCESS_TOKEN&media_id=MEDIA_ID";

    /**
     * @desc ：上传临时素材
     *  
     * @param accessToken   接口访问凭证 
     * @param type   媒体文件类型，分别有图片（image）、语音（voice）、视频（video），普通文件(file) 
     * @param fileUrl  本地文件的url。例如 "D/1.img"。
     * @return JSONObject   上传成功后，微信服务器返回的参数，有type、media_id    、created_at
     */
    public JSONObject uploadTempMaterial(String accessToken,String type,String fileUrl){
        //1.创建本地文件
        File file=new File(fileUrl);

        //2.拼接请求url
        uploadTempMaterial_url = uploadTempMaterial_url.replace("ACCESS_TOKEN", accessToken)
                .replace("TYPE", type);

        //3.调用接口，发送请求，上传文件到微信服务器
        String result=WeiXinUtil.httpRequest(uploadTempMaterial_url, file);

        //4.json字符串转对象：解析返回值，json反序列化
        result = result.replaceAll("[\\]", "");
        System.out.println("result:" + result);
        JSONObject resultJSON = JSONObject.fromObject(result);

        //5.返回参数判断
        if (resultJSON != null) {
            if (resultJSON.get("media_id") != null) {
                System.out.println("上传" + type + "临时素材成功:"+resultJSON.get("media_id"));
                return resultJSON;
            } else {
                System.out.println("上传" + type + "临时素材成功失败");
            }
        }
        return null;
    }

    /** 2.获取临时素材
     * 
     * @param accessToken
     * @param mediaId
     * @return
     * @throws UnsupportedEncodingException 
     */
    public void getTempMaterial(String accessToken,String mediaId,String savePath) throws UnsupportedEncodingException{

        //String savePath=System.getProperty("user.dir").replaceAll("\\", "/")+"/WebContent/img/"+mediaId+".png"; 
        //System.out.println("service savePath:"+savePath);
        
        //1.拼接请求url
        getTempMaterial_url=getTempMaterial_url.replace("ACCESS_TOKEN", accessToken)
                .replace("MEDIA_ID", mediaId);

        savePath=savePath+mediaId;
        //2.调用接口，发送请求，获取临时素材
        File file=null;
        try {
            file = WeiXinUtil.getFile(getTempMaterial_url,savePath);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        System.out.println("file:"+file.getName());

    
    }

    
    


}

在此类的获取临时素材方法中：

（1）拼接微信获取临时素材的接口url

（2）调用WeiXinUtil.getFile(getTempMaterial_url,savePath)，向微信发起https请求，并将接收到的图片下载到savePath指定的路径下

2.3 微信工具类—WeiXinUtil

package com.ray.util;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Formatter;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.servlet.http.HttpServletRequest;


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.ray.pojo.AccessToken;




import net.sf.json.JSONException;
import net.sf.json.JSONObject;

public class WeiXinUtil {

    private static Logger log = LoggerFactory.getLogger(WeiXinUtil.class);  
    //微信的请求url
    //获取access_token的接口地址（GET） 限200（次/天）  
    public final static String access_token_url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid={corpId}&corpsecret={corpsecret}";  
    //获取jsapi_ticket的接口地址（GET） 限200（次/天）  
    public final static String jsapi_ticket_url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=ACCESSTOKEN";  



    /**
     * 1.发起https请求并获取结果 
     *  
     * @param requestUrl 请求地址 
     * @param requestMethod 请求方式（GET、POST） 
     * @param outputStr 提交的数据 
     * @return JSONObject(通过JSONObject.get(key)的方式获取json对象的属性值) 
     */  
    public static JSONObject httpRequest(String requestUrl, String requestMethod, String outputStr) {  
        JSONObject jsonObject = null;  
        StringBuffer buffer = new StringBuffer();  
        try {  
            // 创建SSLContext对象，并使用我们指定的信任管理器初始化  
            TrustManager[] tm = { new MyX509TrustManager() };  
            SSLContext sslContext = SSLContext.getInstance("SSL", "SunJSSE");  
            sslContext.init(null, tm, new java.security.SecureRandom());  
            // 从上述SSLContext对象中得到SSLSocketFactory对象  
            SSLSocketFactory ssf = sslContext.getSocketFactory();  

            URL url = new URL(requestUrl);  
            HttpsURLConnection httpUrlConn = (HttpsURLConnection) url.openConnection();  
            httpUrlConn.setSSLSocketFactory(ssf);  

            httpUrlConn.setDoOutput(true);  
            httpUrlConn.setDoInput(true);  
            httpUrlConn.setUseCaches(false);  
            // 设置请求方式（GET/POST）  
            httpUrlConn.setRequestMethod(requestMethod);  

            if ("GET".equalsIgnoreCase(requestMethod))  
                httpUrlConn.connect();  

            // 当有数据需要提交时  
            if (null != outputStr) {  
                OutputStream outputStream = httpUrlConn.getOutputStream();  
                // 注意编码格式，防止中文乱码  
                outputStream.write(outputStr.getBytes("UTF-8"));  
                outputStream.close();  
            }  

            // 将返回的输入流转换成字符串  
            InputStream inputStream = httpUrlConn.getInputStream();  
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "UTF-8");  
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);  

            String str = null;  
            while ((str = bufferedReader.readLine()) != null) {  
                buffer.append(str);  
            }  
            bufferedReader.close();  
            inputStreamReader.close();  
            // 释放资源  
            inputStream.close();  
            inputStream = null;  
            httpUrlConn.disconnect();  
            jsonObject = JSONObject.fromObject(buffer.toString());  
        } catch (ConnectException ce) {  
            log.error("Weixin server connection timed out.");  
        } catch (Exception e) {  
            log.error("https request error:{}", e);  
        }  
        return jsonObject;  
    }  

   /**
     * 2.发送https请求之获取临时素材 
     * @param requestUrl
     * @param savePath  文件的保存路径，此时还缺一个扩展名
     * @return
     * @throws Exception
     */
    public static File getFile(String requestUrl,String savePath) throws Exception {  
        //String path=System.getProperty("user.dir")+"/img//1.png";
    
        
            // 创建SSLContext对象，并使用我们指定的信任管理器初始化  
            TrustManager[] tm = { new MyX509TrustManager() };  
            SSLContext sslContext = SSLContext.getInstance("SSL", "SunJSSE");  
            sslContext.init(null, tm, new java.security.SecureRandom());  
            // 从上述SSLContext对象中得到SSLSocketFactory对象  
            SSLSocketFactory ssf = sslContext.getSocketFactory();  

            URL url = new URL(requestUrl);  
            HttpsURLConnection httpUrlConn = (HttpsURLConnection) url.openConnection();  
            httpUrlConn.setSSLSocketFactory(ssf);  

            httpUrlConn.setDoOutput(true);  
            httpUrlConn.setDoInput(true);  
            httpUrlConn.setUseCaches(false);  
            // 设置请求方式（GET/POST）  
            httpUrlConn.setRequestMethod("GET");  

            httpUrlConn.connect();  

            //获取文件扩展名
            String ext=getExt(httpUrlConn.getContentType());
            savePath=savePath+ext;
            System.out.println("savePath"+savePath);
            //下载文件到f文件
            File file = new File(savePath);

            
            // 获取微信返回的输入流
            InputStream in = httpUrlConn.getInputStream(); 
            
            //输出流，将微信返回的输入流内容写到文件中
            FileOutputStream out = new FileOutputStream(file);
             
            int length=100*1024;
            byte[] byteBuffer = new byte[length]; //存储文件内容
            
            int byteread =0;
            int bytesum=0;
            
            while (( byteread=in.read(byteBuffer)) != -1) {  
                bytesum += byteread; //字节数 文件大小 
                out.write(byteBuffer,0,byteread);  
                
            }  
            System.out.println("bytesum: "+bytesum);
            
            in.close();  
            // 释放资源  
            out.close();  
            in = null;  
            out=null;
            
            httpUrlConn.disconnect();  

            
            return file;
    }  
    
    

    /**
     * @desc ：2.微信上传素材的请求方法
     *  
     * @param requestUrl  微信上传临时素材的接口url
     * @param file    要上传的文件
     * @return String  上传成功后，微信服务器返回的消息
     */
    public static String httpRequest(String requestUrl, File file) {  
        StringBuffer buffer = new StringBuffer();  

        try{
            //1.建立连接
            URL url = new URL(requestUrl);
            HttpURLConnection httpUrlConn = (HttpURLConnection) url.openConnection();  //打开链接

            //1.1输入输出设置
            httpUrlConn.setDoInput(true);
            httpUrlConn.setDoOutput(true);
            httpUrlConn.setUseCaches(false); // post方式不能使用缓存
            //1.2设置请求头信息
            httpUrlConn.setRequestProperty("Connection", "Keep-Alive");
            httpUrlConn.setRequestProperty("Charset", "UTF-8");
            //1.3设置边界
            String BOUNDARY = "----------" + System.currentTimeMillis();
            httpUrlConn.setRequestProperty("Content-Type","multipart/form-data; boundary="+ BOUNDARY);

            // 请求正文信息
            // 第一部分：
            //2.将文件头输出到微信服务器
            StringBuilder sb = new StringBuilder();
            sb.append("--"); // 必须多两道线
            sb.append(BOUNDARY);
            sb.append("
");
            sb.append("Content-Disposition: form-data;name="media";filelength="" + file.length()
            + "";filename=""+ file.getName() + ""
");
            sb.append("Content-Type:application/octet-stream

");
            byte[] head = sb.toString().getBytes("utf-8");
            // 获得输出流
            OutputStream outputStream = new DataOutputStream(httpUrlConn.getOutputStream());
            // 将表头写入输出流中：输出表头
            outputStream.write(head);

            //3.将文件正文部分输出到微信服务器
            // 把文件以流文件的方式 写入到微信服务器中
            DataInputStream in = new DataInputStream(new FileInputStream(file));
            int bytes = 0;
            byte[] bufferOut = new byte[1024];
            while ((bytes = in.read(bufferOut)) != -1) {
                outputStream.write(bufferOut, 0, bytes);
            }
            in.close();
            //4.将结尾部分输出到微信服务器
            byte[] foot = ("
--" + BOUNDARY + "--
").getBytes("utf-8");// 定义最后数据分隔线
            outputStream.write(foot);
            outputStream.flush();
            outputStream.close();


            //5.将微信服务器返回的输入流转换成字符串  
            InputStream inputStream = httpUrlConn.getInputStream();  
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");  
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);  

            String str = null;  
            while ((str = bufferedReader.readLine()) != null) {  
                buffer.append(str);  
            }  

            bufferedReader.close();  
            inputStreamReader.close();  
            // 释放资源  
            inputStream.close();  
            inputStream = null;  
            httpUrlConn.disconnect();  


        } catch (IOException e) {
            System.out.println("发送POST请求出现异常！" + e);
            e.printStackTrace();
        } 
        return buffer.toString();
    }

    /** 
     * 2.发起http请求获取返回结果 
     *  
     * @param requestUrl 请求地址 
     * @return 
     */  
    public static String httpRequest(String requestUrl) {  
        StringBuffer buffer = new StringBuffer();  
        try {  
            URL url = new URL(requestUrl);  
            HttpURLConnection httpUrlConn = (HttpURLConnection) url.openConnection();  

            httpUrlConn.setDoOutput(false);  
            httpUrlConn.setDoInput(true);  
            httpUrlConn.setUseCaches(false);  

            httpUrlConn.setRequestMethod("GET");  
            httpUrlConn.connect();  

            // 将返回的输入流转换成字符串  
            InputStream inputStream = httpUrlConn.getInputStream();  
            //InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");  
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);  
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);  

            String str = null;  
            while ((str = bufferedReader.readLine()) != null) {  
                buffer.append(str);  

            }  
            bufferedReader.close();  
            inputStreamReader.close();  
            // 释放资源  
            inputStream.close();  
            inputStream = null;  
            httpUrlConn.disconnect();  

        } catch (Exception e) {  
        }  
        return buffer.toString();  
    }  


    /** 
     * 3.获取access_token 
     *  
     * @param appid 凭证 
     * @param appsecret 密钥 
     * @return 
     */  
    public static AccessToken getAccessToken(String appid, String appsecret) {  
        AccessToken accessToken = null;  

        String requestUrl = access_token_url.replace("{corpId}", appid).replace("{corpsecret}", appsecret);  
        JSONObject jsonObject = httpRequest(requestUrl, "GET", null);  
        // 如果请求成功  
        if (null != jsonObject) {  
            try {  
                accessToken = new AccessToken();  
                accessToken.setToken(jsonObject.getString("access_token"));  
                accessToken.setExpiresIn(jsonObject.getInt("expires_in"));  
            } catch (JSONException e) {  
                accessToken = null;  
                // 获取token失败  
                log.error("获取token失败 errcode:{} errmsg:{}", jsonObject.getInt("errcode"), jsonObject.getString("errmsg"));  
            }  
        }  
        return accessToken;  
    }  

    /**
     * 4. 获取JsapiTicket
     * @param accessToken
     * @return
     */
    public static String getJsapiTicket(String accessToken){


        String requestUrl = jsapi_ticket_url.replace("ACCESSTOKEN", accessToken);  
        JSONObject jsonObject = httpRequest(requestUrl, "GET", null);  

        String  jsapi_ticket="";
        // 如果请求成功  
        if (null != jsonObject) {  
            try {  
                jsapi_ticket=jsonObject.getString("ticket");  

            } catch (JSONException e) {  

                // 获取token失败  
                log.error("获取token失败 errcode:{} errmsg:{}", jsonObject.getInt("errcode"), jsonObject.getString("errmsg"));  
            }  
        }  
        return jsapi_ticket;  
    }

    /**
     * 3.获取企业微信的JSSDK配置信息
     * @param request
     * @return
     */
    public static Map<String, Object> getWxConfig(HttpServletRequest request) {
        Map<String, Object> ret = new HashMap<String, Object>();
        //1.准备好参与签名的字段

        String nonceStr = UUID.randomUUID().toString(); // 必填，生成签名的随机串
        //System.out.println("nonceStr:"+nonceStr);
        String accessToken=WeiXinUtil.getAccessToken(WeiXinParamesUtil.corpId, WeiXinParamesUtil.agentSecret).getToken();
        String jsapi_ticket =getJsapiTicket(accessToken);// 必填，生成签名的H5应用调用企业微信JS接口的临时票据
        //System.out.println("jsapi_ticket:"+jsapi_ticket);
        String timestamp = Long.toString(System.currentTimeMillis() / 1000); // 必填，生成签名的时间戳
        //System.out.println("timestamp:"+timestamp);
        String url=request.getRequestURL().toString();
        //System.out.println("url:"+url);
        
        //2.字典序           ，注意这里参数名必须全部小写，且必须有序
        String sign = "jsapi_ticket=" + jsapi_ticket + "&noncestr=" + nonceStr+ "&timestamp=" + timestamp + "&url=" + url;

        //3.sha1签名
        String signature = "";
        try {
            MessageDigest crypt = MessageDigest.getInstance("SHA-1");
            crypt.reset();
            crypt.update(sign.getBytes("UTF-8"));
            signature = byteToHex(crypt.digest());
            //System.out.println("signature:"+signature);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        ret.put("appId", WeiXinParamesUtil.corpId);
        ret.put("timestamp", timestamp);
        ret.put("nonceStr", nonceStr);
        ret.put("signature", signature);
        return ret;
    }


    /**
     * 方法名：byteToHex</br>
     * 详述：字符串加密辅助方法 </br>
     * 开发人员：souvc  </br>
     * 创建时间：2016-1-5  </br>
     * @param hash
     * @return 说明返回值含义
     * @throws 说明发生此异常的条件
     */
    private static String byteToHex(final byte[] hash) {
        Formatter formatter = new Formatter();
        for (byte b : hash) {
            formatter.format("%02x", b);
        }
        String result = formatter.toString();
        formatter.close();
        return result;

    }
    
    
    
    private static String getExt(String contentType){
        if("image/jpeg".equals(contentType)){
            return ".jpg";
        }else if("image/png".equals(contentType)){
            return ".png";
        }else if("image/gif".equals(contentType)){
            return ".gif";
        }
        
        return null;
    }
}

获取临时素材的方法为：WeiXinUtil.getFile（String requestUrl,String savePath)

在此方法中：

（1）发起https请求，获取输入流

（2）从输入流中获取文件类型，与savePath一起组成图片最终的路径（或者说是文件名A）

（3）根据文件名A创建输出流

（4）将输入流中的数据写入到输出流中，这样图片就保存到了文件A中。

（5）返回文件A