java微信开发之上传下载多媒体文件，java上传下载回复图片、音频、视频消息都是需要media_id的，这个是需要将多媒体文件上传到微信服务器才有的。
将多媒体文件上传到微信服务器，以及从微信服务器下载文件，可以参考：http://mp.weixin.qq.com/wiki/index.php?title=上传下载多媒体文件
上传下载多媒体文件的方法还是写到weixinutil.java中。
代码如下：
import java.io.bufferedoutputstream;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.net.httpurlconnection;import java.net.malformedurlexception;import java.net.url;import java.security.keymanagementexception;import java.security.nosuchalgorithmexception;import java.security.nosuchproviderexception;import java.security.securerandom;import java.util.calendar;import java.util.date;import java.util.hashmap;import java.util.map;import javax.net.ssl.httpsurlconnection;import javax.net.ssl.sslcontext;import javax.net.ssl.sslsocketfactory;import javax.net.ssl.trustmanager;import net.sf.json.jsonobject;import org.apache.commons.lang.stringutils;import org.apache.log4j.logger;import com.company.project.model.menu.accesstoken;import com.company.project.model.menu.menu;public class weixinutil { private static logger log = logger.getlogger(weixinutil.class); public final static string appid = wxb927d4280e6db674; public final static string app_secret = 21441e9f3226eee81e14380a768b6d1e; // 获取access_token的接口地址（get） 限200（次/天） public final static string access_token_url = https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=appid&secret=appsecret; // 创建菜单 public final static string create_menu_url = https://api.weixin.qq.com/cgi-bin/menu/create?access_token=access_token; // 存放：1.token，2：获取token的时间,3.过期时间 public final static map accesstokenmap = new hashmap(); /** * 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 handlerequest(string requesturl,string requestmethod,string outputstr) { jsonobject jsonobject = null; try { url url = new url(requesturl); httpsurlconnection conn = (httpsurlconnection) url.openconnection(); sslcontext ctx = sslcontext.getinstance(ssl, sunjsse); trustmanager[] tm = {new myx509trustmanager()}; ctx.init(null, tm, new securerandom()); sslsocketfactory sf = ctx.getsocketfactory(); conn.setsslsocketfactory(sf); conn.setdoinput(true); conn.setdooutput(true); conn.setrequestmethod(requestmethod); conn.setusecaches(false); if (get.equalsignorecase(requestmethod)) { conn.connect(); } if (stringutils.isnotempty(outputstr)) { outputstream out = conn.getoutputstream(); out.write(outputstr.getbytes(utf-8)); out.close(); } inputstream in = conn.getinputstream(); bufferedreader br = new bufferedreader(new inputstreamreader(in,utf-8)); stringbuffer buffer = new stringbuffer(); string line = null; while ((line = br.readline()) != null) { buffer.append(line); } in.close(); conn.disconnect(); jsonobject = jsonobject.fromobject(buffer.tostring()); } catch (malformedurlexception e) { e.printstacktrace(); log.error(url错误！); } catch (ioexception e) { e.printstacktrace(); } catch (nosuchalgorithmexception e) { e.printstacktrace(); } catch (nosuchproviderexception e) { e.printstacktrace(); } catch (keymanagementexception e) { e.printstacktrace(); } return jsonobject; } /** * 获取access_token * * @author qincd * @date nov 6, 2014 9:56:43 am */ public static accesstoken getaccesstoken(string appid,string appsecret) { accesstoken at = new accesstoken(); // 每次获取access_token时，先从accesstokenmap获取，如果过期了就重新从微信获取 // 没有过期直接返回 // 从微信获取的token的有效期为2个小时 if (!accesstokenmap.isempty()) { date gettokentime = (date) accesstokenmap.get(gettokentime); calendar c = calendar.getinstance(); c.settime(gettokentime); c.add(calendar.hour_of_day, 2); gettokentime = c.gettime(); if (gettokentime.after(new date())) { log.info(缓存中发现token未过期，直接从缓存中获取access_token); // token未过期，直接从缓存获取返回 string token = (string) accesstokenmap.get(token); integer expire = (integer) accesstokenmap.get(expire); at.settoken(token); at.setexpiresin(expire); return at; } } string requesturl = access_token_url.replace(appid, appid).replace(appsecret, appsecret); jsonobject object = handlerequest(requesturl, get, null); string access_token = object.getstring(access_token); int expires_in = object.getint(expires_in); log.info(\naccess_token: + access_token); log.info(\nexpires_in: + expires_in); at.settoken(access_token); at.setexpiresin(expires_in); // 每次获取access_token后，存入accesstokenmap // 下次获取时，如果没有过期直接从accesstokenmap取。 accesstokenmap.put(gettokentime, new date()); accesstokenmap.put(token, access_token); accesstokenmap.put(expire, expires_in); return at; } /** * 创建菜单 * * @author qincd * @date nov 6, 2014 9:56:36 am */ public static boolean createmenu(menu menu,string accesstoken) { string requesturl = create_menu_url.replace(access_token, accesstoken); string menujsonstring = jsonobject.fromobject(menu).tostring(); jsonobject jsonobject = handlerequest(requesturl, post, menujsonstring); string errorcode = jsonobject.getstring(errcode); if (!0.equals(errorcode)) { log.error(string.format(菜单创建失败！errorcode:%d,errormsg:%s,jsonobject.getint(errcode),jsonobject.getstring(errmsg))); return false; } log.info(菜单创建成功！); return true; } // 上传多媒体文件到微信服务器 public static final string upload_media_url = http://file.api.weixin.qq.com/cgi-bin/media/upload?access_token=access_token&type=type; /** * 上传多媒体文件到微信服务器
* @see http://www.oschina.net/code/snippet_1029535_23824 * @see http://mp.weixin.qq.com/wiki/index.php?title=上传下载多媒体文件 * * @author qincd * @date nov 6, 2014 4:11:22 pm */ public static jsonobject uploadmediatowx(string filepath,string type,string accesstoken) throws ioexception{ file file = new file(filepath); if (!file.exists()) { log.error(文件不存在！); return null; } string url = upload_media_url.replace(access_token, accesstoken).replace(type, type); url urlobj = new url(url); httpurlconnection conn = (httpurlconnection) urlobj.openconnection(); conn.setdoinput(true); conn.setdooutput(true); conn.setusecaches(false); conn.setrequestproperty(connection, keep-alive); conn.setrequestproperty(charset, utf-8); // 设置边界 string boundary = ---------- + system.currenttimemillis(); conn.setrequestproperty(content-type, multipart/form-data; boundary= + boundary); // 请求正文信息 // 第一部分： stringbuilder sb = new stringbuilder(); sb.append(--); // ////////必须多两道线 sb.append(boundary); sb.append(\r\n); sb.append(content-disposition: form-data;name=\file\;filename=\ + file.getname() + \\r\n); sb.append(content-type:application/octet-stream\r\n\r\n); byte[] head = sb.tostring().getbytes(utf-8); // 获得输出流 outputstream out = new dataoutputstream(conn.getoutputstream()); out.write(head); // 文件正文部分 datainputstream in = new datainputstream(new fileinputstream(file)); int bytes = 0; byte[] bufferout = new byte[1024]; while ((bytes = in.read(bufferout)) != -1) { out.write(bufferout, 0, bytes); } in.close(); // 结尾部分 byte[] foot = (\r\n-- + boundary + --\r\n).getbytes(utf-8);// 定义最后数据分隔线 out.write(foot); out.flush(); out.close(); /** * 读取服务器响应，必须读取,否则提交不成功 */ try { // 定义bufferedreader输入流来读取url的响应 stringbuffer buffer = new stringbuffer(); bufferedreader reader = new bufferedreader(new inputstreamreader( conn.getinputstream())); string line = null; while ((line = reader.readline()) != null) { buffer.append(line); } reader.close(); conn.disconnect(); return jsonobject.fromobject(buffer.tostring()); } catch (exception e) { log.error(发送post请求出现异常！ + e); e.printstacktrace(); } return null; } public static final string download_media_url = http://file.api.weixin.qq.com/cgi-bin/media/get?access_token=access_token&media_id=media_id; /** * 从微信服务器下载多媒体文件 * * @author qincd * @date nov 6, 2014 4:32:12 pm */ public static string downloadmediafromwx(string accesstoken,string mediaid,string filesavepath) throws ioexception { if (stringutils.isempty(accesstoken) || stringutils.isempty(mediaid)) return null; string requesturl = download_media_url.replace(access_token, accesstoken).replace(media_id, mediaid); url url = new url(requesturl); httpurlconnection conn = (httpurlconnection) url.openconnection(); conn.setrequestmethod(get); conn.setdoinput(true); conn.setdooutput(true); inputstream in = conn.getinputstream(); file dir = new file(filesavepath); if (!dir.exists()) { dir.mkdirs(); } if (!filesavepath.endswith(/)) { filesavepath += /; } string contentdisposition = conn.getheaderfield(content-disposition); string weixinserverfilename = contentdisposition.substring(contentdisposition.indexof(filename)+10, contentdisposition.length() -1); filesavepath += weixinserverfilename; bufferedoutputstream bos = new bufferedoutputstream(new fileoutputstream(filesavepath)); byte[] data = new byte[1024]; int len = -1; while ((len = in.read(data)) != -1) { bos.write(data,0,len); } bos.close(); in.close(); conn.disconnect(); return filesavepath; }}
测试代码：
public class weixinutiltest { /** * * @author qincd * @date nov 6, 2014 9:57:54 am */ public static void main(string[] args) { // 1).获取access_token accesstoken accesstoken = weixinutil.getaccesstoken(weixinutil.appid, weixinutil.app_secret); string filepath = c:\\users\\qince\\pictures\\壁纸20141029091612.jpg; jsonobject uploadjsonobj = testuploadmedia(filepath,image,accesstoken.gettoken()); if (uploadjsonobj == null) { system.out.println(上传图片失败); return; } int errcode = 0; if (uploadjsonobj.containskey(errcode)) { errcode = uploadjsonobj.getint(errcode); } if (errcode == 0) { system.out.println(图片上传成功); string mediaid = uploadjsonobj.getstring(media_id); long createat = uploadjsonobj.getlong(created_at); system.out.println(--details:); system.out.println(media_id: + mediaid); system.out.println(created_at: + createat); } else { system.out.println(图片上传失败！); string errmsg = uploadjsonobj.getstring(errmsg); system.out.println(--details:); system.out.println(errcode: + errcode); system.out.println(errmsg: + errmsg); } string mediaid = 6w-uvsrq2hkdsdvqjjxshwtfdplfbgi1qnbnfy8wezyb9jac2xxxcauwt8p4syph; string filepath = testdownloadmedia(accesstoken.gettoken(), mediaid, d:/test); system.out.println(filepath); } /** * 上传多媒体文件到微信 * * @author qincd * @date nov 6, 2014 4:15:14 pm */ public static jsonobject testuploadmedia(string filepath,string type,string accesstoken) { try { return weixinutil.uploadmediatowx(filepath, type, accesstoken); } catch (ioexception e) { e.printstacktrace(); } return null; } /** * 从微信下载多媒体文件 * * @author qincd * @date nov 6, 2014 4:56:25 pm */ public static string testdownloadmedia(string accesstoken,string mediaid,string filesavedir) { try { return weixinutil.downloadmediafromwx(accesstoken, mediaid, filesavedir); } catch (ioexception e) { e.printstacktrace(); } return null; }}
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