（8）java代码实现回复image类型的消息

• 按消息的来源，可以将消息分为两种，一种是用户过来的消息（即接受的普通消息），另一种是我的服务器返回给用户的消息（即被动回复消息）。
• 用户发送的普通消息可以是：文本，图片，语音，视频，小视频，地址位置，连接，这7种类型。点击跳转官方文档说明
• 被动回复消息只能是：文本，图片，语音，视频，音乐，图文，这6种类型。点击跳转官方文档说明

下面就重点讲解一下，如何依照官方文档编写被动回复消息的java代码，本文以image消息为例。

图片消息

    xml格式：

    <xml>
    <ToUserName><![CDATA[toUser]]></ToUserName>
    <FromUserName><![CDATA[fromUser]]></FromUserName>
    <CreateTime>12345678</CreateTime>#
    <MsgType><![CDATA[image]]></MsgType>
    <Image>
    <MediaId><![CDATA[media_id]]></MediaId>
    </Image>
    </xml>

    参数说明：

1 如何获取MediaId？

1. 要想获得MediaId，就必须将多媒体文件上传到通过素材管理中的接口地址中。
2. 在官方文档中，素材管理-新增临时素材查看详细说明，点我查看官方说明
   接口url：
   https://api.weixin.qq.com/cgibin/media/upload?access_token=ACCESS_TOKEN&type=TYPE
3. url地址参数说明
   
4. 所以，下面我们就需要获取参数access_token（type我们代码中手动写入，media文件上传的时候会指定）。

2 如何获取access_token？

• 在官方文档中，开始开发-获取access_token，查看详细说明，点我查看官方说明
• 公众号可以使用AppID和AppSecret调用本接口来获取access_token。AppID和AppSecret可在“微信公众平台-开发-基本配置”页中获得（需要已经成为开发者，且帐号没有异常状态）。调用接口时，请登录“微信公众平台-开发-基本配置”提前将服务器IP地址添加到IP白名单中，点击查看设置方法，否则将无法调用成功。
• 
• 

3 如何用代码实现回复image消息？

• 要构建image的xml格式（除了前4个基本元素外，还有个image元素，它内部又包含一个MediaId元素，所以就需要给MediaId传值），就要先获得MediaId，要想获得MediaId，又必须先获得access_token。
• 所以基本思路：
  第一步 获取access_token
  第一步 获取MediaId
  第三步 拼装image的xml格式

    
3.1 获取access_token

• 导入7个jar包

<!-- https://mvnrepository.com/artifact/net.sf.json-lib/json-lib -->
        <dependency>
            <groupId>net.sf.json-lib</groupId>
            <artifactId>json-lib</artifactId>
            <version>2.4</version>
            <classifier>jdk15</classifier>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-beanutils/commons-beanutils -->
        <dependency>
            <groupId>commons-beanutils</groupId>
            <artifactId>commons-beanutils</artifactId>
            <version>1.8.3</version>
        </dependency>
<!-- https://mvnrepository.com/artifact/commons-collections/commons-collections -->
    <dependency>
        <groupId>commons-collections</groupId>
        <artifactId>commons-collections</artifactId>
        <version>3.2.1</version>
    </dependency>
<!-- https://mvnrepository.com/artifact/commons-lang/commons-lang -->
    <dependency>
        <groupId>commons-lang</groupId>
        <artifactId>commons-lang</artifactId>
        <version>2.5</version>
    </dependency>
<!-- https://mvnrepository.com/artifact/commons-logging/commons-logging -->
    <dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging</artifactId>
        <version>1.1.1</version>
    </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpcore -->
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpcore</artifactId>
            <version>4.4.6</version>
</dependency>

• 定义AccessToken对象

public class AccessToken{
        private String access_token;
        private int expires_in;
        public String getAccess_token() {
            return access_token;
        }
        public void setAccess_token(String access_token) {
            this.access_token = access_token;
        }
        public int getExpires_in() {
            return expires_in;
}
        public void setExpires_in(int expires_in) {
            this.expires_in = expires_in;
        }
}

• 定义常量传入需要的值

public final static String APPID="wxb66105e88b4179b6";
    public final static String APPSECRET="e1e872b97cf1591adfa56813f2a87559";
    public final static String AccessTokenUrl="https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=APPID&secret=APPSECRET";

• 定义getAccessToken方法

public static AccessToken getAccessToken(){
        AccessToken token = new AccessToken();
        String url = AccessTokenUrl.replace("APPID", APPID).replaceAll("APPSECRET", APPSECRET);//替换到接口地址中的APPID和APPSECRET
        JSONObject jsonObject = doGet(url);//调用doGet方法发送get请求到url
        System.out.println("微信服务器返回的accessToken数据："+jsonObject);
        if (jsonObject!=null) {
            token.setAccess_token(jsonObject.getString("access_token"));
            token.setExpires_in(jsonObject.getInt("expires_in"));
        }
        return token;
}   

• 定义doGet方法

public static JSONObject doGet(String url){
        JSONObject jsonObject = null;
        CloseableHttpClient httpClient  = HttpClients.createDefault();//替代DefaultHttpClient
        HttpGet httpGet = new HttpGet(url);
        try {
            HttpResponse response = httpClient.execute(httpGet);
            HttpEntity entity = response.getEntity();
            if (entity!=null) {
                String result = EntityUtils.toString(entity);
                jsonObject=JSONObject.fromObject(result);
            }
        } 
        catch (ClientProtocolException e) {
            e.printStackTrace();
        } 
        catch (IOException e) {
            e.printStackTrace();
        }
        return jsonObject;
}

• 测试

@Test
    public void test1() throws Exception{
        AccessToken token = weiXinUtil.getAccessToken();
        System.out.println("票据："+token.getAccess_token());
        System.out.println("accessToken有效时间："+token.getExpires_in());
}

• • 正确输出

微信服务器返回的accessToken数据：{"access_token":"NrnXLx8Q5WWYHKgnswgf_EnM4FulqKj0O59jotaJWZ-6MTFXasE-qwqY_EeHmC1xfY5zzN9waAoNJe0Y6Lz6T31wKThQAk-onBk5NUq1xAVvwewcAisUGwKyQ9JqPM5GSVSfACALOL","expires_in":7200}

• • 如果console输出：

微信服务器返回的accessToken数据：{"errcode":40164,"errmsg":"invalid ip 60.12.8.170, not in whitelist hint: 

添加本机IP（60.12.8.170）到白名单，如下图

• • 如果console输出：

微信服务器返回的accessToken数据：{"errcode":40125,"errmsg":"invalid appsecret, view more at http://t.cn/RAEkdVq hint: [e89qca0917nfo1]"}

说明：工具类weixinUtil中的常量public final static String APPSECRET=””与基本配置中的AppSecret不一致

    
3.2 获取MediaId

微信服务器返回的json数据包：{"type":"TYPE","media_id":"MEDIA_ID","created_at":123456789}

• 素材上传接口地址

public final static String UploadUrl=
"https://api.weixin.qq.com/cgi-bin/media/upload?access_token=ACCESS_TOKEN&type=TYPE";

• 文件上传工具类upload

public static String upload(String filePath,String accessToken,String type) throws IOException{
        File file = new File(filePath);
        if (!file.isFile() || !file.exists()) {
            throw new IOException("文件不存在");
        }
        String url = UploadUrl.replace("ACCESS_TOKEN", accessToken).replaceAll("TYPE", type);
        URL urlObj = new URL(url);

        HttpURLConnection connection = (HttpURLConnection)urlObj.openConnection();
        connection.setRequestMethod("POST");
        connection.setDoInput(true);
        connection.setDoOutput(true);
        connection.setUseCaches(false);

        //设置请求头
        connection.setRequestProperty("Connection", "Keep-Alive");
        connection.setRequestProperty("Charset", "utf-8");

        //设置边界
        String BOUNDARY = "----------"+System.currentTimeMillis();
        connection.setRequestProperty("Content-Type","multipart/form-data;boundary="+BOUNDARY);

        StringBuilder sb = new StringBuilder();
        sb.append("--");
        sb.append(BOUNDARY);
        sb.append("\r\n");
        sb.append("Content-Disposition;form-data;name=\"flie\";filename=\""+file.getName()+"\"\r\n");
        sb.append("Content-Type:application/octet-stream\r\n\r\n"); 
        byte[] head = sb.toString().getBytes("utf-8");

        //获取输出流
        OutputStream out = new DataOutputStream(connection.getOutputStream());
        out.write(head);

        //文件正文部分，把文件以流的方式push到url中
        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");
        out.write(foot);
        out.close();

        StringBuffer buffer = new StringBuffer();
        BufferedReader reader = null;
        String result = null;
        try {
            //读取url响应结果
            reader=new BufferedReader(new InputStreamReader(connection.getInputStream() ));
            String line = null;
            while((line = reader.readLine())!=null){
                buffer.append(line);
            }
            if (result==null) {
                result=buffer.toString();
            }
        } catch (Exception e) {
            // TODO: handle exception
        } finally {
            if (reader!=null) {
                reader.close();
            }
        }
        JSONObject jsonObject = JSONObject.fromObject(result);
        System.out.println(jsonObject);
        String mediaId = jsonObject.getString("media_id");
        return mediaId;
}

• 测试

@Test
public void test2() throws Exception{
    AccessToken token = weiXinUtil.getAccessToken();
    String path = "D:/3.jpg";
    String mediaId = weiXinUtil.upload(path, token.getAccess_token(), "image");
    System.out.println("微信服务器返回的mediaId："+mediaId);
}

微信服务器返回的mediaId：
hcBIDu0UhtNpm3oixqLgpJ8HjbaAgLBbfFq6oJ8aoQW3mDWX90aVpoC4pEiONNw2 

    
3.3 拼装image的xml格式

• 创建Image实体对象

  public class Image {
    private String MediaId;
    public String getMediaId() {
        return MediaId;
    }
    public void setMediaId(String mediaId) {
        MediaId = mediaId;
    }   
}

• 创建imageMessage实体对象

public class baseMessage {
    private String ToUserName;
    private String FromUserName;
    private long CreateTime;
    private String MsgType;
    public String getToUserName() {
        return ToUserName;
    }
    public void setToUserName(String toUserName) {
        ToUserName = toUserName;
    }
    public String getFromUserName() {
        return FromUserName;
    }
    public void setFromUserName(String fromUserName) {
        FromUserName = fromUserName;
    }
    public long getCreateTime() {
        return CreateTime;
    }
    public void setCreateTime(long createTime) {
        CreateTime = createTime;
    }
    public String getMsgType() {
        return MsgType;
    }
    public void setMsgType(String msgType) {
        MsgType = msgType;
    }

}

public class imageMessage extends baseMessage{
    private Image Image;
    public Image getImage() {
        return Image;
    }
    public void setImage(Image image) {
        Image = image;
    }
}

• 创建sendImageMessage方法

public final static String userResp_message_type_image = "image";//常量
public static String sendImageMessage(String toUserName,String fromUserName) throws Exception{
        Image img = new Image();
        String mediaId ="p483hrUP4Zf19H7XRWLKaT-Vt3FTArsj7dQPrWAy_lLbEgGc6DTrLvQT3_iqJ8j3";//复制成功上传文件后返回的media_id
        img.setMediaId(mediaId);//上传多媒体文件到素材管理的接口中，微信服务器会返回mediaId

        imageMessage image = new imageMessage();
        image.setFromUserName(toUserName);
        image.setToUserName(fromUserName);
        image.setCreateTime(new Date().getTime());
        image.setMsgType(messageUtil.userResp_message_type_image);
        image.setImage(img);

        String reponseMessage = messageUtil.imageMessageToXml(image);//利用写好的工具类将text类型消息拼装成微信服务器接受的xml格式
        System.out.println("imgReponseMessage=\n"+reponseMessage);
        return reponseMessage;
    }

• handleRequestUtil的reponseInfo方法处理用户请求（用户发送B，服务器就回复一张图片）

if ("B".equals(map.get("Content").toUpperCase())) {
        reponseMessage = messageUtil.sendImageMessage(toUserName, fromUserName);
    }

• Sevlet执行doPost请求

@Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, {
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        String responseMessage = handleRequestUtil.reponseInfo(request);
//工具类 handleRequestUtil的reponseInfo方法处理用户请求
        PrintWriter out = response.getWriter(); 
        out.print(responseMessage);
        out.close();
    }

• 测试
  

到此为止，被动回复image类型的消息就此结束了。