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在安卓系统中实现GCM

javaandroidjsoneclipse
3
我正在实现在Android中使用GCM。我按照“http://hmkcode.com/android-google-cloud-messaging-tutorial/”中的步骤进行操作。 我从android端获得了regId。然后将其输入到Java项目（eclipse）中。在Java项目中，我导入了jackson-all-1.9.0.jar。 在这个Java项目中，我总共有3个java文件。

1）Content.java

import java.io.Serializable;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
public class Content implements Serializable{
    private List<String> registration_ids;
    private Map<String,String> data;

    public void addRegId(String regId){
        if(registration_ids == null)
            registration_ids = new LinkedList<String>();
        registration_ids.add(regId);
    }

    public void createData(String title, String message){
        if(data == null)
            data = new HashMap<String,String>();

        data.put("title", title);
        data.put("message", message);
}
}

2）POST2GCM.java

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;


import org.codehaus.jackson.map.ObjectMapper;


public class POST2GCM {

    public static void post(String apiKey, Content content){

        try{

        // 1. URL
        URL url = new URL("https://android.googleapis.com/gcm/send");

        // 2. Open connection
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();

        // 3. Specify POST method
        conn.setRequestMethod("POST");

        // 4. Set the headers
        conn.setRequestProperty("Content-Type", "application/json");
        conn.setRequestProperty("Authorization", "key="+apiKey);

        conn.setDoOutput(true);

            // 5. Add JSON data into POST request body

            //`5.1 Use Jackson object mapper to convert Contnet object into JSON
            ObjectMapper mapper = new ObjectMapper();

            // 5.2 Get connection output stream
            DataOutputStream wr = new DataOutputStream(conn.getOutputStream());

            // 5.3 Copy Content "JSON" into

            mapper.writeValue(wr, content);

            // 5.4 Send the request
            wr.flush();

            // 5.5 close
            wr.close();

            // 6. Get the response
            int responseCode = conn.getResponseCode();
            System.out.println("\nSending 'POST' request to URL : " + url);
            System.out.println("Response Code : " + responseCode);

            BufferedReader in = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));
            String inputLine;
            StringBuffer response = new StringBuffer();

            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
            in.close();

            // 7. Print result
            System.out.println(response.toString());

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
}

3)App.java

public class App {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println( "Sending POST to GCM" );

        String apiKey = "my api key which i got from //console.developers.google.com";
        Content content = createContent();

        POST2GCM.post(apiKey, content);
    }
     public static Content createContent(){

            Content c = new Content();

            c.addRegId("MyRegKey which i got from android side");
            c.createData("Test Title", "Test Message");

            return c;
        }
}

我收到的错误信息是：
org.codehaus.jackson.map.JsonMappingException: No serializer found for class Content and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS) )
    at org.codehaus.jackson.map.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:52)
    at org.codehaus.jackson.map.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:25)
    at org.codehaus.jackson.map.ser.StdSerializerProvider._serializeValue(StdSerializerProvider.java:610)
    at org.codehaus.jackson.map.ser.StdSerializerProvider.serializeValue(StdSerializerProvider.java:256)
    at org.codehaus.jackson.map.ObjectMapper._configAndWriteValue(ObjectMapper.java:2575)
    at org.codehaus.jackson.map.ObjectMapper.writeValue(ObjectMapper.java:2065)
    at POST2GCM.post(POST2GCM.java:45)
    at App.main(App.java:14)

请问有人能帮我解决这个问题吗？ 我没有找到具体的答案。尝试了以前发过的一些方法，但都没有解决这个问题，这个错误一直存在。 提前谢谢。

2个回答
1

将Content类中的变量registration_ids和data设置为公共变量。

public class Content implements Serializable {
    public List<String> registration_ids;
    public Map<String,String> data;

由于 jackson api 从类或 公共 getter/setter 中读取 公共变量，而在您的情况下变量不是公共的，也没有提供 getter/setter，因此会出现异常。

希望它能起作用。

0
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