问题描述
我正在努力实施GCM。我写了一个测试代码来了解它是如何工作的，但是我在响应中一直收到错误400.
我正在用Java编写（JDK 7） 。
我遵循 toturial的主题。
我在那里修改了给定的代码，并将ObjectMapper的使用改为Gson。
这是我的Data对象的代码：
public class Data {
private ArrayList< String> registration_ids;
public Data（）{
this.registration_ids = new ArrayList< String>（）;
this.registration_ids.add（APA91 ...）; //这里有真实的设备注册ID。
}
}
*我在，在HTTP协议中，我可以使用registration_ids发送消息。 （所有其他都是可选的）
以下是发送消息的代码：
b
$ b // public static void post（String apiKey，Data data）{
// // 1. URL
URL url = new URL（ https://android.googleapis.com/gcm/send）;
// 2.打开连接
HttpURLConnection conn =（HttpURLConnection）url.openConnection（）;
// 3.指定POST方法
conn.setRequestMethod（POST）;
// 4.设置头文件
conn.setRequestProperty（Content-Type，application / json）;
conn.setRequestProperty（Authorization，key =+ apiKey）;
conn.setDoOutput（true）;
// 5.将JSON数据添加到POST请求体中
// 5.1将对象转换为JSON
Gson gson = new Gson（）;
Type type = new TypeToken< Data>（）{} .getType（）;
字符串json = gson.toJson（data，type）;
System.out.println（json）;
//打印的字符串是
// {registration_ids：[APA91 ...]}
//带有我的设备的正确注册ID。
// 5.2获取连接输出流
DataOutputStream wr = new DataOutputStream（conn.getOutputStream（））;
// 5.3将内容JSON复制到
wr.writeUTF（json）;
// 5.4发送请求
wr.flush（）;
// 5.5关闭
wr.close（）;
//获取响应
int responseCode = conn.getResponseCode（）;
System.out.println（\\\
发送'POST'请求到URL：+ url）;
System.out.println（Response Code：+ responseCode）;
BufferedReader in = new BufferedReader（
new InputStreamReader（conn.getInputStream（）））;
String inputLine;
StringBuffer response = new StringBuffer（）; （（inputLine = in.readLine（））！= null）{
response.append（inputLine）;
}
in.close（）;
// 7.打印结果
System.out.println（response.toString（））;
catch（MalformedURLException e）{
e.printStackTrace（）;
} catch（IOException e）{
e.printStackTrace（）;
}
}
我知道错误400意味着json问题，但我为我发送的数据尝试了很多变化，并且它们都没有工作（我在这些测试中手动创建了字符串，没有gson）。
这是错误消息我收到：
你能帮我解决这个问题吗？
非常感谢，
Yuval。
问题出在DataOutputStream.writeChars（）和DataOutputStream.writeUTF（）。
感谢，我将post函数中的write命令更改为：
wr.write（json.getBytes（UTF- 8\" ））;
现在邮件已成功发送！
I am tring to implement GCM.I wrote a test code to understand how it works, but I keep getting error 400 in the response.
I'm writing in Java (JDK 7).
I followed this toturial on the subject.I modified the given code there, and changed the use of ObjectMapper to Gson.
This is my code for the Data object:
public class Data {
private ArrayList<String> registration_ids;
public Data() {
this.registration_ids = new ArrayList<String>();
this.registration_ids.add("APA91..."); // There is the real device registration id here.
}
}
*I saw in the server reference that in HTTP protocol, I can send a message just with registration_ids. (All other are optional)
Here is the code to send the message:
public static void post(String apiKey, Data data){
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 Convert object to JSON
Gson gson = new Gson();
Type type = new TypeToken<Data>() {}.getType();
String json = gson.toJson(data, type);
System.out.println(json);
// The printed string is
// {"registration_ids":["APA91..."]}
// with the correct registration id of my device.
// 5.2 Get connection output stream
DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
// 5.3 Copy Content "JSON" into
wr.writeUTF(json);
// 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();
}
}
I know that error 400 means a json problem, but I tried many variations for the data I'm sending, and none of them worked (I created the string manually, without gson, in these tests).
This is the error message I'm receiving:
Can you please help me with this issue?Thank you very much,Yuval.
The problem was in DataOutputStream.writeChars() and DataOutputStream.writeUTF().
Thanks to the link given by @Koh, I changed the write command in the post function to:
wr.write(json.getBytes("UTF-8"));
Now the message is being sent successfully!
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