How to send Request payload to REST API in java?

问题

I want to retrieve the JSON data from the following: https://git.eclipse.org/r/#/c/11376/

Request URL: https://git.eclipse.org/r/gerrit/rpc/ChangeDetailService

Request Method: POST

Request Headers:

Accept:application/json

Content-Type:application/json; charset=UTF-8

Request Payload:

{\"jsonrpc\":\"2.0\",\"method\":\"changeDetail\",\"params\":[{\"id\":11376}],\"id\":1}

I already tried this answer but I am getting 400 BAD REQUEST.

Can anyone help me sort this out?

Thanks.

回答1:

The following code works for me.

//escape the double quotes in json string
String payload="{\"jsonrpc\":\"2.0\",\"method\":\"changeDetail\",\"params\":[{\"id\":11376}],\"id\":2}";
String requestUrl="https://git.eclipse.org/r/gerrit/rpc/ChangeDetailService";
sendPostRequest(requestUrl, payload);

method implementation:

public static String sendPostRequest(String requestUrl, String payload) {
    try {
        URL url = new URL(requestUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        connection.setDoInput(true);
        connection.setDoOutput(true);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Accept", "application/json");
        connection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
        OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
        writer.write(payload);
        writer.close();
        BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        StringBuffer jsonString = new StringBuffer();
        String line;
        while ((line = br.readLine()) != null) {
                jsonString.append(line);
        }
        br.close();
        connection.disconnect();
        return jsonString.toString();
    } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
    }

}

回答2:

I tried with a rest client.

Headers :

• POST /r/gerrit/rpc/ChangeDetailService HTTP/1.1
• Host: git.eclipse.org
• User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:18.0) Gecko/20100101 Firefox/18.0
• Accept: application/json
• Accept-Language: null
• Accept-Encoding: gzip,deflate,sdch
• accept-charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
• Content-Type: application/json; charset=UTF-8
• Content-Length: 73
• Connection: keep-alive

it works fine. I retrieve 200 OK with a good body.

Why do you set a status code in your request? and multiple declaration "Accept" with Accept:application/json,application/json,application/jsonrequest. just a statement is enough.

来源：https://stackoverflow.com/questions/15570656/how-to-send-request-payload-to-rest-api-in-java