为什么我收到 HTTP 400 错误请求

Question

我正在使用 HTTP 客户端（从 http://www.mkyong.com/java/apache-httpclient-examples/) to send post requests. I have been trying to use it with http://postcodes.io to look up a bulk of postcodes but failed. According to http://postcodes.io I should send a post request to http://api.postcodes.io/postcodes 复制的代码采用以下 JSON 形式：{"postcodes" : ["OX49 5NU", "M32 0JG", "NE30 1DP"]} 但我总是收到 HTTP 响应代码 400。我在下面包含了我的代码。请告诉我我做错了什么？谢谢

private void sendPost() throws Exception {

    String url = "http://api.postcodes.io/postcodes";
    HttpClient client = HttpClientBuilder.create().build();
    HttpPost post = new HttpPost(url);

    List<NameValuePair> urlParameters = new ArrayList<NameValuePair>();
    urlParameters.add(new BasicNameValuePair("postcodes", "[\"OX49 5NU\", \"M32 0JG\", \"NE30 1DP\"]"));
    post.setEntity(new UrlEncodedFormEntity(urlParameters));
    HttpResponse response = client.execute(post);

    System.out.println("Response Code : " 
                + response.getStatusLine().getStatusCode());
    System.out.println("Reason : " 
            + response.getStatusLine().getReasonPhrase());
    BufferedReader br = new BufferedReader(
            new InputStreamReader(response.getEntity().getContent()));
    StringBuffer result = new StringBuffer();
    String line = "";
    while ((line = br.readLine()) != null) {
        result.append(line);
    }
    br.close();
    System.out.println(result.toString());
}

Answer 1

Jon Skeet 是对的（像往常一样，我可能会补充），您基本上是在发送一个表单，它默认为表单-url-编码。你可以尝试这样的事情：

String jsonString = "{\"postcodes\" : [\"OX49 5NU\", \"M32 0JG\", \"NE30 1DP\"]}";
StringEntity entity = new StringEntity(jsonObj.toString(), HTTP.UTF_8);
entity.setContentType("application/json");
post.setEntity(entity);

Answer 2

有效，HTTP。UTF_8 已弃用：

String url = "http://api.postcodes.io/postcodes";
HttpClient client = HttpClientBuilder.create().build();
HttpPost post = new HttpPost(url);

StringEntity params =new StringEntity("{\"postcodes\" : [\"OX49 5NU\", \"M32 0JG\", \"NE30 1DP\"]}");
post.addHeader("Content-Type", "application/json");
post.setEntity(params);

为什么我收到 HTTP 400 错误请求

Why am I getting HTTP 400 bad request

java

post

httpclient