在 Java 中作为 Rest 调用的一部分获取 JSON 响应
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Getting JSON response as part of Rest call in Java
提问by Umesh K
I am trying to make rest service call in Java. I am new to web and rest service. I have rest service which returns json as response. I have the following code but I think its incomplete because I dont know how to process output using json.
我正在尝试用 Java 进行休息服务调用。我是网络和休息服务的新手。我有休息服务，它返回 json 作为响应。我有以下代码，但我认为它不完整，因为我不知道如何使用 json 处理输出。
public static void main(String[] args) {
try {
URL url = new URL("http://xyz.com:7000/test/db-api/processor");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(false);
connection.setRequestMethod("PUT");
connection.setRequestProperty("Content-Type", "application/json");
OutputStream os = connection.getOutputStream();
//how do I get json object and print it as string
os.flush();
connection.getResponseCode();
connection.disconnect();
} catch(Exception e) {
throw new RuntimeException(e);
}
}
Please help. I am new to rest services and json. Thanks a lot in advance.
请帮忙。我是休息服务和 json 的新手。非常感谢。
采纳答案by SudoRahul
Since this is a PUTrequest you're missing a few things here:
由于这是一个PUT请求，因此您在这里遗漏了一些东西：
OutputStream os = conn.getOutputStream();
os.write(input.getBytes()); // The input you need to pass to the webservice
os.flush();
...
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream()))); // Getting the response from the webservice
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output); // Instead of this, you could append all your response to a StringBuffer and use `toString()` to get the entire JSON response as a String.
// This string json response can be parsed using any json library. Eg. GSON from Google.
}
Have a look at thisto have a more clear idea on hitting webservices.
看看这个，对点击网络服务有一个更清晰的想法。
回答by djs
Since your Content-Type is application/json, you could directly cast the response to a JSON object for example
由于您的 Content-Type 是 application/json，因此您可以直接将响应转换为 JSON 对象，例如
JSONObject recvObj = new JSONObject(response);
回答by Sergey Morozov
Your code is mostly correct, but there is mistake about OutputStream.
As R.J said OutputStreamis needed to pass requestbody to the server.
If your rest service doesn't required any body you don't need to use this one.
您的代码大部分是正确的，但是关于OutputStream. 正如 RJ 所说OutputStream，需要将请求正文传递给服务器。如果您的休息服务不需要任何机构，您就不需要使用这个机构。
For reading the server responseyou need use InputStream(R.J also show you example) like that:
要读取您需要使用的服务器响应InputStream（RJ 也向您展示了示例），如下所示：
try (InputStream inputStream = connection.getInputStream();
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();) {
byte[] buf = new byte[512];
int read = -1;
while ((read = inputStream.read(buf)) > 0) {
byteArrayOutputStream.write(buf, 0, read);
}
System.out.println(new String(byteArrayOutputStream.toByteArray()));
}
This way is good if you don't want to depends on third-part libraries. So I recommend you to take a look on Jersey- very nice library with huge amount of very useful feature.
如果您不想依赖第三方库，这种方式很好。所以我建议你看看Jersey- 非常好的库，有大量非常有用的功能。
Client client = JerseyClientBuilder.newBuilder().build();
Response response = client.target("http://host:port").
path("test").path("db-api").path("processor").path("packages").
request().accept(MediaType.APPLICATION_JSON_TYPE).buildGet().invoke();
System.out.println(response.readEntity(String.class));
回答by Konzern
JsonKey jsonkey = objectMapper.readValue(new URL("http://echo.jsontest.com/key/value/one/two"), JsonKey.class);
System.out.println("jsonkey.getOne() : "+jsonkey.getOne())
