Java 中的 RESTful 调用

我想分享我的个人经验，通过 Post JSON 调用 REST WS:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.URL;
import java.net.URLConnection;


public class HWS {


public static void main(String[] args) throws IOException {
URL url = new URL("INSERT YOUR SERVER REQUEST");
//Insert your JSON query request
String query = "{'PARAM1': 'VALUE','PARAM2': 'VALUE','PARAM3': 'VALUE','PARAM4': 'VALUE'}";
//It change the apostrophe char to double quote char, to form a correct JSON string
query=query.replace("'", "\"");


try{
//make connection
URLConnection urlc = url.openConnection();
//It Content Type is so important to support JSON call
urlc.setRequestProperty("Content-Type", "application/xml");
Msj("Conectando: " + url.toString());
//use post mode
urlc.setDoOutput(true);
urlc.setAllowUserInteraction(false);
    

//send query
PrintStream ps = new PrintStream(urlc.getOutputStream());
ps.print(query);
Msj("Consulta: " + query);
ps.close();
    

//get result
BufferedReader br = new BufferedReader(new InputStreamReader(urlc.getInputStream()));
String l = null;
while ((l=br.readLine())!=null) {
Msj(l);
}
br.close();
} catch (Exception e){
Msj("Error ocurrido");
Msj(e.toString());
}
}
    

private static void Msj(String texto){
System.out.println(texto);
}
}

实际上，这“在 Java 中非常复杂”:

发信人: https://jersey.java.net/documentation/latest/client.html

Client client = ClientBuilder.newClient();
WebTarget target = client.target("http://foo").path("bar");
Invocation.Builder invocationBuilder = target.request(MediaType.TEXT_PLAIN_TYPE);
Response response = invocationBuilder.get();

您可以这样使用 异步 HTTP 客户端(该库也支持 WebSocket协议) :

    String clientChannel = UriBuilder.fromPath("http://localhost:8080/api/{id}").build(id).toString();


try (AsyncHttpClient asyncHttpClient = new AsyncHttpClient())
{
BoundRequestBuilder postRequest = asyncHttpClient.preparePost(clientChannel);
postRequest.setHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON);
postRequest.setBody(message.toString()); // returns JSON
postRequest.execute().get();
}

最简单的解决方案将使用 Apache http 客户端库。 此代码使用基本的安全性进行身份验证。

添加以下依赖项。

<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.4</version>
</dependency>

CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
Credentials credentials = new UsernamePasswordCredentials("username", "password");
credentialsProvider.setCredentials(AuthScope.ANY, credentials);
HttpClient client = HttpClientBuilder.create().setDefaultCredentialsProvider(credentialsProvider).build();
HttpPost request = new HttpPost("https://api.plivo.com/v1/Account/MAYNJ3OT/Message/");HttpResponse response = client.execute(request);
// Get the response
BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
String line = "";
while ((line = rd.readLine()) != null) {
textView = textView + line;
}
System.out.println(textView);

我看到了许多答案，这里是我们在2020年使用的 网络客户端，顺便说一句，RestTemplate将被弃用。(可以检查这个) 将不推荐使用 RestTemplate

下面是一个 GET 请求的示例，它将响应正文打印为 字符串与 请求:

   HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("http://example.org/"))
.build();
client.sendAsync(request, BodyHandlers.ofString())
.thenApply(HttpResponse::body)
.thenAccept(System.out::println)
.join();

如果需要设置头部，可以在 HttpRequest.Builder中使用以下方法:

.setHeader("api-key", "value")

下面是我用来调用一些内部 API 的实用程序类(2022年9月)。除了用于 Json 反序列化的 Gson 之外的所有核心 java。 发送和获取。

package com.somepackagename.utils;


import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.util.HashMap;
import java.util.Map;




public class HTTPCaller {


private final String BEARER_TOKEN;
private static Gson gson = new GsonBuilder().setPrettyPrinting().serializeSpecialFloatingPointValues().create();


public HTTPCaller(String bearerToken) {
this.BEARER_TOKEN = bearerToken;
}


public Map<String, Object> post(String endpoint, String jsonPayload, Map<String, String> headers)
throws IOException, URISyntaxException, InterruptedException {


HttpRequest.Builder reqBuilder = HttpRequest.newBuilder();
if (headers != null) {
for (Map.Entry<String, String> header : headers.entrySet()) {
reqBuilder.header(header.getKey(), header.getValue());
}
}
//always add these anyway, or not
reqBuilder.header("content-type", "application/json")
.header("Authorization", "Bearer " + BEARER_TOKEN);


HttpRequest request = reqBuilder
.uri(new URI(endpoint))
.POST(HttpRequest.BodyPublishers.ofByteArray(jsonPayload.getBytes()))
.build();


HttpResponse<String> response = HttpClient.newBuilder()
.build()
.send(request, java.net.http.HttpResponse.BodyHandlers.ofString());
String responseBody = response.body();
Map<String, Object> output = (Map<String, Object>) gson.fromJson(responseBody, HashMap.class);


return output;


}


public Map<String, Object> get(String endpoint) throws Exception {


HttpRequest.Builder reqBuilder = HttpRequest.newBuilder();


//always add these anyway
reqBuilder.header("content-type", "application/json")
.header("Authorization", "Bearer " + BEARER_TOKEN);


HttpRequest request = reqBuilder
.uri(new URI(endpoint))
.GET()
.build();


HttpResponse<String> response = HttpClient.newBuilder()
.build()
.send(request, java.net.http.HttpResponse.BodyHandlers.ofString());
String responseBody = response.body();
Map<String, Object> output = (Map<String, Object>) gson.fromJson(responseBody, HashMap.class);


return output;


}
}