使用Java 11+的HttpClient (推荐)#
Java 11引入了新的HttpClient API，位于java.net.http包中：
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import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Duration;
public class Java11HttpClientExample {
// GET请求示例
public static void sendGetRequest() throws Exception {
HttpClient client = HttpClient.newBuilder()
.version(HttpClient.Version.HTTP_2)
.connectTimeout(Duration.ofSeconds(10))
.build();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("https://jsonplaceholder.typicode.com/posts/1"))
.header("User-Agent", "Java 11 HttpClient")
.GET()
.build();
HttpResponse<String> response = client.send(
request, HttpResponse.BodyHandlers.ofString());
System.out.println("GET Response Code :: " + response.statusCode());
System.out.println(response.body());
}
// POST请求示例
public static void sendPostRequest() throws Exception {
HttpClient client = HttpClient.newBuilder()
.version(HttpClient.Version.HTTP_2)
.connectTimeout(Duration.ofSeconds(10))
.build();
String requestBody = "{\"title\": \"foo\", \"body\": \"bar\", \"userId\": 1}";
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("https://jsonplaceholder.typicode.com/posts"))
.header("User-Agent", "Java 11 HttpClient")
.header("Content-Type", "application/json")
.POST(HttpRequest.BodyPublishers.ofString(requestBody))
.build();
HttpResponse<String> response = client.send(
request, HttpResponse.BodyHandlers.ofString());
System.out.println("POST Response Code :: " + response.statusCode());
System.out.println(response.body());
}
public static void main(String[] args) throws Exception {
sendGetRequest();
sendPostRequest();
}
}
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使用Spring的RestTemplate#
需要添加Spring Web依赖：
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<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>2.5.0</version>
</dependency>
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代码：
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import org.springframework.http.*;
import org.springframework.web.client.RestTemplate;
public class RestTemplateExample {
// GET请求示例
public static void sendGetRequest() {
RestTemplate restTemplate = new RestTemplate();
String url = "https://jsonplaceholder.typicode.com/posts/1";
HttpHeaders headers = new HttpHeaders();
headers.set("User-Agent", "RestTemplate");
HttpEntity<String> entity = new HttpEntity<>(headers);
ResponseEntity<String> response = restTemplate.exchange(
url, HttpMethod.GET, entity, String.class);
System.out.println("GET Response Code :: " + response.getStatusCodeValue());
System.out.println(response.getBody());
}
// POST请求示例
public static void sendPostRequest() {
RestTemplate restTemplate = new RestTemplate();
String url = "https://jsonplaceholder.typicode.com/posts";
HttpHeaders headers = new HttpHeaders();
headers.set("User-Agent", "RestTemplate");
headers.setContentType(MediaType.APPLICATION_JSON);
headers.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON));
String requestBody = "{\"title\": \"foo\", \"body\": \"bar\", \"userId\": 1}";
HttpEntity<String> entity = new HttpEntity<>(requestBody, headers);
ResponseEntity<String> response = restTemplate.exchange(
url, HttpMethod.POST, entity, String.class);
System.out.println("POST Response Code :: " + response.getStatusCodeValue());
System.out.println(response.getBody());
}
public static void main(String[] args) {
sendGetRequest();
sendPostRequest();
}
}
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使用OkHttp#
添加需要的依赖：
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<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>4.9.1</version>
</dependency>
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代码示例：
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import okhttp3.*;
import java.io.IOException;
public class OkHttpExample {
// GET请求示例
public static void sendGetRequest() throws IOException {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("https://jsonplaceholder.typicode.com/posts/1")
.addHeader("User-Agent", "OkHttp")
.build();
try (Response response = client.newCall(request).execute()) {
System.out.println("GET Response Code :: " + response.code());
System.out.println(response.body().string());
}
}
// POST请求示例
public static void sendPostRequest() throws IOException {
OkHttpClient client = new OkHttpClient();
MediaType JSON = MediaType.get("application/json; charset=utf-8");
String json = "{\"title\": \"foo\", \"body\": \"bar\", \"userId\": 1}";
RequestBody body = RequestBody.create(json, JSON);
Request request = new Request.Builder()
.url("https://jsonplaceholder.typicode.com/posts")
.addHeader("User-Agent", "OkHttp")
.post(body)
.build();
try (Response response = client.newCall(request).execute()) {
System.out.println("POST Response Code :: " + response.code());
System.out.println(response.body().string());
}
}
public static void main(String[] args) throws IOException {
sendGetRequest();
sendPostRequest();
}
}
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使用Apache HttpClient#
需要添加依赖：
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<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.13</version>
</dependency>
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代码示例：
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import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
public class ApacheHttpClientExample {
// GET请求示例
public static void sendGetRequest() throws Exception {
try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
HttpGet request = new HttpGet("https://jsonplaceholder.typicode.com/posts/1");
// 添加请求头
request.addHeader("User-Agent", "Apache HttpClient");
try (CloseableHttpResponse response = httpClient.execute(request)) {
System.out.println("GET Response Code :: " + response.getStatusLine().getStatusCode());
HttpEntity entity = response.getEntity();
if (entity != null) {
String result = EntityUtils.toString(entity);
System.out.println(result);
}
}
}
}
// POST请求示例
public static void sendPostRequest() throws Exception {
try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
HttpPost request = new HttpPost("https://jsonplaceholder.typicode.com/posts");
// 添加请求头
request.addHeader("User-Agent", "Apache HttpClient");
request.addHeader("Content-Type", "application/json");
request.addHeader("Accept", "application/json");
// 请求体
String json = "{\"title\": \"foo\", \"body\": \"bar\", \"userId\": 1}";
request.setEntity(new StringEntity(json));
try (CloseableHttpResponse response = httpClient.execute(request)) {
System.out.println("POST Response Code :: " + response.getStatusLine().getStatusCode());
HttpEntity entity = response.getEntity();
if (entity != null) {
String result = EntityUtils.toString(entity);
System.out.println(result);
}
}
}
}
public static void main(String[] args) throws Exception {
sendGetRequest();
sendPostRequest();
}
}
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使用Java原生HttpURLConnection#
这是Java标准库提供的HTTP客户端，无需额外依赖。
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import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
public class HttpUrlConnectionExample {
// GET请求示例
public static void sendGetRequest() throws Exception {
String url = "https://jsonplaceholder.typicode.com/posts/1";
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
// 设置请求方法
con.setRequestMethod("GET");
// 添加请求头
con.setRequestProperty("User-Agent", "Mozilla/5.0");
int responseCode = con.getResponseCode();
System.out.println("GET Response Code :: " + responseCode);
if (responseCode == HttpURLConnection.HTTP_OK) { // 成功
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
System.out.println(response.toString());
} else {
System.out.println("GET request not worked");
}
}
// POST请求示例
public static void sendPostRequest() throws Exception {
String url = "https://jsonplaceholder.typicode.com/posts";
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
// 设置请求方法
con.setRequestMethod("POST");
con.setRequestProperty("User-Agent", "Mozilla/5.0");
con.setRequestProperty("Content-Type", "application/json; utf-8");
con.setRequestProperty("Accept", "application/json");
// 启用输出流
con.setDoOutput(true);
// 请求体
String jsonInputString = "{\"title\": \"foo\", \"body\": \"bar\", \"userId\": 1}";
try(OutputStream os = con.getOutputStream()) {
byte[] input = jsonInputString.getBytes(StandardCharsets.UTF_8);
os.write(input, 0, input.length);
}
int responseCode = con.getResponseCode();
System.out.println("POST Response Code :: " + responseCode);
if (responseCode == HttpURLConnection.HTTP_CREATED) { // 成功
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
System.out.println(response.toString());
} else {
System.out.println("POST request not worked");
}
}
public static void main(String[] args) throws Exception {
sendGetRequest();
sendPostRequest();
}
}
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