java 发送 http 请求练习两年半（HttpURLConnection） - IT评测·应用市场-qidao123.com

@GetMapping("/http/get")
public ResponseEntity<String> testHttpGet(@RequestParam("param") String param) {
System.out.println(param);
return ResponseEntity.ok("---------> revive http get request --------->");
}
@PostMapping("/http/post")
public ResponseEntity<String> testHttpPost(@RequestBody List<Object> body) {
System.out.println(body);
return ResponseEntity.ok("---------> receive http post request --------->");
}

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import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.Map;
public class MyHttpClient {
private final HttpURLConnection connection;
private MyHttpClient(String url, Map<String, String> params) throws IOException {
connection = buildConnection(url, params);
}
private MyHttpClient(String url, Map<String, String> params, String jsonBody) throws IOException {
connection = buildConnection(url, params);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/json;charset=utf-8");
connection.setDoOutput(true);
try (DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream())) {
outputStream.writeBytes(jsonBody);
outputStream.flush();
}
}
public static MyHttpClient get(String url, Map<String, String> params) throws IOException {
return new MyHttpClient(url, params);
}
public static MyHttpClient post(String url, Map<String, String> params, String jsonBody) throws IOException {
return new MyHttpClient(url, params, jsonBody);
}
/**
* 创建 http 连接
*
* @param url 请求路径
* @param params 请求参数，可以为空
* @return http 连接
*/
private HttpURLConnection buildConnection(String url, Map<String, String> params) throws IOException {
String requestParams = getParamsString(params);
return (HttpURLConnection) new URL(requestParams != null ? url + "?" + requestParams : url).openConnection();
}
/**
* 获取 http 请求响应结果
*
* @return 响应结果，失败抛异常
*/
public String getResponse() throws IOException {
int responseCode = connection.getResponseCode();
if (responseCode >= HttpURLConnection.HTTP_OK && responseCode < HttpURLConnection.HTTP_MULT_CHOICE) {
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
connection.disconnect();
return response.toString();
} else {
connection.disconnect();
InputStream errorStream = connection.getErrorStream();
if (errorStream == null) {
throw new ConnectException("request fail");
}
throw new ConnectException(new String(errorStream.readAllBytes(), StandardCharsets.UTF_8));
}
}
/**
* 拼接请求参数
*
* @param params 参数 map
* @return 请求参数字符串
*/
public static String getParamsString(Map<String, String> params) {
if (params == null || params.isEmpty()) {
return null;
}
StringBuilder result = new StringBuilder();
for (Map.Entry<String, String> entry : params.entrySet()) {
result.append(URLEncoder.encode(entry.getKey(), StandardCharsets.UTF_8));
result.append("=");
result.append(URLEncoder.encode(entry.getValue(), StandardCharsets.UTF_8));
result.append("&");
}
String resultString = result.toString();
return resultString.length() > 0
? resultString.substring(0, resultString.length() - 1)
: resultString;
}
}

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public static void main(String[] args) throws IOException {
MyHttpClient myHttpClient = MyHttpClient.get("http://127.0.0.1:8083/springboot/http/get",
Map.of("param", "1"));
String resultGet = myHttpClient.getResponse();
System.out.println(resultGet);
MyHttpClient httpClient = MyHttpClient.post("http://127.0.0.1:8083/springboot/http/post",
null,
"[1,2,3,4,5]");
String resultPost = httpClient.getResponse();
System.out.println(resultPost);
}

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---------> revive http get request --------->
---------> receive http post request --------->
Process finished with exit code 0

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