Java编程实现调用HTTP URL接口并获取返回内容的方法解析

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class Main {
public static void main(String[] args) throws Exception {
String url = "http://example.com/api/resource";

// 创建一个URL对象
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection)obj.openConnection();

// 设置必要的连接属性如方法类型(GET),是否保持链接(true)
con.setRequestMethod("GET");
con.setConnectTimeout(5000); // 连接超时时间（单位毫秒）
con.setRequestProperty("User-Agent", "Mozilla/5.0");

int responseCode = con.getResponseCode();
System.out.println("Response Code : " + responseCode);

if(responseCode == HttpURLConnection.HTTP_OK){
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
StringBuffer content = new StringBuffer();

String inputLine;
while ((inputLine = in.readLine()) != null) {
content.append(inputLine);
}

in.close();

// 输出从服务端获得的信息
System.out.println(content.toString());
} else{
System.err.print("Failed to fetch data from the provided endpoint.");
}

con.disconnect();
}
}

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class OkHttpRequestExample {

OkHttpClient client = new OkHttpClient();

private final MediaType JSON = MediaType.get("application/json; charset=utf-8");

public void run() throws IOException {
Request request = new Request.Builder()
.url("https://jsonplaceholder.typicode.com/todos/1")
.build();

try(Response response = client.newCall(request).execute()){
if (!response.isSuccessful()) throw new RuntimeException("Unexpected code " + response);

// Get Response Body as string and process it.
String responseBody = response.body().string();
System.out.println(responseBody);
}
}
}