java后端发起post请求

在Java后端发起POST请求，可以使用Java内置的HttpURLConnection类或第三方库如Apache HttpClient库。

使用HttpURLConnection类发起POST请求的示例代码如下：

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

public class HttpPostExample {
    public static void main(String[] args) throws Exception {
        String url = "http://example.com/api/create";
        String data = "param1=value1&param2=value2";

        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        // 设置请求方法为POST
        con.setRequestMethod("POST");

        // 设置请求头部信息
        con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

        // 启用输出流，将请求参数写入请求体
        con.setDoOutput(true);
        OutputStream os = con.getOutputStream();
        os.write(data.getBytes());
        os.flush();
        os.close();

        // 获取返回结果
        int responseCode = con.getResponseCode();
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        // 打印返回结果
        System.out.println(response.toString());
    }
}

使用Apache HttpClient库发起POST请求的示例代码如下：

import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.HttpResponse;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class HttpPostExample {
    public static void main(String[] args) throws Exception {
        String url = "http://example.com/api/create";
        String data = "{\"param1\":\"value1\",\"param2\":\"value2\"}";

        CloseableHttpClient client = HttpClientBuilder.create().build();
        HttpPost post = new HttpPost(url);

        // 设置请求头部信息
        post.setHeader("Content-Type", "application/json");

        // 设置请求体
        StringEntity entity = new StringEntity(data);
        post.setEntity(entity);

        // 发送请求
        HttpResponse response = client.execute(post);

        // 获取返回结果
        BufferedReader in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
        String inputLine;
        StringBuffer result = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            result.append(inputLine);
        }
        in.close();

        // 打印返回结果
        System.out.println(result.toString());
    }
}