java 发起post请求

在Java中，发起POST请求通常有两种常见的方式：使用基础的Java API `java.net.HttpURLConnection`，或者使用第三方库如Apache HttpClient或OkHttp。以下是使用`HttpURLConnection`的基本示例：

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

public class PostRequest {
    private static final String URL = "http://example.com/api"; // 替换为你实际的URL
    private static final String PARAMS = "key1=value1&key2=value2"; // 示例参数

    public void doPost() throws Exception {
        URL url = new URL(URL);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

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

        // 添加请求头，告诉服务器这是个JSON请求
        connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

        // 打开连接并获取输入流
        OutputStream os = connection.getOutputStream();
        os.write(PARAMS.getBytes()); // 写入参数

        // 提交请求并关闭输入流
        os.flush();
        os.close();

        // 获取响应码
        int responseCode = connection.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            System.out.println("POST request successful");
            // 读取并处理响应内容
            byte[] responseData = readResponse(connection.getInputStream());
            // 省略了响应数据的解析部分...
        } else {
            throw new RuntimeException("POST request failed with response code: " + responseCode);
        }

        // 关闭连接
        connection.disconnect();
    }

    // 辅助函数用于从InputStream读取字节数组
    private byte[] readResponse(InputStream in) throws Exception {
        byte[] buffer = new byte[1024];
        int length = 0;
        byte[] data = new byte[length];
        while ((length = in.read(buffer)) != -1) {
            data = Arrays.copyOf(data, length + data.length);
            System.arraycopy(buffer, 0, data, length, buffer.length);
        }
        return data;
    }
}

如果你想使用更现代、功能丰富的库，如OkHttp，可以参考其文档来创建异步或线程安全的POST请求。