java httppost 传输base64字符串

可以使用 Apache HttpComponents 库发送 POST 请求，并将 Base64 字符串作为请求体的一部分进行传输。以下是使用该库的示例代码：

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import org.apache.commons.codec.binary.Base64;
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class HttpPostBase64Example {

    public static void main(String[] args) throws IOException {
        String url = "http://example.com/endpoint";
        String base64String = "VGVzdCBzdHJpbmc=";
        String requestBody = "{ \"data\": \"" + base64String + "\" }";

        HttpPost httpPost = new HttpPost(url);
        httpPost.setEntity(new StringEntity(requestBody, ContentType.APPLICATION_JSON));

        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = httpClient.execute(httpPost);

        HttpEntity responseEntity = response.getEntity();
        String responseBody = responseEntity != null ? EntityUtils.toString(responseEntity, StandardCharsets.UTF_8) : "";

        System.out.println("Response status code: " + response.getStatusLine().getStatusCode());
        System.out.println("Response body: " + responseBody);

        response.close();
        httpClient.close();
    }
}

在上述代码中，首先定义了一个字符串 `base64String`，它是待传输的 Base64 字符串。然后，将该字符串添加到请求体中，生成一个 JSON 格式的请求体。接着，创建一个 HttpPost 实例，并将请求体设置为该实例的实体。最后，执行该 POST 请求并处理响应。

需要注意的是，在使用该库时，需要添加以下依赖项：

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>
<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.15</version>
</dependency>