httpclient使用post提交表单参数

要使用HttpClient进行POST请求并提交表单参数，您需要按照以下步骤进行操作：
1. 创建一个HttpClient实例：
```java
CloseableHttpClient httpClient = HttpClientBuilder.create().build();
```
2. 创建一个HttpPost请求实例，并设置URL：
```java
HttpPost httpPost = new HttpPost("http://example.com/api/endpoint");
```
3. 创建一个List对象，用于存储表单参数：
```java
List params = new ArrayList<>();
params.add(new BasicNameValuePair("param1", "value1"));
params.add(new BasicNameValuePair("param2", "value2"));
```
4. 将参数设置为请求实体的一部分：
```java
httpPost.setEntity(new UrlEncodedFORMEntity(params));
```
5. 发送请求并获取响应：
```java
CloseableHttpResponse response = httpClient.execute(httpPost);
```
6. 处理响应结果：
```java
HttpEntity entity = response.getEntity();
if (entity != null) {
String responseContent = EntityUtils.toString(entity);
System.out.println(responseContent);
}
```
7. 关闭HttpClient和响应：
```java
response.close();
httpClient.close();
```
完整的示例代码如下：
```java
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import java.io.IOException;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;
public class HttpClientExample {
public static void main(String[] args) {
try {
CloseableHttpClient httpClient = HttpClientBuilder.create().build();
HttpPost httpPost = new HttpPost("http://example.com/api/endpoint");
List params = new ArrayList<>();
params.add(new BasicNameValuePair("param1", "value1"));
params.add(new BasicNameValuePair("param2", "value2"));
httpPost.setEntity(new UrlEncodedFormEntity(params));
CloseableHttpResponse response = httpClient.execute(httpPost);
HttpEntity entity = response.getEntity();
if (entity != null) {
String responseContent = EntityUtils.toString(entity);
System.out.println(responseContent);
}
response.close();
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
```
请注意，上述示例中使用了Apache HttpClient 4.5版本的库。您需要确保在您的项目中引入了相关的依赖包。