1. 引入httpclient依赖
首先，需要确认项目中是否已引入过httpclient依赖，如果没有引入过，需要在pom.xml中添加以下代码引入httpclient依赖：
<dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpclient</artifactId><version>4.5.13</version>
</dependency>
2. 发送GET请求
2.1 发送GET请求(无参数)
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.nio.charset.StandardCharsets;public class HttpClientUtils {public static String doGet() throws IOException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpGet httpGet = new HttpGet("https://www.example.com/getDataList");try (CloseableHttpResponse httpResponse = httpClient.execute(httpGet)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
2.2 发送GET请求(带参数)
第一种方法是直接在url上拼接上参数，如下所示：
HttpGet httpGet = new HttpGet("https://www.example.com/getDataList?pageIndex=1&pageSize=20");
第二种方法是使用URIBuilder添加参数，如下所示：
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.net.URISyntaxException;
import java.nio.charset.StandardCharsets;public class HttpClientUtils {public static String doGet() throws IOException, URISyntaxException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {URIBuilder uriBuilder = new URIBuilder("https://www.example.com/getDataList");uriBuilder.addParameter("pageIndex", "1");uriBuilder.addParameter("pageSize", "20");HttpGet httpGet = new HttpGet(uriBuilder.build());try (CloseableHttpResponse httpResponse = httpClient.execute(httpGet)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
3. 发送POST请求
3.1 发送POST请求(无参数)
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.nio.charset.StandardCharsets;public class HttpClientUtils {public static String doPost() throws IOException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpPost httpPost = new HttpPost("https://www.example.com/updateData");try (CloseableHttpResponse httpResponse = httpClient.execute(httpPost)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
3.2 发送POST请求(带参数、form表单方式)
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;public class HttpClientUtils {public static String doPost() throws IOException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpPost httpPost = new HttpPost("https://www.example.com/updateData");List<NameValuePair> params = new ArrayList<>();params.add(new BasicNameValuePair("id", "1"));params.add(new BasicNameValuePair("name", "新名字"));UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(params, StandardCharsets.UTF_8);httpPost.setEntity(formEntity);try (CloseableHttpResponse httpResponse = httpClient.execute(httpPost)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
3.3 发送POST请求(带参数、json方式)
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.nio.charset.StandardCharsets;public class HttpClientUtils {public static String doPost() throws IOException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpPost httpPost = new HttpPost("https://www.example.com/updateData");String jsonBody = "{\"id\":\"1\",\"name\":新名字}";StringEntity stringEntity = new StringEntity(jsonBody);stringEntity.setContentType("application/json;charset=utf-8");httpPost.setEntity(stringEntity);try (CloseableHttpResponse httpResponse = httpClient.execute(httpPost)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
4. 发送PUT请求
4.1 发送PUT请求(无参数)
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.nio.charset.StandardCharsets;public class HttpClientUtils {public static String doPut() throws IOException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpPut httpPut = new HttpPut("https://www.example.com/updateData");try (CloseableHttpResponse httpResponse = httpClient.execute(httpPut)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
4.2 发送PUT请求(带参数、form表单方式)
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;public class HttpClientUtils {public static String doPut() throws IOException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpPut httpPut = new HttpPut("https://www.example.com/updateData");List<NameValuePair> params = new ArrayList<>();params.add(new BasicNameValuePair("id", "1"));params.add(new BasicNameValuePair("name", "新名字"));UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(params, StandardCharsets.UTF_8);httpPut.setEntity(formEntity);try (CloseableHttpResponse httpResponse = httpClient.execute(httpPut)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
4.3 发送PUT请求(带参数、json方式)
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.nio.charset.StandardCharsets;public class HttpClientUtils {public static String doPut() throws IOException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpPut httpPut = new HttpPut("https://www.example.com/updateData");String jsonBody = "{\"id\":\"1\",\"name\":新名字}";StringEntity stringEntity = new StringEntity(jsonBody);stringEntity.setContentType("application/json;charset=utf-8");httpPut.setEntity(stringEntity);try (CloseableHttpResponse httpResponse = httpClient.execute(httpPut)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
5. 发送DELETE请求
5.1 发送DELETE请求(无参数)
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.nio.charset.StandardCharsets;public class HttpClientUtils {public static String doDelete() throws IOException {try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpDelete httpDelete = new HttpDelete("https://www.example.com/updateData");try (CloseableHttpResponse httpResponse = httpClient.execute(httpDelete)) {if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {return EntityUtils.toString(httpResponse.getEntity(), StandardCharsets.UTF_8);}return null;}}}
}
6. 添加请求头
一般情况下，请求第三方接口都需要签名、时间戳等请求头，以POST请求为例，添加请求头的代码如下所示：
httpPost.setHeader("Content-Type", "application/json;charset=utf-8");
httpPost.setHeader("signature", "3045022100875efcef9eb54626bb0168a6baa7c61265d0001d49243f");
httpPost.setHeader("timestamp", String.valueOf(System.currentTimeMillis()));
GET请求、PUT请求、DELETE请求添加请求头的方法同上。
7. 超时时间设置
如果需要自定义HTTP请求的连接超时时间和数据传输超时时间，代码如下所示（以POST请求为例）：
RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(5000).setSocketTimeout(10000).build();
httpPost.setConfig(requestConfig);
GET请求、PUT请求、DELETE请求设置超时时间的方法同上。
8.工具类封装
完整的工具类代码如下所示：
import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.client.utils.URIBuilder;
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;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.net.URISyntaxException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;public class HttpClientUtils {/*** 连接建立超时时间(单位:毫秒)*/private static final int CONNECT_TIMEOUT = 5000;/*** 数据传输超时时间(单位:毫秒)*/private static final int SOCKET_TIMEOUT = 10000;/*** 执行GET请求** @param url 请求地址* @param headers 请求头* @return 响应内容字符串*/public static String doGet(String url, Map<String, String> headers) throws IOException {HttpGet httpGet = new HttpGet(url);// 设置请求头setHeaders(httpGet, headers);return executeRequest(httpGet);}/*** 执行GET请求** @param url 请求地址* @param headers 请求头* @param params 请求参数* @return 响应内容字符串*/public static String doGet(String url, Map<String, String> headers, Map<String, String> params) throws IOException, URISyntaxException {URIBuilder uriBuilder = new URIBuilder(url);// 设置请求参数if (params != null && !params.isEmpty()) {for (Map.Entry<String, String> entry : params.entrySet()) {uriBuilder.setParameter(entry.getKey(), entry.getValue());}}HttpGet httpGet = new HttpGet(uriBuilder.build());// 设置请求头setHeaders(httpGet, headers);return executeRequest(httpGet);}/*** 执行POST请求(表单方式)** @param url 请求地址* @return 响应内容字符串*/public static String doPost(String url) throws IOException {return doPost(url, null, null);}/*** 执行POST请求(表单方式)** @param url 请求地址* @param headers 请求头* @return 响应内容字符串*/public static String doPost(String url, Map<String, String> headers) throws IOException {return doPost(url, headers, null);}/*** 执行POST请求(表单方式)** @param url 请求地址* @param headers 请求头* @param params 请求参数* @return 响应内容字符串*/public static String doPost(String url, Map<String, String> headers, Map<String, String> params) throws IOException {HttpPost httpPost = new HttpPost(url);// 设置请求头setHeaders(httpPost, headers);// 构建表单参数if (params != null) {List<NameValuePair> paramList = new ArrayList<>();for (Map.Entry<String, String> entry : params.entrySet()) {paramList.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));}httpPost.setEntity(new UrlEncodedFormEntity(paramList, StandardCharsets.UTF_8));}return executeRequest(httpPost);}/*** 执行POST请求(JSON格式)** @param url 请求地址* @param headers 请求头* @return 响应内容字符串*/public static String doPostJson(String url, Map<String, String> headers) throws IOException {return doPostJson(url, headers, null);}/*** 执行POST请求(JSON格式)** @param url 请求地址* @param headers 请求头* @param jsonBody JSON请求体字符串* @return 响应内容字符串*/public static String doPostJson(String url, Map<String, String> headers, String jsonBody) throws IOException {HttpPost httpPost = new HttpPost(url);// 添加JSON请求头addJsonHeader(httpPost, headers);// 添加自定义请求头setHeaders(httpPost, headers);// 设置JSON请求体if (jsonBody != null) {StringEntity entity = new StringEntity(jsonBody,ContentType.APPLICATION_JSON.withCharset(StandardCharsets.UTF_8));httpPost.setEntity(entity);}return executeRequest(httpPost);}/*** 执行PUT请求(JSON格式)** @param url 请求地址* @param headers 请求头* @param jsonBody JSON请求体字符串* @return 响应内容字符串*/public static String doPut(String url, Map<String, String> headers, String jsonBody) throws IOException {HttpPut httpPut = new HttpPut(url);// 添加JSON请求头addJsonHeader(httpPut, headers);// 添加自定义请求头setHeaders(httpPut, headers);// 设置JSON请求体if (jsonBody != null) {StringEntity entity = new StringEntity(jsonBody,ContentType.APPLICATION_JSON.withCharset(StandardCharsets.UTF_8));httpPut.setEntity(entity);}return executeRequest(httpPut);}/*** 执行DELETE请求** @param url 请求地址* @param headers 请求头* @return 响应内容字符串*/public static String doDelete(String url, Map<String, String> headers) throws IOException {HttpDelete httpDelete = new HttpDelete(url);// 设置请求头setHeaders(httpDelete, headers);return executeRequest(httpDelete);}/*** 创建带超时配置的HttpClient** @return HttpClient实例*/private static CloseableHttpClient createHttpClient() {RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(CONNECT_TIMEOUT).setSocketTimeout(SOCKET_TIMEOUT).build();return HttpClients.custom().setDefaultRequestConfig(requestConfig).build();}/*** 添加JSON请求头** @param httpRequest HTTP请求对象* @param headers 请求头*/private static void addJsonHeader(HttpRequestBase httpRequest, Map<String, String> headers) {if (headers == null || !headers.containsKey("Content-Type")) {httpRequest.addHeader("Content-Type", "application/json;charset=utf-8");}}/*** 设置请求头** @param httpRequest HTTP请求对象* @param headers 请求头*/private static void setHeaders(HttpRequestBase httpRequest, Map<String, String> headers) {if (headers == null || headers.isEmpty()) {return;}for (Map.Entry<String, String> entry : headers.entrySet()) {httpRequest.setHeader(entry.getKey(), entry.getValue());}}/*** 统一执行请求并处理响应** @param httpRequest HTTP请求对象* @return 响应内容字符串*/private static String executeRequest(HttpRequestBase httpRequest) throws IOException {try (CloseableHttpClient httpClient = createHttpClient()) {try (CloseableHttpResponse response = httpClient.execute(httpRequest)) {return handleResponse(response);}}}/*** 处理响应结果** @param response HTTP响应对象* @return 响应内容字符串*/private static String handleResponse(CloseableHttpResponse response) throws IOException {int statusCode = response.getStatusLine().getStatusCode();if (statusCode != HttpStatus.SC_OK) {throw new RuntimeException("HTTP请求失败，状态码：" + statusCode);}HttpEntity entity = response.getEntity();if (entity != null) {return EntityUtils.toString(entity, StandardCharsets.UTF_8);}return null;}
}
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