HttpClient使用方法总结及工具类封装

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;
    }
}