SpringBoot 整合 HttpClient，后端调用远程接口

SpringBoot 整合 HttpClient

添加 HttpClient 依赖

在 SpringBoot 项目中的 pom.xml 文件中添加 HttpClient 的起步依赖：

<!-- HttpClient 起步依赖 -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
</dependency>

HttpClient 发送 GET 请求

先尝试通过 HttpClient 发送 GET 请求：

@RestController
public class HttpClientController {

    @GetMapping("/testGet")
    public String httpClientTestGet() throws IOException {
        String result = "";
        // 要请求的远程连接（此为我本地另开的一个服务，即：http://localhost:8082/queryUser）
        String url = "http://172.20.10.2:8082/queryUser";

        // 创建httpclient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        // 创建GET方式请求对象
        HttpGet httpGet = new HttpGet(url);

        // 设置请求头信息
        // httpGet.setHeader("Cookie", "JSESSIONID=xxxxxxx");

        // 执行请求操作，并拿到结果（同步阻塞）
        CloseableHttpResponse response = httpClient.execute(httpGet);

        // 获取结果实体
        // 判断网络连接状态码是否正常(0--200都数正常)
        if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
            result = EntityUtils.toString(response.getEntity(), "utf-8");
        }
        // 释放链接
        response.close();

        return result;
    }
}

通过访问：http://localhost:8080/testGet 测试该远程 GET 请求是否成功。

HttpClient 发送 POST 请求

@GetMapping("/testPost")
public String httpClientTestPost() throws IOException {
    String result = "";
    // json数据：{"username": "testPost","password": "1234","realname": "post 测试"}
    String json="{\"username\": \"testPost\",\"password\": \"1234\",\"realname\": \"post 测试\"}";
    // 若传入的是个对象，可使用 fastjson 工具包将其转为json字符串

    // 要请求的远程连接
    String url = "http://172.20.10.2:8088/addUser";

    // 创建httpclient对象
    CloseableHttpClient httpClient = HttpClients.createDefault();

    // 创建post方式请求对象
    HttpPost httpPost = new HttpPost(url);

    // 设置参数到请求对象中，这里内容类型设为json
    StringEntity stringEntity = new StringEntity(json, ContentType.APPLICATION_JSON);
    stringEntity.setContentEncoding("utf-8");
    httpPost.setEntity(stringEntity);

    // 执行请求操作，并拿到结果（同步阻塞）
    CloseableHttpResponse response = httpClient.execute(httpPost);

    // 获取结果实体
    // 判断网络连接状态码是否正常(0--200都属正常)
    if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
        result = EntityUtils.toString(response.getEntity(), "utf-8");
    }
    System.out.println(response.getStatusLine().getStatusCode());
    // 释放链接
    response.close();

    return result;
}

通过访问：http://localhost:8080/testGet 测试该远程 POST 请求是否成功。

查询数据库，添加成功。

PUT 和 DELETE 同理可以这样进行请求，不一一赘述。

下面将这常用的四个请求方法整合为一个工具类，以使得大部分的请求都能直接调用工具类中的方法实现。

整合 HttpClient 请求方法

编写 CommonMethod.java 工具类，该类为静态类，可直接通过类名调用里面的方法。

package com.rk.utils;

import org.apache.http.HttpStatus;
import org.apache.http.client.methods.*;
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.util.EntityUtils;

import java.io.IOException;

public class CommonMethod {

    // GET 请求
    public static String commonGet(String url) throws IOException {
        String result = "";

        CloseableHttpClient httpClient = HttpClients.createDefault();

        HttpGet httpGet = new HttpGet(url);

        CloseableHttpResponse response = httpClient.execute(httpGet);

        if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
            result = EntityUtils.toString(response.getEntity(), "utf-8");
        }

        return result;
    }

    // POST 请求
    public static String commonPost(String url, String json) throws IOException {
        String result = "";

        CloseableHttpClient httpClient = HttpClients.createDefault();

        HttpPost httpPost = new HttpPost(url);

        StringEntity stringEntity = new StringEntity(json, ContentType.APPLICATION_JSON);
        stringEntity.setContentEncoding("utf-8");

        httpPost.setEntity(stringEntity);

        CloseableHttpResponse response = httpClient.execute(httpPost);

        if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
            result = EntityUtils.toString(response.getEntity(), "utf-8");
        }

        return result;
    }

    // PUT 请求
    public static String commonPut(String url, String json) throws IOException {
        String result = "";

        CloseableHttpClient httpClient = HttpClients.createDefault();

        HttpPut httpPut = new HttpPut(url);

        StringEntity stringEntity = new StringEntity(json, ContentType.APPLICATION_JSON);
        stringEntity.setContentEncoding("utf-8");

        httpPut.setEntity(stringEntity);

        CloseableHttpResponse response = httpClient.execute(httpPut);

        if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
            result = EntityUtils.toString(response.getEntity(), "utf-8");
        }

        return result;
    }

    // DELETE 请求
    public static String commonDelete(String url) throws IOException {
        String result = "";

        CloseableHttpClient httpClient = HttpClients.createDefault();

        HttpDelete httpDelete = new HttpDelete(url);

        CloseableHttpResponse response = httpClient.execute(httpDelete);

        if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
            result = EntityUtils.toString(response.getEntity(), "utf-8");
        }

        return result;
    }

}

该工具类的调用：

// 调用 GET
CommonMethod.commonGet(url);
// 调用 POST
CommonMethod.commonPost(url, json);
// 调用 PUT
CommonMethod.commonPut(url, json);
// 调用 DELETE
CommonMethod.commonDelete(url);

常用的请求是 GET、POTS、PUT 和 DELETE 这四个请求方法。其中 GET 和 DELETE 一般只需要传入请求路径 url 就可完成调用，简单的 POST 和 PUT 方法也只需传入 url 和 body 数据就可调用成功。

这是学习工作中整理的，有参考网上别人的教程。只是简单的远程调用接口，复杂的可以设置请求头参数，POST 的时候传入 Map 或者 form 表单数据等。这些我暂时用不到，暂不深究。