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Java如何實(shí)現(xiàn)調(diào)用外部Api

更新時(shí)間：2024年05月13日 10:28:01 作者：韓一聰

這篇文章主要介紹了Java如何實(shí)現(xiàn)調(diào)用外部Api問(wèn)題,具有很好的參考價(jià)值,希望對(duì)大家有所幫助,如有錯(cuò)誤或未考慮完全的地方,望不吝賜教

Java調(diào)用外部Api

在日常開(kāi)發(fā)的時(shí)候，經(jīng)常會(huì)遇到需要調(diào)用別人的接口的場(chǎng)景。但是每次需要的時(shí)候，都需要百度，很麻煩，所以這里總結(jié)一下，經(jīng)常調(diào)用的方法。

1.含有文件的post請(qǐng)求

	public static String requestOCRForHttp(String url, Map<String, String> requestParams, String filePathAndName)
			throws Exception {
		String result = null;
		CloseableHttpClient httpClient = HttpClients.createDefault();
		/** HttpPost */
		HttpPost httpPost = new HttpPost(url);
		MultipartEntity reqEntity = new MultipartEntity(); // 建立多文件實(shí)例
		FileBody filebody = new FileBody(new File(filePathAndName));
		reqEntity.addPart("pic", filebody);// upload為請(qǐng)求后臺(tái)的File upload;
		for (String key : requestParams.keySet()) {
			String value = requestParams.get(key);
			reqEntity.addPart(key, new StringBody(value, Charset.forName("utf-8")));
		}
		httpPost.setEntity(reqEntity); // 設(shè)置實(shí)體
		/** HttpResponse */
		CloseableHttpResponse httpResponse = httpClient.execute(httpPost);
		try {
			HttpEntity httpEntity = httpResponse.getEntity();
			result = EntityUtils.toString(httpEntity, "utf-8");
			EntityUtils.consume(httpEntity);
		} finally {
			try {
				if (httpResponse != null) {
					httpResponse.close();
				}
			} catch (IOException e) {
				logger.info("## release resouce error ##" + e);
			}
		}
		return result;
	}

2.單純的Json

	public static String sendHttpPost(String url, String JSONBody) throws Exception {
		CloseableHttpClient httpClient = HttpClients.createDefault();
		HttpPost httpPost = new HttpPost(url);
		httpPost.addHeader("Content-Type", "application/json");
		httpPost.setEntity(new StringEntity(JSONBody));
		CloseableHttpResponse response = httpClient.execute(httpPost);
//		System.out.println(response.getStatusLine().getStatusCode() + "\n");
		HttpEntity entity = response.getEntity();
		String responseContent = EntityUtils.toString(entity, "UTF-8"); 
//		System.out.println(responseContent);
		response.close();
		httpClient.close();
		return responseContent;
	}

3.String參數(shù)

	public static String requestOCRForHttp(String url, Map<String, String> requestParams) throws Exception {
		String result = null;
		CloseableHttpClient httpClient = HttpClients.createDefault();
		/** HttpPost */
		HttpPost httpPost = new HttpPost(url);
		List<NameValuePair> params = new ArrayList<NameValuePair>();
		Iterator<Entry<String, String>> it = requestParams.entrySet().iterator();
//		System.out.println(params.toString());
		while (it.hasNext()) {
			Entry<String, String> en = it.next();
			String key = en.getKey();
			String value = en.getValue();
			if (value != null) {
				params.add(new BasicNameValuePair(key, value));
			}
		}
		httpPost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));
		/** HttpResponse */
		CloseableHttpResponse httpResponse = httpClient.execute(httpPost);
		try {
			HttpEntity httpEntity = httpResponse.getEntity();
			result = EntityUtils.toString(httpEntity, "utf-8");
			EntityUtils.consume(httpEntity);
		} finally {
			try {
				if (httpResponse != null) {
					httpResponse.close();
				}
			} catch (IOException e) {
				logger.info("## release resouce error ##" + e);
			}
		}
		return result;
	}

Java對(duì)接外部API這個(gè)問(wèn)題

有一個(gè)小學(xué)妹來(lái)問(wèn)我可以將我其他項(xiàng)目的api接入到我現(xiàn)在的項(xiàng)目中嗎？我回答“可以”！

需求提出

那么拿到一個(gè)需求首先話(huà)不多說(shuō)先分析這個(gè)需求的整體思路！需求上面大概有介紹，這里我更深入化的說(shuō)明一下。

對(duì)接外部api接口就是說(shuō)我在A項(xiàng)目寫(xiě)了一個(gè)接口時(shí)我的B項(xiàng)目需要到A這個(gè)接口的數(shù)據(jù)，那么在A項(xiàng)目上線(xiàn)的基礎(chǔ)上使用B項(xiàng)目去調(diào)用A項(xiàng)目的這個(gè)所需的接口，如下圖：

其實(shí)對(duì)接外部api就是這么一個(gè)過(guò)程，當(dāng)然我們拿到外部數(shù)據(jù)后面的操作都是由自己去自由發(fā)揮了，比如將讀取到的數(shù)據(jù)來(lái)顯示在這個(gè)項(xiàng)目中去給前端顯示?；蛘叽嫒霐?shù)據(jù)庫(kù)等等。

解決思路

上面已經(jīng)理解了調(diào)用的的思路，有了思路就好解決，現(xiàn)在很多的外部api接口可以給開(kāi)發(fā)時(shí)帶來(lái)便利，當(dāng)然，調(diào)用的方式可能也會(huì)有稍些不同，比如手機(jī)號(hào)查詢(xún)歸屬地、郵箱等等。

像這種的一般都是有官方文檔可以給我們，很方便。

但是我們?nèi)フ{(diào)用自己的api又不是在一個(gè)項(xiàng)目中的那就要想想怎么實(shí)現(xiàn)了。

話(huà)不多說(shuō)我就拿我之前寫(xiě)了一個(gè)DEMO中的數(shù)據(jù)吧，剛好項(xiàng)目還在線(xiàn)上。

編碼

package edu.controller;

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.aliyun.oss.HttpMethod;
import edu.entity.EventVo;
import org.springframework.http.ResponseEntity;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @Author Fujii
 * @Date 2021-10-11 23:12
 * @Version SpringBoot 2.2.2
 * @projectName 調(diào)用外部api接口
 */
@RestController
public class BackEndApiDemo {

    @GetMapping("apiList")
    public Map<String,Object> getByApiList(){
        //這里先創(chuàng)建一個(gè)map用于返回api格式
        Map<String,Object> mapList = new HashMap<>();
        //1.我們是要去調(diào)用外部api，那么肯定要有一個(gè)外部api的地址,這里我是拿我的DEMO作為數(shù)據(jù)傳輸
        String apiURL = "這里直接放入你的api接口即可，我的api就不展示了，請(qǐng)諒解!";
        //2.這里有幾種方式，你們?nèi)ピ嚵诉^(guò)后會(huì)發(fā)現(xiàn)不只有GET，這里因?yàn)槲覀兪侨カ@取數(shù)據(jù)，所以是用GET
        HttpMethod method = HttpMethod.GET;
        //用于接口返回的JSONObject（）
        LinkedMultiValueMap map = new LinkedMultiValueMap();
        //json接收數(shù)據(jù)
        JSONObject  urlMethod = client(apiURL,method,map);
        JSONObject jsonObject = JSONObject.parseObject(urlMethod.toJSONString());
        JSONArray object = JSONObject.parseArray(jsonObject.get("data").toString());
        if (jsonObject!=null){
            List<EventVo> list = JSONArray.parseArray(object.toJSONString(), EventVo.class);
            mapList.put("list",list);
            mapList.put("code",200);
            mapList.put("msg", "獲取成功!");

        }else{
            mapList.put("code",500);
            mapList.put("msg", "獲取失敗!");
            return mapList;
        }
        return mapList;
    }
    
    //注意：因?yàn)槭菧y(cè)試，所有我所有內(nèi)容全部寫(xiě)在一個(gè)文件內(nèi)方便展示清晰，正規(guī)寫(xiě)法應(yīng)寫(xiě)在服務(wù)層
    private JSONObject client(String url, HttpMethod method, LinkedMultiValueMap params) {
        RestTemplate template = new RestTemplate();
        ResponseEntity<JSONObject> response = template.getForEntity(url, JSONObject.class);
        return response.getBody();
    }
}