1. 概述
在实际开发过程中，我们经常需要调用对方提供的接口或测试自己写的接口是否合适。很多项目都会封装规定好本身项目的接口规范，所以大多数需要去调用对方提供的接口或第三方接口（短信、天气等）。
在Java项目中调用第三方接口的方式有：
①通过JDK网络类Java.net.HttpURLConnection；
②通过common封装好的HttpClient；
③通过Apache封装好的CloseableHttpClient；
④通过SpringBoot-RestTemplate；
2.?Java调用第三方http接口的方式
2.1?通过JDK网络类Java.net.HttpURLConnection
?比较原始的一种调用做法，这里把get请求和post请求都统一放在一个方法里面，直接上代码：
import java.io.*;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
/**
* @Author: Yang JianQiu
* @Date: 2019/4/26 11:34
* jdk类HttpURLConnection调用第三方http接口
*
* 通常分get和post两种方式
*
* 参考资料：
* http://www.cnblogs.com/angusbao/p/7727649.html
*/
public class HttpUrlConnectionToInterface {
/**
* 以post或get方式调用对方接口方法，
* @param pathUrl
*/
public static void doPostOrGet(String pathUrl, String data){
OutputStreamWriter out = null;
BufferedReader br = null;
String result = "";
try {
URL url = new URL(pathUrl);
//打开和url之间的连接
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
//请求方式
conn.setRequestMethod("POST");
//conn.setRequestMethod("GET");
//设置通用的请求属性
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
conn.setRequestProperty("Content-Type", "application/json;charset=utf-8");
//DoOutput设置是否向httpUrlConnection输出，DoInput设置是否从httpUrlConnection读入，此外发送post请求必须设置这两个
conn.setDoOutput(true);
conn.setDoInput(true);
/**
* 下面的三句代码，就是调用第三方http接口
*/
//获取URLConnection对象对应的输出流
out = new OutputStreamWriter(conn.getOutputStream(), "UTF-8");
//发送请求参数即数据
out.write(data);
//flush输出流的缓冲
out.flush();
/**
* 下面的代码相当于，获取调用第三方http接口后返回的结果
*/
//获取URLConnection对象对应的输入流
InputStream is = conn.getInputStream();
//构造一个字符流缓存
br = new BufferedReader(new InputStreamReader(is));
String str = "";
while ((str = br.readLine()) != null){
result += str;
}
System.out.println(result);
//关闭流
is.close();
//断开连接，disconnect是在底层tcp socket链接空闲时才切断，如果正在被其他线程使用就不切断。
conn.disconnect();
} catch (Exception e) {
e.printStackTrace();
}finally {
try {
if (out != null){
out.close();
}
if (br != null){
br.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
/**
*手机信息查询接口：http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=手机号
* http://api.showji.com/Locating/www.showji.com.aspx?m=手机号&output=json&callback=querycallback
*/
doPostOrGet("https://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", "");
}
}
2.2?通过apache common封装好的HttpClient
httpClient的get或post请求方式步骤：
- 生成一个HttpClient对象并设置相应的参数；
- 生成一个GetMethod对象或PostMethod并设置响应的参数；
- 用HttpClient生成的对象来执行GetMethod生成的Get方法；
- 处理响应状态码；
- 若响应正常，处理HTTP响应内容；
- 释放连接。
导入如下jar包：
<!--HttpClient-->
<dependency>
<groupId>commons-httpclient</groupId>
<artifactId>commons-httpclient</artifactId>
<version>3.1</version>
</dependency>
代码如下：
import com.alibaba.fastjson.JSONObject;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;
import java.io.IOException;
import java.io.InputStream;
/**
* @Author: Yang JianQiu
* @Date: 2019/4/28 11:07
*
* HttpClient模拟get、post请求并发送请求参数（json等）
* 【参考资料】
* https://javasam.iteye.com/blog/2117845
* https://blog.csdn.net/qq_28379809/article/details/82898792
*/
public class HttpClientToInterface {
/**
* httpClient的get请求方式
* 使用GetMethod来访问一个URL对应的网页实现步骤：
* 1.生成一个HttpClient对象并设置相应的参数；
* 2.生成一个GetMethod对象并设置响应的参数；
* 3.用HttpClient生成的对象来执行GetMethod生成的Get方法；
* 4.处理响应状态码；
* 5.若响应正常，处理HTTP响应内容；
* 6.释放连接。
* @param url
* @param charset
* @return
*/
public static String doGet(String url, String charset){
/**
* 1.生成HttpClient对象并设置参数
*/
HttpClient httpClient = new HttpClient();
//设置Http连接超时为5秒
httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(5000);
/**
* 2.生成GetMethod对象并设置参数
*/
GetMethod getMethod = new GetMethod(url);
//设置get请求超时为5秒
getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 5000);
//设置请求重试处理，用的是默认的重试处理：请求三次
getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler());
String response = "";
/**
* 3.执行HTTP GET 请求
*/
try {
int statusCode = httpClient.executeMethod(getMethod);
/**
* 4.判断访问的状态码
*/
if (statusCode != HttpStatus.SC_OK){
System.err.println("请求出错：" + getMethod.getStatusLine());
}
/**
* 5.处理HTTP响应内容
*/
//HTTP响应头部信息，这里简单打印
Header[] headers = getMethod.getResponseHeaders();
for (Header h: headers){
System.out.println(h.getName() + "---------------" + h.getValue());
}
//读取HTTP响应内容，这里简单打印网页内容
//读取为字节数组
byte[] responseBody = getMethod.getResponseBody();
response = new String(responseBody, charset);
System.out.println("-----------response:" + response);
//读取为InputStream，在网页内容数据量大时候推荐使用
//InputStream response = getMethod.getResponseBodyAsStream();
} catch (HttpException e) {
//发生致命的异常，可能是协议不对或者返回的内容有问题
System.out.println("请检查输入的URL!");
e.printStackTrace();
} catch (IOException e){
//发生网络异常
System.out.println("发生网络异常!");
}finally {
/**
* 6.释放连接
*/
getMethod.releaseConnection();
}
return response;
}
/**
* post请求
* @param url
* @param json
* @return
*/
public static String doPost(String url, JSONObject json){
HttpClient httpClient = new HttpClient();
PostMethod postMethod = new PostMethod(url);
postMethod.addRequestHeader("accept", "*/*");
postMethod.addRequestHeader("connection", "Keep-Alive");
//设置json格式传送
postMethod.addRequestHeader("Content-Type", "application/json;charset=utf-8");
//必须设置下面这个Header
postMethod.addRequestHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");
//添加请求参数
postMethod.addParameter("commentId", json.getString("commentId"));
String res = "";
try {
int code = httpClient.executeMethod(postMethod);
if (code == 200){
res = postMethod.getResponseBodyAsString();
System.out.println(res);
}
} catch (IOException e) {
e.printStackTrace();
}
return res;
}
public static void main(String[] args) {
doGet("http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", "UTF-8");
System.out.println("-----------分割线------------");
System.out.println("-----------分割线------------");
System.out.println("-----------分割线------------");
JSONObject jsonObject = new JSONObject();
jsonObject.put("commentId", "13026194071");
doPost("http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", jsonObject);
}
}
2.3 通过Apache封装好的CloseableHttpClient
?CloseableHttpClient是在HttpClient的基础上修改更新而来的，这里还涉及到请求头token的设置（请求验证），利用fastjson转换请求或返回结果字符串为json格式，当然上面两种方式也是可以设置请求头token、json的，这里只在下面说明。
导入如下jar包：
<!--CloseableHttpClient-->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.2</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.28</version>
</dependency>
代码如下：
import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.HttpGet;
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.HttpClientBuilder;
import org.apache.http.util.EntityUtils;
import java.io.IOException;
/**
* @Author: Yang JianQiu
* @Date: 2019/4/26 11:41
* Apache封装好的CloseableHttpClient
* 【参考资料】
* https://www.cnblogs.com/siv8/p/6222709.html
* https://blog.csdn.net/qq_35860138/article/details/82967727
*/
public class CloseableHttpClientToInterface {
private static String tokenString = "";
private static String AUTH_TOKEN_EXPIRED = "AUTH_TOKEN_EXPIRED";
private static CloseableHttpClient httpClient = null;
/**
* 以get方式调用第三方接口
* @param url
* @return
*/
public static String doGet(String url, String token){
//创建HttpClient对象
CloseableHttpClient httpClient = HttpClientBuilder.create().build();
HttpGet get = new HttpGet(url);
try {
if (tokenString != null && !tokenString.equals("")){
tokenString = getToken();
}
//api_gateway_auth_token自定义header头，用于token验证使用
get.addHeader("api_gateway_auth_token", tokenString);
get.addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");
HttpResponse response = httpClient.execute(get);
if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
//返回json格式
String res = EntityUtils.toString(response.getEntity());
return res;
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
/**
* 以post方式调用第三方接口
* @param url
* @param json
* @return
*/
public static String doPost(String url, JSONObject json){
try {
if (httpClient == null){
httpClient = HttpClientBuilder.create().build();
}
HttpPost post = new HttpPost(url);
if (tokenString != null && !tokenString.equals("")){
tokenString = getToken();
}
//api_gateway_auth_token自定义header头，用于token验证使用
post.addHeader("api_gateway_auth_token", tokenString);
post.addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");
StringEntity s = new StringEntity(json.toString());
s.setContentEncoding("UTF-8");
//发送json数据需要设置contentType
s.setContentType("application/x-www-form-urlencoded");
//设置请求参数
post.setEntity(s);
HttpResponse response = httpClient.execute(post);
if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
//返回json格式
String res = EntityUtils.toString(response.getEntity());
return res;
}
} catch (Exception e) {
e.printStackTrace();
}finally {
if (httpClient != null){
try {
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
/**
* 获取第三方接口的token
*/
public static String getToken(){
String token = "";
JSONObject object = new JSONObject();
object.put("appid", "appid");
object.put("secretkey", "secretkey");
try {
if (httpClient == null){
httpClient = HttpClientBuilder.create().build();
}
HttpPost post = new HttpPost("http://localhost/login");
post.addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");
StringEntity s = new StringEntity(object.toString());
s.setContentEncoding("UTF-8");
//发送json数据需要设置contentType
s.setContentType("application/x-www-form-urlencoded");
//设置请求参数
post.setEntity(s);
HttpResponse response = httpClient.execute(post);
//这里可以把返回的结果按照自定义的返回数据结果，把string转换成自定义类
//ResultTokenBO result = JSONObject.parseObject(response, ResultTokenBO.class);
//把response转为jsonObject
JSONObject result = JSONObject.parseObject(response);
if (result.containsKey("token")){
token = result.getString("token");
}
} catch (Exception e) {
e.printStackTrace();
}
return token;
}
/**
* 测试
*/
public static void test(String telephone){
JSONObject object = new JSONObject();
object.put("telephone", telephone);
try {
//首先获取token
tokenString = getToken();
String response = doPost("http://localhost/searchUrl", object);
//如果返回的结果是list形式的，需要使用JSONObject.parseArray转换
//List<Result> list = JSONObject.parseArray(response, Result.class);
System.out.println(response);
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
test("12345678910");
}
}
2.4 通过SpringBoot-RestTemplate
?springBoot-RestTemple是上面三种方式的集大成者，代码编写更加简单，目前可以采用的调用第三方接口有：
- delete() 在特定的URL上对资源执行HTTP DELETE操作
- exchange()?在URL上执行特定的HTTP方法，返回包含对象的ResponseEntity，这个对象是从响应体中映射得到的
- execute() 在URL上执行特定的HTTP方法，返回一个从响应体映射得到的对象
- getForEntity()?发送一个HTTP GET请求，返回的ResponseEntity包含了响应体所映射成的对象
- getForObject()?发送一个HTTP GET请求，返回的请求体将映射为一个对象
- postForEntity()?POST 数据到一个URL，返回包含一个对象的ResponseEntity，这个对象是从响应体中映射得到的
- postForObject()?POST 数据到一个URL，返回根据响应体匹配形成的对象
- headForHeaders() 发送HTTP HEAD请求，返回包含特定资源URL的HTTP头
- optionsForAllow() 发送HTTP OPTIONS请求，返回对特定URL的Allow头信息
- postForLocation() POST 数据到一个URL，返回新创建资源的URL
- put() PUT 资源到特定的URL
注意：目前标红的为常用的
首先导入springboot的web包
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.4.RELEASE</version>
</parent>
<dependencies>
<!--CloseableHttpClient-->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.2</version>
</dependency>
<!--spring restTemplate-->
<!-- @ConfigurationProperties annotation processing (metadata for IDEs)
生成spring-configuration-metadata.json类，需要引入此类-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jetty</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
在启动类同包下创建RestTemplateConfig.java类
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;
/**
* @Author: Yang JianQiu
* @Date: 2019/4/28 14:01
*/
@Configuration
public class RestTemplateConfig {
@Bean
public RestTemplate restTemplate(ClientHttpRequestFactory factory){
return new RestTemplate(factory);
}
@Bean
public ClientHttpRequestFactory simpleClientHttpRequestFactory(){
SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
factory.setConnectTimeout(15000);
factory.setReadTimeout(5000);
return factory;
}
}
然后在Service类（RestTemplateToInterface?）中注入使用
具体代码如下：
import com.alibaba.fastjson.JSONObject;
import com.swordfall.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.*;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
/**
* @Author: Yang JianQiu
* @Date: 2019/4/28 14:13
*
* 【参考资料】
* https://blog.csdn.net/qq_15452971/article/details/79416469
* https://blog.csdn.net/weixin_40461281/article/details/83540604
*/
@Service
public class RestTemplateToInterface {
@Autowired
private RestTemplate restTemplate;
/**
* 以get方式请求第三方http接口 getForEntity
* @param url
* @return
*/
public User doGetWith1(String url){
ResponseEntity<User> responseEntity = restTemplate.getForEntity(url, User.class);
User user = responseEntity.getBody();
return user;
}
/**
* 以get方式请求第三方http接口 getForObject
* 返回值返回的是响应体，省去了我们再去getBody()
* @param url
* @return
*/
public User doGetWith2(String url){
User user = restTemplate.getForObject(url, User.class);
return user;
}
/**
* 以post方式请求第三方http接口 postForEntity
* @param url
* @return
*/
public String doPostWith1(String url){
User user = new User("小白", 20);
ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, user, String.class);
String body = responseEntity.getBody();
return body;
}
/**
* 以post方式请求第三方http接口 postForEntity
* @param url
* @return
*/
public String doPostWith2(String url){
User user = new User("小白", 20);
String body = restTemplate.postForObject(url, user, String.class);
return body;
}
/**
* exchange
* @return
*/
public String doExchange(String url, Integer age, String name){
//header参数
HttpHeaders headers = new HttpHeaders();
String token = "asdfaf2322";
headers.add("authorization", token);
headers.setContentType(MediaType.APPLICATION_JSON);
//放入body中的json参数
JSONObject obj = new JSONObject();
obj.put("age", age);
obj.put("name", name);
//组装
HttpEntity<JSONObject> request = new HttpEntity<>(obj, headers);
ResponseEntity<String> responseEntity = restTemplate.exchange(url, HttpMethod.POST, request, String.class);
String body = responseEntity.getBody();
return body;
}
}
总结
【github地址】
https://github.com/SwordfallYeung/JavaInvokingHttpInterface.git
【参考资料】
java如何调用对方http接口(II) - 流年煮雪 - 博客园?纯Java?api?HttpURLConnection
Java调用外部接口_天空海的眼·的博客-CSDN博客_java调用外部接口?纯Java?api?HttpURLConnection
java代码调用第三方接口 - 雪菇 - 博客园?封装api HttpClient
httpClient4.5 closeableHttpClient用法 - 就这个名字好 - 博客园
Java调用第三方接口示范_inner_peace8的博客-CSDN博客_java调用第三方接口?封装api HttpClient
SpringBoot-RestTemplate实现调用第三方API_David在学习的博客-CSDN博客_springboot调用第三方api?SpringBoot-RestTemplate
