在日常工作中，经常需要跟第三方系统对接，我们做为客户端，调用他们的接口进行业务处理，常用的几种调用方式有：
1.原生的Java.net.HttpURLConnection（jdk）；
2.再次封装的HttpClient、CloseableHttpClient（Apache）；
3.Spring提供的RestTemplate；
当然还有其他工具类进行封装的接口，比如hutool的HttpUtil工具类，里面除了post、get请求外，还有下载文件的方法downloadFile等。
HttpURLConnection调用方法
HTTP正文的内容是通过OutputStream流写入,向流中写入的数据不会立即发送到网络,而是存在于内存缓冲区中,待流关闭时，根据写入的内容生成HTTP正文。
调用getInputStream()方法时,会返回一个输入流,用于从中读取服务器对于HTTP请求的返回报文
@Slf4j
public class HttpURLConnectionUtil {
/**
*
* Description: 发送http请求发送post和json格式
* @param url 请求URL
* @param params json格式的请求参数
*/
public static String doPost(String url, String params) throws Exception {
OutputStreamWriter out = null;
BufferedReader reader = null;
StringBuffer response = new StringBuffer();
URL httpUrl = null; // HTTP URL类 用这个类来创建连接
try {
// 创建URL
httpUrl = new URL(url);
log.info("--------发起Http Post 请求 ------------- url:" + url + "---------params:" + params);
// 建立连接
HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection();
//设置请求的方法为"POST"，默认是GET
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("connection", "keep-alive");
conn.setUseCaches(false);// 设置不要缓存
conn.setInstanceFollowRedirects(true);
//由于URLConnection在默认的情况下不允许输出，所以在请求输出流之前必须调用setDoOutput(true)
conn.setDoOutput(true);
// 设置是否从httpUrlConnection读入
conn.setDoInput(true);
//设置超时时间
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
conn.connect();
// POST请求
out = new OutputStreamWriter(conn.getOutputStream());
out.write(params);
out.flush();
// 读取响应
reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), "utf-8"));
String lines;
while ((lines = reader.readLine()) != null) {
response.append(lines);
}
reader.close();
// 断开连接
conn.disconnect();
} catch (Exception e) {
log.error("--------发起Http Post 请求 异常 {}-------------", e);
throw new Exception(e);
}
// 使用finally块来关闭输出流、输入流
finally {
try {
if (out != null) {
out.close();
}
if (reader != null) {
reader.close();
}
} catch (IOException ex) {
log.error(String.valueOf(ex));
}
}
return response.toString();
}
}
CloseableHttpClient调用
CloseableHttpClient 是一个抽象类，实现了httpClient接口，也实现了java.io.Closeable;
支持连接池管理，可复用已建立的连接 PoolingHttpClientConnectionManager
通过 httpClient.close() 自动管理连接释放
支持HTTPS访问 HttpHost proxy = new HttpHost(“127.0.0.1”, 8080, “http”);文章来源：https://www.toymoban.com/news/detail-861048.html
@Slf4j
public class CloseableHttpClientUtil {
/**
*url 第三方接口地址
*json 传入的报文体，可以是dto对象，string、json等
*header 额外传入的请求头参数
*/
public static String doPost(String url, Object json,Map<String,String> header) {
CloseableHttpClient httpclient = HttpClientBuilder.create().build();
HttpPost httpPost= new HttpPost(url);//post请求类型
String result="";//返回结果
String requestJson="";//发送报文体
try {
requestJson=JSONObject.toJSONString(json);
log.info("发送地址："+url+"发送报文："+requestJson);
//StringEntity s = new StringEntity(requestJson, Charset.forName("UTF-8"));
StringEntity s= new StringEntity(requestJson, "UTF-8");
// post请求是将参数放在请求体里面传过去的;这里将entity放入post请求体中
httpPost.setHeader("Content-Type", "application/json;charset=utf8");
httpPost.setEntity(s);
if(header!=null){
Set<String> strings = header.keySet();
for(String str:strings){
httpPost.setHeader(str,header.get(str));
}
}
HttpResponse res = httpclient.execute(httpPost);
if (res.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
result = EntityUtils.toString(res.getEntity());
//也可以把返回的报文转成json类型
// JSONObject response = JSONObject.parseObject(result);
}
} catch (Exception e) {
throw new RuntimeException(e);
}
finally {
//此处可以加入记录日志的方法
// 关闭连接,释放资源
if (httpclient!= null){
try {
httpclient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return result;
}
}
RestTemplate调用
//可以在项目启动类中添加RestTemplate 的bean,后续就可以在代码中@Autowired引入。文章来源地址https://www.toymoban.com/news/detail-861048.html
@Bean
public RestTemplate restTemplate() {
return new RestTemplate();
}
@Slf4j
@Component
public class RestTemplateUtils {
@Autowired
private RestTemplate restTemplate;
/**
* get 请求 参数在url后面 http://xxxx?aa=xxx&page=0&size=10";
* @param urls
* @return string
*/
public String doGetRequest(String urls) {
URI uri = UriComponentsBuilder.fromUriString(urls).build().toUri();
log.info("请求接口:{}", urls);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> httpEntity = new HttpEntity<>(headers);
//通用的方法exchange,这个方法需要你在调用的时候去指定请求类型，可以是get,post,也能是其它类型的请求
ResponseEntity<String> responseEntity = restTemplate.exchange(uri, HttpMethod.GET, httpEntity, String.class);
if (responseEntity == null) {
return null;
}
log.info("返回报文:{}", JSON.toJSONString(responseEntity));
return responseEntity.getBody();
}
/**
* post 请求 参数在 request里;
* @param url, request
* @return string
*/
public String doPostRequest(String url, Object request){
URI uri = UriComponentsBuilder.fromUriString(url).build().toUri();
String requestStr= JSONObject.toJSONString(request);
log.info("请求接口:{}, 请求报文:{}", url, requestStr);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> httpEntity = new HttpEntity<>(requestStr, headers);
ResponseEntity<String> responseEntity = restTemplate.exchange(uri, HttpMethod.POST, httpEntity, String.class);
if (responseEntity == null) {
return null;
}
String seqResult = "";
try {
if(responseEntity.getBody() != null ) {
if(responseEntity.getBody().contains("9001")) {
seqResult = new String(responseEntity.getBody().getBytes("ISO8859-1"),"utf-8");
}else {
seqResult = new String(responseEntity.getBody().getBytes(),"utf-8");
}
}
log.info("返回报文:{}", seqResult);
} catch (UnsupportedEncodingException e) {
log.error("接口返回异常", e);
}
return seqResult;
}
}到了这里，关于java对接第三方接口的三种方式的文章就介绍完了。如果您还想了解更多内容，请在右上角搜索TOY模板网以前的文章或继续浏览下面的相关文章，希望大家以后多多支持TOY模板网！
