在上一篇文章中，我们详细的介绍了RestTemplate工具类的用法，相比直接使用Apache的HttpClient进行网络传输，采用RestTemplate开发代码确实简化了很多，甚至可以做到傻瓜式操作，但是基于当前的团队人员开发习惯，我们可不可以继续基于RestTemplate再做一层封装呢？以便于操作Http网络请求，更加简单、便捷！
答案是肯定的！
本文要介绍的这个工具类，就是小编基于RestTemplate做了一层代码封装，里面涵盖了GET、POST、PUT、DELETE、文件上传与下载等等方法，同时支持自定义头部传参，通过灵活的传参，可以满足绝大部分业务场景下的网络请求场景！
同时，在上一篇介绍RestTemplate的《真不是我吹，Spring里这款牛逼的网络工具库我估计你都没用过！》文章里，我们还漏掉了一个最常用的场景，假如返回的对象，是一个范型类型，该怎么处理？
在本篇的文章里，我们也会详细的介绍这种问题的处理方法！
废话也不多说，直接上代码，希望对网友们能有所帮助！
下面以SpringBoot项目为例，如果是Spring项目，操作也类似，在配置类初始化的时候，实例化一个RestTemplate。
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.6</version>
</dependency>
@Configuration
public class HttpConfiguration {
/**
* 没有实例化RestTemplate时，初始化RestTemplate
* @return
*/
@ConditionalOnMissingBean(RestTemplate.class)
@Bean
public RestTemplate restTemplate(){
RestTemplate restTemplate = new RestTemplate(getClientHttpRequestFactory());
return restTemplate;
}
/**
* 使用HttpClient作为底层客户端
* @return
*/
private ClientHttpRequestFactory getClientHttpRequestFactory() {
int timeout = 5000;
RequestConfig config = RequestConfig.custom()
.setConnectTimeout(timeout)
.setConnectionRequestTimeout(timeout)
.setSocketTimeout(timeout)
.build();
CloseableHttpClient client = HttpClientBuilder
.create()
.setDefaultRequestConfig(config)
.build();
return new HttpComponentsClientHttpRequestFactory(client);
}
}
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.ParameterizedTypeReference;
import org.springframework.http.*;
import org.springframework.stereotype.Component;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RequestCallback;
import org.springframework.web.client.ResponseExtractor;
import org.springframework.web.client.RestTemplate;
import JAVA.NET.URI;
import java.util.Arrays;
import java.util.Map;
import java.util.Objects;
@Component
public class HttpTemplate {
private static final Logger log = LoggerFactory.getLogger(HttpTemplate.class);
@Autowired
private RestTemplate restTemplate;
/**
* get请求，返回响应实体（响应业务对象不支持范型）
* 支持restful风格
* @param url
* @param headers
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> T get(String url, Map<String, String> headers, Class<T> responseType, Object... uriVariables){
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.GET, new HttpEntity<>(createHeaders(headers)), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* get请求，返回响应实体（响应业务对象支持范型）
* 支持restful风格
* @param url
* @param headers
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> T get(String url, Map<String, String> headers, ParameterizedTypeReference<T> responseType, Object... uriVariables){
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.GET, new HttpEntity<>(createHeaders(headers)), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* post请求，form表单提交（响应业务对象不支持范型）
* 支持restful风格
* @param url
* @param headers
* @param paramMap
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> T postByFrom(String url, Map<String, String> headers, Map<String, Object> paramMap, Class<T> responseType, Object... uriVariables){
//指定请求头为表单类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.AppLICATION_FORM_URLENCODED);
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.POST, new HttpEntity<>(createBody(paramMap), httpHeaders), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* post请求，form表单提交（响应业务对象支持范型）
* 支持restful风格
* @param url
* @param headers
* @param paramMap
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> T postByFrom(String url, Map<String, String> headers, Map<String, Object> paramMap, ParameterizedTypeReference<T> responseType, Object... uriVariables){
//指定请求头为表单类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.POST, new HttpEntity<>(createBody(paramMap), httpHeaders), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* post请求，json提交（响应业务对象不支持范型）
* 支持restful风格
* @param url
* @param headers
* @param request
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> T postByJson(String url, Map<String, String> headers, Object request, Class<T> responseType, Object... uriVariables){
//指定请求头为json类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.APPLICATION_JSON_UTF8);
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.POST, new HttpEntity<>(request, httpHeaders), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* post请求，json提交（响应业务对象支持范型）
* 支持restful风格
* @param url
* @param headers
* @param request
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> T postByJson(String url, Map<String, String> headers, Object request, ParameterizedTypeReference<T> responseType, Object... uriVariables){
//指定请求头为json类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.APPLICATION_JSON_UTF8);
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.POST, new HttpEntity<>(request, httpHeaders), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* post请求，json提交，重定项
* 支持restful风格
* @param url
* @param headers
* @param request
* @param uriVariables
* @return
*/
public String postForLocation(String url, Map<String, String> headers, Object request, Object... uriVariables){
//指定请求头为json类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.APPLICATION_JSON_UTF8);
URI uri = restTemplate.postForLocation(url, new HttpEntity<>(request, httpHeaders), uriVariables);
if(Objects.nonNull(uri)){
return uri.toString();
}
return null;
}
/**
* put请求，json提交（响应业务对象不支持范型）
* @param url
* @param headers
* @param request
* @param uriVariables
*/
public <T> T put(String url, Map<String, String> headers, Object request, Class<T> responseType, Object... uriVariables){
//指定请求头为json类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.APPLICATION_JSON_UTF8);
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.PUT, new HttpEntity<>(request, httpHeaders), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* put请求，json提交（响应业务对象支持范型）
* @param url
* @param headers
* @param request
* @param uriVariables
*/
public <T> T put(String url, Map<String, String> headers, Object request, ParameterizedTypeReference<T> responseType, Object... uriVariables){
//指定请求头为json类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.APPLICATION_JSON_UTF8);
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.PUT, new HttpEntity<>(request, httpHeaders), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* delete请求（响应业务对象不支持范型）
* @param url
* @param headers
* @param uriVariables
* @return
*/
public <T> T delete(String url, Map<String, String> headers, Class<T> responseType, Object... uriVariables){
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.DELETE, new HttpEntity<>(createHeaders(headers)), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* delete请求（响应业务对象支持范型）
* @param url
* @param headers
* @param uriVariables
* @return
*/
public <T> T delete(String url, Map<String, String> headers, ParameterizedTypeReference<T> responseType, Object... uriVariables){
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.DELETE, new HttpEntity<>(createHeaders(headers)), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* post请求，文件表单上传提交（响应业务对象不支持范型）
* 支持restful风格
* @param url
* @param headers
* @param paramMap
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> T uploadFile(String url, Map<String, String> headers, MultiValueMap<String, Object> paramMap, Class<T> responseType, Object... uriVariables){
//指定请求头为文件&表单类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.POST, new HttpEntity<>(paramMap, httpHeaders), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* post请求，文件表单上传提交（响应业务对象支持范型）
* 支持restful风格
* @param url
* @param headers
* @param paramMap
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> T uploadFile(String url, Map<String, String> headers, MultiValueMap<String, Object> paramMap, ParameterizedTypeReference<T> responseType, Object... uriVariables){
//指定请求头为文件&表单类型
HttpHeaders httpHeaders = createHeaders(headers);
httpHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);
ResponseEntity<T> rsp = commonExchange(url, HttpMethod.POST, new HttpEntity<>(paramMap, httpHeaders), responseType, uriVariables);
return buildResponse(rsp);
}
/**
* 下载文件
* @param url
* @param headers
* @param uriVariables
* @return
*/
public byte[] downloadFile(String url, Map<String, String> headers, Object... uriVariables){
ResponseEntity<byte[]> rsp = commonExchange(url, HttpMethod.GET, new HttpEntity<>(createHeaders(headers)), byte[].class, uriVariables);
return buildResponse(rsp);
}
/**
* 下载大文件
* @param url
* @param headers
* @param responseExtractor
* @param uriVariables
*/
public void downloadBigFile(String url, Map<String, String> headers, ResponseExtractor responseExtractor, Object... uriVariables){
RequestCallback requestCallback = request -> {
//指定请求头信息
request.getHeaders().addAll(createHeaders(headers));
//定义请求头的接收类型
request.getHeaders().setAccept(Arrays.asList(MediaType.APPLICATION_OCTET_STREAM, MediaType.ALL));
};
restTemplate.execute(url, HttpMethod.GET, requestCallback,responseExtractor, uriVariables);
}
/**
* 公共http请求方法（响应业务对象不支持范型）
* @param url
* @param method
* @param requestEntity
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> ResponseEntity<T> commonExchange(String url, HttpMethod method, HttpEntity<?> requestEntity, Class<T> responseType, Object... uriVariables){
return restTemplate.exchange(url, method, requestEntity, responseType, uriVariables);
}
/**
* 公共http请求方法（响应业务对象支持范型）
* @param url
* @param method
* @param requestEntity
* @param responseType
* @param uriVariables
* @param <T>
* @return
*/
public <T> ResponseEntity<T> commonExchange(String url, HttpMethod method, HttpEntity<?> requestEntity, ParameterizedTypeReference<T> responseType, Object... uriVariables){
return restTemplate.exchange(url, method, requestEntity, responseType, uriVariables);
}
/**
* 封装头部参数
* @param headers
* @return
*/
private HttpHeaders createHeaders(Map<String, String> headers){
return new HttpHeaders(){{
if(headers != null && !headers.isEmpty()){
headers.entrySet().forEach(item -> {
set(item.getKey(), item.getValue());
});
}
}};
}
/**
* 封装请求体
* @param paramMap
* @return
*/
private MultiValueMap<String, Object> createBody(Map<String, Object> paramMap){
MultiValueMap<String, Object> valueMap = new LinkedMultiValueMap<>();
if(paramMap != null && !paramMap.isEmpty()){
paramMap.entrySet().forEach(item -> {
valueMap.add(item.getKey(), item.getValue());
});
}
return valueMap;
}
/**
* 返回响应对象
* @param rsp
* @param <T>
* @return
*/
private <T> T buildResponse(ResponseEntity<T> rsp){
if(!rsp.getStatusCode().is2xxSuccessful()){
throw new RuntimeException(rsp.getStatusCode().getReasonPhrase());
}
return rsp.getBody();
}
}
@RunWith(SpringRunner.class)
@SpringBootTest
public class HttpControllerJunit {
@Autowired
private HttpTemplate httpTemplate;
/**
* get请求测试
*/
@Test
public void testGet(){
//请求地址
String url = "http://localhost:8080/testGet";
//发起请求,直接返回对象
ResponseBean responseBean = httpTemplate.get(url, createHeader("get"), ResponseBean.class);
System.out.println(responseBean.toString());
}
/**
* get请求测试，restful风格
*/
@Test
public void testGetByRestFul(){
//请求地址
String url = "http://localhost:8080/testGetByRestFul/{1}";
//发起请求,直接返回对象（restful风格）
ResponseBean responseBean = httpTemplate.get(url, createHeader("testGetByRestFul"), ResponseBean.class, "张三");
System.out.println(responseBean.toString());
}
/**
* 模拟表单提交，post请求
*/
@Test
public void testPostByForm(){
//请求地址
String url = "http://localhost:8080/testPostByFormAndObj";
//表单参数
Map<String, Object> paramMap = new HashMap<>();
paramMap.put("userName", "唐三藏");
paramMap.put("userPwd", "123456");
//发起请求
ResponseBean responseBean = httpTemplate.postByFrom(url, createHeader("testPostByFormAndObj"), paramMap, ResponseBean.class);
System.out.println(responseBean.toString());
}
/**
* 模拟JSON提交，post请求
*/
@Test
public void testPostByJson(){
//请求地址
String url = "http://localhost:8080/testPostByJson";
//入参
RequestBean request = new RequestBean();
request.setUserName("唐三藏");
request.setUserPwd("123456789");
//发送post请求，并打印结果，以String类型接收响应结果JSON字符串
ResponseBean responseBean = httpTemplate.postByJson(url, createHeader("testPostByJson"), request, ResponseBean.class);
System.out.println(responseBean.toString());
}
/**
* 重定向，post请求，json方式提交
*/
@Test
public void testPostByLocation(){
//请求地址
String url = "http://localhost:8080/testPostByLocation";
//入参
RequestBean request = new RequestBean();
request.setUserName("唐三藏");
request.setUserPwd("123456789");
//用于提交完成数据之后的页面跳转
String uri = httpTemplate.postForLocation(url, createHeader("testPostByLocation"), request);
System.out.println(uri);
}
/**
* put请求，json方式提交
*/
@Test
public void testPutByJson(){
//请求地址
String url = "http://localhost:8080/testPutByJson";
//入参
RequestBean request = new RequestBean();
request.setUserName("唐三藏");
request.setUserPwd("123456789000");
//模拟JSON提交，put请求
ResponseBean responseBean = httpTemplate.put(url, createHeader("testPutByJson"), request, ResponseBean.class);
System.out.println(responseBean.toString());
}
/**
* delete请求，json方式提交
*/
@Test
public void testDeleteByJson(){
//请求地址
String url = "http://localhost:8080/testDeleteByJson";
//模拟JSON提交，delete请求
ResponseBean responseBean = httpTemplate.delete(url, createHeader("testDeleteByJson"), ResponseBean.class);
System.out.println(responseBean.toString());
}
/**
* 文件上传，post请求
*/
@Test
public void uploadFile(){
//需要上传的文件
String filePath = "/Users/panzhi/Desktop/Jietu20220205-194655.jpg";
//请求地址
String url = "http://localhost:8080/upload";
//提交参数设置
MultiValueMap<String, Object> param = new LinkedMultiValueMap<>();
param.add("uploadFile", new FileSystemResource(new File(filePath)));
//服务端如果接受额外参数，可以传递
param.add("userName", "张三");
ResponseBean responseBean = httpTemplate.uploadFile(url, createHeader("uploadFile"), param, ResponseBean.class);
System.out.println(responseBean.toString());
}
/**
* 小文件下载
* @throws IOException
*/
@Test
public void downloadFile() throws IOException {
String userName = "张三";
String fileName = "f9057640-90b2-4f86-9a4b-72ad0e253d0d.jpg";
//请求地址
String url = "http://localhost:8080/downloadFile/{1}/{2}";
//发起请求,直接返回对象（restful风格）
byte[] stream = httpTemplate.downloadFile(url, createHeader("downloadFile"), userName,fileName);
// 将下载下来的文件内容保存到本地
String targetPath = "/Users/panzhi/Desktop/" + fileName;
Files.write(Paths.get(targetPath), Objects.requireNonNull(stream, "未获取到下载文件"));
}
/**
* 大文件下载
* @throws IOException
*/
@Test
public void downloadBigFile() {
String userName = "张三";
String fileName = "f9057640-90b2-4f86-9a4b-72ad0e253d0d.jpg";
String targetPath = "/Users/panzhi/Desktop/" + fileName;
//请求地址
String url = "http://localhost:8080/downloadFile/{1}/{2}";
//对响应进行流式处理而不是将其全部加载到内存中
httpTemplate.downloadBigFile(url, createHeader("downloadBigFile"), clientHttpResponse -> {
Files.copy(clientHttpResponse.getBody(), Paths.get(targetPath));
return null;
}, userName, fileName);
}
/**
* 自定义请求头部
* @param value
* @return
*/
private Map<String, String> createHeader(String value){
Map<String, String> headers = new HashMap<>();
headers.put("token", value);
return headers;
}
}
在上篇文章中，我们介绍的返回对象都是非范型，例如返回的都是ResponseBean这个业务对象，用法也很简单，以POST请求+JSON提交方式为例，通过如下方式即可实现返回对象的序列化！
ResponseBean responseBean = httpTemplate.postByJson(url, createHeader("testPostByJson"), request, ResponseBean.class);
但是，假如返回的对象是ResponseBean<xxx>这样的，通过上面的方式来操作会直接报错！
当遇到返回的对象是范型类型的时候，我们可以这样操作！
以下面这个/testPostByJsonObj接口为例！
/**
* 模拟JSON请求，post方法测试
* @param request
* @return
*/
@RequestMapping(value = "testPostByJsonObj", method = RequestMethod.POST)
public ResponseBeanObj<ResponseBean> testPostByJsonObj(@RequestBody RequestBean requestBean,
HttpServletRequest request){
HttpServletRequestLog.systemLog(request);
//范型测试
ResponseBean responseBean = new ResponseBean();
responseBean.setCode("200000");
responseBean.setMsg("responseBean");
//范型测试
ResponseBeanObj<ResponseBean> result = new ResponseBeanObj<>();
result.setCode("200");
result.setMsg("请求成功，方法：testPostByJsonObj，请求参数：" + JSON.toJSONString(requestBean));
result.setObj(responseBean);
System.out.println(JSON.toJSONString(result));
return result;
}
使用RestTemplate工具发起网络请求，代码如下！
//将返回的范型对象包装到ParameterizedTypeReference对象里面
ParameterizedTypeReference<ResponseBeanObj<ResponseBean>> typeRef = new ParameterizedTypeReference<ResponseBeanObj<ResponseBean>>() {};
//使用restTemplate发起网络请求
ResponseBeanObj<ResponseBean> responseBean = restTemplate.exchange(url, HttpMethod.POST, request, typeRef);
采用restTemplate.exchange()方法，即可实现返回对象范型类型的反序列化！
如果使用上面封装的HttpTemplate工具进行操作，也更简单，代码如下：
/**
* 模拟JSON提交，post请求，范型返回对象测试
*/
@Test
public void testPostByJsonObj(){
//请求地址
String url = "http://localhost:8080/testPostByJsonObj";
//入参
RequestBean request = new RequestBean();
request.setUserName("唐三藏");
request.setUserPwd("123456789");
//发送post请求
ParameterizedTypeReference<ResponseBeanObj<ResponseBean>> typeRef = new ParameterizedTypeReference<ResponseBeanObj<ResponseBean>>() {};
//范型测试
ResponseBeanObj<ResponseBean> responseBean = httpTemplate.postByJson(url, createHeader("testPostByJsonObj"), request, typeRef);
System.out.println(JSON.toJSONString(responseBean));
}
在某些场景下，当你使用restTemplate发起网络请求时，所有的请求头部需要带上统一的参数，例如Authorization鉴权码，这个时候改怎么办呢？
可能有的同学，想到的就是在传参数的时候，带上请求头部参数！这种方法也可以解决问题！
有没有好的办法统一入口加入呢？
答案肯定是有的，我们可以利用RestTemplate提供的拦截器链来解决这个问题。
例如在RestTemplate初始化之后，添加一个拦截器，然后在拦截器的请求头部统一注入鉴权码，就可以轻松实现全局加入某个参数，方式如下！
/**
* 初始化RestTemplate
* @return
*/
@Bean
public RestTemplate restTemplate(){
RestTemplate restTemplate = new RestTemplate(getClientHttpRequestFactory());
// 添加一个拦截器，在请求头部添加 Authorization 鉴权码
restTemplate.getInterceptors().add((request, body, execution) -> {
request.getHeaders().add("Authorization", "xxxxxXXXXX");
return execution.execute(request, body);
});
return restTemplate;
}
通过本章的讲解，想必读者初步的了解了如何基于RestTemplate做第二次封装，以便于更佳适配当前团队开发人员的习惯。
RestTemplate的功能其实非常强大，作者也仅仅学了点皮毛，在后续如果有新的功能，也会分享给大家，希望对网友们有所帮助！
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