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Java Http请求方式之RestTemplate常用方法详解

作者：Real_ma　　发布时间：2021-06-29 02:32:51　

标签：Java,Http,请求方式,RestTemplate

引言

在开发中有时候经常需要一些Http请求，请求数据，下载内容，也有一些简单的分布式应用直接使用Http请求作为跨应用的交互协议。

在Java中有不同的Http请求方式，主要就是HttpURLConnection或者ApacheHttpClient，但是这两个用起来都感觉有那么一点点的复杂；

好在Spring内置了RestTemplate作为Http请求的工具类，简化了很多操作，虽然Spring5推出了WebClient，但是整体感觉还是RestTemplate用起来更简单方便一些。

这里记录分享下RestTemplate的常见使用方式，RestTemplate作为Java中最简单好用的Http请求工具类一定要了解一下

常见用法

简单Get\Post请求

@Test
public void testGetPost(){
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new FastJsonHttpMessageConverter());
String res = restTemplate.postForObject("http://test.aihe.space/", null, String.class);
System.out.println(res);
String res2 = restTemplate.getForObject("http://test.aihe.space/", String.class);
System.out.println(res2);
}

Post提交常规表单

@Test
public void testPostFrom(){
RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
MultiValueMap<String, String> map= new LinkedMultiValueMap<>();
map.add("id", "1");
HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(map, headers);
String fooResourceUrl = "http://test.aihe.space/";
ResponseEntity<String> response = restTemplate.postForEntity(fooResourceUrl, request, String.class);
System.out.println(response.getStatusCode());
System.out.println(response.getBody());
}

Post上传文件

注意：上传文件时的value为FileSystemResource

@Test
public void testPostFile(){
RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);
MultiValueMap<String, Object> map= new LinkedMultiValueMap<>();
map.add("id", "1");
map.add("file",new FileSystemResource("/Users/aihe/code/init/src/test/java/me/aihe/RestTemplateTest.java"));
HttpEntity<MultiValueMap<String, Object>> request = new HttpEntity<>(map, headers);
String fooResourceUrl = "http://test.aihe.space/";
ResponseEntity<String> response = restTemplate.postForEntity(fooResourceUrl, request, String.class);
System.out.println(response.getStatusCode());
System.out.println(response.getBody());
}

配置项

请求添加Cookie\Header

@Test
public void testCookieHeader(){
RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);
MultiValueMap<String, Object> map= new LinkedMultiValueMap<>();
// 常见的Header都可以直接设置
// headers.set
headers.set("custom1","customValue1");
// 设置Cookie
headers.set(HttpHeaders.COOKIE,"xxxx");
map.add("id", "1");
HttpEntity<MultiValueMap<String, Object>> request = new HttpEntity<>(map, headers);
String fooResourceUrl = "http://test.aihe.space/";
ResponseEntity<String> response = restTemplate.postForEntity(fooResourceUrl, request, String.class);
System.out.println(response.getStatusCode());
System.out.println(response.getBody());
}

配置请求工厂超时、代理

使用Rest请求的时候注意设置超时时间

@Test
public void testHttpFactory(){
RestTemplate restTemplate = new RestTemplate();
SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
requestFactory.setReadTimeout(5000);
requestFactory.setConnectTimeout(3000);
Proxy proxy = new Proxy(Proxy.Type.SOCKS, new InetSocketAddress("127.0.0.1", 7890));
requestFactory.setProxy(proxy);
restTemplate.setRequestFactory(requestFactory);
restTemplate.getMessageConverters().add(new FastJsonHttpMessageConverter());
String res = restTemplate.postForObject("http://test.aihe.space/", null, String.class);
System.out.println(res);
}

配置 * 、转换器，错误处理

@Test
public void testConverterInterceptor(){
RestTemplate restTemplate = new RestTemplate();
restTemplate.setInterceptors(Collections.singletonList(new BasicAuthenticationInterceptor("admin","admin")));
restTemplate.getMessageConverters().add(new FastJsonHttpMessageConverter());
restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
String res = restTemplate.postForObject("http://test.aihe.space/", null, String.class);
System.out.println(res);
}

错误重试(额外)

可以考虑使用Spring Retry，但是相当于引入了新的东西，如果没有特殊必要，可以自己简单用for循环做下；

SSL请求

参考：stackoverflow.com/questions/1…

@Test
public void testSSL() throws FileNotFoundException, NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException {
String keyStorePassword = "123456";
KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
keyStore.load(new FileInputStream(new File("keyStoreFile")),
keyStorePassword.toCharArray());
SSLConnectionSocketFactory socketFactory = new SSLConnectionSocketFactory(
new SSLContextBuilder()
.loadTrustMaterial(null, new TrustSelfSignedStrategy())
.loadKeyMaterial(keyStore, keyStorePassword.toCharArray())
.build(),
NoopHostnameVerifier.INSTANCE);
HttpClient httpClient = HttpClients.custom().setSSLSocketFactory(
socketFactory).build();
ClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory(
httpClient);
RestTemplate restTemplate = new RestTemplate(requestFactory);
String res = restTemplate.postForObject("http://test.aihe.space/", null, String.class);
System.out.println(res);
}

基于RestTemplate一些工具

钉钉机器人通知

可以支持发送普通文本、ActionCard，Markdown的消息

import java.util.ArrayList;
import java.util.List;
import lombok.Data;
import lombok.Getter;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestTemplate;
/**
* 使用场景：
* 功能描述：https://developers.dingtalk.com/document/app/custom-robot-access/title-72m-8ag-pqw
*/
@Slf4j
public class RobotUtils {
private static RestTemplate restTemplate = new RestTemplate();
private static String URL = "";
public static void main(String[] args) {
sendMarkDownMsg(
URL,
"测试",
"测试",
new ArrayList<>()
);
}
/**
* {
* "msgtype": "text",
* "text": {
* "content": "我就是我, @150XXXXXXXX 是不一样的烟火"
* },
* "at": {
* "atMobiles": [
* "150XXXXXXXX"
* ],
* "isAtAll": false
* }
* }
*/
public static void sendTextMsg(String url, String content, List<String> atPerson) {
RobotMsg robotMsg = new RobotMsg();
robotMsg.setMsgtype("text");
RobotAt robotAt = new RobotAt();
robotAt.setAtAll(false);
if (atPerson != null && atPerson.size() > 0) {
robotAt.setAtMobiles(atPerson);
}
robotMsg.setAt(robotAt);
RobotText robotText = new RobotText();
robotText.setContent(content);
robotMsg.setText(robotText);
ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, robotMsg, String.class);
log.info("sendTextMsg {}",responseEntity.getBody());
}
/**
* @param url 机器人地址
* @param title actionCard标题
* @param text 缩略内容
* @param vertical 按钮方向
* @param btns 按钮内容
*/
public static void sendActionCardMsg(String url, String title, String text, Boolean vertical, List<RobotBtn> btns) {
RobotMsg robotMsg = new RobotMsg();
robotMsg.setMsgtype("actionCard");
RobotAt robotAt = new RobotAt();
robotAt.setAtAll(false);
RobotActionCard robotActionCard
= new RobotActionCard();
robotActionCard.setTitle(title);
robotActionCard.setText(text);
robotActionCard.setBtnOrientation((vertical == null || vertical) ? "0" : "1");
robotActionCard.setBtns(btns);
robotMsg.setActionCard(robotActionCard);
ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, robotMsg, String.class);
System.out.println(responseEntity.getBody());
}
public static void sendMarkDownMsg(String url,String title,String text,List<String> atPerson){
RobotMarkDownMsg markDownMsg = new RobotMarkDownMsg();
markDownMsg.setMsgtype("markdown");
RobotAt robotAt = new RobotAt();
robotAt.setAtAll(false);
if (atPerson != null && atPerson.size() > 0) {
robotAt.setAtMobiles(atPerson);
}
markDownMsg.setAt(robotAt);
RobotMarkdownText markdownText = new RobotMarkdownText();
markdownText.setTitle(title);
markdownText.setText(text);
markDownMsg.setMarkdown(markdownText);
ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, markDownMsg, String.class);
System.out.println(responseEntity.getBody());
}
public enum SupportRobotEnum {
/**
* 测试机器人群
*/
CESHI("测试机器人群",
"");
@Getter
private String desc;
@Getter
private String url;
SupportRobotEnum(String desc, String url) {
this.desc = desc;
this.url = url;
}
}
@Data
public static class RobotAt {
public List<String> atMobiles;
public boolean isAtAll;
}
@Data
public static class RobotMarkDownMsg{
public String msgtype;
public RobotAt at;
public RobotMarkdownText markdown;
}
@Data
public static class RobotMarkdownText {
String title;
String text;
}
@Data
public static class RobotMsg {
public String msgtype;
public RobotAt at;
/**
* 普通文字消息类型消息
*/
public RobotText text;
/**
* actionCard类型消息时支持
*/
public RobotActionCard actionCard;
}
@Data
public static class RobotText {
public String content;
}
@Data
public static class RobotActionCard {
public String title;
public String text;
public String hideAvatar;
public String btnOrientation;
public List<RobotBtn> btns;
}
@Data
public static class RobotBtn {
public String title;
public String actionURL;
public static RobotBtn buildBtn(String title, String actionUrl) {
RobotBtn robotBtn = new RobotBtn();
robotBtn.setActionURL(actionUrl);
robotBtn.setTitle(title);
return robotBtn;
}
}
}

来源：https://juejin.cn/post/7147334077740220447

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