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SpringBoot RestTemplate GET POST請求的例項講解

一)RestTemplate簡介

RestTemplate是HTTP客戶端庫提供了一個更高水平的API。主要用於Rest服務呼叫。

RestTemplate方法:

方法組 描述

getForObject

通過GET檢索表示形式。

getForEntity

ResponseEntity通過使用GET 檢索(即狀態,標頭和正文)。

headForHeaders

通過使用HEAD檢索資源的所有標頭。

postForLocation

通過使用POST建立新資源,並Location從響應中返回標頭。

postForObject

通過使用POST建立新資源,並從響應中返回表示形式。

postForEntity

通過使用POST建立新資源,並從響應中返回表示形式。

put

通過使用PUT建立或更新資源。

patchForObject

通過使用PATCH更新資源,並從響應中返回表示形式。請注意,JDK HttpURLConnection不支援PATCH,但是Apache HttpComponents和其他支援。

delete

使用DELETE刪除指定URI處的資源。

optionsForAllow

通過使用ALLOW檢索資源的允許的HTTP方法。

exchange

前述方法的通用性強(且意見少的版本),在需要時提供了額外的靈活性。它接受RequestEntity(包括HTTP方法,URL,標頭和正文作為輸入)並返回ResponseEntity。

這些方法允許使用ParameterizedTypeReference而不是Class使用泛型來指定響應型別。

execute

執行請求的最通用方法,完全控制通過回撥介面進行的請求準備和響應提取。

二)RestTemplate案例

第一步:建立一個maven專案,在pom.xml引入一個springboot的版本

pom.xml內容:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.oysept</groupId>
  <artifactId>spring_resttemplate</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
 
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.4.RELEASE</version>
    <relativePath/>
  </parent>
 
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
  </dependencies>
  
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <configuration>
          <mainClass>com.oysept.RestTemplateApplication</mainClass>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.tomcat.maven</groupId>
        <artifactId>tomcat7-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

application.yml配置:該配置就一個預設埠

server:

port: 8080

建立一個springboot啟動類RestTemplateApplication

package com.oysept;
 
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
 
@SpringBootApplication
public class RestTemplateApplication {
 
  public static void main(String[] args) {
    new SpringApplicationBuilder(RestTemplateApplication.class).run(args);
  }
}

到此步驟時,可以先執行RestTemplateApplication中的main方法,檢驗springboot啟動是否正常。

第二步:建立一個RestTemplate配置類並注入,因為在使用時,不提前注入ResttTemplate,在通過@Autowired使用會報RestTemplate找不到

package com.oysept.config;
 
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
 
/**
 * 註冊一個RestTemplate Bean,否則直接通過@Autowired使用會報RestTemplate找不到
 * @author ouyangjun
 */
@Configuration
public class RestTemplateConfig {
 
  /**
   * 方式一: 預設是使用JDK原生java.net.HttpURLConnection請求
   * @return
   */
  @Bean(name = "restTemplate")
  public RestTemplate restTemplate() {
    return new RestTemplate();
  }
 
  /**
   * 方式二: 使用apache http內建請求,需要在pom.xml中引入相應的apache jar
   * 可以使用HttpClient,設定一些http連線池等資訊
   * @return
   *
  @Bean(name = "restTemplate")
  public RestTemplate restTemplate() {
    return new RestTemplate(new HttpComponentsClientHttpRequestFactory());
  }
   */
 
  /**
   * 方式三: 使用OkHttp內建請求,需要在pom.xml中引入相應的OkHttp3 jar
   * 可以使用OkHttpClient,設定一些http連線池資訊
   * @return
   *
  @Bean(name = "restTemplate")
  public RestTemplate restTemplate() {
    return new RestTemplate(new OkHttp3ClientHttpRequestFactory());
  }
  */
}

第三步:建立一個VO類,用於測試入參和出參

package com.oysept.vo; 
public class MsgVO { 
  private String msgKey;
  private String msgValue;
 
  public String getMsgKey() {return msgKey;}
  public void setMsgKey(String msgKey) {this.msgKey = msgKey;}
 
  public String getMsgValue() {return msgValue;}
  public void setMsgValue(String msgValue) {this.msgValue = msgValue;}
 
  public String toString() {
    return "MsgVO [msgKey: "+this.msgKey+",msgValue: "+this.msgValue+"]";
  }
}

第四步:建立一個服務端介面,用於測試

package com.oysept.controller;
 
import java.util.ArrayList;
import java.util.List; 
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
 
import com.oysept.vo.MsgVO;
 
/**
 * 服務端,提供介面被呼叫
 * @author ouyangjun
 */
@RestController
public class ServerController {
 
  // 無參GET請求: http://localhost:8080/server/get
  @RequestMapping(value = "/server/get",method = RequestMethod.GET)
  public String get() {
    return "/server/get";
  }
 
  // 帶參GET請求: http://localhost:8080/server/get/param?param=111222333444
  @RequestMapping(value = "/server/get/param",method = RequestMethod.GET)
  public String getParam(@RequestParam(value = "param") String param) {
    return "/server/get/param," + param;
  }
 
  // 路徑中帶參GET請求: http://localhost:8080/server/get/url/AAAA/BBBB
  @RequestMapping(value = "/server/get/url/{one}/{two}",method = RequestMethod.GET)
  public String getUrl(@PathVariable("one") String one,@PathVariable("two") String two) {
    return "/get/url/{one}/{two}," + one + "," + two;
  }
 
  // 無參GET請求,返回List: http://localhost:8080/server/get/list
  @RequestMapping(value = "/server/get/list",method = RequestMethod.GET)
  public List<Object> getList() {
    List<Object> list = new ArrayList<Object>();
    list.add(11);
    list.add("AA");
    return list;
  }
 
  // 無參GET請求,返回物件: http://localhost:8080/server/get/MsgVO
  @RequestMapping(value = "/server/get/MsgVO",method = RequestMethod.GET)
  public MsgVO getMsgVO() {
    MsgVO vo = new MsgVO();
    vo.setMsgKey("keyAAA");
    vo.setMsgValue("valueBBB");
    return vo;
  }
 
  // POST請求,表單引數,application/x-www-form-urlencoded
  @RequestMapping(value = "/server/post/form",method = RequestMethod.POST,consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE)
  public MsgVO postForm(MsgVO msgVO) {
    System.out.println("msgKey: " + msgVO.getMsgKey() + ",msgValue: " + msgVO.getMsgValue());
    return msgVO;
  }
 
  // POST請求,JSON引數,application/json
  @RequestMapping(value = "/server/post/json",consumes = MediaType.APPLICATION_JSON_UTF8_VALUE,produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
  public MsgVO postJson(@RequestBody MsgVO msgVO) {
    System.out.println("msgKey: " + msgVO.getMsgKey() + ",msgValue: " + msgVO.getMsgValue());
    return msgVO;
  }
}

第五步:建立一個測試服務端介面的API

import的類和注入的RestTemplate:

package com.oysept.controller; 
import java.net.URI;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.RequestEntity;
import org.springframework.http.ResponseEntity;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.util.UriComponentsBuilder;
 
import com.oysept.vo.MsgVO;
 
/**
 * 客戶端,呼叫服務端提供的介面
 * @author ouyangjun
 */
@RestController
public class ClientController {
 
  // 使用預設請求方式
  @Autowired
  @Qualifier(value = "restTemplate")
  private RestTemplate restTemplate;
 
  // 在此處新增客戶端測試程式碼
}

1、GET請求

// 直接在瀏覽中輸入訪問地址: http://localhost:8080/client/get
@RequestMapping(value = "/client/get",method = RequestMethod.GET)
public String get() {
  // 無參GET請求
  String get = restTemplate.getForObject("http://localhost:8080/server/get",String.class);
  System.out.println("==>/server/get return: " + get);
 
  // 帶參GET請求
  String getParam = restTemplate.getForObject("http://localhost:8080/server/get/param?param=111222333444",String.class);
  System.out.println("==>/server/get/param return: " + getParam);
 
  // 帶參GET url請求
  String getUrlParam = restTemplate.getForObject("http://localhost:8080/server/get/url/{one}/{two}",String.class,"AAAA","BBBB");
  System.out.println("==>/server/get/url/{one}/{two} return: " + getUrlParam);
 
  // 帶參GET url請求
  Map<String,String> vars = new HashMap<String,String>();
  vars.put("one","HHHH");
  vars.put("two","EEEE");
  String getUrlVars = restTemplate.getForObject("http://localhost:8080/server/get/url/{one}/{two}",vars);
  System.out.println("==>/server/get/url/{one}/{two} return: " + getUrlVars);
 
  // 無參GET請求,返回List
  @SuppressWarnings("unchecked")
  List<String> getList = restTemplate.getForObject("http://localhost:8080/server/get/list",List.class);
  System.out.println("==>/server/get/list return: " + getList);
 
  // GET請求,返回物件
  ResponseEntity<MsgVO> entity = restTemplate.getForEntity("http://localhost:8080/server/get/MsgVO",MsgVO.class);
  System.out.println("==>/server/get/list return: " + entity.getBody());
  return "GET SUCCESS";
}

2、GET url中傳參請求

// 直接在瀏覽中輸入訪問地址: http://localhost:8080/client/get/request
// GET請求,url引數,在表頭中新增引數
@RequestMapping(value = "/client/get/request",method = RequestMethod.GET)
public String getRequest() {
  // url中引數
  Map<String,"EEEE");
 
  // 請求地址
  String uriTemplate = "http://localhost:8080/server/get/url/{one}/{two}";
  // 給URL地址encode轉碼
  URI uri = UriComponentsBuilder.fromUriString(uriTemplate).buildAndExpand(vars).toUri();
  // GET請求引數
  RequestEntity<Void> requestEntity = 
        RequestEntity.get(uri)
        .header("MyHeader","aaabbbcccddd")
        .build();
  // 響應
  ResponseEntity<String> response = restTemplate.exchange(requestEntity,String.class);
  // 結果
  System.out.println("==>/get/request header: " + response.getHeaders().getFirst("MyHeader"));
  System.out.println("==>/get/request body: " + response.getBody());
  return "POST SUCCESS";
}

3、POST application/x-www-form-urlencoded表單傳參請求

// 直接在瀏覽中輸入訪問地址: http://localhost:8080/client/postForm
// POST請求,form表單入參
@RequestMapping(value = "/client/postForm",method = RequestMethod.GET)
public String postForm() {
  // uri
  String uriTemplate = "http://localhost:8080/server/post/form";
 
  // 設定請求頭為form形式: application/x-www-form-urlencoded
  HttpHeaders headers = new HttpHeaders();
  headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
 
  // 設定引數,和MsgVO中變數名對應
  MultiValueMap<String,String> map = new LinkedMultiValueMap<String,String>();
  map.add("msgKey","1234");
  map.add("msgValue","TestTest");
 
  // 封裝請求引數
  HttpEntity<MultiValueMap<String,String>> requestb = new HttpEntity<MultiValueMap<String,String>>(map,headers);
  ResponseEntity<String> response = restTemplate.postForEntity(uriTemplate,requestb,String.class);
  System.out.println("==>/server/post/form return: " + response.getBody());
  return "POST SUCCESS";
}

4、POST application/json JSON傳參請求

// 直接在瀏覽中輸入訪問地址: http://localhost:8080/client/postJson
// POST請求,JSON入參
@RequestMapping(value = "/client/postJson",method = RequestMethod.GET)
public String postJson() {
  // json入參
  MsgVO vo = new MsgVO();
  vo.setMsgKey("TTT");
  vo.setMsgValue("KKK");
 
  String uriTemplate = "http://localhost:8080/server/post/json";
  URI uri = UriComponentsBuilder.fromUriString(uriTemplate).buildAndExpand().toUri();
 
  RequestEntity<MsgVO> requestEntity = 
      RequestEntity.post(uri)
      .header("Content-Type","application/json; charset=UTF-8")
      .body(vo);
  
  ResponseEntity<MsgVO> response = restTemplate.exchange(requestEntity,MsgVO.class);
  System.out.println("==>/server/post/json return: " + response.getBody());
  return "POST SUCCESS";
}

專案結構圖:

SpringBoot RestTemplate GET POST請求的例項講解

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