restTemplate的使用

怼烎@ 2024-04-01 17:19 106阅读 0赞

##  ##

**目录**

一、概述？

二、使用步骤

1.引入依赖

2.创建RestTemplate对象，交由spring容器进行管理

3.使用方法

3.1 GET请求

3.2 POST请求

4 exchange

总结

--------------------

## 一、概述？ ##

[RestTemplate][]是Spring提供的用于访问Rest服务的客户端，RestTemplate提供了多种便捷访问远程Http服务的方法,能够大大提高客户端的编写效率。

## 二、使用步骤 ##

### 1.引入依赖`` ###

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

### 2.创建RestTemplate对象，交由spring容器进行管理 ###

列举常见的创建方式

1.启动类中注入RestTemplate对象

package com.example.demo;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.context.annotation.Bean;
    import org.springframework.web.client.RestTemplate;
    
    @SpringBootApplication
    public class DemoApplication {
    
        @Bean
        public RestTemplate getRestTemplate(){
            return new RestTemplate();
        }
        public static void main(String[] args) {
            SpringApplication.run(DemoApplication.class, args);
        }
    
    }

2.创建配置类，注入RestTemplate的对象

package com.czxy.ssm.config;
    
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.web.client.RestTemplate;
    
    /**
     * RestTemplate工具类，主要用来提供RestTemplate对象
     */
    @Configuration//加上这个注解作用，可以被Spring扫描
    public class RestTemplateConfig {
        /**
         * 创建RestTemplate对象，将RestTemplate对象的生命周期的管理交给Spring
         */
        @Bean
        public RestTemplate restTemplate(){
            return new RestTemplate();
        }
    }

3.创建配置类，注入RestTemplate的对象，并设置连接和请求的时间

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;
    
    /**
     * RestTemplate工具类，主要用来提供RestTemplate对象
     */
    @Configuration//加上这个注解作用，可以被Spring扫描
    public class RestTemplateConfig {
    
        @Bean
        public RestTemplate restTemplate(ClientHttpRequestFactory factory){
            return new RestTemplate(factory);
        }
    
        @Bean
        public ClientHttpRequestFactory simpleClientHttpRequestFactory(){
            SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
            factory.setReadTimeout(500000);//单位为ms
            factory.setConnectTimeout(500000);//单位为ms
            return factory;
        }
    }

### 3.使用方法 ###

#### 3.1 GET请求 ####

**3.1.1 getForEntity(String url, Class<T> responseType, Object... uriVariables)**  
解析： url为请求地址，responseType为请求响应体body的包装类型，uriVariables为url中的参数绑定。uriVariables是一个数组，所以他的顺序会对应url中占位符定义的数字的顺序

请求接口：

@Slf4j
    @RestController
    @RequestMapping("/memo")
    public class BmsBillMemoController {
        @Autowired
        private IBmsBillMemoService bmsBillMemoService;
    
        /**
         * 获取结算账单手账详细信息
         */
        @GetMapping(value = "/{id}/{name}")
        public AjaxResult getInfo(@PathVariable("id") Long id,@PathVariable("name") String name) {
            return AjaxResult.success(bmsBillMemoService.selectBmsBillMemoById(id));
        }

请求代码

@Test
        public void Rest() {
            String url = "http://localhost:8080/memo/{1}/{2}";
            Class responseType = String.class;
            String [] str = new String[2];
            str[0] = "3";
            str[1] = "小林";
            ResponseEntity<String> responseEntity = restTemplate.getForEntity(url, responseType, str);
            System.out.println("1     "+responseEntity.getStatusCode());
            System.out.println("2     "+responseEntity.getStatusCodeValue());
            System.out.println("3     "+responseEntity.getHeaders());
            System.out.println("4     "+responseEntity.getBody());
            String body = responseEntity.getBody();
            AjaxResult ajaxResult = JSONUtil.toBean(body, AjaxResult.class);
            Object data = ajaxResult.get("data");
            BmsBillMemo bmsBillMemo = JSONUtil.toBean(data.toString(), BmsBillMemo.class);
            System.out.println(bmsBillMemo);
        }

**3.1.2getForEntity(String url, Class<T> responseType, Map<String, ?> uriVariables)**  
解析：这里只有uriVariables这个参数不同，这里使用了Map类型，  
注意：使用该方法进行参数绑定时需要在占位符中指定Map的key

请求接口

@Slf4j
    @RestController
    @RequestMapping("/memo")
    public class BmsBillMemoController {
        @Autowired
        private IBmsBillMemoService bmsBillMemoService;
    
        /**
         * 查询结算账单手账列表
         */
        @GetMapping("/list")
        public TableDataInfo list(BmsBillMemo bmsBillMemo) {
            List<BmsBillMemo> list = bmsBillMemoService.selectBmsBillMemoList(bmsBillMemo);
            return getDataTable(list);
        }

请求代码

@Test
        public void Rest2() {
            String url = "http://localhost:8080/memo/list?id={id}&clientName={clientName}";
            Class responseType = String.class;
            Map<String,String> map = new HashMap<>();
            map.put("id","3");
            map.put("clientName","顾客");
            ResponseEntity<String> responseEntity = restTemplate.getForEntity(url, responseType, map);
            System.out.println("1     "+responseEntity.getStatusCode());
            System.out.println("2     "+responseEntity.getStatusCodeValue());
            System.out.println("3     "+responseEntity.getHeaders());
            System.out.println("4     "+responseEntity.getBody());
            String body = responseEntity.getBody();
            TableDataInfo result = JSONUtil.toBean(body, TableDataInfo.class);
            Object data = result.getRows();
            List<BmsBillMemo> bmsBillMemos = JSONUtil.toList(JSONUtil.parseArray(data.toString()), BmsBillMemo.class);
            bmsBillMemos.stream().forEach(System.out::println);
        }

**3.1.3 getForEntity(URI url, Class<T> responseType)**  
解析：该方法使用URI替换之前的url和urlVariables参数来指定访问地址和参数绑定。  
例如：  
RestTemplate restTemplate = new RestTemplate();  
UriComponents uriComponenets = UriComponentsBuilder.formUriString\{  
"http://USER-SERVICE/user?name=\{name\}"  
.build()  
.expand("dodo")  
.encode();  
\}  
URI uri = UriComponents.toUri();  
ResponseEntity<String> responseEntity = restTemplate.getForEntity(uri,  
String.class).getBody();

**3.1.4 getForObject()函数**

解析：它可以理解为getForEntity的进一步封装，它通过HttpMessageConverterExtractor对HTTP请求响应体body内容进行对象转换，实现请求直接返回包装好的对象内容  
使用场景：当不需要关注请求响应除body外的其他内容时，该函数就非常好用，可以少一个从Response中获取body的步骤。

1.getForObject(String url, Class<T> responseType, Object... uriVariables)  
解析：url指定访问的地址，responseType指定访问的地址，urlVariables为url中占位符对应的参数  
2.getForObject(String url, Class<T> responseType, Map<String, ?> uriVariables)  
解析：该函数使用Map类型的urlVariables替代上面数组形式的urlVariables，因此使用时在url中需要将占位符的名称与Map类型中的Key一一对应设置

3.getForObject(URI url, Class<T> responseType)  
解析：该方法使用URI对象来替换之前的url和urlVariabels参数使用

请求代码

@Test
        public void Rest3() {
            String url = "http://localhost:8080/memo/{1}/{2}";
            Class<AjaxResult> responseType = AjaxResult.class;
            String [] str = new String[2];
            str[0] = "3";
            str[1] = "小林";
            AjaxResult ajaxResult = restTemplate.getForObject(url, responseType, str);
            Object data = ajaxResult.get("data");
            JSONObject jsonObject = JSONUtil.parseObj(data);
            System.out.println(jsonObject);
    //        BmsBillMemo bmsBillMemo = JSONUtil.toBean(jsonObject, BmsBillMemo.class);
            BmsBillMemo bmsBillMemo = JSONUtil.toBean(JSONUtil.toJsonStr(data), BmsBillMemo.class);
            System.out.println(bmsBillMemo);
    
        }

--------------------

#### 3.2 POST请求 ####

1.postForEntity(String url, Object request, Class<T> responseType, Object... uriVariables)  
2.postForEntity(String url, Object request, Class<T> responseType, Map<String, ?> uriVariables)  
3.postForEntity(URI url, Object request, Class<T> responseType)

解析：重载函数中的uriVariables用来对url中的参数进行绑定，responseType参数是对请求响应的body内容的类型定义  
注意：新增的request参数，改参数可以是一个普通的对象，也可以是一个HttpEntity对象。  
如果request是一个普通对象时，RestTemplate会将这个普通对象转换成HttpEntity对象来处理，其中Object就是request的类型，request内容会被当成一个完整的body来处理；  
如果resuqet是一个HttpEntity对象时，那么request会被当成一个完整的HTTP请求对象来处理，这个request中不仅包含了body内容，也包含了header的内容  
下面的测试代码是第二种的，其他的和上面get的类似

请求接口

/**
         * 查询结算账单手账列表
         */
        @PostMapping("/list1")
        public AjaxResult list1(@RequestBody BmsBillMemo bmsBillMemo, BmsBillMemo bmsBillMemo2) {
            List<BmsBillMemo> list = bmsBillMemoService.selectBmsBillMemoList(bmsBillMemo);
            List<BmsBillMemo> list2 = bmsBillMemoService.selectBmsBillMemoList(bmsBillMemo2);
            list.addAll(list2);
            return AjaxResult.success(list);
        }

请求代码

@Test
        public void Rest5() {
            String url = "http://localhost:8080/memo/list1?clientId={clientId}&supplierId={supplierId}";
            Class responseType = String.class;
            HttpHeaders head = new HttpHeaders();
            head.add("Content-Type","application/json");
            //设置请求体参数
            BmsBillMemo memo = new BmsBillMemo();
            memo.setId(3l);
            memo.setClientId(8l);
            memo.setSupplierId(33l);
            //设置请求头参数
            Map<String,String> map = new HashMap<>();
            map.put("clientId","8");
            map.put("supplierId","66");
            HttpEntity<String> entity = new HttpEntity(JSONUtil.toJsonStr(memo),head);
            ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, entity, responseType,map);
            System.out.println(responseEntity.getHeaders());
            System.out.println(responseEntity.getStatusCode());
            System.out.println(responseEntity.getStatusCodeValue());
            System.out.println(responseEntity.getBody());
        }

HttpEntity中也可以换成具体的实体类对象

@Test
        public void Rest5() {
            String url = "http://localhost:8080/memo/list1?clientId={clientId}&supplierId={supplierId}";
            Class responseType = String.class;
            HttpHeaders head = new HttpHeaders();
            head.add("Content-Type","application/json");
            //设置请求体参数
            BmsBillMemo memo = new BmsBillMemo();
            memo.setId(3l);
            memo.setClientId(8l);
            memo.setSupplierId(33l);
            //设置请求头参数
            Map<String,String> map = new HashMap<>();
            map.put("clientId","8");
            map.put("supplierId","66");
            HttpEntity<BmsBillMemo> entity = new HttpEntity(memo,head);
            ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, entity, responseType,map);
            System.out.println(responseEntity.getHeaders());
            System.out.println(responseEntity.getStatusCode());
            System.out.println(responseEntity.getStatusCodeValue());
            System.out.println(responseEntity.getBody());
        }

4.postForObject()函数  
解析：它简化了postForEntity()的后续处理，通过直接将请求响应的body内容包装陈对象来简化返回使用。  
RestTemplate restTemplate = new RestTemplate();  
User user = new User("didi", 20);  
String postResult = restTemplate.postForObject("http\[://USER-SERVICE/user", user, String.class);

三个重载方法：  
postForObject(String url, Object request, Class<T> responseType, Object... uriVariables)  
postForObject(String url, Object request, Class<T> responseType, Map<String, ?> uriVariables)  
postForObject(URI url, Object request, Class<T> responseType)

## 4 exchange ##

exchange(String url, HttpMethod method, @Nullable HttpEntity<?> requestEntity, Class<T> responseType, Map<String, ?> uriVariables)

有关exchange方法，这边只介绍这一种，其他的基本类似

get请求代码

@Test
        public void rest6(){
            String url = "http://localhost:8080/memo/list?id={id}&clientId={clientId}&clientName={clientName}";
            //设置请求头
            HttpHeaders head = new HttpHeaders();
            head.add("Content-Type","application/json");
            //封装请求体和请求头
            HttpEntity<String>  entity = new HttpEntity<>(null,head);
            //设置请求返回值类型（一般设置为string，再进行转换）
            Class responseType = String.class;
            //设置请求url中的参数，可以用map或者数组
            Map<String,String> map = new HashMap<>();
            map.put("id","3");
            map.put("clientName","顾客");
            map.put("clientId","4");
            //发起请求
            ResponseEntity<String> responseEntity = restTemplate.exchange(url, HttpMethod.GET,entity,responseType, map);
            //判断请求状态并获取请求的结果
            System.out.println("1     "+responseEntity.getStatusCode());
            System.out.println("2     "+responseEntity.getStatusCodeValue());
            System.out.println("3     "+responseEntity.getHeaders());
            System.out.println("4     "+responseEntity.getBody());
            String body = responseEntity.getBody();
            TableDataInfo result = JSONUtil.toBean(body, TableDataInfo.class);
            Object data = result.getRows();
            List<BmsBillMemo> bmsBillMemos = JSONUtil.toList(JSONUtil.parseArray(data.toString()), BmsBillMemo.class);
            bmsBillMemos.stream().forEach(System.out::println);
        }

post请求代码

@Test
        public void rest7() {
            String url = "http://localhost:8080/memo/list1?clientId={clientId}&supplierId={supplierId}";
            //设置请求头
            HttpHeaders head = new HttpHeaders();
            head.add("Content-Type", "application/json");
            //设置请求体参数
            BmsBillMemo memo = new BmsBillMemo();
            memo.setId(3l);
            memo.setClientId(8l);
            memo.setSupplierId(33l);
            //封装请求头和请求体
            HttpEntity<BmsBillMemo> entity = new HttpEntity(memo, head);
            //设置请求的返回类型（一般为String，便于共用）
            Class responseType = String.class;
            //设置请求头参数
            Map<String, String> map = new HashMap<>();
            map.put("clientId", "8");
            map.put("supplierId", "66");
            ResponseEntity<String> responseEntity = restTemplate.exchange(url, HttpMethod.POST, entity, responseType, map);
            System.out.println(responseEntity.getHeaders());
            System.out.println(responseEntity.getStatusCode());
            System.out.println(responseEntity.getStatusCodeValue());
            System.out.println(responseEntity.getBody());
        }

### 总结 ###

还有常用的delete和put请求相对简单，这里就不一一介绍的，常用的请求中请求头中通常需要添加token进行访问，这点需要注意，

[RestTemplate]: https://so.csdn.net/so/search?q=RestTemplate&spm=1001.2101.3001.7020