restTemplate配置及使用過程

更新時間：2025年11月10日 09:14:49 作者：水煮魚又失敗了

本文介紹了在Java開發(fā)中使用HttpClient和OKHttp進行HTTP連接的復(fù)雜性,推薦使用Spring框架的RestTemplate進行簡化,RestTemplate支持多種HTTP連接方式,并提供了豐富的API進行GET、POST請求和文件上傳,文章還提供了具體的代碼示例

1 場景

java開發(fā)中，使用http連接，訪問第三方網(wǎng)絡(luò)接口，通常使用的連接工具為HttpClient和OKHttp。

這兩種連接工具，使用起來比較復(fù)雜，新手容易出問題。如果使用spring框架，可以使用restTemplate來進行http連接請求。

restTemplate默認的連接方式是java中的HttpConnection，可以使用ClientHttpRequestFactory指定不同的HTTP連接方式。

2 依賴

maven依賴如下：

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>5.2.2.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.7</version>
</dependency>

3 配置

import org.apache.http.client.HttpClient;
import org.apache.http.conn.HttpClientConnectionManager;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;

@Configuration
public class RestTemplateConfig {
    
    /**
     * http連接管理器
     * @return
     */
    @Bean
    public HttpClientConnectionManager poolingHttpClientConnectionManager() {
        /*// 注冊http和https請求
        Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory>create()
                .register("http", PlainConnectionSocketFactory.getSocketFactory())
                .register("https", SSLConnectionSocketFactory.getSocketFactory())
                .build();
        PoolingHttpClientConnectionManager poolingHttpClientConnectionManager = new PoolingHttpClientConnectionManager(registry);*/
        
        PoolingHttpClientConnectionManager poolingHttpClientConnectionManager = new PoolingHttpClientConnectionManager();
        // 最大連接數(shù)
        poolingHttpClientConnectionManager.setMaxTotal(500);
        // 同路由并發(fā)數(shù)（每個主機的并發(fā)）
        poolingHttpClientConnectionManager.setDefaultMaxPerRoute(100);
        return poolingHttpClientConnectionManager;
    }
    
    /**
     * HttpClient
     * @param poolingHttpClientConnectionManager
     * @return
     */
    @Bean
    public HttpClient httpClient(HttpClientConnectionManager poolingHttpClientConnectionManager) {
        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
        // 設(shè)置http連接管理器
        httpClientBuilder.setConnectionManager(poolingHttpClientConnectionManager);
        
        /*// 設(shè)置重試次數(shù)
        httpClientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(3, true));*/
        
        // 設(shè)置默認請求頭
        /*List<Header> headers = new ArrayList<>();
        headers.add(new BasicHeader("Connection", "Keep-Alive"));
        httpClientBuilder.setDefaultHeaders(headers);*/
        
        return httpClientBuilder.build();
    }
    
    /**
     * 請求連接池配置
     * @param httpClient
     * @return
     */
    @Bean
    public ClientHttpRequestFactory clientHttpRequestFactory(HttpClient httpClient) {
        HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory();
        // httpClient創(chuàng)建器
        clientHttpRequestFactory.setHttpClient(httpClient);
        // 連接超時時間/毫秒（連接上服務(wù)器(握手成功)的時間，超出拋出connect timeout）
        clientHttpRequestFactory.setConnectTimeout(5 * 1000);
        // 數(shù)據(jù)讀取超時時間(socketTimeout)/毫秒（務(wù)器返回數(shù)據(jù)(response)的時間，超過拋出read timeout）
        clientHttpRequestFactory.setReadTimeout(10 * 1000);
        // 連接池獲取請求連接的超時時間，不宜過長，必須設(shè)置/毫秒（超時間未拿到可用連接，會拋出org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection from pool）
        clientHttpRequestFactory.setConnectionRequestTimeout(10 * 1000);
        return clientHttpRequestFactory;
    }
    
    /**
     * rest模板
     * @return
     */
    @Bean
    public RestTemplate restTemplate(ClientHttpRequestFactory clientHttpRequestFactory) {
        // boot中可使用RestTemplateBuilder.build創(chuàng)建
        RestTemplate restTemplate = new RestTemplate();
        // 配置請求工廠
        restTemplate.setRequestFactory(clientHttpRequestFactory);
        return restTemplate;
    }
    
}

4 使用

使用到的實體類如下：

@Data
@ToString
public class TempUser implements Serializable {
    private String userName;   
    private Integer age;
}

4.1 GET請求

后臺接口代碼：

@RequestMapping("getUser")
public TempUser getUser(TempUser form) {
    TempUser tempUser = new TempUser();
    tempUser.setUserName(form.getUserName());
    tempUser.setAge(form.getAge());
    return tempUser;
}

4.1.1 普通訪問

TempUser result = restTemplate.getForObject("http://localhost:8080/cs-admin/rest/getUser?userName=張三&age=18", TempUser.class);

4.1.2 返回HTTP狀態(tài)

ResponseEntity<TempUser> responseEntity = restTemplate.getForEntity("http://localhost:8080/cs-admin/rest/getUser?userName=張三&age=18", TempUser.class);
// 獲取狀態(tài)對象
HttpStatus httpStatus = responseEntity.getStatusCode();
// 獲取狀態(tài)碼
int statusCodeValue = responseEntity.getStatusCodeValue();
// 獲取headers
HttpHeaders httpHeaders = responseEntity.getHeaders();
// 獲取body
TempUser result = responseEntity.getBody();

4.1.3 映射請求參數(shù)

Map<String, Object> paramMap = new HashMap<>();
paramMap.put("userName", "張三");
paramMap.put("age", 18);
TempUser result = restTemplate.getForObject("http://localhost:8080/cs-admin/rest/getUser?userName={userName}&age={age}", TempUser.class, paramMap);

4.2 POST請求

4.2.1 普通訪問

后臺接口代碼：

RequestMapping("getPostUser")
    public TempUser getPostUser(@RequestBody TempUser form) {
    TempUser tempUser = new TempUser();
    tempUser.setUserName(form.getUserName());
    tempUser.setAge(form.getAge());
    return tempUser;
}

（1）普通訪問接口

TempUser param = new TempUser();
param.setUserName("張三");
param.setAge(18);
TempUser result = restTemplate.postForObject("http://localhost:8080/cs-admin/rest/getPostUser", param, TempUser.class);

（2）帶HEAD訪問接口

// 請求頭信息
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.valueOf("application/json;charset=UTF-8"));
//headers.add("headParam1", "headParamValue");

// 請求體內(nèi)容
TempUser param = new TempUser();
param.setUserName("張三");
param.setAge(18);

// 組裝請求信息
HttpEntity<TempUser> httpEntity=new HttpEntity<>(param,headers);

TempUser result = restTemplate.postForObject("http://localhost:8080/cs-admin/rest/getPostUser", httpEntity, TempUser.class);

4.2.2 無請求體的訪問

僅method為post，傳參方式仍然為get的param方式

后臺接口代碼：

@RequestMapping("getPostUserNoBody")
public TempUser getPostUserNoBody(TempUser form) {
    TempUser tempUser = new TempUser();
    tempUser.setUserName(form.getUserName());
    tempUser.setAge(form.getAge());
    return tempUser;
}

訪問方式：

Map<String, Object> paramMap = new HashMap<>();
paramMap.put("userName", "張三");
paramMap.put("age", 18);
TempUser result = restTemplate.postForObject("http://localhost:8080/cs-admin/rest/getPostUserNoBody?userName={userName}&age={age}", null, TempUser.class, paramMap);
System.out.println(result);

4.3 上傳文件

后臺接口代碼：

@RequestMapping("uploadFile")
public TempUser uploadFile(HttpServletRequest request, TempUser form) {
    MultipartHttpServletRequest multipartHttpServletRequest = (MultipartHttpServletRequest) request;
    //獲取文件信息
    MultipartFile multipartFile = multipartHttpServletRequest.getFile("file");
    TempUser tempUser = new TempUser();
    if (multipartFile != null) {
        tempUser.setUserName(form.getUserName()+" "+multipartFile.getOriginalFilename());
    }
    if(form!=null){
        tempUser.setAge(form.getAge());
    }
    return tempUser;
}

訪問方式：

// 文件
FileSystemResource file=new FileSystemResource("D:\\Elasticsearch權(quán)威指南（中文版）.pdf");

// 設(shè)置請求內(nèi)容
MultiValueMap<String, Object> param=new LinkedMultiValueMap<>();
param.add("file", file);
// 其他參數(shù)
param.add("userName", "張三");
param.add("age", 18);

// 組裝請求信息
HttpEntity<MultiValueMap<String, Object>> httpEntity=new HttpEntity<>(param);

// 發(fā)送請求
TempUser result = restTemplate.postForObject("http://localhost:8080/cs-admin/rest/uploadFile", httpEntity, TempUser.class);