Java RestTemplate中几种常见的请求方式

在REST接口的设计中,利用RestTemplate进行接口测试是种常见的方法。本文主要从以下四个方面来看RestTemplate的使用:

  • GET请求
  • POST请求
  • PUT请求
  • DELETE请求

OK,开始吧。

1. 用exchange方法提交

exchange既可以执行POST方法,还可以执行GET,设置header,所以应用最为广泛

/**
 * 发送GET请求
 *
 * @param uri
 * @param params
 * @param headers
 * @return
 */
public Object doGet(String uri, Map params, HttpHeaders headers) {
  HttpEntity entity = new HttpEntity<>(params, headers);
  return restTemplate.exchange(uri, HttpMethod.GET, entity, Object.class);
}

public Object doPost(String uri, String token, Map params) {
  HttpHeaders headers = new HttpHeaders();
  headers.setContentType(MediaType.APPLICATION_JSON_UTF8);
  headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
  headers.add(AUTHORIZATION, "Bearer " + token);
  HttpEntity entity = new HttpEntity<>(params, headers);
  return restTemplate.exchange(uri, HttpMethod.POST, entity, Object.class);
} 
  

2. 用postForEntity进行提交

//  上面的代码完全一样仅需替换exchange方法
ResponseEntity response = client.postForEntity(url, requestEntity , String.class );


Map map = new HashMap<>();
map.put("name", "李四");
ResponseEntity responseEntity = restTemplate.getForEntity("http://HELLO-SERVICE/sayhello?name={name}", String.class, map);
return responseEntity.getBody();
  • 也可以前面使用name={name}这种形式,最后一个参数是一个map,map的key即为前边占位符的名字,map的value为参数值
  • getForEntity第二个参数String.class表示我希望返回的body类型是String

2.1 postForObject

HttpHeaders headers = new HttpHeaders();
headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
headers.add("Authorization", "Bearer " + token);
HttpEntity entity = new HttpEntity<>(params, headers);
Object responseEntity = client.postForObject(uri, entity, Object.class); 
  

3.PUT请求

在RestTemplate中,PUT请求可以通过put方法调用,put方法的参数和前面介绍的postForEntity方法的参数基本一致,只是put方法没有返回值而已。举一个简单的例子,如下

Book book = new Book();
book.setName("红楼梦");
restTemplate.put("http://HELLO-SERVICE/getbook3/{1}", book, 99);

4.DELETE请求

delete请求我们可以通过delete方法调用来实现,如下例子:

restTemplate.delete("http://HELLO-SERVICE/getbook4/{1}", 100);

RestTemplate能大幅简化了提交表单数据的难度,并且附带了自动转换JSON数据的功能

JSONObject param = new JSONObject();
param.put("message", '短信内容');
JSONObject item = new JSONObject();
item.put("user_mobile", mobile);
item.put("signature", "短信签名");
param.put("sms", item);

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity requestEntity = new HttpEntity(param, headers);
log.info("调用发送短信通知失败接口,requestEntity:{}", requestEntity);
ResponseEntity responseEntity = restTemplate.exchange("http://notification.test.com", HttpMethod.POST, requestEntity, JSONObject.class);
JSONObject retJson = responseEntity.getBody();
log.info("调用发送短信通知接口,返回:{}", retJson);
Integer code = (Integer) retJson.get("code");
String msg = (String) retJson.get("message");
if (code > 0) {
    throw new BaseException("调用发送短信通知失败,原因:", msg);
}

5. HttpEntity与uriVariables

在RestTemplate的使用中,HttpEntity用于传递具体的参数值,而uriVariables则用于格式化Http地址,而不是地址参数,正确的用法如下:

//  在地址中加入格式化参数path
String url = "http://localhost/mirana-ee/app/{path}";
//  准备格式化参数
Map varParams = new HashMap();
varParams.put("path", "login");
//  其他代码略
//  格式化提交地址
ResponseEntity response = client.postForEntity(url, requestEntity , String.class, varParams);

6. 关于HttpMessageConverter的说明

在网上的很多例子中,我发现很多人为了处理Payload提交,都添加了自定义的HttpMessageConverter,如下

//  完全没有必要
client.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
client.getMessageConverters().add(new StringHttpMessageConverter());

然后,经过我查看源码与调试发现,RestTemplate内置了7种HttpMessageConverter,如下:

  1. org.springframework.http.converter.ByteArrayHttpMessageConverter
  2. org.springframework.http.converter.StringHttpMessageConverter
  3. org.springframework.http.converter.ResourceHttpMessageConverter
  4. org.springframework.http.converter.xml.SourceHttpMessageConverter
  5. org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter
  6. org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter
  7. org.springframework.http.converter.json.MappingJackson2HttpMessageConverter

7. 关于表单提交与Payload提交的差异

当POST请求的请求头里设置Content-Type: application/x-www-form-urlencoded(默认), 参数在请求体以标准的Form Data的形式提交,以&符号拼接,参数格式为key=value&key=value&key=value…. 
如果使用AJAX原生POST请求,请求头里设置Content-Type:application/json,请求的参数会显示在Request Payload中,参数格式为JSON格式:{“key”:”value”,”key”:”value”…},这种方式可读性会更好。对于Payload方式,提交的内容一定要是String,且Header要设置为“application/json”,示例如下:

//  请求地址
String url = "http://localhost/mirana-ee/app/login";
RestTemplate client = new RestTemplate();
//  一定要设置header
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON_UTF8);
//  将提交的数据转换为String
//  最好通过bean注入的方式获取ObjectMapper
ObjectMapper mapper = new ObjectMapper();
Map params= new HashMap();
params.put("username", "国米");
params.put("password", "123456");
String value = mapper.writeValueAsString(params);
HttpEntity requestEntity = new HttpEntity(value, headers);
//  执行HTTP请求
ResponseEntity response = client.postForEntity(url, requestEntity , String.class );
System.out.println(response.getBody());

8.超时时间设置

SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
requestFactory.setConnectTimeout(30 * 1000);
requestFactory.setReadTimeout(30 * 1000);
restTemplate.setRequestFactory(requestFactory);

不依赖第三方库的请求类

package net.demo.my.common.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

public class HttpUtil {
    public static final String APPLICATION_JSON = "application/json";
    public static final String APPLICATION_JSON_UTF8 = "application/json;charset=UTF-8";

    /**
     * Send a get request
     *
     * @param url
     * @return response
     * @throws IOException
     */
    static public String get(String url) throws IOException {
        return get(url, null);
    }

    /**
     * Send a get request
     *
     * @param url     Url as string
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String get(String url,
                             Map headers) throws IOException {
        return fetch("GET", url, null, headers);
    }

    /**
     * Send a post request
     *
     * @param url     Url as string
     * @param body    Request body as string
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String post(String url, String body,
                              Map headers) throws IOException {
        return fetch("POST", url, body, headers);
    }

    /**
     * Send a post request
     *
     * @param url  Url as string
     * @param body Request body as string
     * @return response   Response as string
     * @throws IOException
     */
    static public String post(String url, String body) throws IOException {
        return post(url, body, null);
    }

    /**
     * Post a form with parameters
     *
     * @param url    Url as string
     * @param params map with parameters/values
     * @return response   Response as string
     * @throws IOException
     */
    static public String postForm(String url, Map params)
            throws IOException {
        return postForm(url, params, null);
    }

    /**
     * Post a form with parameters
     *
     * @param url     Url as string
     * @param params  Map with parameters/values
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String postForm(String url, Map params,
                                  Map headers) throws IOException {
        // set content type
        if (headers == null) {
            headers = new HashMap();
        }


        headers.put("Content-Type", "application/x-www-form-urlencoded");

        // parse paramet  ers
        String body = "";
        if (params != null) {
            boolean first = true;
            for (String param : params.keySet()) {
                if (first) {
                    first = false;
                } else {
                    body += "&";
                }
                String value = params.get(param);
                body += URLEncoder.encode(param, "UTF-8") + "=";
                body += URLEncoder.encode(value, "UTF-8");
            }
        }

        return post(url, body, headers);
    }

    /**
     * Send a put request
     *
     * @param url     Url as string
     * @param body    Request body as string
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String put(String url, String body,
                             Map headers) throws IOException {
        return fetch("PUT", url, body, headers);
    }

    /**
     * Send a put request
     *
     * @param url Url as string
     * @return response   Response as string
     * @throws IOException
     */
    static public String put(String url, String body) throws IOException {
        return put(url, body, null);
    }

    /**
     * Send a delete request
     *
     * @param url     Url as string
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String delete(String url,
                                Map headers) throws IOException {
        return fetch("DELETE", url, null, headers);
    }

    /**
     * Send a delete request
     *
     * @param url Url as string
     * @return response   Response as string
     * @throws IOException
     */
    static public String delete(String url) throws IOException {
        return delete(url, null);
    }

    /**
     * Append query parameters to given url
     *
     * @param url    Url as string
     * @param params Map with query parameters
     * @return url        Url with query parameters appended
     * @throws IOException
     */
    static public String appendQueryParams(String url,
                                           Map params) throws IOException {
        String fullUrl = url;
        if (params != null) {
            boolean first = (fullUrl.indexOf('?') == -1);
            for (String param : params.keySet()) {
                if (first) {
                    fullUrl += '?';
                    first = false;
                } else {
                    fullUrl += '&';
                }
                String value = params.get(param);
                fullUrl += URLEncoder.encode(param, "UTF-8") + '=';
                fullUrl += URLEncoder.encode(value, "UTF-8");
            }
        }

        return fullUrl;
    }

    /**
     * Retrieve the query parameters from given url
     *
     * @param url Url containing query parameters
     * @return params     Map with query parameters
     * @throws IOException
     */
    static public Map getQueryParams(String url)
            throws IOException {
        Map params = new HashMap();

        int start = url.indexOf('?');
        while (start != -1) {
            // read parameter name
            int equals = url.indexOf('=', start);
            String param = "";
            if (equals != -1) {
                param = url.substring(start + 1, equals);
            } else {
                param = url.substring(start + 1);
            }

            // read parameter value
            String value = "";
            if (equals != -1) {
                start = url.indexOf('&', equals);
                if (start != -1) {
                    value = url.substring(equals + 1, start);
                } else {
                    value = url.substring(equals + 1);
                }
            }

            params.put(URLDecoder.decode(param, "UTF-8"),
                    URLDecoder.decode(value, "UTF-8"));
        }

        return params;
    }

    /**
     * Returns the url without query parameters
     *
     * @param url Url containing query parameters
     * @return url        Url without query parameters
     * @throws IOException
     */
    static public String removeQueryParams(String url)
            throws IOException {
        int q = url.indexOf('?');
        if (q != -1) {
            return url.substring(0, q);
        } else {
            return url;
        }
    }

    /**
     * Send a request
     *
     * @param method  HTTP method, for example "GET" or "POST"
     * @param url     Url as string
     * @param body    Request body as string
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String fetch(String method, String url, String body,
                               Map headers) throws IOException {
        // connection
        URL u = new URL(url);
        HttpURLConnection conn = (HttpURLConnection) u.openConnection();
        conn.setConnectTimeout(10000);
        conn.setReadTimeout(10000);

        // method
        if (method != null) {
            conn.setRequestMethod(method);
        }

        // headers
        if (headers != null) {
            for (String key : headers.keySet()) {
                conn.addRequestProperty(key, headers.get(key));
            }
        }

        // body
        if (body != null) {
            conn.setDoOutput(true);
            OutputStream os = conn.getOutputStream();
            os.write(body.getBytes());
            os.flush();
            os.close();
        }

        // response
        InputStream is = conn.getInputStream();
        String response = streamToString(is);
        is.close();

        // handle redirects
        if (conn.getResponseCode() == 301) {
            String location = conn.getHeaderField("Location");
            return fetch(method, location, body, headers);
        }

        return response;
    }

    /**
     * Read an input stream into a string
     *
     * @param in
     * @return
     * @throws IOException
     */
    static public String streamToString(InputStream in) throws IOException {
        StringBuffer out = new StringBuffer();
        byte[] b = new byte[4096];
        for (int n; (n = in.read(b)) != -1; ) {
            out.append(new String(b, 0, n));
        }
        return out.toString();
    }
}

调用例子:

String url = "https://tcc.taobao.com/cc/json/mobile_tel_segment.htm";
Map param = new HashMap<>();
param.put("tel", mobileNum);
String fullUrl = HttpUtil.appendQueryParams(url, param);
String res = HttpUtil.get(fullUrl);

Map headers = new HashMap<>();
headers.put("content-type", HttpUtil.APPLICATION_JSON_UTF8);
Map param = new HashMap<>();
param.put("dataId", called);
String body = JSON.toJSONString(param);
String retJson = HttpUtil.post(url, body, headers);

基于RestTemplate的封装类

import com.alibaba.fastjson.JSON;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections.MapUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.*;
import org.springframework.stereotype.Component;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Map;

@Component
@Slf4j
public class HttpClientService {
    public static final String AUTHORIZATION = "Authorization";
    @Autowired
    private RestTemplate customRestTemplate;

    public  T doPost(final String uri, final Map params, Class cls, String token) {
        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + uri);
            log.info("请求参数:" + JSON.toJSONString(params));
        }
        final HttpHeaders headers = new HttpHeaders();
        headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_UTF8_VALUE);
        headers.add("keepalive_timeout", "30s");
        final HttpEntity> entity = new HttpEntity<>(params, headers);
        return customRestTemplate.postForObject(uri, entity, cls);
    }

    public  T doPostUrlencoded(final String uri, final MultiValueMap params, Class cls, String token) {
        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + uri);
            log.info("请求参数:" + JSON.toJSONString(params));
        }
        final HttpHeaders headers = new HttpHeaders();
        headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_FORM_URLENCODED_VALUE);
        headers.add("keepalive_timeout", "30s");
        final HttpEntity> entity = new HttpEntity<>(params, headers);
        return customRestTemplate.postForObject(uri, entity, cls);
    }

    public  T doFormDataPost(final String uri, final Object params, Class cls, String token) {
        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + uri);
            log.info("请求参数:" + JSON.toJSONString(params));
        }
        final HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.MULTIPART_FORM_DATA);
        final HttpEntity entity = new HttpEntity<>(params, headers);
        return customRestTemplate.postForObject(uri, entity, cls);
    }

    public  T doPostByToken(final String uri, final Object params, Class cls, String token) {
        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + uri);
            log.info("请求参数:" + JSON.toJSONString(params));
        }
        final HttpHeaders headers = new HttpHeaders();
        headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
        headers.add(AUTHORIZATION, "Bearer " + token);
        final HttpEntity entity = new HttpEntity<>(params, headers);
        return customRestTemplate.postForObject(uri, entity, cls);
    }

    public  T doPatchByToken(final String uri, final Object params, Class cls, String token) {
        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + uri);
            log.info("请求参数:" + JSON.toJSONString(params));
        }
        final HttpHeaders headers = new HttpHeaders();
        headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
        headers.add(AUTHORIZATION, "Bearer " + token);
        final HttpEntity entity = new HttpEntity<>(params, headers);
        return customRestTemplate.patchForObject(uri, entity, cls);
    }

    public  T doDeleteByToken(final String uri, final Object params, Class cls, String token) {
        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + uri);
            log.info("请求参数:" + JSON.toJSONString(params));
        }
        final HttpHeaders headers = new HttpHeaders();
        headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
        headers.add(AUTHORIZATION, "Bearer " + token);
        final HttpEntity entity = new HttpEntity<>(params, headers);
        ResponseEntity resultEntity = customRestTemplate.exchange(uri, HttpMethod.DELETE, entity, cls);
        return resultEntity.getBody();
    }

    public  T doGet(final String uri, final Map params, Class cls) {
        final StringBuilder uriBuilder = new StringBuilder(uri);
        if (!uri.contains("?")) {
            uriBuilder.append("?");
        }
        uriBuilder.append("t=").append(System.currentTimeMillis());
        if (MapUtils.isNotEmpty(params)) {
            params.forEach((key, value) -> {
                uriBuilder.append("&");
                uriBuilder.append(key).append("=");
                try {
                    uriBuilder.append(URLEncoder.encode(String.valueOf(value), "UTF-8"));
                } catch (UnsupportedEncodingException e) {
                    log.info(e.getCause().getMessage());
                }
            });
        }

        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + uriBuilder.toString());
        }
        return customRestTemplate.getForObject(uriBuilder.toString(), cls);
    }

    public  T doGet(final String uri, String param, Class cls) {
        final String url = uri + "/" + param;
        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + url);
        }
        return customRestTemplate.getForObject(url, cls);
    }

    public  T doGet(final String uri, Class cls) {
        if (log.isInfoEnabled()) {
            log.info("请求 URL:" + uri);
        }
        return customRestTemplate.getForObject(uri, cls);
    }
}
 
  

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