十分钟学会 RestTemplate 的简单使用

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文章目录

前言

本篇主要记录工作上遇到的 RestTemplate 的基本使用，它是 Spring 提供的用来访问 Rest 服务的客户端，RestTmplate 提供了很多便捷的方法，可以大大提供开发效率。

一、不带参数的默认 headers 的 Get 请求

String url = "http://ip:port/testGetMethod";
String str = restTemplate.getForObject(url , String.class);

二、带参数的默认 headers 的 Get 请求

String url = "http://ip:port/testGetMethod/{talk}/{name}"; 
//或者testGetMethod/{1}/{2} {里面的参数无所谓，只是根据下面的Object... uriVariables 逐一绑定到上面{} 中去的}
String str = restTemplate.getForObject(url , String.class,"hello" , "johnny");

或者

String url = "http://ip:port/testGetMethod/{talk}/{name}";
Map<String,String> map = new HashMap<>(); 
map.put("talk" , "hello"); 
map.put("name" , "johnny"); 
String str = restTemplate.getForObject(url , String.class,map);

三、带参数的 Get 下载文件请求（下载 pdf 文件为例，参数直接拼接到 url）

public ResponseEntity<byte[]> requestSendDownloadFile(String url){
        HttpHeaders headers = new HttpHeaders();
        headers.set(HttpHeaders.ACCEPT_CHARSET, StandardCharsets.UTF_8.toString());

        List list = new ArrayList<>();
        list.add(MediaType.valueOf("application/pdf"));
        headers.setAccept(list);

        headers = gap(headers);

        HttpEntity<byte[]> entity = new HttpEntity<>(headers);
        ResponseEntity<byte[]> rsp = restTemplate.exchange(
                url,
                HttpMethod.GET,
                entity,
                byte[].class);

        log.info("文件下载请求结果状态码：" + rsp.getStatusCode());
        log.info("文件下载请求结果文件名：" + rsp.getHeaders().getContentDisposition().getFilename());
        log.info("文件下载请求结果内容:" + rsp.getBody());
        return rsp;
    }

四、带参数的 Post 请求

public ResponseEntity<Object> requestSend(String url, Map<String, String> requestParm) {
        HttpHeaders headers = new HttpHeaders();
        headers.add(HttpHeaders.CONTENT_TYPE, "application/x-www-form-urlencoded;charset=UTF-8");
        headers.set(HttpHeaders.ACCEPT_CHARSET, StandardCharsets.UTF_8.toString());

        headers = gap(headers);

        MultiValueMap<String, Object> requestParmMap =new LinkedMultiValueMap<>();
        //循环转换
        Iterator it =requestParm.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry<String, Object> entry = (Map.Entry<String, Object>) it.next();
            requestParmMap.add(entry.getKey(), entry.getValue());
        }

        HttpEntity<MultiValueMap> httpEntity = new HttpEntity<>(requestParmMap, headers);
        log.info("url:" + url + ",httpEntity:" + JSON.toJSONString(httpEntity));
        return restTemplate.postForEntity(url, httpEntity, Object.class);
    }

五、发起整段 json 参数的 Post 请求

public ResponseEntity<Object> requestSendPost(String url, Map<String, Object> requestParm) {
        HttpHeaders headers = new HttpHeaders();
        headers.add(HttpHeaders.CONTENT_TYPE, "application/json;charset=UTF-8");
        headers.set(HttpHeaders.ACCEPT_CHARSET, StandardCharsets.UTF_8.toString());

        headers = gap(headers);

        HttpEntity<Map<String, Object>> httpEntity = new HttpEntity<>(requestParm, headers);

        log.info("url:" + url + ",httpEntity:" + JSON.toJSONString(httpEntity));
        return restTemplate.postForEntity(url, httpEntity, Object.class);
    }

附录：

补充上面示例代码中处理 headers 部分的 gap 方法

public HttpHeaders gap(HttpHeaders headers){
        log.info("into intercept ,paasid = {},paastoken = {}",passId,passToken);
        // 加入自定义字段
        ZoneOffset zoneOffset=ZoneOffset.ofHours(8);
        //初始化LocalDateTime对象
        LocalDateTime localDateTime=LocalDateTime.now();
        //获取LocalDateTime对象对应时区的Unix时间戳
        long x_tif_timeStamp = localDateTime.toEpochSecond(zoneOffset);
        String x_tif_nonce = UUID.randomUUID().toString();
        String plain = x_tif_timeStamp + passToken + x_tif_nonce + x_tif_timeStamp;
        log.info("into intercept ,plain = {}",plain);
        String x_tif_signature = encrypt(plain,"SHA-256");
        headers.add("x-tif-paasid", passId);
        headers.add("x-tif-signature", x_tif_signature);
        headers.add("x-tif-timestamp", Long.toString(x_tif_timeStamp));
        headers.add("x-tif-nonce", x_tif_nonce);
        return headers;
    /**
     * 软摘要算法
     *
     * @param plain 需要摘要的数据
     * @return base64摘要的值
     */
    public static String sm3(String plain) {
        byte[] md = new byte[32];
        byte[] psw = null;
        try {
            psw = plain.getBytes("utf-8");
        } catch (Exception e) {
            e.printStackTrace();
        }

        SM3Digest sm3 = new SM3Digest();
        sm3.update(psw, 0, psw.length);
        sm3.doFinal(md, 0);
        System.out.println(Hex.toHexString(md));
        return Base64.getEncoder().encodeToString(md);
    }

    private static String encrypt(String inputText, String algorithmName)
    {
        if (inputText == null || "".equals(inputText.trim()))
        {
            throw new IllegalArgumentException("请输入要加密的内容");
        }
        if (algorithmName == null || "".equals(algorithmName.trim()))
        {
            algorithmName = "md5";
        }
        String encryptText = null;
        try
        {
            MessageDigest m = MessageDigest.getInstance(algorithmName);
            m.update(inputText.getBytes("UTF8"));
            byte s[] = m.digest();
            // m.digest(inputText.getBytes("UTF8"));
            return hex(s);
        } catch (Exception e){

        }
        return encryptText;
    }

    /**
     * 返回十六进制字符串
     *
     * @param arr
     * @return
     */
    private static String hex(byte[] arr)
    {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < arr.length; ++i)
        {
            sb.append(Integer.toHexString((arr[i] & 0xFF) | 0x100).substring(1, 3));
        }
        return sb.toString();
    }
    }