RestTemplate发送HTTP请求

Spring 中的 RestTemplate 可以很方便的发送HTTP请求，来看看如何使用

RestTemplate 发送 GET 请求

RestAPI - 通过@RequestParam接收参数的GET接口

@RequestMapping(value = "accounts/filter", method = RequestMethod.GET)
public Account filter(@RequestParam String name, @RequestParam Integer age) {
    return new Account(new Random().nextLong(), name, age, "********");
}

RestTemplate Demo

/** * 使用 RestTemplate 发送 GET 请求 * RestTemplate 发送 GET 请求时，如果需要传入参数，需要以示例方法 url 的方式传入 * RestTemplate有两组方法发送 Get 请求 * <code> * restTemplate.getForObject(String url, Class responseType, Map uriVariables)<br/> * restTemplate.getForEntity(String url, Class responseType, Map uriVariables)<br/> * </code> * restTemplate.getForObject是对restTemplate.getForEntity的简化，<br/> * 通过restTemplate.getForEntity，我们可以获取HttpStatus的相关信息并加以使用.<br/> * 如果我们不关心 HttpStatus，那么使用 restTemplate.getForObject() 即可. */
@Test
public void getMethodTest() {
    // http://ip:port/project-name/accounts/filter
    String url = "http://192.168.1.121:9001/rest-server/accounts/filter?name={name}&age={age}";
    RestTemplate restTemplate = new RestTemplate();
    Map<String, Object> params = new HashMap<>();
    params.put("age", "26");
    params.put("name", "lee");
    Account account = restTemplate.getForObject(url, Account.class, params);
    System.out.println(account);
    // 上面 2 行等价于下面 5 行
    /*ResponseEntity<Account> responseEntity = restTemplate.getForEntity(url, Account.class, params); if (responseEntity.getStatusCode().is2xxSuccessful()) { Account account1 = responseEntity.getBody(); System.out.println(account1); }*/
}

RestAPI - 通过@PathVariable提取url变量的GET接口

@RequestMapping(value = "accounts/{id}", method = RequestMethod.GET)
public Account get(@PathVariable("id") Long id, @RequestParam String name) {
    return new Account(id, name, 18, "!@#$%^&*");
}

RestTemplate Demo

@Test
public void getMethodTest2() {
    String url = "http://192.168.1.121:9001/rest-server/accounts/{id}?name={name}";
    RestTemplate restTemplate = new RestTemplate();
    Map<String, Object> params = new HashMap<>();
    params.put("id", "100001");
    params.put("name", "libai");
    Account account = restTemplate.getForObject(url, Account.class, params);
    Assert.assertEquals(account.toString(), "Account{id=100001, age=18, name='libai', pwd='!@#$%^&*'}");
}

使用 RestTemplate 发送 POST 请求

RestAPI - 使用@RequestBody接收请求参数的POST接口

@RequestMapping(value = "accounts", method = RequestMethod.POST)
public Account create(@RequestBody Account account) {
    return account;
}

RestTemplate Demo

/** * 使用 RestTemplate 发送 POST 请求<br/> * 请求接口：{@link RestServer#create(Account)}<br/> * <br/> * 根据接口{@link RestServer#create(Account)}的要求，我们需要使用Payload提交方式来提交数据<br/> * Payload提交方式区别于Form提交方式<br/> * Form提交方式提交的数据，服务端可以通过{@link HttpServletRequest#getParameter(String)}方法获取，<br/> * 体现在SpringMVC框架中，即数据参数通过 {@link org.springframework.web.bind.annotation.RequestParam} 注解绑定获取<br/> * Payload提交方式提交的数据，服务端可以通过{@link HttpServletRequest#getInputStream()}方法获取，<br/> * 体现在SpringMVC框架中，即数据参数通过 {@link org.springframework.web.bind.annotation.RequestBody} 注解绑定获取<br/> * <br/> * RestTemplate 默认使用 Payload 方式提交数据，数据的格式是 json。<br/> * 即本示例中 <code>params</code> 会被格式化成 json 格式数据，并放在request body中发送给服务端 */
@Test
public void postMethodTest() {
    String url = "http://192.168.1.121:9001/rest-server/accounts";
    RestTemplate restTemplate = new RestTemplate();
    Map<String, Object> params = new HashMap<>();
    params.put("id", "100001");
    params.put("name", "李白");
    params.put("age", "100001");
    params.put("pwd", "&*()#$%^");
    Account account = restTemplate.postForObject(url, params, Account.class);
    System.out.println(account);
}

RestAPI - 使用@RequestParam接收请求参数的POST接口

@RequestMapping(value = "accounts/create", method = RequestMethod.POST)
public Account create(@RequestParam Long id,
                        @RequestParam String name,
                      @RequestParam Integer age,
                      @RequestParam String pwd) {
    return new Account(id, name, age, pwd);
}

RestTemplate Demo

/** * 使用 RestTemplate 发送 POST 请求<br/> * 请求接口：{@link RestServer#create(Long, String, Integer, String)}<br/> * <br/> * 根据接口 {@link RestServer#create(Long, String, Integer, String)}的要求，我们需要使用Form提交方式来提交数据<br/> * RestTemplate 默认使用 Payload 方式提交数据，想要使用Form方式提交，需要通过 HttpHeaders 设置<br/> * 另外，多个参数需要使用{@link LinkedMultiValueMap}来封装 */
@Test
public void postMethodTest2() {
    String url = "http://192.168.1.121:9001/rest-server/accounts/create";
    RestTemplate restTemplate = new RestTemplate();
    // 此处不能换成 HashMap
    MultiValueMap<String, Object> params = new LinkedMultiValueMap<>();
    params.add("id", "100001");
    params.add("name", "杜甫");
    params.add("age", "100001");
    params.add("pwd", "&*()#$%^");
    // 通过 HttpHeaders 设置Form方式提交
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
    HttpEntity<MultiValueMap<String, Object>> httpEntity = new HttpEntity<>(params, headers);
    Account account = restTemplate.postForObject(url, httpEntity, Account.class);
    System.out.println(account);
}

使用 RestTemplate 发送带有 HttpHeader 信息的请求

RestAPI - 使用@RequestHeader获取请求头信息的POST接口

@RequestMapping(value = "accounts/authorization", method = RequestMethod.POST)
public Account create(@RequestHeader("authorization") String authorization,
                      @RequestHeader("token") String token,
                      @RequestBody Account account) {
    if (authorization.equals("12345678") && token.equals("bce235emn97jjf00")) {
        return account;
    }
    return new Account();
}

RestTemplate Demo

@Test
public void httpHeaderTest() {
    String url = "http://192.168.1.121:9001/rest-server/accounts/authorization";
    HttpHeaders headers = new HttpHeaders();
    headers.add("authorization", "12345678");
    headers.add("token", "bce235emn97jjf00");

    Map<String, Object> params = new HashMap<>();
    params.put("id", "100001");
    params.put("name", "李白");
    params.put("age", "100001");
    params.put("pwd", "&*()#$%^");

    HttpEntity<Map<String, Object>> httpEntity = new HttpEntity<>(params, headers);
    RestTemplate restTemplate = new RestTemplate();
    Account account = restTemplate.postForObject(url, httpEntity, Account.class);
    System.out.println(account.toString());
}

使用 RestTemplate 进行文件上传

使用@RequestPart接收文件上传请求的POST接口

@RequestMapping(value = "accounts/logo", method = RequestMethod.POST)
public boolean changeLogo(@RequestPart("logo") MultipartFile file, 
    @RequestParam(value = "nickname", required = false) String nickname) throws IOException {
    String fileName = file.getOriginalFilename();
    File f = new File(fileName);
    file.transferTo(f);
    System.out.println(f.getAbsolutePath());
    return true;
}

RestTemplate Demo

@Test
public void uploadImgTest() {
    String url = "http://192.168.1.121:9001/rest-server/accounts/logo";
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.MULTIPART_FORM_DATA);

    MultiValueMap<String, Object> params = new LinkedMultiValueMap<>();
    params.add("logo", new FileSystemResource("C:\\Users\\lixiangke\\Pictures\\Saved Pictures\\jdsadh.jpg"));
    params.add("nickname", "nick");

    HttpEntity<MultiValueMap<String, Object>> httpEntity = new HttpEntity<>(params, headers);
    RestTemplate restTemplate = new RestTemplate();
    String str = restTemplate.postForObject(url, httpEntity, String.class);
    System.out.println(str);
}

Account.java

package com.springboot.web.rest_template;

/** * @author lixiangke * @date 2017/12/25 */
public class Account {
    private Long id;
    private int age;
    private String name;
    private String pwd;

    public Account() {
    }

    public Account(Long id, String name, int age, String pwd) {
        this.id = id;
        this.age = age;
        this.name = name;
        this.pwd = pwd;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", age=" + age +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}