What are the annotations used by SpringBoot to receive parameters?
1. Basic introduction
SpringBoot will use relevant annotations when receiving data/parameters submitted by the client
Detailed explanation of @PathVariable, @RequestHeader, @ModelAttribute, @RequestParam, @MatrixVariable, @CookieValue , @RequestBody
2. Receive parameter-related annotation application examples
1. Requirements: Demonstrate various ways to submit data/parameters to the server, and how the server uses annotations to receive
2 .Application example demonstration
Requirements: Demonstrate various ways to submit data/parameters to the server, and how the server uses annotations to receive
Create src\main\resources\ static\index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>index</title>
</head>
<body>
<h2 id="hello-nbsp-llp">hello, llp</h2>
基本注解：
<hr/>
<a href="/monster/200/jack" rel="external nofollow" >@PathVariable-路径变量 monster/200/jack</a><br/><br/>
</body>
</html>@PathVariable use
Demonstrate the use of @PathVariable, create src\main\java\com\llp\springboot\controller\ParameterController.java, and complete the test
@RestController
public class ParameterController {
/**
* /monster/{id}/{name} 解读
* 1. /monster/{id}/{name} 构成完整请求路径
* 2. {id} {name} 就是占位变量
* 3. @PathVariable("name"): 这里name 和{name} 命名保持一致
* 4. String name_ 这里自定义，和{name}命名无关
* 5. @PathVariable Map<String, String> map 把所有传递的值传入map
* 6. 可以看下@PathVariable源码
*/
@GetMapping("/monster/{id}/{name}")
public String pathVariable(@PathVariable("id") Integer id,
@PathVariable("name") String name,
@PathVariable Map<String, String> map) {
System.out.println("id-" + id);
System.out.println("name-" + name);
System.out.println("map-" + map);
return "success";
}
}
@RequestHeader Use
Demonstrate the use of @RequestHeader, modify ParameterController.java, complete the test
√ Modify index.html
<a href="/requestHeader" rel="external nofollow" >@RequestHeader-获取Http请求头 </a><br/><br/>
√ Modify ParameterController.java
/**
* @RequestHeader("Host") 获取http请求头的 host信息
* @RequestHeader Map<String, String> header: 获取到http请求的所有信息
*/
@GetMapping("/requestHeader")
public String requestHeader(@RequestHeader("host") String host,
@RequestHeader Map<String, String> header,
@RequestHeader("accept") String accept) {
System.out.println("host-" + host);
System.out.println("header-" + header);
System.out.println("accept-" + accept);
return "success";
}
@RequestParam Use
Demonstrate the use of @RequestParam, modify ParameterController.java, and complete the test
√ Modify index.html
<a href="/hi?name=wukong&fruit=apple&fruit=pear&id=300&address=北京" rel="external nofollow" >@RequestParam-获取请求参数</a><br/><br/>
√ Modify ParameterController.java
/**
* @param username wukong
* @param fruits List<String> fruits 接收集合 [apple, pear]
* @param paras Map<String, String> paras 如果我们希望将所有的请求参数的值都获取到，
* 可以通过@RequestParam Map<String, String> paras这种方式
* 一次性的接收所有的请求参数 {name=wukong, fruit=apple, id=300, address=北京}
* 如果接收的某个参数中有多个之值比如这里fruits是一个集合，从map中只能拿到一个
* 可以理解map底层会将相同的key的value值进行覆盖
* @return
* @RequestParam
*/
@GetMapping("/hi")
public String hi(@RequestParam(value = "name") String username,
@RequestParam("fruit") List<String> fruits,
@RequestParam Map<String, String> paras) {
//username-wukong
System.out.println("username-" + username);
//fruit-[apple, pear]
System.out.println("fruit-" + fruits);
//paras-{name=wukong, fruit=apple, id=300, address=北京}
System.out.println("paras-" + paras);
return "success";
}@CookieValue use
Demonstrate the use of @CookieValue, modify ParameterController.java, and complete the test
√ Modify index.html
<a href="/cookie" rel="external nofollow" >@CookieValue-获取cookie值</a><br/><br/>
√ Modify ParameterController.java
/**
* 因为我的浏览器目前没有cookie，我们可以自己设置cookie[技巧还是非常有用]
* 如果要测试，可以先写一个方法，在浏览器创建对应的cookie
* 说明 1. value = "cookie_key" 表示接收名字为 cookie_key的cookie
* 2. 如果浏览器携带来对应的cookie , 那么 后面的参数是String ,则接收到的是对应对value
* 3. 后面的参数是Cookie ,则接收到的是封装好的对应的cookie
*/
@GetMapping("/cookie")
public String cookie(@CookieValue(value = "cookie_key", required = false) String cookie_value,
HttpServletRequest request,
@CookieValue(value = "username", required = false) Cookie cookie) {
System.out.println("cookie_value-" + cookie_value);
if (cookie != null) {
System.out.println("username-" + cookie.getName() + "-" + cookie.getValue());
}
System.out.println("-------------------------");
Cookie[] cookies = request.getCookies();
for (Cookie cookie1 : cookies) {
System.out.println(cookie1.getName() + "=>" + cookie1.getValue());
}
return "success";
}
@RequestBody Use
Demo Use @RequestBody, modify ParameterController.java, complete the test
√ Modify index.html
<hr/>
<h2 id="测试-RequestBody获取数据-nbsp-获取POST请求体">测试@RequestBody获取数据: 获取POST请求体</h2>
<form action="/save" method="post">
姓名: <input name="name"/> <br>
年龄: <input name="age"/> <br/>
<input type="submit" value="提交"/>
</form>√ Modify ParameterController.java
/**
* @RequestBody 是整体取出Post请求内容
*/
@PostMapping("/save")
public String postMethod(@RequestBody String content) {
System.out.println("content-" + content);
return "success";
}@RequestAttribute and @SessionAttribute use
Demonstrate the use of @RequestAttribute @SessionAttribute, create com/hspedu/web/controller/RequestController.java, complete the test
√ Modify index.html
<a href="/login" rel="external nofollow" >@RequestAttribute、@SessionAttribute-获取request域、session属性-</a>
√ Create RequestController .java
@GetMapping("/login")
public String login(HttpServletRequest request) {
request.setAttribute("user", "llp");
//向session中添加数据
request.getSession().setAttribute("website", "http://www.baidu.com");
//这里需要使用forward关键字，如果不适用则会走视图解析器，这
//里视图解析器前缀配置的是/ 后缀配置的.html ---> /ok.html
//而请求转发在服务器端执行，/被解析成 ip:port/工程路径
//进而最终得到的完整路径是 ip:port/工程路径/ok.html
//但是我们这里希望访问的是 ip:port/工程路径/ok这个请求路径
//因此这里手动的设置forward:/ok ，底层会根据我们设置的路径进行请求转发
return "forward:/ok";
}
@GetMapping("ok")
//返回字符串，不走视图解析器
@ResponseBody
public String ok(@RequestAttribute(value = "user", required = false) String username,
@SessionAttribute(value = "website",required = false) String website, HttpServletRequest request) {
System.out.println("username= " + username);
System.out.println("通过servlet api 获取 username-" + request.getAttribute("user"));
System.out.println("website = " + website);
System.out.println("通过servlet api 获取 website-"+request.getSession().getAttribute("website"));
return "success";
}
}
3. Complex parameters
1. Basic introduction
In development, SpringBoot is When responding to client requests, complex parameters
Map, Model, Errors/BindingResult, RedirectAttributes, ServletResponse, SessionStatus, UriComponentsBuilder, ServletUriComponentsBuilder, HttpSession
- are also supported.
Map and Model data will be placed in the request field, and the underlying request.setAttribute()
RedirectAttributes redirects carry data
2 .Complex parameter application examples
#1. Description: Demonstrates the use of complex parameters, focusing on: Map, Model, ServletResponse2. Code implementation//响应一个注册请求
@GetMapping("/register")
public String register(Map<String,Object> map,
Model model,
HttpServletResponse response) {
//如果一个注册请求,会将注册数据封装到map或者model
//map中的数据和model的数据，会被放入到request域中
map.put("user","llp");
map.put("job","码农");
model.addAttribute("sal", 2500);
//一会我们再测试response使用
//我们演示创建cookie,并通过response 添加到浏览器/客户端
Cookie cookie = new Cookie("email", "123@sohu.com");
response.addCookie(cookie);
//请求转发
return "forward:/registerOk";
}
@ResponseBody
@GetMapping("/registerOk")
public String registerOk(HttpServletRequest request) {
System.out.println("user-" + request.getAttribute("user"));
System.out.println("job-" + request.getAttribute("job"));
System.out.println("sal-" + request.getAttribute("sal"));
return "success";
}
4. Custom object parameters - automatic encapsulation 1. Basic introduction - During development, SpringBoot responds to client requests , also supports custom object parameters
- Complete automatic type conversion and formatting
- Supports cascade encapsulation
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>添加妖怪</title></head>
<body><h2 id="添加妖怪-坐骑-测试封装-nbsp-POJO">添加妖怪-坐骑[测试封装 POJO；]</h2>
<form action="/savemonster" method="post">
编号： <input name="id" value="100"><br/>
姓名： <input name="name" value="牛魔王"/><br/>
年龄： <input name="age" value="120"/> <br/>
婚否： <input name="isMarried" value="true"/> <br/>
生日： <input name="birth" value="2000/11/11"/> <br/>
<!--注意这里car对象是monster的属性，给对象属性赋值时需要以对象名.字段名的方式-->
坐骑：<input name="car.name" value="法拉利"/><br/>
价格：<input name="car.price" value="99999.9"/>
<input type="submit" value="保存"/>
</form>
</body>
</html>@PostMapping("/savemonster")
public String saveMonster(Monster monster) {
System.out.println("monster= " + monster);
return "success";
}
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