What are the annotations used by SpringBoot to receive parameters?-javaTutorial-php.cn

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

What are the annotations used by SpringBoot to receive parameters?

Create src\main\resources\ static\index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>index</title>
</head>
<body>
<h2>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>

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@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";
    }
}

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What are the annotations used by SpringBoot to receive parameters?

@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/>

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√ 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";
}

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What are the annotations used by SpringBoot to receive parameters?

@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/>

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√ 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";
}

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@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/>

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√ 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";
}

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What are the annotations used by SpringBoot to receive parameters?

@RequestBody Use

Demo Use @RequestBody, modify ParameterController.java, complete the test

√ Modify index.html

<hr/>
<h2>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>

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√ 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";
}

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@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>

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√ 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";
    }
}

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What are the annotations used by SpringBoot to receive parameters?

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, ServletResponse

2. 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";
}

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What are the annotations used by SpringBoot to receive parameters?

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

2. Custom object parameters - application example

1. Requirement description: Demonstrate the use of custom object parameters, complete automatic encapsulation and type conversion

What are the annotations used by SpringBoot to receive parameters?

2. Code implementation

1. Create src\main\resources\static\save.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>添加妖怪</title></head>
<body><h2>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>

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2. Modify src\main\java\com\llp\springboot\controller\ ParameterController.java

@PostMapping("/savemonster")
public String saveMonster(Monster monster) {
    System.out.println("monster= " + monster);
    return "success";
}

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