SpringMVC 學習（三）——對映請求引數 & 請求引數
阿新 • • 發佈：2018-12-25
請求處理方法籤名
•Spring MVC 通過分析處理方法的籤名，將 HTTP 請求信 息綁定到處理方法的相應人蔘中。
•Spring MVC 對控制器處理方法籤名的限制是很寬鬆的， 幾乎可以按喜歡的任何方式對方法進行籤名。
•必要時可以對方法及方法入參標注相應的註解（
@PathVariable
、@RequestParam、@RequestHeader 等）、Spring
MVC 框架會將 HTTP 請求的資訊綁定到相應的方法入參 中，並根據方法的返回值類型做出相應的後續處理。
使用 @RequestParam 綁定請求引數值
•在處理方法入參處使用 @RequestParam 可以把請求參 數傳遞給請求方法
–value：引數名
–required：是否必須。默認為 true, 表示請求引數中必須包含對應 的引數，若不存在，將丟擲異常
使用 @RequestHeader 綁定請求報頭的屬性值
•請求頭包含了若干個屬性，服務器可據此獲知客戶端的信 息，通過 @RequestHeader 即可將請求頭中的屬性值綁 定到處理方法的入參中
使用 @CookieValue 綁定請求中的 Cookie 值
•@CookieValue 可讓處理方法入參綁定某個 Cookie 值
使用 POJO 對象綁定請求引數值
•Spring MVC 會按請求引數名和 POJO 屬性名進行自動匹 配，自動為該對象填充屬性值。支援級聯屬性。
如：dept.deptId、dept.address.tel 等
使用 Servlet API 作為入參
MVC 的 Handler 方法可以接受哪些 ServletAPI 類型的引數
•HttpServletRequest
•HttpServletResponse
•HttpSession
•java.security.Principal
•Locale
•InputStream
•OutputStream
•Reader
•Writer
程式碼示例：
address.java
package com.xuehj.springmvc.entity;
/**
* @program: SpringMVC-1
* @description: TODO
* @author: Mr.Xue
* @create: 2018-12-24 19:13
**/
public class Address {
private String province;
private String city;
public String getProvince() {
return province;
}
public void setProvince(String province) {
this.province = province;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
@Override
public String toString() {
return "Address [province=" + province + ", city=" + city + "]";
}
}user.java
package com.xuehj.springmvc.entity;
/**
* @program: SpringMVC-1
* @description: TODO
* @author: Mr.Xue
* @create: 2018-12-24 19:13
**/
public class User {
private Integer id;
private String username;
private String password;
private String email;
private int age;
private Address address;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", email='" + email + '\'' +
", age=" + age +
", address=" + address +
'}';
}
}test.java
package com.xuehj.springmvc.handler;
import com.xuehj.springmvc.entity.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.CookieValue;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.Writer;
/**
* @program: SpringMVC
* @description: TODO
* @author: Mr.Xue
* @create: 2018-12-24 09:36
**/
@Controller
@RequestMapping("/view")
public class HelloWorld {
/**
* @RequestParam 來對映請求引數.
* value 值即請求引數的引數名
* required 該引數是否必須. 預設為 true
* defaultValue 請求引數的預設值
* int age 改成 Integer 比較好，有 null 值
*/
@RequestMapping(value = "/testRequestParam")
public String testRequestParam(
@RequestParam(value = "username") String un,
@RequestParam(value = "age", required = false, defaultValue = "0") int age) {
System.out.println("testRequestParam, username: " + un + ", age: "
+ age);
return "success.jsp";
}
/**
* 瞭解:
* 對映請求頭資訊 用法同 @RequestParam
*/
@RequestMapping("/testRequestHeader")
public String testRequestHeader(
@RequestHeader(value = "Accept-Language") String al) {
System.out.println("testRequestHeader, Accept-Language: " + al);
return "success.jsp";
}
/**
* 瞭解:
*
* @CookieValue: 對映一個 Cookie 值. 屬性同 @RequestParam
*/
@RequestMapping("/testCookieValue")
public String testCookieValue(@CookieValue("JSESSIONID") String sessionId) {
System.out.println("testCookieValue: sessionId: " + sessionId);
return "success.jsp";
}
/**
* Spring MVC 會按請求引數名和 POJO 屬性名進行自動匹配，
* 自動為該物件填充屬性值。支援級聯屬性。
* 如：dept.deptId、dept.address.tel 等
*/
@RequestMapping("/testPojo")
public String testPojo(User user) {
System.out.println("testPojo: " + user);
return "success.jsp";
}
/**
* 可以使用 Serlvet 原生的 API 作為目標方法的引數 具體支援以下型別
* <p>
* HttpServletRequest
* HttpServletResponse
* HttpSession
* java.security.Principal
* Locale InputStream
* OutputStream
* Reader
* Writer
*
* @throws IOException
*/
@RequestMapping("/testServletAPI")
public void testServletAPI(HttpServletRequest request,
HttpServletResponse response, Writer out) throws IOException {
System.out.println("testServletAPI, " + request + ", " + response);
out.write("hello springmvc");
//return "success.jsp";
}
}index.jsp
<%--
Created by IntelliJ IDEA.
User: 薛恆傑
Date: 2018/12/24
Time: 9:21
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<a href="view/testRequestParam?username=Xue&age=20">Test RequestParam</a>
<br><br>
<a href="view/testRequestHeader">Test RequestHeader</a>
<br><br>
<a href="view/testCookieValue">Test CookieValue</a>
<br><br>
<form action="view/testPojo" method="post">
username: <input type="text" name="username"/>
<br>
password: <input type="password" name="password"/>
<br>
email: <input type="text" name="email"/>
<br>
age: <input type="text" name="age"/>
<br>
city: <input type="text" name="address.city"/>
<br>
province: <input type="text" name="address.province"/>
<br>
<input type="submit" value="Submit"/>
</form>
<br><br>
<a href="view/testServletAPI">Test ServletAPI</a>
<br><br>
</body>
</html>