SpringMVC02_數據綁定
- 示例1:
通過 @RequestParam 註解將請求參數中的屬性綁定至方法的形參(由HandlerAdapter來完成)
@RequestMapping(value = "/index",method = RequestMethod.GET,params = {"name","id=10"})
public String index(@RequestParam("name") String str,@RequestParam("id") int age){
System.out.println(str);
System.out.println(age);
System.out.println("執行了index...");
return "index";
}
- 示例2:
傳統請求url:http://localhost:8080/hello/index?name=zhangsan&id=10
REST風格的請求url:http://localhost:8080/hello/index/zhangsan/10
通過 @PathVariable 註解完成REST風格的請求參數與形參的映射
@RequestMapping("/rest/{name}/{id}")
public String rest(@PathVariable("name") String name,@PathVariable("id") int id){
System.out.println(name);
System.out.println(id);
return "index";
}
- 示例3:
通過 @CookieValue 註解獲取Cookie值
@RequestMapping("/cookie")
public String cookie(@CookieValue(value = "JSESSIONID") String sessionId){
System.out.println(sessionId);
return "index";
}
- 示例4:
SpringMVC會根據請求參數名和JavaBean屬性名進行自動匹配,自動爲對象填充屬性值。
Address實體類:
package com.blu.entity;
import lombok.Data;
@Data
public class Address {
private String value;
}
User實體類:
package com.blu.entity;
import lombok.Data;
@Data
public class User {
private long id;
private String name;
private Address address;
}
register.jsp頁面:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="/save" method="post">
用戶id:<input type="text" name="id"/><br/>
用戶名:<input type="text" name="name"/><br/>
<input type="text" name="address.value"/><br/>
<input type="submit" value="註冊"/>
</form>
</body>
</html>
Handler方法:
@RequestMapping("/register")
public String Login() {
return "login";
}
@RequestMapping(value = "/save", method = RequestMethod.POST)
public String save(User user) {
System.out.println(user);
return "register";
}
輸入url進入register頁面
輸入值提交:
控制檯打印結果出現中文亂碼:
User(id=1, name=BLU, address=Address(value=?±?è????????))
解決方法:
修改web.xml,添加處理中文亂碼的過濾器:
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
<display-name>Archetype Created Web Application</display-name>
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>dispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
重啓運行,輸入中文值提交,控制檯收到了正確的中文值:
User(id=1, name=BLU, address=Address(value=江蘇南京))
注:該過濾器解決了前端發送給後端的中文亂碼問題
而SpringMVC的@ResponseBody註解可以將請求方法返回的對象直接轉換成JSON對象,但是當返回值是String的時候,也會出現中文亂碼
示例:
@ResponseBody
@RequestMapping("/hello")
public String hello() {
return "你好!BLU";
}
解決辦法1:
只要在springmvc.xml配置文件中添加如下配置即可:
<mvc:annotation-driven>
<!-- 消息轉換器(所謂的消息就是指後臺返回給前端的數據) -->
<mvc:message-converters register-defaults="true">
<bean class="org.springframework.http.converter.StringHttpMessageConverter">
<constructor-arg value="UTF-8" />
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
重試結果:
解決辦法2:
在 @RequestMapping 註解中添加屬性:produces = "text/html;charset=UTF-8"
@ResponseBody
@RequestMapping(value= "/hello2", produces = "text/html;charset=UTF-8")
public String hello() {
return "你好!BLU";
}