SpringMVC02_数据绑定&中文乱码处理

绝地灬酷狼 2023-02-20 02:38 117阅读 0赞

**SpringMVC02\_数据绑定&中文乱码处理**

--------------------

*  示例1：  
    通过 **@RequestParam** 注解将请求参数中的属性绑定至方法的形参（由**HandlerAdapter**来完成）

@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("执行了index...");
    	return "index";
    }

*  示例2：

传统请求url：**http://localhost:8080/hello/index?name=zhangsan&id=10**  
REST风格的请求url：**http://localhost:8080/hello/index/zhangsan/10**  
通过 **@PathVariable** 注解完成REST风格的请求参数与形参的映射

@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：  
    通过 **@CookieValue** 注解获取Cookie值

@RequestMapping("/cookie")
    public String cookie(@CookieValue(value = "JSESSIONID") String sessionId){ 
    	System.out.println(sessionId);
    	return "index";
    }

*  示例4：  
    SpringMVC会根据请求参数名和JavaBean属性名进行自动匹配，自动为对象填充属性值。

Address实体类：

package com.blu.entity;
    import lombok.Data;
    
    @Data
    public class Address { 
        private String value;
    }

User实体类：

package com.blu.entity;
    import lombok.Data;
    
    @Data
    public class User { 
        private long id;
        private String name;
        private Address address;
    }

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
        <head>
            <title>Title</title>
        </head>
        <body>
            <form action="/save" method="post">
                用户id：<input type="text" name="id"/><br/>
                用户名：<input type="text" name="name"/><br/>
                <input type="text" name="address.value"/><br/>
                <input type="submit" value="注册"/>
            </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";
    }

输入url进入register页面  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JMVV8xMTE_size_16_color_FFFFFF_t_70]  
输入值提交：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JMVV8xMTE_size_16_color_FFFFFF_t_70 1]  
控制台打印结果出现中文乱码：

User(id=1, name=BLU, address=Address(value=?±?è????????))

解决方法：  
修改web.xml，添加处理中文乱码的过滤器：

<!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>

重启运行，输入中文值提交，控制台收到了正确的中文值：

User(id=1, name=BLU, address=Address(value=江苏南京))

注：该过滤器解决了前端发送给后端的中文乱码问题  
而SpringMVC的@ResponseBody注解可以将请求方法返回的对象直接转换成JSON对象，但是当返回值是String的时候，也会出现中文乱码

示例：

@ResponseBody
    @RequestMapping("/hello")
    public String hello() { 
    	return "你好！BLU";
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JMVV8xMTE_size_16_color_FFFFFF_t_70 2]  
解决办法1：  
只要在springmvc.xml配置文件中添加如下配置即可：

<mvc:annotation-driven>
    	
    	<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>

重试结果：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JMVV8xMTE_size_16_color_FFFFFF_t_70 3]  
解决办法2：  
在 **@RequestMapping** 注解中添加属性：**produces = "text/html;charset=UTF-8"**

@ResponseBody
    @RequestMapping(value= "/hello2", produces = "text/html;charset=UTF-8")
    public String hello() { 
    	return "你好！BLU";
    }

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