SpringMVC-获取参数

目录

环境

IDE：idea 2020.3
构建工具：maven-3.8.1
服务器：tomcat9
Spring版本：5.3.1

<dependencies>
    <!-- SpringMVC -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.3.1</version>
    </dependency>

    <!-- 日志 -->
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.2.3</version>
    </dependency>

    <!-- ServletAPI -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
    </dependency>

    <!-- Spring5和Thymeleaf整合包 -->
    <dependency>
        <groupId>org.thymeleaf</groupId>
        <artifactId>thymeleaf-spring5</artifactId>
        <version>3.0.12.RELEASE</version>
    </dependency>
</dependencies>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">

<!--   springMVC.xml -->
    <!-- 自动扫描包 -->
    <context:component-scan base-package="com.fly.controller"/>

    <!-- 配置Thymeleaf视图解析器 -->
    <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">
        <property name="order" value="1"/>
        <property name="characterEncoding" value="UTF-8"/>
        <property name="templateEngine">
            <bean class="org.thymeleaf.spring5.SpringTemplateEngine">
                <property name="templateResolver">
                     <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">
                    <!-- 视图前缀 -->
                    <property name="prefix" value="/WEB-INF/templates/"/>
                    <!-- 视图后缀 -->
                    <property name="suffix" value=".html"/>
                    <property name="templateMode" value="HTML5"/>
                    <property name="characterEncoding" value="UTF-8" />
                    </bean>
                 </property>
            </bean>
        </property>
    </bean>

</beans>

<!--  web.xml  -->
    <servlet>
        <servlet-name>springMVC</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <!--
               作为框架的核心组件，在启动过程中有大量的初始化操作要做
               而这些操作放在第一次请求时才执行会严重影响访问速度
               因此需要通过此标签将启动控制DispatcherServlet的初始化时间提前到服务器启动时
            -->
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springMVC.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>springMVC</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

通过ServletAPI获取

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
  <meta charset="UTF-8">
  <title>首页</title>
</head>
<body>
<!--index.html-->
<form th:action="@{/testParam}" method="get">
  用户名：<label>
  <input type="text" name="userName">
</label>
  <input type="submit">
</form>
</body>
</html>

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
  <meta charset="UTF-8">
  <title>hello</title>
</head>
<body>
<!--hello.html-->
<h2>hello</h2>
</body>
</html>

  /**
   *HelloController
   */

  @RequestMapping("/")
  public String index() {
    return "index";
  }
  
  @RequestMapping("/testParam")
  public String testParam(HttpServletRequest request) {
    String userName = request.getParameter("userName");
    System.out.println("userName = " + userName);
    return "hello";
  }


通过控制器方法的形参获取请求参数

在控制器方法中设置与请求参数名一样的形参，DispatcherServlet就会将请求参数赋值给相应的形参


如果请求参数中有多个同名的参数，可以设置一个数组来接收

@RequestParam


@RequestParam将请求参数和控制器方法的形参进行绑定，有三个属性：
1：value：指定为形参赋值的请求参数的参数名
2：required：设置是否必须传输此请求参数，默认值为true
3：defaultValue：不管required属性值为true或false，当value所指定的请求参数没有传输或传输的值为""时，则使用默认值为形参赋值

@RequestHeader


@RequestHeader是将请求头信息和控制器方法的形参创建映射关系,用法同@RequestParam

@CookieValue


@CookieValue是将cookie数据和控制器方法的形参创建映射关系，用法同@RequestParam

通过POJO获取请求参数

可以在控制器方法中设置一个实体类类型的形参，如果请求参数的参数名和实体类中的属性名一致，那么请求参数就会为此属性赋值

package com.fly.entity;

/**
 * @author 26414
 */
public class Person {

  private String userName;

  public String getUserName() {
    return userName;
  }

  public void setUserName(String userName) {
    this.userName = userName;
  }

  public Person() {
  }

  @Override
  public String toString() {
    return "Person{" +
            "userName='" + userName + '\'' +
            '}';
  }

  public Person(String userName) {
    this.userName = userName;
  }
}

解决乱码

在web.xml中注册编码过滤器CharacterEncodingFilte

通过源码可以得出过滤器

<filter>
        <filter-name>CharacterEncodingFilter</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>
        <init-param>
            <param-name>forceResponseEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CharacterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
posted @ 2021-11-23 21:59  翻蹄亮掌一皮鞋  阅读(72)  评论(0)    收藏  举报