springmvc基础（1）

2021-03-15 分类 springmvc 作者 Nayuki ~7.09K 字

SpringMvc介绍

使用@Controller创建控制器对象
SpringMvc中有一个对象是Servlet
- DispatcherServlet：负责接收用户所有请求，把请求转发给Controller对象
Controller用来处理请求

创建SpringMvc项目

在Maven中勾上Create from archetype（从原型创建）
选择org.apache.maven.archetype:maven-archetype-webapp
pom.xml中加入依赖

<dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.2.5.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.9.8</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.9.8</version>
    </dependency>
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.6</version>
    </dependency>
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.6</version>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.13</version>
    </dependency>
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.2.5</version>
    </dependency>

将web.xml更替为4.0版本
创建DispatcherServlet

<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:conf/dispatcherServlet.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>*.do</url-pattern>
</servlet-mapping>

DispatcherServlet介绍
- Tomcat服务器启动后，会创建DispatcherServlet对象的实例
- 在创建DispatcherServlet对象的实例时，会springmvc容器对象，所以会读取dispatcherServlet.xml
- load-on-startup标签数值（>=0的整数）越小表示tomcat创建对象的时间越早
- init-param标签用来自定义springmvc配置文件的位置，若不写，则路径是/WEB-INF/< servlet-name >-servlet.xml
- url-pattern标签用来指定要处理的请求
在index.jsp页面中发起请求

1	<a href="Nayuki.do">发起Nayuki.do请求</a>

创建Controller类

@Controller
public class MyController{
    @RequestMapping(value= "/Nayuki.do" )
    public ModelAndView doNayuki(){
        ModelAndView modelAndView =new ModelAndView();
        modelAndView.addObject("massage","发起Nayuki.do请求成功！");
        modelAndView.setViewName("/result.jsp");
        return modelAndView;
    }
}

创建result.jsp读取modelAndView的massage参数

1	<h3>massage数据：${massage}</h3>

创建dispatcherServlet.xml

1	<context:component-scan base-package="com.nayuki.controller"/>

配置视图解析器

在WEB-INF创建view文件夹
把result.jsp放入view文件夹
WEB-INF不允许客户端直接访问

在dispatcherServlet.xml中配置视图解析器

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/jsp/"></property>
    <property name="suffix" value=".jsp"></property>
</bean>

在Controller类中指定视图
1
modelAndView.setViewName("result");

RequestMapping的定义请求规则

多个请求可以映射到同一个方法

1	@RequestMapping(value= {"/Nayuki.do","/Chiyao.do"} )

可以加入前缀路径来统一管理
- 可以直接放到类上面当模块名称
  1
  @RequestMapping("/user" )
- 也可以单独在方法上指定
  1
  @RequestMapping("/user/Nayuki.do" )
- 指定后要修改请求
  1
  <a href="user/Nayuki.do">发起Nayuki.do请求</a>

指定请求的接收方式

指定为POST时只能接收POST方式的请求

1	@RequestMapping(value= "/Nayuki.do",method = RequestMethod.POST)

指定后要修改请求方式

1
2
3

<form action="Nayuki.do" method="post">
    <input type="submit" value="发起Nayuki.do请求"/>
</form>

接收请求的参数

request、response、session

public ModelAndView doNayuki(HttpServletRequest request,HttpServletResponse response,HttpSession session){
        ModelAndView modelAndView =new ModelAndView();
        modelAndView.addObject("massage","发起Nayuki.do请求成功！"+request.getParameter("name"));
        modelAndView.setViewName("/result.jsp");
}

逐个接收

创建请求表单

<form action="Nayuki.do" method="POST">
    姓名：<input type="text" name="name"/><br>
    年龄：<input type="text" name="age" /><br>
    <input type="submit" value="发起Nayuki.do请求"/>
</form>

创建接收请求方法

public ModelAndView doNayuki(String name,int age){
    ModelAndView modelAndView =new ModelAndView();
    modelAndView.addObject("name",name);
    modelAndView.addObject("age",age);
    modelAndView.setViewName("/result.jsp");
    return modelAndView;
}

解决POST乱码问题

在web.xml中加入过滤器

<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>forceRequestEncoding</param-name>
        <param-value>true</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>