SpringMVC学习笔记

1.1、简介

SpringMVC是Spring Framework的一部分，是基于Java实现MVC的轻量级框架。

官方文档：Spring Framework Reference Documentation

SpringMVC特点

轻量级，简单易学
高效、基于请求响应的MVC框架
与Spring兼容性好，无缝结合
约定大于配置
功能强大：RESTful、数据验证、格式化、本地化、主题、注解、单元测试等
简洁灵活

1.2、Hello SpringMVC

resources/springmvc-servlet.xml

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

    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

    <!--视图解析器：DispatcherServlet给它的ModelAndView-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--Handler-->
    <bean id="/hello" class="com.zhang.controller.HelloController"/>
</beans>

com.zhang.controller.HelloController

package com.zhang.controller;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * @author zhangxiny
 * @apiNote
 * @date 2021-12-30 20:03
 */
public class HelloController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        //视图和模型
        ModelAndView mv = new ModelAndView();

        //封装对象，放在ModelAndView中。Model
        mv.addObject("msg", "HelloSpringMVC!");
        //封装要跳转的视图，放在ModelAndView中
        mv.setViewName("hello");
        return mv;
    }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--关联一个Spring配置文件-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <!--启动级别1-->
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- / 匹配所有请求：（不包括 jsp）-->
    <!-- /* 匹配所有请求：（包括jsp）-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

pom.xml

<!--依赖-->
<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.1.9.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.2</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>
</dependencies>

1.3、Spring执行原理

个人理解：SpringMVC底层还是Servlet，在web.xml配置后，SpringMVC就完全代理了Servlet。所以，所有的web请求，全都转入了SpringMVC。

Spring执行的话，简单分为三步，第一步是调用处理器映射器，有很多种映射方式，选择得到bean的方式。第二步是调用处理器适配器，将Contrller中的设置解析，并返回ModelAndView类，第三步调用视图解析器，解析视图并渲染至浏览器。

@Component

@Service

@Controller

@Repository

1.4、RestFul风格

优点：

请求路径更加简洁
获得参数更加方便，框架会自动进行类型转换
通过路径类型约束访问的类型，类型不一致，则请求不到对应的方法，会出现 405错误。
安全，不暴露变量名在url

1.5、重定向与转发

@RequestMapping("login")
public String test2(Model model){
    model.addAttribute("msg", "login");
    return "admin/hello";
}

重定向

@RequestMapping("login")
public String test2(Model model){
    model.addAttribute("msg", "login");
    return "redirect:/hello1";
}

1.6、接收请求参数

第一种，普通接收

public String test1(String name, Model model){}

http://localhost:9091/user/t1?name=fdada

第二种，指定名称接收

public String test1(@RequestParam("username") String name, Model model) {

http://localhost:9091/user/t1?username=fdada

第三种，接收对象

public String test2(User user){

http://localhost:9091/user/t2?name=fdada&id=3&age=2

1.7、乱码问题解决

在web.xml中配置

<!--配置SpringMVC乱码过滤-->
<filter>
    <filter-name>encoding</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>encoding</filter-name>
    <url-pattern>/</url-pattern>
</filter-mapping>

在tomcat中配置

<Connector port="9091" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" 
			   URIEncoding="UTF-8"/>

1.8、Jackson使用

导入包 pom.xml

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.10.5.1</version>
</dependency>

配置编码 springmvc-servlet.xml

<mvc:annotation-driven>
    <mvc:message-converters>
        <bean class="org.springframework.http.converter.StringHttpMessageConverter">
            <constructor-arg value="UTF-8"/>
        </bean>
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper">
                <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                    <property name="failOnEmptyBeans" value="false"/>
                </bean>
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

使用ObjectMapper将Object转成json

@ResponseBody
@RequestMapping(value="/t1")
public String test1() throws JsonProcessingException {
    User user = new User(1,"张三",32);
    ObjectMapper mapper = new ObjectMapper();
    String str = mapper.writeValueAsString(user);
    return str;
}

使用ObjectMapper将LIst转成json

@RequestMapping(value="/j2")
public String json2() throws JsonProcessingException {
    User user = new User(1,"张三",32);
    User user1 = new User(1,"张三",32);
    User user2 = new User(1,"张三",32);
    User user3 = new User(1,"张三",32);
    User user4 = new User(1,"张三",32);
    List<User> userList = new ArrayList<User>();
    userList.add(user);
    userList.add(user1);
    userList.add(user2);
    userList.add(user3);
    userList.add(user4);
    ObjectMapper mapper = new ObjectMapper();
    String str = mapper.writeValueAsString(userList);
    return str;
}

封装工具类 com.zhang.utils

public class JsonUtils {
    public static String getJson(Object object) throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        return objectMapper.writeValueAsString(object);
    }

    public static String getJson(Object object,String dateFormat) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        //不使用时间戳的方式
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
        //自定义日期的格式
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
        mapper.setDateFormat(sdf);
        return mapper.writeValueAsString(object);
    }
}

1.9、fastjson使用

导入包

<dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>fastjson</artifactId>
     <version>1.2.60</version>
</dependency>

将JSON转成String

 @RequestMapping("j4")
    public String json4(){
        User user = new User(1,"张三",32);
        User user1 = new User(1,"张三",32);
        User user2 = new User(1,"张三",32);
        User user3 = new User(1,"张三",32);
        User user4 = new User(1,"张三",32);
        List<User> userList = new ArrayList<User>();
        userList.add(user);
        userList.add(user1);
        userList.add(user2);
        userList.add(user3);
        userList.add(user4);
        String s = JSON.toJSONString(userList);
        return s;
    }

1.10、ssm整合

代码包下载：https://zxy-me.oss-cn-beijing.aliyuncs.com/note/ssmbuild.rar

1.11、ssm总结

posted @ 2022-01-11 09:55 zhangxiny 阅读(36) 评论(0) 收藏举报

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