SpringMvc
MVC
- 什么是MVC
- MVC是采用业务逻辑、数据、显示分离的方法来组织代码,是一种软件设计规范
- MVC不是一种设计模式,MVC是一种架构模式
- 职责分析
- Model模型层(dao,service)
- View视图层(jsp/html)
- Controller控制层(Servlet)
SpringMvc执行原理(底层实现)
- 为什么要学习SpringMvc
- 轻量级,简洁灵活易用
- 基于请求响应的MVC框架,不是以事件作为驱动
- 约定大于配置
- Spring MVC执行原理(三者结合看效果更佳!!!)
一、SpringMvc执行原理文字描述
1 用户发出请求,DispatcherServlet接收请求并拦截请求
2 DispatcherServlet调用HandlerMapping,HandlerMapping根据请求的url(比如/hello)查找控制器,返回控制器所在的类(或方法)给DispatcherServlet
3 DispatcherServlet将控制器所在类(或方法)给HandlerAdapter,HandlerAdapter执行控制器所在类(或方法),返回ModelAndView给DispatcherServlet
4 DispatcherServlet调用ViewResolver,ViewResolver将解析的逻辑视图名传给DispatcherServlet
5 DispatcherServlet根据ViewResolver解析的视图结果,调用具体的视图,呈现视图给用户
二、SpringMvc执行原理代码实现
1.web.xml配置文件
<?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">
<!--配置DispatcherServlet 前端控制器 所有请求都要经过它-->
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--DispatcherServlet要绑定配置文件-->
<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>
<!--过滤器 拦截所有 用于解决乱码问题-->
<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>
<!--只能用'/',不能用'/*',否则会无限套娃(a.jsp.jsp)-->
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
2.springmvc-servlet.xml配置文件
<?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
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--处理器映射器-->
<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
<!--处理器适配器-->
<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
<!--视图解析器 接收到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.kuang.controller.HelloController"/>
</beans>
3.控制器所在类HelloController
package com.kuang.controller;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloController implements Controller {
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
ModelAndView mv = new ModelAndView();
//实现业务逻辑
//封装模型
mv.addObject("msg","HelloSpringMVC!");
//封装要跳转的视图
mv.setViewName("hello"); // 在视图解析器中被解析为/WEB-INF/jsp/hello.jsp
return mv;
}
}
4.视图/WEB-INF/jsp/hello.jsp
<%--
Created by IntelliJ IDEA.
User: kison-yk
Date: 2020-07-29
Time: 10:14
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>HELLO</title>
</head>
<body>
${
msg}
</body>
</html>
使用注解开发SpringMvc
1.web.xml配置文件 和上面一样
2.springmvc-servlet.xml配置文件
<?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"
xmlns:mvc="http://www.springframework.org/schema/mvc"
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
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!--自动扫描包,让指定包下的注解生效,由IOC容器统一管理-->
<context:component-scan base-package="com.kuang.controller"/>
<!--让Spring MVC不处理静态资源.css,.html,.js-->
<mvc:default-servlet-handler />
<!--
支持mvc注解驱动
在spring中一般采用@RequestMapping注解来完成映射关系
要想使@RequestMapping注解生效
必须向上下文中注册DefaultAnnotationHandlerMapping
和一个AnnotationMethodHandlerAdapter实例
这两个实例分别在类级别和方法级别处理。
而annotation-driven配置帮助我们自动完成上述两个实例的注入。
-->
<!--处理器映射器 处理器配置器-->
<mvc:annotation-driven />
<!--视图解析器-->
<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>
</beans>
3.控制器所在类HelloController
package com.kuang.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
public class HelloController {
@RequestMapping("/hello")
public String sayHello(Model model){
model.addAttribute("msg","Hello SpringMvc");
return "hello";
}
}
4.视图/WEB-INF/jsp/hello.jsp 和上面一样
转发与重定向
一、通过SpringMVC来实现转发和重定向 无需视图解析器
1.底层实现原理
@Controller
public class ResultGo {
@RequestMapping("/result/t1")
public void test1(HttpServletRequest req, HttpServletResponse rsp) throws IOException {
rsp.getWriter().println("Hello,Spring BY servlet API");
}
@RequestMapping("/result/t2")
public void test2(HttpServletRequest req, HttpServletResponse rsp) throws IOException {
rsp.sendRedirect("/index.jsp");
}
@RequestMapping("/result/t3")
public void test3(HttpServletRequest req, HttpServletResponse rsp) throws Exception {
req.setAttribute("msg","/result/t3");
req.getRequestDispatcher("/WEB-INF/jsp/test.jsp").forward(req,rsp);
}
}
2.推荐使用
@Controller
public class ResultSpringMVC {
@RequestMapping("/rsm/t1")
public String test1(){
return "/index.jsp";
}
@RequestMapping("/rsm/t2")
public String test2(){
return "forward:/index.jsp";
}
@RequestMapping("/rsm/t3")
public String test3(){
return "redirect:/index.jsp";
}
}
二、通过SpringMVC来实现转发和重定向 有视图解析器
1.视图解析器
<!-- 视图解析器 -->
<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>
2.ModelAndView实现跳转(底层实现原理)
public class ControllerTest1 implements Controller {
public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
ModelAndView mv = new ModelAndView();
mv.addObject("msg","ControllerTest1");
mv.setViewName("test");
return mv;
}
}
3.推荐使用
@Controller
public class ResultSpringMVC2 {
@RequestMapping("/rsm2/t1")
public String test1(){
return "test";
}
@RequestMapping("/rsm2/t2")
public String test2(){
return "redirect:/index.jsp";
}
}
数据处理
1.请求URL为:http://localhost:8080/hello?username=ykk(提交表单或者其他基本数据类型的参数)
@RequestMapping("/hello")
public String hello(@RequestParam("username") String name){
System.out.println(name);
return "hello";
}
2.请求URL为:http://localhost:8080/user?name=ykk&id=1&age=19(提交一个对象)
@RequestMapping("/user")
public String user(User user){
System.out.println(user);
return "hello";
}
3.请求URL为:http://localhost:8080/commit/1/2(提交RestFul风格的参数)
@RequestMapping("/commit/{p1}/{p2}")
public String index(@PathVariable int p1, @PathVariable int p2, Model model){
int result = p1+p2;
model.addAttribute("msg", "结果:"+result);
return "test";
}
Controller返回JSON数据
一、Jackson的使用
1.pom.xml导入依赖
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.11.1</version>
</dependency>
2.springmvc-servlet.xml配置文件 解决乱码问题
<!--解决乱码问题-->
<mvc:annotation-driven>
<mvc:message-converters register-defaults="true">
<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>
3.UserController类返回json数据(调用了自定义的工具类)
package com.kuang.controller;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.kuang.pojo.User;
import com.kuang.utils.JsonUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
@RestController
public class UserController {
@RequestMapping("/j1")
public String json01() throws JsonProcessingException {
User user1=new User("ykk",19,"男");
User user2 = new User("kison", 20, "男");
List<User> userList=new ArrayList<User>();
userList.add(user1);
userList.add(user2);
return JsonUtils.getJson(userList);
}
@RequestMapping("/j2")
public String json02() throws JsonProcessingException {
Date date = new Date();
return JsonUtils.getJson(date,"yyyy-MM-dd HH:mm:ss");
}
}
4.自定义的工具类JsonUtils(采用重载方式)
package com.kuang.utils;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import java.text.SimpleDateFormat;
public class JsonUtils {
public static String getJson(Object object) {
return getJson(object,"yyyy-MM-dd HH:mm:ss");
}
public static String getJson(Object object,String dateFormat){
ObjectMapper mapper=new ObjectMapper();
mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
mapper.setDateFormat(sdf);
try {
return mapper.writeValueAsString(object);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
return null;
}
}
二、Fastjson的使用
1.pom.xml导入依赖
<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.72</version>
</dependency>
2.UserController类返回Json数据
@RequestMapping("/j3")
public String json03(){
List<User> userList=new ArrayList<User>();
User user1=new User("ykk",19,"男");
User user2 = new User("kison", 20, "男");
userList.add(user1);
userList.add(user2);
String str=JSON.toJSONString(userList);
System.out.println(str);
User user=JSON.parseObject(JSON.toJSONString(user1),User.class);
System.out.println(user);
return str;
}
3.运行结果
[{
"age":19,"name":"ykk","sex":"男"},{
"age":20,"name":"kison","sex":"男"}]
User(name=ykk, age=19, sex=男)