springmvc学习笔记2

一、Controller和RestFul

第一步：配置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>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring_mvc_servlet.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>springMvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

   <!-- <filter>
        <filter-name>encode</filter-name>
        <filter-class>com.ssl.filter.EncodeFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>encode</filter-name>
        <url-pattern>/</url-pattern>
    </filter-mapping>-->
    <filter>
        <filter-name>encode</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>encode</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

第二步：spring_mvc_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"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://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.ssl.controller"/>
    <!--让SpringMvc不处理静态资源。让.css,.js等不进视图解析器-->
    <mvc:default-servlet-handler/>
    <!--注解加载映射器、适配器，不用之前那么麻烦配置了-->
    <mvc:annotation-driven/>
    <!--以上的是定死的代码，
        以下是配置视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
    </bean>
    <!--不使用注解开发的适配器：/demo1,注意点是id需要配置/-->
    <bean id="/demo" class="com.ssl.controller.ControllerDemo1"/>
</beans>

参考文档：https://blog.csdn.net/Edward_He_/article/details/122310741

Controller不使用注解：

不使用注解，极其不推荐使用，因为：

配置麻烦：<bean id="/demo" class="com.ssl.controller.ControllerDemo1"/>，并且需要 implements Controller

不够灵活，太费力气，浪费时间

访问：http://localhost:8080/springmvc_04_controller/demo

public class ControllerDemo1 implements Controller {
    @Override
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject("demo1","demo1:Controller会返回一个modelAndView");
        modelAndView.setViewName("demo1");
        return modelAndView;
    }
}

@Controller

使用注解开发，@Controller注册进Spring容器，如果返回值是String，并且有具体的页面可以跳转，那么就会被视图解析器解析访问：http://localhost:8080/springmvc_04_controller/demo2

@Controller
public class ControllerDemo2 {
    @RequestMapping("/demo2")
    public String test1(Model model) {
        model.addAttribute("demo2", "demo2");
        return "demo2";
    }
}

@RequestMapping

可以在类和方法上配置url访问路径访问：http://localhost:8080/springmvc_04_controller/controller/demo3

@Controller
@RequestMapping("/controller")
public class ControllerDemo3 {
    @RequestMapping("/demo3")
    public String test1(Model model) {
        model.addAttribute("demo3", "demo3");
        return "demo3";
    }
}

RestFul风格

优点：
最大的优势是安全，看不出源代码的参数和意义
实现地址复用，使得get和post访问url相同，框架会自动进行类型转换
高效：支持缓存
缺点：
不像原生的url见名知意，url理解不直观
实现方式：
1：url @GetMapping("/addRest/{a}/{b}") + 参数@PathVariable int a, @PathVariable int b
访问：http://localhost:8080/springmvc_04_controller/addRest/1/2
2：url @PostMapping("/addRest/{a}/{b}") + 参数不变@PathVariable int a, @PathVariable int b
使用Postman中的post访问：http://localhost:8080/springmvc_04_controller/addRest/1/2

@Controller
public class RestFulController {

    /**
     * 原生的url：http://localhost:8080/springmvc_04/add?a=1&b=1
     */
    @RequestMapping("/add")
    public String getAdd1(int a, int b, Model model) {
        int result = a + b;
        model.addAttribute("add", "原生的url：结果为" + result);
        return "add";
    }

    /**
     * RestFul方式一：method = get
     * RequestMapping("/addRest/{a}/{b}" method=requestMethod.GET) = @GetMapping()
     * http://localhost:8080/springmvc_04/addRest/1/1
     */
    @GetMapping("/addRest/{a}/{b}")
    public String getAdd2(@PathVariable int a, @PathVariable int b, Model model) {
        int result = a + b;
        model.addAttribute("add", "Rest的url：结果为" + result);
        return "addRest";
    }

    /**
     * 复用相同的url
     * RestFul方式二：method=post，使用RestFul的话，请求的url和GET就一样了
     */
    @PostMapping("/addRest/{a}/{b}")
    public String getAdd3(@PathVariable int a, @PathVariable int b, Model model) {
        int result = a + b;
        model.addAttribute("add", "Rest的url：结果为" + result);
        return "addRest";
    }
}

重定向和转发
可以使用原生的request转发或者response重定向
推荐使用SpringMvc的return “forward:xxx”/"redirect:xxx"

@Controller
public class ModelTest1 {
    //原生的转发：返回值是void，没有经过视图解析器；原生的重定向同样如此，都不走视图解析器，直接重定向
    @RequestMapping("/test1")
    public void test1(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String id = request.getSession().getId();
        System.out.println(id);
        request.getRequestDispatcher("index.jsp").forward(request,response);
    }
    //SpringMvc转发：测试结果是不走视图解析器，url没变是转发
    @RequestMapping("/test2")
    public String test2(Model model) {
        model.addAttribute("demo1","这是test2中的Spring转发");
        return "forward:/WEB-INF/jsp/demo1.jsp";
    }
    //SpringMvc重定向：测试结果是不走视图解析器
    @RequestMapping("/test3")
    public String test3() {
        System.out.println("跳转回首页index.jsp");
        return "redirect:index.jsp";
    }
}

接受请求参数和数据回显

前端提交的name和后端映射器接受的形参名一样，则直接接受
前端提交的name和后端映射器接受的形参名不用一样，再形参前@RequestParam("xxx")更改名称一致
养成习惯：无论是否一样，都必须加上@RequestParam
后端参数封装如果成一个pojo，前端传过来的name会自动pojo中的成员属性，不匹配的属性=null/0

乱码问题

方法一：web.xml里面配置的SpringMvc自带的过滤器CharacterEncodingFilter

<url-pattern>/*</url-pattern>：因为要跳转到xxx.jsp页面，所以url是/*(≠/)

<?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SpringMVC-->
    <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:spring_mvc_servlet.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>springMvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <!--web容器解决中文乱码问题-->
    <filter>
        <filter-name>encode</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>encode</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

方法二：一劳永逸，但需要重启Tomcat服务器，修改Tomcat里面的server.xml配置文件：URIEncoding = "UTF-8"

<Connector port="8080" protocol="HTTP/1.1"
           connectionTimeout="20000"
           redirectPort="8443"
           URIEncoding = "UTF-8"/>
<!-- A "Connector" using the shared thread pool-->

posted on 2022-06-02 15:28 小熊冰淇淋阅读(24) 评论(0) 收藏举报

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