(7)spring expression

Note: Read the properties of bean s

1. Use annotations to simplify configuration files

(1) What is component scanning?

The container scans the specified package and all of its subpackages

Class, if there are specific annotations in front of it, such as @Component,

Then the container will incorporate it into the container management (equivalent to in the configuration file).

There is a bean element.

(2) How to scan components?

Step 1. Add specific annotations before the class, such as @Component

Note: The default id is the class name after lowercase.

Step 2. In the configuration file, the configuration component scans.

(3) Dependency Injection-related annotations

1)@Autowired @Qualifier

Note: This annotation supports set method and constructor injection.

2)@Resource

Note: This annotation only supports set method injection.

(4) Injecting values of basic types and values of spring expressions

SpringMVC

(1) What is Spring MVC?

It is used to simplify the framework of web application development based on MVC architecture.

Note: Spring MVC is a module in spring.

(2) Five components

1) What are the five components?

Dispatcher Servlet Front-end Controller

Handler Mapping Mapping Processor

Controller processor

ModelAndView

ViewResolver View Parser

2) The relationship between them

a. Requests are sent to Dispatcher Servlet for processing, Dispatcher Servlet

The corresponding Controller is invoked based on the configuration of the Handler Mapping.

b.Controller encapsulates the processing results as ModelAndView and returns them to

DispatcherServlet. 

C. Dispatcher Servlet calls the corresponding one based on ViewResolver's parsing

View objects (such as jsp) are used to generate corresponding pages.

Note: The view section can use jsp or other view technologies, such as

    freemarker,velocity, etc.

(3) Programming steps

step1. Guide bag

spring-webmvc

step2. Add configuration files.

step3. To configure DispatcherServlet. 

step4. write Controller. 

step5. write jsp. 

step6.In the configuration file, add HandlerMapping,

    ViewResolver Configuration.

Code demo:

/springmvc-day01/src/main/java/controller/HelloController.java

package controller;

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

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

/**
 * processor
 *
 */
public class HelloController implements Controller {

    public ModelAndView handleRequest(HttpServletRequest arg0, HttpServletResponse arg1) throws Exception {
        System.out.println("handleRequest()");
        /*
         * ModelAndView There are two common constructors: Model AndView (String viewName)
         * ModelAndView(String viewName, Map data) Note: viewName: view name data: processing results
         */
        return new ModelAndView("hello");
    }

}

/springmvc-day01/src/main/resources/spring-mvc.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:jdbc="http://www.springframework.org/schema/jdbc" xmlns:jee="http://www.springframework.org/schema/jee"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:util="http://www.springframework.org/schema/util"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
        http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">
    <!-- To configure HandlerMapping -->
    <bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
        <property name="mappings">
            <props>
                <prop key="/hello.do">helloController</prop>
            </props>
        </property>
    </bean>
    <!-- To configure Controller -->
    <bean id="helloController" class="controller.HelloController" />
    <!-- Configuration view parser -->
    <bean
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/" />
        <property name="suffix" value=".jsp" />
    </bean>

</beans>

/springmvc-day01/src/main/webapp/WEB-INF/hello.jsp

<h1>Hello Kitty</h1>

/springmvc-day01/src/main/webapp/WEB-INF/web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
 <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>
             org.springframework.web.servlet.DispatcherServlet
    </servlet-class>
    <!-- 
        DispatcherServlet The initialization method will start
        spring Container, contextConfigLocation use
        //To specify the location of the spring configuration file.
     -->
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring-mvc.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>

</web-app>

/springmvc-day01/pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>welkin</groupId>
  <artifactId>springmvc-day01</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>3.2.8.RELEASE</version>
    </dependency>
  </dependencies>
</project>