framework learning notes Day10 --- spring MVC Foundation

Posted by PigsHidePies on Fri, 31 Dec 2021 23:07:14 +0100

Spring MVC overview

Three layer structure
summary
- Spring MVC is a lightweight Web framework based on Java to implement MVC model.
- Spring MVC has become one of the most popular MVC frameworks, and with spring 3 0, comprehensively surpassing struts 2 and becoming the best MVC framework. Through a set of annotations, it makes a simple Java class a controller for processing requests without implementing any interface. It also supports RESTful programming style requests.

Introduction to spring MVC

Development steps
- ① Introduce related dependencies
- ② Write web xml
  - Configure dispatcher servlet and load spring MVC xml . Similar to ModelBaseServlet
- ③ Write spring MVC xml
  - Scan annotation
  - Configure the view parser. Similar to ViewBaseServlet
- ④ Write UserController
- ⑤ Code test

① Introduce related dependencies

<properties>
    <maven.compiler.source>8</maven.compiler.source>
    <maven.compiler.target>8</maven.compiler.target>
    <junit.version>4.13.2</junit.version>
    <lombok.version>1.18.22</lombok.version>
    <spring.version>5.3.13</spring.version>
    <logback.version>1.2.7</logback.version>
    <slf4j.version>1.7.32</slf4j.version>
    <servlet.version>4.0.1</servlet.version>
</properties>

<dependencies>


    <!--web start-->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>${servlet.version}</version>
    </dependency>
    <!--web end-->



    <!--logback start-->
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>${logback.version}</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>${slf4j.version}</version>
    </dependency>
    <!--logback end-->

    <!--junit start-->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>${junit.version}</version>
        <scope>test</scope>
    </dependency>
    <!--junit end-->

    <!--lombok start-->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>${lombok.version}</version>
    </dependency>
    <!--lombok end-->

    <!--spring start-->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aspects</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <!--spring end-->

</dependencies>

② Write web xml

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>



    <!--be similar to ModelBaseServlet-->
    <servlet>
        <servlet-name>mvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--load spring-mvc.xml-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
    </servlet>

    <servlet-mapping>
        <servlet-name>mvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

③ Write 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"
       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">


    <!--Scan annotation-->
    <context:component-scan base-package="com.atguigu"></context:component-scan>

    <!--View parser, similar to ViewBaseServlet-->
    <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">
        <property name="order" value="1"/>
        <property name="characterEncoding" value="UTF-8"/>
        <property name="templateEngine">
            <bean class="org.thymeleaf.spring5.SpringTemplateEngine">
                <property name="templateResolver">
                    <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">

                        <!--View prefix-->
                        <property name="prefix" value="/WEB-INF/templates/"/>
                        <!--View suffix-->
                        <property name="suffix" value=".html"/>
                        <property name="templateMode" value="HTML5"/>
                        <property name="characterEncoding" value="UTF-8" />
                    </bean>
                </property>
            </bean>
        </property>
    </bean>
</beans>

④ Write UserController

@Controller
public class UserController  {

    @RequestMapping("/selectUserList")
    public ModelAndView selectUserList(){
        List<User> userList = new ArrayList<>();
        userList.add(new User(1,"Chen Lei","alei"));
        userList.add(new User(2,"Tu'ao","tuAo"));
        //Store the data and jump to the page
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject("userList",userList);
        modelAndView.setViewName("demo01");
        return modelAndView;
    }

}

⑤ Code test

Execution process of spring MVC

Execution process
- ① The browser initiates a request (/ framework25/selectUserList) to the front-end controller DispatcherServlet
- ② The front-end controller DispatcherServlet queries all processor execution chains through the processor mapper
- ③ The processor mapper returns the processor execution chain
- ④ The front-end controller DispatcherServlet finds a matching processor through processor adaptation
- ⑤ If a matching processor is found, the processor Handler starts processing the request
- ⑥ The processor Handler returns a response (ModelAndView) to the processor adapter
- ⑦ The processor adapter returns the response (ModelAndView) to the front-end controller
- ⑧ The front-end controller DispatcherServlet sends the response (ModelAndView) to the view parser for parsing
- ⑨ The view parser returns the rendered page file to the front-end controller
- ⑩ The front-end controller displays the rendered page file response to the browser

Spring MVC core components

Core components
- Dispatcher servlet: the front-end controller, which is responsible for scheduling other components
- Handler mapping: the processor mapper, which is responsible for obtaining the processor execution chain
- HandlerAdapter: processor adapter, which is responsible for adapting the corresponding processor to the request
- Handler: processor that handles requests
- ViewResolver: View parser, processing views (ModelAndView)

Spring MVC core component configuration

summary
- Spring MVC has configured HandlerMapping and HandlerAdapter by default

code implementation

<!--Processor mapper-->
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"></bean>

<!--Processor adapter-->
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"></bean>

<!--Processor mapper, processor adapter, and other auxiliary components are also configured: type converter, etc-->
<mvc:annotation-driven></mvc:annotation-driven>

Static resource release

Static resources
- Images, css, js, html, text, etc

Mode 1

<!--Release static resources-->
<!--
    mapping: Access path
    location: Disk path
-->
<mvc:resources mapping="/css/**" location="/css/"></mvc:resources>
<mvc:resources mapping="/js/**" location="/js/"></mvc:resources>
<mvc:resources mapping="/img/**" location="/img/"></mvc:resources>

Mode II

<mvc:default-servlet-handler></mvc:default-servlet-handler>

@RequestMapping annotation overview

summary
- Annotation for mapping web requests onto methods in request-handling classes with flexible method signatures.
- Used to map requests to processor methods.
Common properties
- Path: sets the access path
- Method: set the request method
- params: sets the request parameters that must be carried
effect
- ① Set the access path of the processor
- ② Narrowing request
- ③ Limited request mode

code implementation

@RequestMapping(path = "/request/testRequestMapping" , params = "username")
public ModelAndView testRequestMapping(){

    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

@Access path of RequestMapping annotation

classification
- ① Exact match
- ② Fuzzy matching
① Exact match

② Fuzzy matching

/**
 * Fuzzy matching
 * @return
 */
@RequestMapping(path = "/myrequest/*")
public ModelAndView testRequestMapping2(){
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

@Narrowing request for RequestMapping annotation

summary
- Apply the @ RequestMapping annotation to the class.

code implementation

@Controller
@RequestMapping("/request")
public class RequestController {
}

@Request method of RequestMapping annotation

summary
- Common request methods are: get, post, put and delete

code implementation

/**
 * Process GET
 * @return
 */
@RequestMapping(path = "/request/testRequestMapping3",method = RequestMethod.GET)
public ModelAndView testRequestMapping3(){

    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}


/**
 * Process POST
 * @return
 */
@RequestMapping(path = "/request/testRequestMapping4",method = RequestMethod.POST)
public ModelAndView testRequestMapping4(){

    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

@GetMapping("/request/testRequestMapping3")
public ModelAndView testRequestMapping3(){

    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}



@PostMapping("/request/testRequestMapping4")
public ModelAndView testRequestMapping4(){

    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

Request parameter binding overview

summary
- Is to bind the request parameters on the page to java data.
classification
- Simple type
- javabean
- container
- javabean wrapper class
- ...

Simple type of request parameter binding

code implementation

<form th:action="@{/request/testRequestParam1}" method="get">

    account:<input type="text" name="userName" ><br>
    password:<input type="text" name="userPwd" ><br>
    <button type="submit">Submit</button>

</form>

@RequestMapping("/request/testRequestParam1")
public ModelAndView testRequestParam1(String userName ,String userPwd){
    System.out.println("userName = " + userName);
    System.out.println("userPwd = " + userPwd);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

View controller tab

summary
- When a processor is only used to forward pages, view controller can be used instead.

code implementation

<mvc:view-controller path="/demo02.html" view-name="demo02"></mvc:view-controller>
<mvc:view-controller path="/demo03.html" view-name="demo03"></mvc:view-controller>

@RequestParam annotation

summary
- Pass the parameter value of the specified name in the request to the formal parameter assignment in the controller
effect
- ① Set request parameter name
- ② Set whether the parameter is required
- ③ Set default values for parameters

code implementation

@RequestMapping("/request/testRequestParam2")
public ModelAndView testRequestParam2(@RequestParam(value = "username" ,required = true ,defaultValue = "missing") String userName ){
    System.out.println("userName = " + userName);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

JavaBean for request parameter binding

code implementation

<form th:action="@{/request/testRequestParam3}" method="get">

    account:<input type="text" name="userName" ><br>
    password:<input type="text" name="userPwd" ><br>
    <button type="submit">Submit</button>

</form>

@RequestMapping("/request/testRequestParam3")
public ModelAndView testRequestParam3(User user ){
    System.out.println("user = " + user);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

matters needing attention
- The value of the name attribute in the form is related to the setXxx method name.

JavaBean wrapper class for request parameter binding

summary
- If a JavaBean class (object A) contains another JavaBean class (object B)

code implementation

public class UserWrapper {

    private User user;

}

<form th:action="@{/request/testRequestParam4}" method="get">

    account:<input type="text" name="user.userName" ><br>
    password:<input type="text" name="user.userPwd" ><br>
    <button type="submit">Submit</button>

</form>

@RequestMapping("/request/testRequestParam4")
public ModelAndView testRequestParam4(UserWrapper userWrapper ){
    System.out.println("userWrapper = " + userWrapper);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

Chinese garbled code of request parameters

review
- In tomcat8 0. There is no Chinese parameter garbled problem in get request and Chinese parameter garbled problem in post request.
- Previously, you can solve this problem by customizing characterencoding fitler.
- Similar filters are provided in the spring MVC framework to solve the problem of Chinese parameter scrambling.

code implementation

<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>

Container for request parameter binding

code implementation

<form th:action="@{/request/testRequestParam6}" method="post">

    javase : <input type="checkbox" name="hobbys" value="javase"><br>
    javame : <input type="checkbox" name="hobbys" value="javame"><br>
    javaee : <input type="checkbox" name="hobbys" value="javaee"><br>

    <button type="submit">Submit</button>

</form>

@RequestMapping("/request/testRequestParam5")
public ModelAndView testRequestParam5(String[] hobbys){
    System.out.println(Arrays.toString(hobbys));
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

@RequestMapping("/request/testRequestParam6")
public ModelAndView testRequestParam6(@RequestParam("hobbys") List<String> hobbys){
    System.out.println(hobbys);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

Request parameter binding exercise

Environmental preparation

public class Student {

    private String stuName;
    private School school;
    private List<Subject> subjectList;
    private Subject[] subjectArray;
    private Map<String, Double> scores;
}

public class School {
    private String schoolName;
}

public class Subject { 
    private String subjectName;//Discipline name

}

code implementation

<form th:action="@{/request/testRequestParam7}" method="post">

    Student name:
        <input type="text" name="stuName"><br>
    School name:
        <input type="text" name="school.schoolName"><br>
    Discipline 1 name[List type]:
        <input type="text" name="subjectList[0].subjectName"><br>
    Discipline 2 name[List type]:
        <input type="text" name="subjectList[1].subjectName"><br>
    Discipline 3 name[List type]:
        <input type="text" name="subjectList[2].subjectName"><br>
    Discipline 1 name[Array type]:
        <input type="text" name="subjectArray[0].subjectName"><br>
    Discipline 2 name[Array type]:
        <input type="text" name="subjectArray[1].subjectName"><br>
    Discipline 3 name[Array type]:
        <input type="text" name="subjectArray[2].subjectName"><br>
    Subject 1 score:
        <input type="text" name="scores['javase']"><br>
    Subject 2 score:
        <input type="text" name="scores['javame']"><br>
    Subject 3 score:
        <input type="text" name="scores['javaee']"><br>
    <button type="submit">Submit</button>

</form>

@RequestMapping("/request/testRequestParam7")
public ModelAndView testRequestParam7(Student student){
    System.out.println(student);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

@RequestHeader annotation

summary
- Get the specific data in the request header through this annotation.

code implementation

@RequestMapping("/request/header")
public ModelAndView getRequestHeader(@RequestHeader(value = "user-agent",defaultValue = "missing") String userAgent){
    System.out.println(userAgent);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

@CookieValue annotation

summary
- Gets the Cookie data in the current request

code implementation

@RequestMapping("/request/cookie")
public ModelAndView getCookie(@CookieValue(name = "JSESSIONID",defaultValue = "missing") String JSESSIONID){
    System.out.println(JSESSIONID);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("index");
    return modelAndView;
}

Processor returns ModelAndView

summary
- ModelAndView encapsulates data and logical view names

Processor return string

summary
- In general, it is the logical view name

code implementation

@RequestMapping("/response/testResponseStr")
public String testResponseStr(Model model) {
    List<User> userList = new ArrayList<>();
    userList.add(new User(1, "Chen Lei", "alei"));
    userList.add(new User(2, "Tu'ao", "tuAo"));
    model.addAttribute("userList", userList);//Store data
    return "demo01";//Jump to logical view
}

Processor return value operation forwarding and redirection

summary
- By default, the processor can only jump pages within the directory set by the view parser;
- If you want to jump to resources outside the directory range, you need to use the prefix symbol!!!

code implementation

/**
 * Forward to resources outside the directory range
 *
 * @return
 */
@RequestMapping("/response/forward")
public String response2Forward() {
    return "forward:/mydemo01.html";
}


/**
 * Redirect to resources outside the directory range
 *
 * @return
 */
@RequestMapping("/response/redirect")
public String response2Redirect() {
    return "redirect:/mydemo01.html";
}


/**
 * Redirect to specific processor
 * @return
 */
@RequestMapping("/response/jump2Method")
public String jump2Method(){
    return "redirect:/response/testResponseStr";
}

matters needing attention
- When using "redirect:" operation redirection, the MVC framework has built-in access path of the project.

Native servlet API object

Native Servlet object
- HttpServletRequest
- HttpServletResponse
- HttpSession
- ServletContext

Get request and response objects

code implementation

@RequestMapping("/servlet/getRequestResponse")
public String getRequestResponse(HttpServletRequest request , HttpServletResponse response){
    System.out.println("request = " + request);
    System.out.println("response = " + response);
    return "index";
}

Get session object

code implementation

@RequestMapping("/servlet/getSession")
public String getSession(HttpServletRequest request){
    System.out.println("session = " + request.getSession());
    return "index";
}

@RequestMapping("/servlet/getSession2")
public String getSession2(HttpSession session){
    System.out.println("session = " + session);
    return "index";
}

Get ServletContext object

code implementation

@RequestMapping("/servlet/getServletContext")
public String getServletContext(HttpServletRequest request){
    System.out.println("servletContext = " + request.getServletContext());
    return "index";
}


@Autowired
private ServletContext servletContext;

@RequestMapping("/servlet/getServletContext2")
public String getServletContext2(){
    System.out.println("servletContext = " + servletContext);
    return "index";
}

Elephant (Master)

code implementation

@RequestMapping("/servlet/getSession")
public String getSession(HttpServletRequest request){
    System.out.println("session = " + request.getSession());
    return "index";
}

@RequestMapping("/servlet/getSession2")
public String getSession2(HttpSession session){
    System.out.println("session = " + session);
    return "index";
}

Get ServletContext object

code implementation

@RequestMapping("/servlet/getServletContext")
public String getServletContext(HttpServletRequest request){
    System.out.println("servletContext = " + request.getServletContext());
    return "index";
}


@Autowired
private ServletContext servletContext;

@RequestMapping("/servlet/getServletContext2")
public String getServletContext2(){
    System.out.println("servletContext = " + servletContext);
    return "index";
}

Topics: Java Spring mvc

Programmer Think

framework learning notes Day10 --- spring MVC Foundation

Spring MVC overview

Introduction to spring MVC

Execution process of spring MVC

Spring MVC core components

Spring MVC core component configuration

Static resource release

@RequestMapping annotation overview

@Access path of RequestMapping annotation

@Narrowing request for RequestMapping annotation

@Request method of RequestMapping annotation

Request parameter binding overview

Simple type of request parameter binding

View controller tab

@RequestParam annotation

JavaBean for request parameter binding

JavaBean wrapper class for request parameter binding

Chinese garbled code of request parameters

Container for request parameter binding

Request parameter binding exercise

@RequestHeader annotation

@CookieValue annotation

Processor returns ModelAndView

Processor return string

Processor return value operation forwarding and redirection

Native servlet API object

Get request and response objects

Get session object

Get ServletContext object

Get ServletContext object

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