SpringMVC Framework Basics (02)

Add thymeleaf and Thymeleaf-spring5 dependencies to the project’s pom.xml:

<! -- https://mvnrepository.com/artifact/org.thymeleaf/thymeleaf -->
<dependency>
    <groupId>org.thymeleaf</groupId>
    <artifactId>thymeleaf</artifactId>
    <version>3.0.11. RELEASE</version>
</dependency>
<! -- https://mvnrepository.com/artifact/org.thymeleaf/thymeleaf-spring5 -->
<dependency>
    <groupId>org.thymeleaf</groupId>
    <artifactId>thymeleaf-spring5</artifactId>
    <version>3.0.11. RELEASE</version>
</dependency>
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Note: The samegroupIdNext, eachartifactIdDifferent, but ifversionThe numbering rules are the same and need to be used differently within the same projectartifactIdThe corresponding dependencies must be the sameversion!

package cn.tedu.spring;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.thymeleaf.spring5.SpringTemplateEngine;
import org.thymeleaf.spring5.view.ThymeleafViewResolver;
import org.thymeleaf.templateresolver.ClassLoaderTemplateResolver;

@ComponentScan("cn.tedu.spring")
public class SpringMvcConfigurer implements WebMvcConfigurer {

	private String characterEncoding = "utf-8";
	
	@Bean
	public ViewResolver configViewResolver(a) {
		ClassLoaderTemplateResolver templateResolver = new ClassLoaderTemplateResolver();
		templateResolver.setCharacterEncoding(characterEncoding);
		templateResolver.setTemplateMode("HTML");
		templateResolver.setCacheable(false);
		templateResolver.setPrefix("/templates/");
		templateResolver.setSuffix(".html");
		
		SpringTemplateEngine templateEngine = new SpringTemplateEngine();
		templateEngine.setTemplateResolver(templateResolver);
		
		ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
		viewResolver.setCharacterEncoding(characterEncoding);
		viewResolver.setTemplateEngine(templateEngine);
		returnviewResolver; }}Copy the code

Add parameters of type HttpServletRequest to the parameter list of the methods used to process the request. During processing, the request parameters can be obtained by calling the getParameter() method of the parameter object:

@RequestMapping("handle_reg.do")
@ResponseBody
public String handleReg(HttpServletRequest request) {
    System.out.println("HelloController.handleReg()");

    String username = request.getParameter("username");
    String password = request.getParameter("password");
    Integer age = Integer.valueOf(request.getParameter("age"));
    String phone = request.getParameter("phone");
    String email = request.getParameter("email");
    System.out.println("username=" + username);
    System.out.println("password=" + password);
    System.out.println("age=" + age);
    System.out.println("phone=" + phone);
    System.out.println("email=" + email);

    return "OK."; // We don't care how to respond, so we use @responseBody to return a string
}
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You can encapsulate each request parameter to be submitted by the client into a custom data type, for example:

package cn.tedu.spring;

public class User {

	private String username;
	private String password;
	private Integer age;
	private String phone;
	private String email;
    
    // Getters & Setters
    // toString()
    
}
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Then add the above custom data types to the parameter list of the method that handles the request:

@RequestMapping("handle_reg.do")
@ResponseBody
public String handleReg(User user) {
    System.out.println("HelloController.handleReg()");

    System.out.println(user);

    return "OK."; // We don't care how to respond, so we use @responseBody to return a string
}
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When you need to forward data to the Thymeleaf template page, you should first add ModelMap parameters to the parameter list of the method that processes the request, and when you need to transform the data, call the addAttribute() method of the ModelMap parameter object to encapsulate the data:

@RequestMapping("handle_login.do")
public String handleLogin(String username, String password, ModelMap modelMap) {
    System.out.println("UserController.handleLogin()");
    System.out.println("username=" + username);
    System.out.println("password=" + password);

    // Assume that root/1234 is the correct user name/password
    // Determine the user name
    if ("root".equals(username)) {
        // If the user name is correct, check the password
        if ("1234".equals(password)) {
            // If the password is correct, the login succeeds
            return "OK";
        } else {
            // The password is incorrect
            String message = "Login failed! Wrong password!";
            modelMap.addAttribute("errorMessage", message);
            return "error"; }}else {
        // The username is incorrect
        String message = "Login failed! Wrong username!";
        modelMap.addAttribute("errorMessage", message);
        return "error"; }}Copy the code

Later, in the Thymeleaf template page, use the Thymeleaf expression to display the previously encapsulated data:

<! DOCTYPEhtml>
<html>
<head>
<meta charset="UTF-8">
<title>The operating error</title>
</head>
<body>
<h1>Operation error:<span th:text="${errorMessage}"></span></h1>
</body>
</html>
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