21.扩展SpringMVC的组件

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2. 扩展SpringMVC的组件

1.在容器中注册视图控制器

在以前的开发中，我们想跳转到一个WEB-INF【templates】里面页面必须通过Controller，return

现在可以通过创建一个视图控制器ViewController来控制页面跳转

在pom.xml里添加thymeleaf依赖

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<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

src/main/resources/templates/helloWorld.html

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<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
templates/helloWorld.html
</body>
</html>
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package com.example.demo.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {

	@Override
	public void addViewControllers(ViewControllerRegistry registry) {
		// TODO Auto-generated method stub
		WebMvcConfigurer.super.addViewControllers(registry);
		
		/*
		 * 已经配置了默认的前缀和后缀，
		 * 所以setViewName()不用设置"classpath:/templates/helloWorld.html"，
		 * 直接设置为html的文件名即可
		 */
		registry.addViewController("/index/hello").setViewName("helloWorld");
		// 浏览器访问http://localhost:8080/index/hello，跳转到/templates/helloWorld.html页面
	}
	
}

2.注册格式化器

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package com.example.demo.controller;

import java.util.Date;

import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.example.demo.vo.Student;

@Controller
@RequestMapping("index")
public class IndexController {
		
	@RequestMapping("showDateTime")
	public String showDateTime(Date date) {
		System.out.println("controller date: " + date);
		return "helloWorld";
	}

}

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package com.example.demo.config;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import org.springframework.context.annotation.Configuration;
import org.springframework.format.Formatter;
import org.springframework.format.FormatterRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
	
	/*
	 * 注册格式化器
	 */
	@Override
	public void addFormatters(FormatterRegistry registry) {
		// TODO Auto-generated method stub
		WebMvcConfigurer.super.addFormatters(registry);
		
		/*
		 * Formatter是一个接口，不能被实例化，
		 * 在这里创建一个内部类
		 */
		registry.addFormatter(new Formatter<Date>() {

			@Override
			public String print(Date object, Locale locale) {
				// TODO Auto-generated method stub
				return null;
			}

			@Override
			public Date parse(String text, Locale locale) throws ParseException {
				// TODO Auto-generated method stub
				System.out.println("formatter text: " + text);
				SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
				Date paramDate = format.parse(text);
				return paramDate;
			}
			
		});
	}
}

浏览器访问：http://localhost:8080/index/showDateTime?date=2021-01-01 10:10:10

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formatter text: 2021-01-01 10:10:10
controller date: Fri Jan 01 10:10:10 CST 2021

3.消息转化器扩展fastjson

3.1 Springmvc默认的json转换器为jackson

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package com.example.demo.vo;

import java.util.Date;

import org.springframework.format.annotation.DateTimeFormat;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonProperty;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student {

	private Integer id;
	private String name;
	
	@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
	@JsonProperty(value = "birth")
	private Date birthday;
}
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package com.example.demo.controller;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import com.example.demo.vo.Student;

@Controller
@RequestMapping("index")
public class IndexController {
	
	@RequestMapping(value = "getStudentInfo", method = RequestMethod.GET)
	@ResponseBody
	public Student getStudentInfo() throws ParseException {
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date birthday = format.parse("2020-01-01 10:10:10");
		
		Student student = new Student();
		student.setId(1);
		student.setName("John");
		student.setBirthday(birthday);
		
		return student;
	}

}

浏览器访问http://localhost:8080/index/getStudentInfo，

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{"id":1,"name":"John","birth":"2020-01-01 10:10:10"}

以上的配置默认是jackson去作转换的

3.2 自定义Fastjson转化器

引入fastjson依赖

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<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
	<groupId>com.alibaba</groupId>
	<artifactId>fastjson</artifactId>
	<version>1.2.75</version>
</dependency>

在HttpMessageConverter接口上Ctrl+T，寻找该接口的fastjson实现类

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package com.example.demo.config;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.Locale;

import org.springframework.context.annotation.Configuration;
import org.springframework.format.Formatter;
import org.springframework.format.FormatterRegistry;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import com.example.demo.vo.Student;

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {

	@Override
	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
		// TODO Auto-generated method stub
		WebMvcConfigurer.super.configureMessageConverters(converters);
		
		FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
		
		// 下面的配置可不设置，因为有默认值
		FastJsonConfig fastJsonConfig = new FastJsonConfig();
		// 设置序列化的方式
		fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat);
		fastJsonHttpMessageConverter.setFastJsonConfig(fastJsonConfig);
		
		converters.add(fastJsonHttpMessageConverter);
	}
}
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package com.example.demo.vo;

import java.util.Date;

import org.springframework.format.annotation.DateTimeFormat;

import com.alibaba.fastjson.annotation.JSONField;
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonProperty;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student {

	private Integer id;
	private String name;
	
	// 下面的使用jackson的配置已经不生效了
	// @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
	// @JsonProperty(value = "birth")
	@JSONField(format = "yyyy-MM-dd HH:mm:ss", name = "birth")
	private Date birthday;
		
}

浏览器访问http://localhost:8080/index/getStudentInfo，

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{"birth":"2020-01-01 10:10:10","id":1,"name":"John"}

4.注册拦截器

创建拦截器

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package com.example.demo.interceptor;

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

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class MyInterceptor implements HandlerInterceptor {

	/**
	 * 在调用controller的方法之前执行
	 * @param handler: 要访问的控制器对象
	 */
	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		// TODO Auto-generated method stub
		System.out.println("preHandle controller = " + handler.getClass().getName());
		return HandlerInterceptor.super.preHandle(request, response, handler);
	}
	
	/**
	 * 在执行完controller的方法之后，进行转发/重定向之前执行
	 * @param handler: 要访问的控制器
	 * @param modelAndView: controller执行完之后返回的对象
	 */
	@Override
	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
			ModelAndView modelAndView) throws Exception {
		// TODO Auto-generated method stub
		System.out.println("postHandle controller = " + handler.getClass().getName() + " modelAndView = " + modelAndView.getViewName());
		HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
	}
	
	/**
	 * 页面加载渲染完成之后执行
	 */
	@Override
	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
			throws Exception {
		// TODO Auto-generated method stub
		System.out.println("afterCompletion controller = " + handler.getClass().getName());
		HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
	}
}

注册拦截器

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package com.example.demo.config;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Locale;

import org.springframework.context.annotation.Configuration;
import org.springframework.format.Formatter;
import org.springframework.format.FormatterRegistry;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import com.example.demo.interceptor.MyInterceptor;

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
	
	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		// TODO Auto-generated method stub
		WebMvcConfigurer.super.addInterceptors(registry);
		
		List<String> excludePatternList = new ArrayList<String>();
		excludePatternList.add("/index/hello");
		excludePatternList.add("/index/getStudentInfo");
		
		// 创建拦截器对象
		MyInterceptor myInterceptor = new MyInterceptor();
		// 注册拦截器
		registry.addInterceptor(myInterceptor)
		// 设置拦截路径
		.addPathPatterns("/**")
		// 设置排除拦截的路径
		.excludePathPatterns(excludePatternList);
	}
}

controller

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package com.example.demo.controller;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;

import com.example.demo.vo.Student;

@Controller
@RequestMapping("index")
public class IndexController {
	
	@RequestMapping("hello")
	public String hello() {
		return "helloWorld";
	}
	
	@RequestMapping(value = "getStudentInfo", method = RequestMethod.GET)
	@ResponseBody
	public Student getStudentInfo() throws ParseException {
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date birthday = format.parse("2020-01-01 10:10:10");
		
		Student student = new Student();
		student.setId(1);
		student.setName("John");
		student.setBirthday(birthday);
		
		return student;
	}

	@RequestMapping(value = "getTimeNow")
	public String getTimeNow(Model model) {
		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date dateTime = new Date();
		String timeStamp = simpleDateFormat.format(dateTime);
		model.addAttribute("date", timeStamp);
		return "helloWorld";
	}
}

html

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<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	templates/helloWorld.html
	<br/>
	time: <span th:text="${date}"></span>
</body>
</html>
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1. url: http://localhost:8080/index/hello
页面: 
templates/helloWorld.html
time:(空白)

控制台: 
(空白)

2. url: http://localhost:8080/index/getStudentInfo
页面: 
{ "birth":"2020-01-01 10:10:10", "id":1, "name":"John" }

控制台: 
(空白)

3. url: http://localhost:8080/index/getTimeNow
页面: 
templates/helloWorld.html
time: 2021-08-07 07:49:41

控制台: 
preHandle controller = org.springframework.web.method.HandlerMethod
postHandle controller = org.springframework.web.method.HandlerMethod modelAndView = helloWorld
afterCompletion controller = org.springframework.web.method.HandlerMethod