教你如何集成JSP和Freemarker到SpringBoot项目中

      经常我们开发中一般不会再用JSP了，都会选择freemarker或者thymeleaf。对于JSP，它前后端耦合性太差，而且JSP需要tomcat来解析，nginx解析不了，已经跟不上时代的潮流。我更倾向使用freemarker，他可以很好的解耦前后端，甚至在完全静态化这方面做的相当不错，所有对于那种内容管理型的网站，用freemarker可以大大的节省服务器的开支。

如何集成JSP呢？

1. pom.xml

<dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
</dependency>
<dependency>
       <groupId>org.apache.tomcat.embed</groupId>
       <artifactId>tomcat-embed-jasper</artifactId>
</dependency>

2.application.yml

spring:
  mvc:
    view:
      prefix: /WEB-INF/jsp/
      suffix: .jsp

3.MVCConfig.java (进行MVC注解配置，如果第二步不生效)

package org.joseph.mysite.web.configuration;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.*;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

@Configuration
public class MvcConfig implements WebMvcConfigurer {

    /**
     * 配置请求视图映射
     *
     * @return
     */
    @Bean
    public InternalResourceViewResolver resourceViewResolver() {
        InternalResourceViewResolver internalResourceViewResolver = new InternalResourceViewResolver();
        //请求视图文件的前缀地址
        internalResourceViewResolver.setPrefix("/WEB-INF/jsp/");
        //请求视图文件的后缀
        internalResourceViewResolver.setSuffix(".jsp");
        return internalResourceViewResolver;
    }

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        WebMvcConfigurer.super.addCorsMappings(registry);
        registry.addMapping("/cors/**")
                .allowedHeaders("*")
                .allowedMethods("POST", "GET")
                .allowedOrigins("*");
    }

    /**
     * 视图配置
     *
     * @param registry
     */
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        WebMvcConfigurer.super.configureViewResolvers(registry);
        registry.viewResolver(resourceViewResolver());
        /*registry.jsp("/WEB-INF/jsp/",".jsp");*/
    }


    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
        configurer.enable("defaultServletName");
    }

    /**
     * 配置静态访问资源
     * @param registry
     */
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/statics/**").addResourceLocations("classpath:/statics/");
    }

}

 

4. Application.java （放在controller的父级目录）

package org.joseph.mysite.web;

import org.mybatis.spring.annotation.MapperScan;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@SpringBootApplication(scanBasePackages = {"org.joseph.mysite.web"})
@MapperScan("org.joseph.mysite.db.dao")
@EnableTransactionManagement
@EnableScheduling
public class Application {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(Application.class, args);
    }

}

 

如何集成Freemarker呢？

1. pom.xml

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

2. application.yml

spring:
  http:
    encoding:
      force: true
      charset: UTF-8
  freemarker:
    allow-request-override: false
    cache: false
    check-template-location: true
    charset: UTF-8
    content-type: text/html; charset=utf-8
    expose-request-attributes: false
    expose-session-attributes: false
    expose-spring-macro-helpers: false
    suffix: .html
    template-loader-path: classpath:/templates
    settings:
      urlEscapingCharset: UTF-8
      templateUpdateDelay: 5
      tagSyntax: autoDetect
      whitespaceStripping: true
      classicCompatible: true
      numberFormat: 0.######
      booleanFormat: true,false
      datetimeFormat: yyyy-MM-dd HH:mm:ss
      dateFormat: yyyy-MM-dd
      timeFormat: HH:mm:ss
      apiBuiltinEnabled: true
      objectWrapper: DefaultObjectWrapper(2.3.28)
      templateExceptionHandler: org.joseph.mysite.cmsfreemarker.configuration.FreemarkerExceptionHandler
  mvc:
    static-path-pattern: /static/**

 

3. FreemarkerConfig.java (配置文件)

package org.joseph.mysite.cmsfreemarker.configuration;

import freemarker.template.DefaultObjectWrapper;
import freemarker.template.SimpleDate;
import freemarker.template.TemplateException;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.view.freemarker.FreeMarkerConfig;
import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;
import org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver;

import javax.annotation.Resource;
import java.io.IOException;
import java.sql.Date;
import java.sql.Time;
import java.sql.Timestamp;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.util.Properties;

@Configuration
public class FreemarkerConfig {

    @Resource
    void configureFreemarkerConfigurer(FreeMarkerConfig configurer) {
        configurer.getConfiguration().setObjectWrapper(new CustomObjectWrapper());
    }

    private static class CustomObjectWrapper extends DefaultObjectWrapper {
        @Override
        public TemplateModel wrap(Object obj) throws TemplateModelException {
            if (obj instanceof LocalDateTime) {
                Timestamp timestamp = Timestamp.valueOf((LocalDateTime) obj);
                return new SimpleDate(timestamp);
            }
            if (obj instanceof LocalDate) {
                Date date = Date.valueOf((LocalDate) obj);
                return new SimpleDate(date);
            }
            if (obj instanceof LocalTime) {
                Time time = Time.valueOf((LocalTime) obj);
                return new SimpleDate(time);
            }
            return super.wrap(obj);
        }
    }
}

 

4. 异常处理

package org.joseph.mysite.cmsfreemarker.configuration;
import freemarker.core.Environment;
import freemarker.template.TemplateException;
import freemarker.template.TemplateExceptionHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.io.Writer;

public class FreemarkerExceptionHandler implements TemplateExceptionHandler {
    private static final Logger log = LoggerFactory.getLogger(FreemarkerExceptionHandler.class);
    @Override
    public void handleTemplateException(TemplateException te, Environment env, Writer out) throws TemplateException {
        log.warn("[Freemarker Error: " + te.getMessage() + "]");
        String missingVariable = "undefined";
        try {
            String[] tmp = te.getMessageWithoutStackTop().split("\n");
            if (tmp.length > 1)
                tmp = tmp[1].split(" ");
            if (tmp.length > 1)
                missingVariable = tmp[1];
            out.write("");
            log.error("[出错了，请联系网站管理员]", te);
        } catch (IOException e) {
            throw new TemplateException(
                    "Failed to print error message. Cause: " + e, env);
        }

    }
}