web框架 Spring+SpringMvc+Jpa 纯注解搭建

0.jar包依赖 maven  pom.xml

<properties>
    <spring_version>4.3.25.RELEASE</spring_version>
  </properties>

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

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.9.10</version>
    </dependency>

    <dependency>
      <groupId>org.springframework.data</groupId>
      <artifactId>spring-data-jpa</artifactId>
      <version>1.11.23.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-entitymanager</artifactId>
      <version>3.6.10.Final</version>
    </dependency>

    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-validator</artifactId>
      <version>4.1.0.Final</version>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>6.0.6</version>
    </dependency>

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

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>RELEASE</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

1.可被 servlet3.0 容器自动扫描加载的配置文件，位置不限，作用同 web.xml

package com.sw946.spring_demo.config;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class WebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
    protected Class<?>[] getRootConfigClasses() {   // spring容器的配置文件
        return new Class[]{SpringConfig.class};
    }

    protected Class<?>[] getServletConfigClasses() {    // springMVC容器的配置文件
        return new Class[]{MvcConfig.class};
    }

    protected String[] getServletMappings() {   // 被DisatcjerServlet接管的请求路径
        return new String[]{"/"};
    }
}

2.spring容器的配置文件，管理 除被springMvc容器管理（如控制器） 以外的所有对象，可防止织入事务切面时不生效的情况发生

package com.sw946.spring_demo.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Controller;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

//申明为spring配置文件，spring若开启注解扫描，将会将此类作为spring容器配置的一部分
@Configuration
//开启注解扫描功能，并设置扫描范围，排除springMvc的配置文件和Controller组件
@ComponentScan(basePackages = {"com.sw946.spring_demo"},excludeFilters = @ComponentScan.Filter({EnableWebMvc.class, Controller.class}))
public class SpringConfig {
}

3.springMvc容器的配置文件，仅管理自定义的控制器，与spring容器为互补

package com.sw946.spring_demo.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Controller;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
//开启springMvc注解扫描功能
@EnableWebMvc
//仅扫描有@Controller注解的类纳入容器管理
@ComponentScan(basePackages = "com.sw946.spring_demo",includeFilters = @Filter(Controller.class),useDefaultFilters = false)
public class MvcConfig extends WebMvcConfigurerAdapter {
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {     //配置视图解析器(可选)
        registry.jsp("/", ".jsp");
    }

    //配置静态资源处理器，将对 / 路径下的静态资源请求映射为 对文件夹 classpath:/static/的请求，相比于默认静态资源处理器可指定映射到WEB-INFO的文件夹中（servlet默认规则下此目录不可访问）
　　@Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/**").addResourceLocations("classpath:/static/");
    }
}

4.JPA（数据持久化层）的配置文件，本例使用hibernate + mysql, 持久化框架和数据均可替换，配置思路相同

package com.sw946.spring_demo.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.Database;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;

@Configuration
//开启jpa注解扫描，并给定范围，jpa会为继承了JpaRepository接口的接口生成实现类
@EnableJpaRepositories(basePackages = "com.sw946.spring_demo.repository")
//开启事务管理功能
@EnableTransactionManagement
public class JpaConfig {
    @Bean
    public DataSource productDB() {     //配置数据源,按实际要连接的数据库配置
        DriverManagerDataSource ds = new DriverManagerDataSource();
        ds.setDriverClassName("com.mysql.cj.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/test?serverTimezone=UTC");
        ds.setUsername("admin");
        ds.setPassword("admin");
        return ds;
    }

    @Bean
    public JpaVendorAdapter jpaVendorAdapter() {    //配置ORM框架，这里为hibernate
        HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
        adapter.setDatabase(Database.MYSQL);
        adapter.setShowSql(true);
        adapter.setGenerateDdl(false);
        adapter.setDatabasePlatform("org.hibernate.dialect.MySQLDialect");
        return adapter;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter){   //配置实体管理器工厂
        LocalContainerEntityManagerFactoryBean emf = new LocalContainerEntityManagerFactoryBean();
        emf.setDataSource(dataSource);
        emf.setJpaVendorAdapter(jpaVendorAdapter);
        emf.setPackagesToScan("com.sw946.spring_demo.entity");  //给定实体类的扫描范围，会扫描@Entity注解的类
        return emf;
    }

    @Bean
    public PlatformTransactionManager transactionManager(LocalContainerEntityManagerFactoryBean factoryBean) {
        //配置事务管理器，依赖于实体管理器
        return new JpaTransactionManager(factoryBean.getObject());
    }
}

框架配置完成，下面为使用示例：

a.控制器（注意包的位置，根据扫描范围配置建立）

package com.sw946.spring_demo.controller;

import com.sw946.spring_demo.repository.GradeRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class HomeController {
    @Autowired
    private GradeRepository gradeRepository;

    @RequestMapping("/home")
    @ResponseBody
    public String home() {
        return gradeRepository.findLaster().toString();
    }
}

b.持久层(因示例简单，忽略服务层)

package com.sw946.spring_demo.repository;

import com.sw946.spring_demo.entity.Grade;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface GradeRepository extends JpaRepository<Grade,String>{
    List<Grade> findByIdLessThan(String id);    //方法名查询，jpa提供

    //JPql、原生sql查询
    @Query(nativeQuery=true, value = "select * from grade order by id desc limit 0,1")
    Grade findLaster();
}

package com.sw946.spring_demo.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import java.util.Date;

@Entity
public class Grade {
    @Id
    private String id;
    private String name;

    @Column(name = "create_time")
    private Date createTime;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    @Override
    public String toString() {
        return "Grade{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", createTime=" + createTime +
                '}';
    }
}

c.数据库表

CREATE TABLE `grade` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  `create_time` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
INSERT INTO `grade` (`id`, `name`, `create_time`) VALUES ('', '', '2019-11-18 15:50:41');
INSERT INTO `grade` (`id`, `name`, `create_time`) VALUES ('', '', '2019-11-18 17:32:56');

tomcat运行,访问 127.0.0.1:端口号/home ，即可看到数据库返回的json字符串，框架搭建完成！