一、测试数据准备

/*
 Navicat Premium Data Transfer

 Source Server         : swp-mysql
 Source Server Type    : MySQL
 Source Server Version : 50730
 Source Host           : localhost:3306
 Source Schema         : project

 Target Server Type    : MySQL
 Target Server Version : 50730
 File Encoding         : 65001

 Date: 24/07/2022 23:56:58
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for employee
-- ----------------------------
DROP TABLE IF EXISTS `employee`;
CREATE TABLE `employee`  (
  `id` int(5) NOT NULL,
  `name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `email` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `age` int(3) NULL DEFAULT NULL,
  `dept_id` int(5) NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of employee
-- ----------------------------
INSERT INTO `employee` VALUES (1, '张三', 'zhangsan@qq.com', 28, 101);
INSERT INTO `employee` VALUES (2, '王五', 'wangwu@qq.com', 24, 102);

SET FOREIGN_KEY_CHECKS = 1;

二、SpringContextUtil编写工具类

编写的工具类为SpringUtil，实现ApplicationContextAware接口，并加入Component注解，让spring扫描到该bean：

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;

@Component
public class SpringContextUtil implements ApplicationContextAware {

    /**
     * 上下文对象实例
     */
    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    /**
     * 获取applicationContext
     *
     * @return
     */
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    /**
     * 获取HttpServletRequest
     */
    public static HttpServletRequest getHttpServletRequest() {
        return ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
    }

    public static String getDomain(){
        HttpServletRequest request = getHttpServletRequest();
        StringBuffer url = request.getRequestURL();
        return url.delete(url.length() - request.getRequestURI().length(), url.length()).toString();
    }

    public static String getOrigin(){
        HttpServletRequest request = getHttpServletRequest();
        return request.getHeader("Origin");
    }

    /**
     * 通过name获取 Bean.
     *
     * @param name
     * @return
     */
    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    /**
     * 通过class获取Bean.
     *
     * @param clazz
     * @param       <T>
     * @return
     */
    public static <T> T getBean(Class<T> clazz) {
        return getApplicationContext().getBean(clazz);
    }

    /**
     * 通过name,以及Clazz返回指定的Bean
     *
     * @param name
     * @param clazz
     * @param       <T>
     * @return
     */
    public static <T> T getBean(String name, Class<T> clazz) {
        return getApplicationContext().getBean(name, clazz);
    }
}

三、SpringContextUtil工具类实例测试

（1）.编写测试的mapper实例：

/**
 * @Project:
 * @Description:
 * @Auther: songwp
 * @Date: 2022/1/30 10:23
 **/
@Mapper
public interface EmployeeMapper {

    List<Employee> findAll();

    Employee selectById(Integer id);
}

（2）junit单元测试结果如下：

   @Test
   public void contextLoads(){
        EmployeeMapper empService = SpringContextUtil.getBean(EmployeeMapper.class);
        System.out.println(empService.findAll());

    }