1.确定导入依赖：
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>2.确定导入导入了正确的依赖包：
千万注意，导入的包的是 ：
org.junit.Test;
千万不要导成 org.junit.jupiter.api.Test;，否则会报：java.lang.NullPointerException和initializationError
3.测试类要写成public类型，测试方法也要要写成public 。。。并且测试方法要用@Test注解，，测试方法为public void类型的方法，否则也会报initializationError
4.确保你的spring配置文件的指定路径是对的，spring的配置文件没有问题，，所有的spring配置文件都被加载了进来，测试的接口类被加载进了spring的容器中。
下面附上我的代码以供参考（声明式和注解式的）
注解式：
service接口的测试代码：
package cn.itcast.ssm.service;
import cn.itcast.ssm.pojo.Items;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
//@ContextConfiguration(locations = { "classpath*:spring/applicationContext-*.xml", "classpath*:spring/applicationContext-mvc.xml",})*/
@RunWith(SpringJUnit4ClassRunner.class)//使用junit4进行测试
@ContextConfiguration(locations = {"classpath:spring/applicationContext.xml"})
public class ItemsServiceTest {
@Autowired
private ItemsService itemsService;
@Test
public void lmj() throws Exception {
//ItemsService itemsService=new ItemsServiceImpl();
// ItemsService itemsService= (ItemsService) applicationContext.getBean("itemsService");
Items items = itemsService.lmj();
System.out.println(items);
System.out.println(items);
}
}声明式：（这是我ssm之路（9）系列博客里的spring整合mybatis的单元测试文件，这里拿来粘贴一下）
package cn.itcast.ssm.dao;
import cn.itcast.ssm.po.OrdersCustom;
import org.junit.Test;
import org.junit.Before;
import org.junit.After;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.List;
/**
* OrdersMapperCustomImpl Tester.
*
* @author <Authors name>
* @since <pre>ʮһ�� 8, 2018</pre>
* @version 1.0
*/
public class OrdersMapperCustomImplTest {
private ApplicationContext applicationContext;
@Before
public void before() throws Exception {
applicationContext=new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");
}
@After
public void after() throws Exception {
}
/**
*
* Method: findOrdersPlusUser()
*
*/
@Test
public void testFindOrdersPlusUser() throws Exception {
//TODO: Test goes here...
OrdersMapperCustom ordersMapperCustom= (OrdersMapperCustom) applicationContext.getBean("ordersMapperCustom");
List<OrdersCustom> orderslist= ordersMapperCustom.findOrdersPlusUser();
System.out.println(orderslist);
System.out.println(orderslist);
}
}最后再说明一个大错：
Caused by: org.apache.ibatis.builder.BuilderException: Error evaluating expression 'items.name'. Cause: org.apache.ibatis.ognl.OgnlException: source is null for getProperty(null, "name")；
source is null for getProperty(null, "name")
犯这个错，完全是我的粗心，还一直再找是不是sql语法的错误：
先贴一下错误的代码：
先是itemsMapperCustom.xml:
然后是itemsServiceimpl：（我在形参里定义了封装的pojo类，但再写函数时却忘了将参数放进去，导致最后一值报source is null for getProperty(null, "name")；不知道有人与我犯一个错误了吗）
我的itemMapperCustom：
希望引以为戒：最后放正确的带码：
mapper接口 ItemsMapperCustom.java:
public interface ItemsMapperCustom {
public List<Items>finditemsList(ItemsQueryVo itemsQueryVo)throws Exception;
}实体类pojo： Items.java:
public class Items {
private Integer id;
private String name;
private Float price;
private String pic;
private Date createtime;
private String detail;
//省略getter，setter
}基于实体类items的拓展类（即综合查询的封装pojo类） ItemsQueryVo.java：
public class ItemsQueryVo {
private Items items;
public Items getItems() {
return items;
}
public void setItems(Items items) {
this.items = items;
}
}业务层的接口ItemsService.java:
public interface ItemsService {
public List<Items> finditemsList(ItemsQueryVo itemsQueryVo)throws Exception;
}itemsService接口的实现类 ItemsServiceImpl.java:
@Service
public class ItemsServiceImpl implements ItemsService {
@Autowired
private ItemsMapperCustom itemsMapperCustom;
@Override
public List<Items> finditemsList(ItemsQueryVo itemsQueryVo) throws Exception {
List<Items> list=itemsMapperCustom.finditemsList(itemsQueryVo);
return list;
}sql语句的映射文件（mapper接口的实现类）mapper/ItemsMapperCustom.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.itcast.ssm.mapper.ItemsMapperCustom">
<sql id="query_items_where">
<if test="items != null and items != ''">
<if test="items.name != null and items.name != ''">
items.name like '%${items.name}%'
</if>
</if>
</sql>
<select id="finditemsList" parameterType="cn.itcast.ssm.pojo.ItemsQueryVo" resultType="cn.itcast.ssm.pojo.Items">
SELECT * FROM items
<where>
<include refid="query_items_where"></include>
</where>
</select>
</mapper>
ItemsServiceTest测试类：
package cn.itcast.ssm.service;
import cn.itcast.ssm.pojo.Items;
import cn.itcast.ssm.pojo.ItemsQueryVo;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import java.util.List;
//@ContextConfiguration(locations = { "classpath*:spring/applicationContext-*.xml", "classpath*:spring/applicationContext-mvc.xml",})*/
@RunWith(SpringJUnit4ClassRunner.class)//使用junit4进行测试
@ContextConfiguration(locations = {"classpath:spring/applicationContext.xml"})
public class ItemsServiceTest {
@Autowired
private ItemsService itemsService;
@Test
public void finditemsList() throws Exception {
Items items=new Items();
items.setName("水");
ItemsQueryVo itemsQueryVo=new ItemsQueryVo();
itemsQueryVo.setItems(items);
System.out.println(itemsQueryVo);
List<Items>list=itemsService.finditemsList(itemsQueryVo);
System.out.println(list);
System.out.println(list);
}
}测试就到此完成。