通用增删改查架子搭建

每个项目中都会有通用的增删改查基础框架，现在搭一个基本的架子。

代码结构：

代码：

package com.crudTemplate.mapper;

public interface BaseMapper<T> {
    void insert(T t);
}
//================
package com.crudTemplate.mapper;

import com.crudTemplate.entity.User;

public interface UserMapper extends BaseMapper<User> {
}
//================
package com.crudTemplate.service;

public interface BaseService<T> {
    void insert(T entity);
}
//================
package com.crudTemplate.service;

import com.crudTemplate.entity.User;

public interface UserService extends BaseService<User> {
}
//================
package com.crudTemplate.service.impl;

import com.crudTemplate.mapper.BaseMapper;
import com.crudTemplate.service.BaseService;

public class BaseServiceImpl<M extends BaseMapper<T>,T> implements BaseService<T> {
    protected M baseMapper;

    @Override
    public void insert(T entity) {
        System.out.println("添加" + entity + "成功。");
        baseMapper.insert(entity);
    }
}
//================
package com.crudTemplate.service.impl;

import com.crudTemplate.entity.User;
import com.crudTemplate.mapper.UserMapper;
import com.crudTemplate.service.UserService;

public class UserServiceImpl extends BaseServiceImpl<UserMapper,User> implements UserService {
}
//================
//测试 在spring中需要标注注解，protected M baseMapper也需要标注注解
package com.crudTemplate;

import com.crudTemplate.entity.User;
import com.crudTemplate.service.UserService;
import com.crudTemplate.service.impl.UserServiceImpl;

public class CrudTest {
    public static void main(String[] args) {
        User user = new User();
        user.setUserName("令狐冲");
        user.setAge(25);
        UserService us = new UserServiceImpl();
        us.insert(user);
    }
}

运行结果：
Exception in thread "main" java.lang.NullPointerException
	at com.crudTemplate.service.impl.BaseServiceImpl.insert(BaseServiceImpl.java:12)
	at com.crudTemplate.CrudTest.main(CrudTest.java:13)
添加User{userName='令狐冲', age=25}成功。

Process finished with exit code 1

 从结果可以看出打印出User,证明可以运行，空指针异常是因为没有注入baseMapper。