java - 这是 MVC DAO 的正确方法吗？我收到类似 Autowiring 依赖项注入(inject)失败的错误

Question

我是 spring 的新手，我面临以下错误。请帮帮我。提前致谢。

用户界面

package com.system.dao;

import java.util.List;

import com.system.model.User;

public interface UserDAO {

public String createOrUpdate(User user);
public List<User> getAllUser();
public String delete(User user);
} 

用户界面实现

public class UserDAOImpl implements UserDAO {

 private NamedParameterJdbcTemplate jdbc;

@Autowired
public void setJdbc(DataSource jdbc) {
    this.jdbc = new NamedParameterJdbcTemplate(jdbc);
}

@Transactional
@Override
public String createOrUpdate(User user) {
    BeanPropertySqlParameterSource params = new BeanPropertySqlParameterSource(user);
    if (user.isUpdate()) {
        jdbc.update(
                "update login set login_id=:loginId,login_password:loginPassword,user_name=:userName,user_contact=:userContact,user_email=:userEmail where user_id=:userId",
                params);
        return "User Updated";
    } else {
        jdbc.update(
                "insert into login(login_id,login_password,user_name,user_contact,user_email) values(:loginId,:loginPassword,:userName,:userContact,:userEmail)",
                params);
        return "User added";
    }

}

@Override
public List<User> getAllUser() {
    jdbc.query("select * from login", new RowMapper<User>() {
        @Override
        public User mapRow(ResultSet rs, int num) throws SQLException {
            // TODO Auto-generated method stub
            User user = new User();
            user.setLoginId(rs.getString("login_id"));
            user.setLoginPassword(rs.getString("login_password"));
            user.setUserContact(rs.getString("user_contact"));
            user.setUserEmail(rs.getString("user_email"));
            user.setUserId(rs.getInt("user_id"));
            user.setUserName(rs.getString("user_name"));

            return user;
        }
    });
    return null;
}

@Override
public String delete(User user) {
    jdbc.update("delete from login where user_id:userId", new MapSqlParameterSource("userId", user.getUserId()));
    return "User deleted";
}

 }

用户服务

package com.system.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.system.dao.impl.UserDAOImpl;
import com.system.model.User;

@Service
public class UserService  {

private UserDAOImpl userDAOImpl;

@Autowired(required=true)
public void setUserDAOImpl(UserDAOImpl userDAOImpl) {
    this.userDAOImpl = userDAOImpl;
}
public String createOrUpdate(User user) {
    return userDAOImpl.createOrUpdate(user);
}
public List<User> getAllUser() {
    return userDAOImpl.getAllUser();
}

public String delete(User user) {
    return userDAOImpl.delete(user);
}




}

上下文(dao-context)

<context:annotation-config></context:annotation-config>
<context:component-scan base-package="com.system.dao">
</context:component-scan>

<context:component-scan base-package="com.system.dao.impl">
</context:component-scan>
<context:component-scan base-package="com.system.service">
</context:component-scan>

Answer 1

您在 UserDAOImpl 中缺少 @Repository。

@Repository("userDAOImpl")
public class UserDAOImpl implements UserDAO {

要将 java 类转换为 spring 组件，您需要使用以下任意内容注释该类

• @Controller
• @Component
• @Repository
• @Service

由于UserDAOImpl是属于DAO层的dao，因此@Repository是最合适的。

阅读更多内容 http://howtodoinjava.com/spring/spring-core/how-to-use-spring-component-repository-service-and-controller-annotations/