..中构造函数的参数0需要一个类型为org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate的bean

Question

我编写了一个简单的待办事项应用程序（基于apress pro spring boot的内容，其中我们使用jdbc处理数据库，在存储库中，我们有以下代码处理h2数据库

package com.apress.todo.repository;

import java.sql.ResultSet;
import java.time.LocalDateTime;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
import org.springframework.stereotype.Repository;

import com.apress.todo.domain.ToDo;

@Repository
public class ToDoRepository implements CommonRepository<ToDo> {
    private static final String SQL_INSERT ="insert into todo (id,\r\n" + 
            "description, created, modified, completed) values (:id,:description,\r\n" + 
            ":created,:modified,:completed)";
    private static final String SQL_QUERY_FIND_ALL = "select id,"
            +"description, created, modified, completed from todo";
    private static final String SQL_QUERY_FIND_BY_ID = SQL_QUERY_FIND_ALL +
            " where id = :id";
    private static final String SQL_UPDATE = "update todo set description ="
            +":description, modified = :modified, completed = :completed"
            +"where id = :id";
    private static final String SQL_DELETE = "delete from todo where id = :id";
    private final NamedParameterJdbcTemplate jdbcTemplate;





    public ToDoRepository(NamedParameterJdbcTemplate jdbcTemplate) {//HERE IS WHERE THE PROBLEM IS
        System.out.println("hi masoud");
        this.jdbcTemplate = jdbcTemplate;
    }





    private RowMapper<ToDo> toDoRowMapper = (ResultSet rs, int rowNum) -> {
        ToDo toDo = new ToDo();
        toDo.setId(rs.getString("id"));
        toDo.setDescription(rs.getString("description"));
        toDo.setModified(rs.getTimestamp("modified").toLocalDateTime());
        toDo.setCreated(rs.getTimestamp("created").toLocalDateTime());
        toDo.setCompleted(rs.getBoolean("completed"));
        return toDo;
    };

以下是我的主要Spring Boot应用程序运行程序

package com.apress.todo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
public class TodoInMemoryApplication {

    public static void main(String[] args) {
        SpringApplication.run(TodoInMemoryApplication.class, args);
    }

}

但是当我使用spring boot命令行界面运行应用程序时，将出现以下错误：说明：

Parameter 0 of constructor in com.apress.todo.repository.ToDoRepository required a bean of type 'org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate' that could not be found.


Action:

Consider defining a bean of type 'org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate' in your configuration.

书中没有更多解释。

Answer 1

我不知道您的书中的例子是什么样的，但我会尽力帮助您。看，您声明了一个字段private final NamedParameterJdbcTemplate jdbcTemplate;。您希望以某种方式将其初始化。为此，必须在@Bean类中用NamedParameterJdbcTemplate类型声明@Configuration或创建一个扩展@Component的NamedParameterJdbcTemplate类。或扩展NamedParameterJdbcDaoSupport并通过getNamedParameterJdbcTemplate();

实际上是您的示例，加上spring-boot-starter-jdbc

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

并添加属性，例如
spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=

应根据tutorial解决此问题

Answer 2

我不知道您的书中的例子是什么样的，但我会尽力帮助您。看，您声明了一个字段private final NamedParameterJdbcTemplate jdbcTemplate;。您希望以某种方式将其初始化。为此，必须在@Bean类中用NamedParameterJdbcTemplate类型声明@Configuration或创建一个扩展@Component的NamedParameterJdbcTemplate类。或扩展NamedParameterJdbcDaoSupport并通过getNamedParameterJdbcTemplate();

实际上是您的示例，加上spring-boot-starter-jdbc

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

并添加属性，例如
spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=

应根据tutorial解决此问题