.. 中构造函数的参数 0 需要类型为 org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate 的 bean 找不到

Question

我写了一个简单的待办事项应用程序（基于apress pro spring boot中的内容，我们在其中使用jdbc来处理数据库，在存储库中我们有以下代码来处理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;
    };

下面是我的主要 spring 启动应用程序运行ner

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);
    }

}

但是当我运行使用 spring 引导命令行界面的应用程序时，我将收到以下错误：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

我不知道你书中的例子是什么样的，但我会尽力帮助你。看，你声明了一个字段 private final NamedParameterJdbcTemplate jdbcTemplate; 。您希望以某种方式 spring 来初始化它。为此，您必须声明 @Bean 并在 NamedParameterJdbcTemplate 中输入 @Configuration class 或创建一个 @Component class 扩展 NamedParameterJdbcTemplate .或者扩展 NamedParameterJdbcDaoSupport 并通过 getNamedParameterJdbcTemplate();

获取

实际上以你的例子，添加 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=

应该根据tutorial

解决这个问题

.. 中构造函数的参数 0 需要类型为 org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate 的 bean 找不到

Parameter 0 of constructor in .. required a bean of type org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate could not be found

java

spring

spring-boot

dependency-injection

spring-jdbc