JdbcTemplate无法使用自动装配 [英] JdbcTemplate not working with autowiring

问题描述

我正在使用Springboot创建一个REST应用程序.经过研究后，我向其中添加了JdbcTemplate，而不是直接使用Jdbc和结果集.我在application.properties中具有以下配置.

I am creating a REST application using Springboot. After doing some research I added JdbcTemplate to it rather than working directly with Jdbc and resultsets. I have the following configuration in application.properties.

server.context-path=/foo
spring.datasource.driverClassName=com.teradata.jdbc.TeraDriver
spring.datasource.url=jdbc:teradata://url
spring.datasource.username=root
spring.datasource.password=root

我的REST控制器具有以下代码

My REST controller has the following code

@RestController
public class LosController {

    @CrossOrigin
    @RequestMapping("/bar")
    public String Bar(){
        Gson gson = new Gson();
        Bar bar = new Bar();
        response = gson.toJson(bar.getData());
        return response;
    }

在这个对象中，我有

public class Bar {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    public List<BarObject> getData(){
        String selectSql = "SELECT * FROM BAR";
        System.out.println(selectSql);
        System.out.println(jdbcTemplate.getDataSource().toString());

        List<BarObject> barObjs = jdbcTemplate.query(selectSql, new BarMapper());       

        return barObjs;
    }
}

我通过了链接并进行了配置如前所述的一切.我能够看到System.out.println(selectSql)的工作.但是在下一行，我得到的是null pointer exception.因此，JdbcTemplate对象无法获得我所感觉到的数据.我该如何工作?我试图不使用任何xml配置，这就是为什么要使用属性文件的原因.

I went through this link and configured everything as mentioned. I am able to see the System.out.println(selectSql) working. But at the next line, I am getting a null pointer exception. So the JdbcTemplate object isn't getting the data is what I feel. How can I get this working? I am trying to not use any xml configurations, which is the reason why I went for a properties file.

推荐答案

Bar不是spring bean.

Bar is not a spring bean.

要使其正常工作，您可以使用@Component注释Bar并在LosController中自动将其布线，而不是使用new创建.

To get it working, you can annotate Bar with @Component and autowire it in LosController rather than creating with new.

@RestController
public class LosController {

    @Autowired
    private Bar bar;

    @CrossOrigin
    @RequestMapping("/bar")
    public String Bar(){
        Gson gson = new Gson();
        response = gson.toJson(bar.getData());
        return response;
    }
}

@Component
public class Bar {

    @Autowired
    private JdbcTemplate jdbcTemplate;


    public List<BarObject> getData(){
        String selectSql = "SELECT * FROM BAR";
        System.out.println(selectSql);
        System.out.println(jdbcTemplate.getDataSource().toString());

        List<BarObject> barObjs = jdbcTemplate.query(selectSql, new BarMapper());       

        return barObjs;
    }
}

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