與SpringBoot

Question

自動裝配的問題，我有一個類象下面這樣：

package com.company.data.render.model 
@RestController 
public class ControllerClass { 

@Autowired 
ApplicationPropertiesServiceImpl services; 

@RequestMapping(value = "/node1", method = RequestMethod.GET) 
@ResponseBody 
public ParentNode getNode1() 
{ 


    Child node = new Child(); 
    List<Map<String, Object>> properties properties = services.getData("A",xxx); 
    node.addtree(); 
    node.setProperties(properties); 
    return node; 
} 
} ------------------------------------------------------------------------------- 

package com.company.data.service; 
@Component 
public List<Map<String, Object>> getData(String type,String name) 
{ 
     if(type.equalsIgnoreCase("A")) 
     { 
      String sql = "select * from data.data_properties(?)"; 
      List<Map<String, Object>> rows = jdbcTemplate.queryForList(sql,host); 
      return rows; 
     }else if(properties.equalsIgnoreCase("B")) 
     { 
      String sql = "select * from data.application_properties(?)"; 
      List<Map<String, Object>> rows = jdbcTemplate.queryForList(sql,host); 
      return rows; 
     } 

} 

------------------------------------------------------------------------------- 
package com.company.data.render.model; 

@Component 
public class Child { 

@Autowired 
ApplicationPropertiesServiceImpl services; 


public void addtree() 
{ 
List<Map<String, Object>> properties=services.getData("B", "xxy"); 

} 
} 

我如何可以訪問的GetData（）功能兒童 class.I我得到空指針異常的服務對象雖然我已經自動裝配的ApplicationPropertiesServiceImpl

Answer 1

好像你將有2個控制器。

顯然你的控制器做得太多了。將控制器注入另一個控制器並不是一個好主意。

我建議你做一個服務和庫：

該模型接收到來自控制器的數據量，所以我建議創建一個類，使之更加明確，因爲返回地圖過於抽象，使代碼難以閱讀。

public class CarProperties { 
    private Integer id; 
    private String name; 
    private Integer age; 
    private String color; 
    //setters and gettters 
    .... 
} 

服務：

public interface CarPropertiesService { 
    public List<CarProperties> findAll(String type); 
} 

@Service("CarPropertiesService") 
public class CarPropertiesServiceImpl implements CarPropertiesService { 
    @Autowired 
    private CarPropertiesDAO carPropertiesDAO; 

    public List<CarProperties> findAll(String type) { 
     List<CarProperties> result = new ArrayList<>(); 
     if ("XXX".equalsIgnoreCase(type)) { 
     List<Map<String, Object>> carPropertiesList = carPropertiesDAO.findAll(); 
     for(Map<String, Object> carProperties : carPropertiesList) { 
      result.add(getCarPropertiesInstance(carProperties)); 
     } 

     } 
     return result; 
    } 

    private CarProperties getCarPropertiesInstance(Map<String, Object> properties) { 
     CarProperties instance = new CarProperties(); 
     instance.setId(properties.get("id")); 
     instance.setName(properties.get("name")); 
     ... 
     return instance; 
    } 
} 

DAO：

public interface CarPropertiesDAO { 
    public List<Map<String, Object>> findAll(); 
} 

@Repository("CarPropertiesDAO") 
public class CarPropertiesDAOImpl implements CarPropertiesDAO { 
    ... 
    public List<Map<String, Object>> findAll() { 
     String sql = "select * from data.car_properties(?)"; 
     return jdbcTemplate.queryForList(sql,host); 
    } 
} 

，最後你的控制器就可以使服務的使用：

@RestController 
public class ControllerClass { 
    @Autowired 
    private CarPropertiesService carPropertiesService; 

    @RequestMapping(value = "/node1", method = RequestMethod.GET) 
    @ResponseBody 
    public ParentNode getNode1() 
    { 
     List<CarProperties> properties = carPropertiesService.findAllByType("XXX"); 
     return properties; 

    } 

    @RequestMapping(value = "/prop/{type}/{name}", method = RequestMethod.GET) 
    @ResponseBody 
    public List<CarProperties> getData(@PathVariable String type,@PathVariable String name) 
    { 
     List<CarProperties> rows = carPropertiesService.findAllByType(type);  
     ... 
    } 
} 

@Controller 
public class Controller2 { 
    @Autowired 
    CarPropertiesService carPropertiesService; 


    public void addtree(){ 
     List<CarProperties> rows = carPropertiesService.findAllByType("XXX"); 
    } 
} 

恢復：控制器不應該擔心生意只返回數據。服務應該是業務所在的地方，比如計算，數據交換等......你可以清楚地看到它的DAO類用於數據庫操作。同時請記住，DAO對象的訪問權限應該在Services/Facedes中，在Controller推薦的Controller中使用它。因此，使用這種結構，您的代碼將變得更加可重用且易於維護。

Answer 2

請試試這個： -

@Component 
@ComponentScan(basePackages="<provide your base pkg where it will scan for the component ControllerClass>") 
@ConditionalOnBean(ControllerClass.class) 
public class Child { 
    @Autowired(required=true) 
    private ControllerClass controllerClass; 

    public void addtree(){ 
    controllerClass.getData("XXX",xxx) 
    } 
}