第一章-系统设计与搭建

理解Restful

REST是Representational State Transfer的缩写，翻译是”表现层状态转化”。 可以 总结为一句话：REST是所有Web应用都应该遵守的架构设计指导原则。
7个HTTP方法：GET/POST/PUT/DELETE/PATCH/HEAD/OPTIONS。

测试工具Postman

发送HTTP请求的工具。

公共子模块

1.返回结果实体类Result

public class Result{
  private boolean flag;  //是否成功
  private Integer code;  //返回码
  private String message;  //返回信息
  private Object data; //返回数据
  
  //成功并且携带参数的构造器
  public Result(boolean flag,Integer code,String message,Object data){
    super();
    this.flag = flag;
    this,code = code;
    this.message = message;
    this.data = data;
  }
  //失败的构造器
  public Result(boolean flag,Integer code,String message){
    super();
    this.flag = flag;
    this.code = code;
    this.message = message;
  }
  //setter/getter...
}

2.返回分页结果的PageResult

public class PageResult{
    private Long total;
    private List rows;
    
    public PageResult(Long total,List rows){
      super();
      this.total = total;
      this.rows = rows;
    }
    //setter/getter
}

3.分布式ID生成器

@SpringBootApplication
public class BaseApplication{
  public static void main(String[] args){
    SpringBootApplication.run(BaseApplication.class);
  }
  
  @Bean
  public IdWorker idWorker(){
    return new IdWorker(1,1);
  }
}

CRUD的实现

1.实体类

@Entity
@Table(name = "tb_label")
public class Label{
  @Id
  private String id;  //
  private String labelName;  //标签名称
  private String state;  //状态
  private Long count;  //使用数量
  
  //setters/getters
}

2.Jpa数据访问接口

public interface LabelDao extends JpaRespository,JpaSpecificationExecutor{
  
}

3.业务逻辑类

@Service
public class LabelService{
  @Autowired
  private LabelDao labelDao;
  
  @Autowired 
  private IdWorker idWorker;

  public List findAll(){
    return labelDao.findAll();
  }
  
  public Label findById(String id){
    return labelDao.findById(id).get();
  }
  
  public void add(Label label){
    label.setId(idWorker.nextId() + "");
    labelDao.save(label);
  }
  
  public void update(Label label){
    labelDao.save(label);
  }
  
  public void deleteById(String id){
    labelDao.deleteById(id);
  }
}

4.控制器类

@RestController
@RequestMapping("/label")
public class LabelController{

@Autowired
  private LabelService labelService;
  
      /*查询全部列表
       * @return
       */
  @RequestMapping(method = RequestMethod.GET)
  public Result findAll(){
    return new Result<>(true,StatusCode.OK,"查询成功",labelService.findAll());
  }
  
      /**     
      *  根据ID查询标签     
      * @param id      
      * @return      
      */
      @RequestMapping(value = /{id},method = RequestMethod.GET)
      public Result findById(@PathVariable String id){
        return new Result<>(true,StatusCode.OK,"查询成功"，labelService.findById(id));
      }
      
        /**
       *  @param id
       *  @return
       **/
       @RequestMapping(method = RequestMethod.POST)
        public Result add(@RequestBody Label label){
          labelService.add(label);
          return new Result(true,StatusCode.OK,"增加成功")；
        }
        
            /**  
             *  修改标签
             * @param label  
              * @return
              */ 
       @RequestMapping(value="/{id}" ,method = RequestMethod.PUT)          
        public Result update( @RequestBody Label label,@PathVariable String  id){         
        label.setId(id);      
        labelService.update(label);       
          return new Result(true,StatusCode.OK,"修改成功");   
          }
            /**   
             * 删除标签  
              * @param id
             * @return    
              */    
     @RequestMapping(value="/{id}" ,method = RequestMethod.DELETE)           
         public Result deleteById(@PathVariable String id){        
         labelService.deleteById(id);      
         return new Result(true,StatusCode.OK,"删除成功");  
       }
}  

5.接口测试

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