spring如何使用@Data注解

• 目录

  前言

  1. 代码

  2. 优缺点

  ---

• 前言

1. 使用spring中，为了实现类的注入和属性值注入，一般会在定义的类里声明set,get等方法，需要对类里的每个属性值都需声明造成比较冗余，
2. 使用了@Data注解后，就可以在直接定义的类添加即可，就会自动实现类里所有属性的set,get等方法，极大的简化了代码
3. 该类提供了get、set、equals、hashCode、canEqual、toString方法

• 1.使用时代码配置

• 添加依赖包

• <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.12</version>
  </dependency>

  添加@Data注解

• @Data
  @AllArgsConstructor
  @NoArgsConstructor
  public class Books {
      private int bookID;
      private String bookName;
      private int bookCounts;
      private String detail;
  }
  

  讲解一下实体类中另外两个注解
  @AllArgsConstructor ： 注解在类上，有参构造
  @NoArgsConstructor ： 注解在类上，无参构造

• 生成的结果

• package com.kk.pojo;
  
  public class Books {
      private int bookID;
      private String bookName;
      private int bookCounts;
      private String detail;
  
      public int getBookID() {
          return this.bookID;
      }
  
      public String getBookName() {
          return this.bookName;
      }
  
      public int getBookCounts() {
          return this.bookCounts;
      }
  
      public String getDetail() {
          return this.detail;
      }
  
      public void setBookID(int bookID) {
          this.bookID = bookID;
      }
  
      public void setBookName(String bookName) {
          this.bookName = bookName;
      }
  
      public void setBookCounts(int bookCounts) {
          this.bookCounts = bookCounts;
      }
  
      public void setDetail(String detail) {
          this.detail = detail;
      }
  
      public boolean equals(Object o) {
          if (o == this) {
              return true;
          } else if (!(o instanceof Books)) {
              return false;
          } else {
              Books other = (Books)o;
              if (!other.canEqual(this)) {
                  return false;
              } else if (this.getBookID() != other.getBookID()) {
                  return false;
              } else {
                  label41: {
                      Object this$bookName = this.getBookName();
                      Object other$bookName = other.getBookName();
                      if (this$bookName == null) {
                          if (other$bookName == null) {
                              break label41;
                          }
                      } else if (this$bookName.equals(other$bookName)) {
                          break label41;
                      }
  
                      return false;
                  }
  
                  if (this.getBookCounts() != other.getBookCounts()) {
                      return false;
                  } else {
                      Object this$detail = this.getDetail();
                      Object other$detail = other.getDetail();
                      if (this$detail == null) {
                          if (other$detail != null) {
                              return false;
                          }
                      } else if (!this$detail.equals(other$detail)) {
                          return false;
                      }
  
                      return true;
                  }
              }
          }
      }
  
      protected boolean canEqual(Object other) {
          return other instanceof Books;
      }
  
      public int hashCode() {
          int PRIME = true;
          int result = 1;
          int result = result * 59 + this.getBookID();
          Object $bookName = this.getBookName();
          result = result * 59 + ($bookName == null ? 43 : $bookName.hashCode());
          result = result * 59 + this.getBookCounts();
          Object $detail = this.getDetail();
          result = result * 59 + ($detail == null ? 43 : $detail.hashCode());
          return result;
      }
  
      public String toString() {
          return "Books(bookID=" + this.getBookID() + ", bookName=" + this.getBookName() + ", bookCounts=" + this.getBookCounts() + ", detail=" + this.getDetail() + ")";
      }
  
      public Books(int bookID, String bookName, int bookCounts, String detail) {
          this.bookID = bookID;
          this.bookName = bookName;
          this.bookCounts = bookCounts;
          this.detail = detail;
      }
  
      public Books() {
      }
  }
  
  

• 3. 优缺点

优点                                                                                                                                           

1. 自动生成构造器、getter/setter、equals、hashcode、toString等方法，提高了一定的开发效率
2. 让代码变得简洁                                                                                                                

缺点

1. 不支持多种参数构造器的重载
2. 过多的插件容易降低阅读源代码的舒适度