SpringBoot系列——Spring-Data-JPA（升级版） - 好文

前言

　　在上篇博客中：SpringBoot系列——Spring-Data-JPA：
https://www.cnblogs.com/huanzi-qch/p/9970545.html
<https://www.cnblogs.com/huanzi-qch/p/9970545.html>
，我们实现了单表的基础get、save（插入/更新）、list、page、delete接口，但是这样每个单表都要写着一套代码，重复而繁杂，那能不能写成一套通用common代码，每个单表去继承从而实现这套基础接口呢？同时，我们应该用Vo去接收、传输数据，实体负责与数据库表映射。

　　common代码

　　Vo与实体转换
/** * 实体转换工具 */ public class FastCopy { /** * 类型转换：实体Vo <->实体例如：UserVo <->
User * 支持一级复杂对象复制*/ public static <T> T copy(Object src, Class<T> targetType) {
T target= null; try { target = targetType.newInstance(); BeanWrapper targetBean
=new BeanWrapperImpl(target); BeanMap srcBean = new BeanMap(src); for (Object
key : srcBean.keySet()) {try { String srcPropertyName = key + ""; Object
srcPropertyVal= srcBean.get(key); //&&
StringUtils.isEmpty(targetBean.getPropertyValue(srcPropertyName)) if
(!StringUtils.isEmpty(srcPropertyVal) && !"class".equals(srcPropertyName)) {
Class srcPropertyType= srcBean.getType(srcPropertyName); Class
targetPropertyType= targetBean.getPropertyType(srcPropertyName); if
(targetPropertyType !=null) { if (srcPropertyType == targetPropertyType) {
targetBean.setPropertyValue(srcPropertyName, srcPropertyVal); }else { Object
targetPropertyVal= targetPropertyType.newInstance();
BeanUtils.copyProperties(srcPropertyVal, targetPropertyVal);
targetBean.setPropertyValue(srcPropertyName, targetPropertyVal); BeanWrapper
targetBean2= new BeanWrapperImpl(targetPropertyVal); BeanMap srcBean2 = new
BeanMap(srcPropertyVal); srcBean2.keySet().forEach((srcPropertyName2)-> { Class
srcPropertyType2= srcBean2.getType((String) srcPropertyName2); Class
targetPropertyType2= targetBean2.getPropertyType((String) srcPropertyName2); if
(targetPropertyType2 !=null && srcPropertyType2 != targetPropertyType2 &&
srcBean2.get(srcPropertyName2) !=null && !"class".equals(srcPropertyName2)) {
Object targetPropertyVal2= null; try { targetPropertyVal2 =
targetPropertyType2.newInstance(); }catch (Exception e) { e.printStackTrace();
} BeanUtils.copyProperties(srcBean2.get(srcPropertyName2), targetPropertyVal2);
targetBean2.setPropertyValue((String) srcPropertyName2, targetPropertyVal2); }
}); } } } }catch (Exception e) { e.printStackTrace(); } } } catch (Exception e)
{ e.printStackTrace(); }return target; } /** * 类型转换：实体Vo <->实体例如：List<UserVo>
<-> List<User>*/ public static <T> List<T> copyList(List srcList, Class<T>
targetType) { List<T> newList = new ArrayList<>(); for (Object entity :
srcList) { newList.add(copy(entity, targetType)); }return newList; } /** *
获取/过滤对象的空属性*/ public static String[] getNullProperties(Object src) {
BeanWrapper srcBean= new BeanWrapperImpl(src); //1.获取Bean Set<String>
properties =new HashSet<>(); //3.获取Bean的空属性 for (PropertyDescriptor p :
srcBean.getPropertyDescriptors()) { String propertyName= p.getName(); Object
srcValue= srcBean.getPropertyValue(propertyName); if
(StringUtils.isEmpty(srcValue)) { srcBean.setPropertyValue(propertyName,null);
properties.add(propertyName); } } String[] result= new
String[properties.size()];return properties.toArray(result); } /** * 获取对象的非空属性
*/ public static Map<String, Object> getNotNullProperties(Object src) {
BeanWrapper srcBean= new BeanWrapperImpl(src); //1.获取Bean PropertyDescriptor[]
pds = srcBean.getPropertyDescriptors();//2.获取Bean的属性描述 Map<String, Object>
properties =new LinkedHashMap<>(); //3.获取Bean的非空属性 for (PropertyDescriptor p :
pds) { String key= p.getName(); Object value = srcBean.getPropertyValue(key); if
(!StringUtils.isEmpty(value) && !"class".equals(key)) { properties.put(key,
value); } }return properties; } /** * 将Object数组转为实体类VO */ public static <V>
List<V> getEntityVo(List<Object[]> propertyArrayList, Class<V> voClass) { List
<V> list =new ArrayList<>(); try { if (propertyArrayList != null) { for
(Object[] propertyArray : propertyArrayList) { V vo= voClass.newInstance();
Field[] fields= vo.getClass().getDeclaredFields(); for (int i = 0; i <
propertyArray.length; i++) { Field voField = fields[i]; Object queryVal =
propertyArray[i];if (voField.getType() == String.class && queryVal instanceof
BigDecimal) { queryVal= String.valueOf(queryVal); } voField.setAccessible(true);
//获取授权 voField.set(vo, queryVal); } list.add(vo); } } } catch (Exception e) {
throw new RuntimeException(e); } return list; } }
　　注：BeanMap类引入的是：org.apache.commons.beanutils.BeanMap;

　　引入这两个jar
 <dependency> <groupId>commons-beanutils</groupId> <
artifactId>commons-beanutils</artifactId> <version>1.8.0</version> </dependency>
<dependency> <groupId>commons-collections</groupId> <artifactId>
commons-collections</artifactId> <version>3.2.2</version> </dependency>

　　

　　通用service、repository
/** * 通用Service * * @param <V> 实体类Vo * @param <E> 实体类 * @param <T> id主键类型 */
public interface CommonService<V, E,T> { Result<PageInfo<V>> page(V entityVo);
Result<List<V>> list(V entityVo); Result<V> get(T id); Result<V> save(V
entityVo); Result<T> delete(T id); } /** * 通用Service实现类 * * @param <V> 实体类Vo *
@param <E> 实体类 * @param <T> id主键类型 */ public class CommonServiceImpl<V, E, T>
implements CommonService<V, E, T> { private Class<V> entityVoClass;//实体类Vo
private Class<E> entityClass;//实体类 @Autowired private CommonRepository<E, T>
commonRepository;//注入实体类仓库 public CommonServiceImpl() { Type[] types =
((ParameterizedType)this
.getClass().getGenericSuperclass()).getActualTypeArguments();this.entityVoClass
= (Class<V>) types[0]; this.entityClass = (Class<E>) types[1]; } @Override
public Result<PageInfo<V>> page(V entityVo) { //实体类缺失分页信息 if (!(entityVo
instanceof PageCondition)) { throw new RuntimeException("实体类" +
entityClass.getName() + "未继承PageCondition。"); } PageCondition pageCondition =
(PageCondition) entityVo; Page<E> page =
commonRepository.findAll(Example.of(FastCopy.copy(entityVo, entityClass)),
pageCondition.getPageable());return Result.of(PageInfo.of(page,
entityVoClass)); } @Overridepublic Result<List<V>> list(V entityVo) { List<E>
entityList = commonRepository.findAll(Example.of(FastCopy.copy(entityVo,
entityClass))); List<V> entityModelList = FastCopy.copyList(entityList,
entityVoClass);return Result.of(entityModelList); } @Override public Result<V>
get(T id) { Optional<E> optionalE = commonRepository.findById(id); if (!
optionalE.isPresent()) {throw new RuntimeException("ID不存在！"); } return
Result.of(FastCopy.copy(optionalE.get(), entityVoClass)); } @Overridepublic
Result<V> save(V entityVo) { E e =
commonRepository.save(FastCopy.copy(entityVo, entityClass));return
Result.of(FastCopy.copy(e, entityVoClass)); } @Overridepublic Result<T>
delete(T id) { commonRepository.deleteById(id);return Result.of(id); } } /** *
通用Repository * *@param <E> 实体类 * @param <T> id主键类型 */ @NoRepositoryBean public
interface CommonRepository<E,T> extends JpaRepository<E,T>,
JpaSpecificationExecutor<E> { }
　　2019-05-13更新

　　 jpa实现局部更新

　　注意：
jpa原生的save方法，更新的时候是全属性进行updata，如果实体类的属性没有值它会帮你更新成null，如果你想更新部分字段请在通用CommonServiceImpl使用这个save方法，我这里是在调用save之前先查询数据库获取完整对象，将要更新的值复制到最终传入save方法的对象中，从而实现局部更新

@Override public Result<V> save(V entityVo) { //传进来的对象（属性可能残缺） E entity =
CopyUtil.copy(entityVo, entityClass);//最终要保存的对象 E entityFull = entity; //
为空的属性值，忽略属性，BeanUtils复制的时候用到 List<String> ignoreProperties = new
ArrayList<String>(); //获取最新数据，解决部分更新时jpa其他字段设置null问题 try { //
反射获取Class的属性（Field表示类中的成员变量） for (Field field :
entity.getClass().getDeclaredFields()) {//获取授权 field.setAccessible(true); //属性名称
String fieldName = field.getName(); //属性的值 Object fieldValue =
field.get(entity);//找出Id主键 if (field.isAnnotationPresent(Id.class) && !
StringUtils.isEmpty(fieldValue)) { Optional<E> one =
commonRepository.findById((T) fieldValue);if (one.isPresent()) { entityFull =
one.get(); } }//找出值为空的属性，值为空则为忽略属性，我们复制的时候不进行赋值 if(null == fieldValue){
ignoreProperties.add(fieldName); } }/* org.springframework.beans
BeanUtils.copyProperties(A,B); 是A中的值付给B org.apache.commons.beanutils;
BeanUtils.copyProperties(A,B);是B中的值付给A 把entity的值赋给entityFull，第三个参数是忽略属性，表示不进行赋值
*/ BeanUtils.copyProperties(entity, entityFull, ignoreProperties.toArray(new
String[0])); } catch (IllegalAccessException e) { e.printStackTrace(); } E e =
commonRepository.save(entityFull);return Result.of(CopyUtil.copy(e,
entityVoClass)); }

　　单表使用

　　单表继承通用代码，实现get、save（插入/更新）、list、page、delete接口

　　Vo
/** * 用户类Vo */ @Data public class UserVo extends PageCondition implements
Serializable {private Integer id; private String username; private String
password;private Date created; private String descriptionId; //机架类型信息 private
DescriptionVo description; } /** * 用户描述类Vo */ @Data public class DescriptionVo
implements Serializable { private Integer id; private String userId; private
String description; }

　　controller、service、repository
@RestController @RequestMapping("/user") public class UserController {
@Autowiredprivate UserService userService; @RequestMapping("/getAllUser")
public ModelAndView getAllUser(){ Result result=userService.getAllUser();
ModelAndView mv=new ModelAndView(); mv.addObject("userList",result.getData());
mv.setViewName("index.html"); return mv; } /* CRUD、分页、排序 */
@RequestMapping("page") public Result<PageInfo<UserVo>> page(UserVo entityVo) {
return userService.page(entityVo); } @RequestMapping("list") public
Result<List<UserVo>> list(UserVo entityVo) { return userService.list(entityVo);
} @RequestMapping("get/{id}") public Result<UserVo> get(@PathVariable("id")
Integer id) {return userService.get(id); } @RequestMapping("save") public
Result<UserVo> save(UserVo entityVo) { return userService.save(entityVo); }
@RequestMapping("delete/{id}") public Result<Integer> delete(@PathVariable("id"
) Integer id) { return userService.delete(id); } } public interface UserService
extends CommonService<UserVo, User,Integer>{ Result getAllUser(); } @Service
@Transactional public class UserServiceImpl extends CommonServiceImpl<UserVo,
User,Integer>implements UserService { @Autowired private UserRepository
userRepository; @Override public Result getAllUser() { List<User> userList =
userRepository.getAllUser();if(userList != null && userList.size()>0){ ArrayList
<UserVo> userVos =new ArrayList<>(); for(User user : userList){
userVos.add(FastCopy.copy(user, UserVo.class)); } return Result.of(userVos); }
else { return Result.of(userList,false,"获取失败！"); } } } @Repository public
interface UserRepository extends CommonRepository<User, Integer> { @Query(value
= "from User")//HQL // @Query(value = "select * from tb_user",nativeQuery =
true)//原生SQL List<User> getAllUser(); }

　　经测试，所有的接口都可以使用，数据传输正常，因为传输的Vo，分页信息跟杂七杂八的字段、数据都在Vo，所有看起来会比较杂。更新接口依旧跟上一篇的一样，接收到的是什么就保存什么。

　　后记

　　单表的增删改查接口，直接继承这一套通用代码即可实现，无需再重复编写，大大提升开发效率。

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