Java 如何编写Hibernate条件以按投影列表获取嵌套对象?
我想在Hibernate投影列表中获取嵌套对象值。我有Pojo“费用”和“关税”等级,有一对一和多对一的关系 我的示例代码如下所示: 充电Java 如何编写Hibernate条件以按投影列表获取嵌套对象?,java,spring,hibernate,criteria,hibernate-criteria,Java,Spring,Hibernate,Criteria,Hibernate Criteria,我想在Hibernate投影列表中获取嵌套对象值。我有Pojo“费用”和“关税”等级,有一对一和多对一的关系 我的示例代码如下所示: 充电 private String id; private Tariff tariff; private String name; @OneToMany(cascade= {CascadeType.ALL},fetch=FetchType.EAGER,mappedBy="charge") public Tariff getTari
private String id;
private Tariff tariff;
private String name;
@OneToMany(cascade= {CascadeType.ALL},fetch=FetchType.EAGER,mappedBy="charge")
public Tariff getTariff() {
return tariff;
}
public void setTariff(Tariff tariff) {
this.tariff = tariff;
}
关税
private String id;
private String amount;
private Charge charge;
@ManyToOne(cascade={CascadeType.PERSIST},fetch=FetchType.EAGER)
@JoinColumn(name="charge_id")
public Charge getCharge() {
return charge;
}
public void setCharge(Charge charge) {
this.charge = charge;
}
我想通过收费模型从关税中获取金额值
我编写的sql标准在ie中起作用
从费用中选择关税、金额、费用、名称
charge.name类似于“s%”
我尝试了以下标准
Criteria cr = getSession().createCriteria(Charge.class,"charge")
.createAlias("charge.tariff","tariff")
.setProjection(Projections.projectionList()
.add(Projections.property("chargeName"),"chargeName")
.add(Projections.property("id"),"id")
.add(Projections.property("tariff.amount"),"amount"))
.add(Restrictions.like("chargeName", name+"%"))
.setResultTransformer(Transformers.aliasToBean(Charge.class));
return cr.list();
我只是检查restclient,它返回空值。如何编写此sql查询的条件 我经历过这种需求。我尝试使用
Transformers.aliasToBean
将嵌套对象作为嵌套对象获取,但这不起作用。默认情况下,Transformers.aliasToBean
无法选择嵌套对象作为嵌套对象
你可以看看我的问题
要将嵌套对象作为嵌套对象获取,您需要一个能够这样做的自定义转换器
这里有一个由samiandoni编写的自定义转换器
从该链接中提供的自述
class Person {
private Long id;
private String name;
private Car car;
// getters and setters
}
class Car {
private Long id;
private String color;
// getters and setters
}
List<Person> getPeople() {
ProjectionList projections = Projections.projectionList()
.add(Projections.id().as("id"))
.add(Projections.property("name").as("name"))
.add(Projections.property("c.id").as("car.id"))
.add(Projections.property("c.color").as("car.color"));
Criteria criteria = getCurrentSession().createCriteria(Person.class)
.createAlias("car", "c")
.setProjection(projections)
.setResultTransformer(new AliasToBeanNestedResultTransformer(Person.class));
return (List<Person>) criteria.list();
}
// each car of Person will be populated
只要用上述变压器更换samiandoni的变压器即可。它能够获取更多的深层嵌套对象作为各自的对象。AliasToBeanNestedResultTransformer不处理多级嵌套DTO。也就是说,您将无法在其各自的DTO中执行company.employee.location 下面是我编写的一个转换器,它处理多级嵌套DTO。您可以通过以下方式使用它: criteria.setResultTransformer( 别名为NestedMultilevelResultTransformer(映射Bean)) 希望能有帮助
public class AliasToBeanNestedMultiLevelResultTransformer extends AliasedTupleSubsetResultTransformer {
private static final long serialVersionUID = -8047276133980128266L;
public boolean isTransformedValueATupleElement(String[] aliases, int tupleLength) {
return false;
}
private boolean initialized;
private Class<?> resultClass;
private Map<String,Class<?>> clazzMap = new HashMap<>();
private Map<String,Setter> settersMap = new HashMap<>();
public AliasToBeanNestedMultiLevelResultTransformer(Class<?> resultClass) {
this.resultClass = resultClass;
}
public Object transformTuple(Object[] tuples, String[] aliases) {
Map<String,Object> nestedObjectsMap = new HashMap<>();
Object result;
try {
result = resultClass.newInstance();
if (!initialized){
initialized = true;
initialize(aliases);
}
for (int a=0;a<aliases.length;a++){
String alias = aliases[a];
Object tuple = tuples[a];
Object baseObject = result;
int index = alias.lastIndexOf(".");
if(index>0){
String basePath = alias.substring(0, index);
baseObject = nestedObjectsMap.get(basePath);
if (baseObject == null){
baseObject = clazzMap.get(basePath).newInstance();
nestedObjectsMap.put(basePath, baseObject);
}
}
settersMap.get(alias).set(baseObject, tuple,null);
}
for (Entry<String,Object> entry:nestedObjectsMap.entrySet()){
Setter setter = settersMap.get(entry.getKey());
if (entry.getKey().contains(".")){
int index = entry.getKey().lastIndexOf(".");
String basePath = entry.getKey().substring(0, index);
Object obj = nestedObjectsMap.get(basePath);
setter.set(obj, entry.getValue(), null);
}
else{
setter.set(result, entry.getValue(), null);
}
}
}catch ( InstantiationException | IllegalAccessException e) {
throw new HibernateException( "Could not instantiate resultclass: " + resultClass.getName() );
}
return result;
}
private void initialize(String[] aliases) {
PropertyAccessor propertyAccessor = new ChainedPropertyAccessor(
new PropertyAccessor[] {
PropertyAccessorFactory.getPropertyAccessor( resultClass, null ),
PropertyAccessorFactory.getPropertyAccessor( "field" )
}
);
for (int a=0;a<aliases.length;a++){
String alias = aliases[a];
Class<?> baseClass = resultClass;
if (alias.contains(".")){
String[] split = alias.split("\\.");
StringBuffer res = new StringBuffer();
for (int i=0;i<split.length;i++){
if (res.length()>0) res.append(".");
String item = split[i];
res.append(item);
String resString = res.toString();
if (i==split.length-1){
clazzMap.put(resString,baseClass);
settersMap.put(resString, propertyAccessor.getSetter(baseClass, item));
break;
}
Class<?> clazz = clazzMap.get(resString);
if (clazz==null){
clazz = propertyAccessor.getGetter(baseClass,item).getReturnType();
settersMap.put(resString, propertyAccessor.getSetter(baseClass, item));
clazzMap.put(resString,clazz);
}
baseClass = clazz;
}
}
else{
clazzMap.put(alias, resultClass);
settersMap.put(alias, propertyAccessor.getSetter(resultClass, alias));
}
}
}
公共类别名ToBeanNestedMultilevelResultTransformer扩展了别名TupleSubstreSultTransformer{
私有静态最终长serialVersionUID=-8047276133980128266L;
公共布尔值isTransformedValueATupleElement(字符串[]别名,int-tupleLength){
返回false;
}
私有布尔初始化;
私有类resultClass;
私有映射基类=resultClass;
if(别名为.contains(“.”){
String[]split=alias.split(“\\”);
StringBuffer res=新的StringBuffer();
对于(inti=0;i0)res.append(“.”);
字符串项=拆分[i];
附加(项目)决议;
字符串resString=res.toString();
如果(i==split.length-1){
clazzMap.put(resString,基类);
settersMap.put(resString,propertyAccessor.getSetter(基类,项));
打破
}
Class clazz=clazzMap.get(resString);
if(clazz==null){
clazz=propertyAccessor.getGetter(基类,项).getReturnType();
settersMap.put(resString,propertyAccessor.getSetter(基类,项));
clazzMap.put(resString,clazz);
}
baseClass=clazz;
}
}
否则{
clazzMap.put(别名,resultClass);
setterMap.put(别名,propertyAccessor.getSetter(resultClass,别名));
}
}
}
}我的解决方案非常基本。它不像一个合适的结果转换器那样干净,但是当您只需要对一些属性进行快速投影时,它非常有用 代替
.add(Projections.property(“关税.金额”),“金额”)
键入.add(Projections.property(“关税金额”),“关税金额”)
然后,只需在根对象“setTariffAmount”上添加一个setter
缺点是它会用额外的方法“弄脏”你的对象。如果我有person类中的汽车对象列表,仍然可以使用AliasToBeanNestedResultTransformer?@hadi,是和否。你仍然可以使用
AliasToBeanNestedResultTransformer
来处理OneToMany(又名Collections)
,但结果将是每个子对象的单个父行。因此,您将无法将其作为父对象内的集合获取,而只能作为每个子行的单独父对象。我也在寻找能支持OneToMany(又名Collections)
的别名BeannestedResultTransformer
。对于任何可能偶然发现这个答案的人,Miguel Resendiz的原始答案已经更新,以适应OneToMany
案例。在此处签出-也签出此线程:
public class AliasToBeanNestedMultiLevelResultTransformer extends AliasedTupleSubsetResultTransformer {
private static final long serialVersionUID = -8047276133980128266L;
public boolean isTransformedValueATupleElement(String[] aliases, int tupleLength) {
return false;
}
private boolean initialized;
private Class<?> resultClass;
private Map<String,Class<?>> clazzMap = new HashMap<>();
private Map<String,Setter> settersMap = new HashMap<>();
public AliasToBeanNestedMultiLevelResultTransformer(Class<?> resultClass) {
this.resultClass = resultClass;
}
public Object transformTuple(Object[] tuples, String[] aliases) {
Map<String,Object> nestedObjectsMap = new HashMap<>();
Object result;
try {
result = resultClass.newInstance();
if (!initialized){
initialized = true;
initialize(aliases);
}
for (int a=0;a<aliases.length;a++){
String alias = aliases[a];
Object tuple = tuples[a];
Object baseObject = result;
int index = alias.lastIndexOf(".");
if(index>0){
String basePath = alias.substring(0, index);
baseObject = nestedObjectsMap.get(basePath);
if (baseObject == null){
baseObject = clazzMap.get(basePath).newInstance();
nestedObjectsMap.put(basePath, baseObject);
}
}
settersMap.get(alias).set(baseObject, tuple,null);
}
for (Entry<String,Object> entry:nestedObjectsMap.entrySet()){
Setter setter = settersMap.get(entry.getKey());
if (entry.getKey().contains(".")){
int index = entry.getKey().lastIndexOf(".");
String basePath = entry.getKey().substring(0, index);
Object obj = nestedObjectsMap.get(basePath);
setter.set(obj, entry.getValue(), null);
}
else{
setter.set(result, entry.getValue(), null);
}
}
}catch ( InstantiationException | IllegalAccessException e) {
throw new HibernateException( "Could not instantiate resultclass: " + resultClass.getName() );
}
return result;
}
private void initialize(String[] aliases) {
PropertyAccessor propertyAccessor = new ChainedPropertyAccessor(
new PropertyAccessor[] {
PropertyAccessorFactory.getPropertyAccessor( resultClass, null ),
PropertyAccessorFactory.getPropertyAccessor( "field" )
}
);
for (int a=0;a<aliases.length;a++){
String alias = aliases[a];
Class<?> baseClass = resultClass;
if (alias.contains(".")){
String[] split = alias.split("\\.");
StringBuffer res = new StringBuffer();
for (int i=0;i<split.length;i++){
if (res.length()>0) res.append(".");
String item = split[i];
res.append(item);
String resString = res.toString();
if (i==split.length-1){
clazzMap.put(resString,baseClass);
settersMap.put(resString, propertyAccessor.getSetter(baseClass, item));
break;
}
Class<?> clazz = clazzMap.get(resString);
if (clazz==null){
clazz = propertyAccessor.getGetter(baseClass,item).getReturnType();
settersMap.put(resString, propertyAccessor.getSetter(baseClass, item));
clazzMap.put(resString,clazz);
}
baseClass = clazz;
}
}
else{
clazzMap.put(alias, resultClass);
settersMap.put(alias, propertyAccessor.getSetter(resultClass, alias));
}
}
}
public void setTariffAmount(String tariffAmount) {
this.tariff = (this.tariff==null) ? new Tariff() : tariff;
tariff.setAmount(tariffAmount);
}