JPA 查詢通過別名 轉實體
首先 說缺點:對映的物件 如果 引用另外一個實體,是沒辦法對映。
使用的規則:別名和實體的屬性要一一對應。
public class test{
private String name;
private String password;
//必須有get set方法,我這裡就不寫了
}
sql 這樣寫: select aaa as name,bbb as password from tableName;
使用的:
Page<ApppintmentDepositFlowingReportVO> tList =
(Page<ApppintmentDepositFlowingReportVO>) this.query(sql, ApppintmentDepositFlowingReportVO.class, pageable, "A");
最後一個引數 是 為 求 count 用的。後面我會 標出來。
public Page<?> query(String sql, Class<?> classs, Pageable pageable, String header) { EntityManager em = entityManagerFactory.createEntityManager(); Session session = (Session) em.getDelegate(); Sort sort = pageable.getSort(); StringBuilder orderString = new StringBuilder(); if (sort != null) { Iterator<Order> it = sort.iterator(); if (it != null && it.hasNext()) { Order order = it.next(); String dir = order.getDirection().toString(); String name = order.getProperty(); orderString.append(" order by ").append(name).append(" ").append(dir); } } SQLQuery query = session.createSQLQuery(sql + orderString.toString()); String countSql = this.getSqlForCount(sql, header);
SQLQuery query2 = session.createSQLQuery(countSql); Object obj = query2.uniqueResult(); Long totleDatas = SqlResultUtil.getSqlResultLong(obj); query.setResultTransformer(new XaAliasToBeanResultTransformer(classs)); query.setFirstResult((pageable.getPageNumber()) * pageable.getPageSize()); query.setMaxResults(pageable.getPageSize()); List<?> list = query.list(); PageImpl<?> page = new PageImpl<>(list, pageable, totleDatas.longValue()); em.close(); return page; }
private String getSqlForCount(String sql, String header) {
int d = sql.indexOf("from");
return "select count(" + header + ".id) " + sql.substring(d);
}
其實關鍵是這個類:
package com.baihui.base.util;
import java.util.Arrays;
import org.apache.commons.lang.StringUtils;
import org.hibernate.HibernateException;
import org.hibernate.property.ChainedPropertyAccessor;
import org.hibernate.property.PropertyAccessor;
import org.hibernate.property.PropertyAccessorFactory;
import org.hibernate.property.Setter;
import org.hibernate.transform.AliasToBeanResultTransformer;
public class XaAliasToBeanResultTransformer extends AliasToBeanResultTransformer {
public Xa3itAliasToBeanResultTransformer(Class resultClasss) {
super(resultClasss);
this.resultClass = resultClasss;
}
private final Class resultClass;
private boolean isInitialized;
private String[] aliases;
private Setter[] setters;
@Override
public boolean isTransformedValueATupleElement(String[] aliases, int tupleLength) {
return false;
}
@Override
public Object transformTuple(Object[] tuple, String[] aliases) {
Object result;
try {
if ( ! isInitialized ) {
initialize( aliases );
}
else {
//check( aliases );
}
result = resultClass.newInstance();
for ( int i = 0; i < aliases.length; i++ ) {
Setter setter = setters[i];
if ( setter != null )
{
Class[] clas = setter.getMethod().getParameterTypes();
Object obj = this.getNewValObject(clas[0], tuple[i]);
setter.set( result, obj, null );
}
}
}
catch ( InstantiationException e ) {
throw new HibernateException( "Could not instantiate resultclass: " + resultClass.getName() );
}
catch ( IllegalAccessException e ) {
throw new HibernateException( "Could not instantiate resultclass: " + resultClass.getName() );
}
return result;
}
private Object getNewValObject(Class clas,Object val)
{
if(val == null)
{
return null;
}
String name = clas.getName();
if(StringUtils.equals(name, "java.lang.Long"))
{
return SqlResultUtil.getSqlResultLong(val);
}
else if(StringUtils.equals(name,"java.lang.Double"))
{
return SqlResultUtil.getSqlResultDouble(val);
}
else if(StringUtils.equals(name,"java.lang.Integer"))
{
return SqlResultUtil.getSqlResultInteger(val);
}
else if(StringUtils.equals(name,"java.util.Date"))
{
return SqlResultUtil.getSqlResultDate(val);
}
else if(StringUtils.equals(name,"boolean"))
{
String v = SqlResultUtil.getSqlResultString(val);
return Boolean.parseBoolean(v);
}
else if(StringUtils.equals(name, "java.lang.Boolean"))
{
String v = SqlResultUtil.getSqlResultString(val);
if(v.toLowerCase().equals("true") || v.toLowerCase().equals("false"))
{
return Boolean.parseBoolean(v);
}
else
{
if(v.equals("1"))
{
return Boolean.TRUE;
}
else
{
return Boolean.FALSE;
}
}
}
else if(StringUtils.equals(name,"java.lang.String"))
{
return SqlResultUtil.getSqlResultString(val);
}
return null;
}
private void initialize(String[] aliases) {
PropertyAccessor propertyAccessor = new ChainedPropertyAccessor(
new PropertyAccessor[] {
PropertyAccessorFactory.getPropertyAccessor( resultClass, null ),
PropertyAccessorFactory.getPropertyAccessor( "field" )
}
);
this.aliases = new String[ aliases.length ];
setters = new Setter[ aliases.length ];
for ( int i = 0; i < aliases.length; i++ ) {
String alias = aliases[ i ];
if ( alias != null ) {
// this.aliases[ i ] = alias;
this.aliases[i] = this.getSqlAliasToJavaAlias(alias);
setters[ i ] = propertyAccessor.getSetter( resultClass, this.aliases[i] );
}
}
isInitialized = true;
}
private String getSqlAliasToJavaAlias(String s)
{
if(s.indexOf("_") > 0)
{
String[] sss = s.split("_");
StringBuilder sb = new StringBuilder(sss[0]);
for(int i = 1 ; i < sss.length;i++)
{
String ss = sss[i];
String head = ss.substring(0,1);
sb.append(head.toUpperCase()).append(ss.substring(1));
}
return sb.toString();
}
else
{
return s;
}
}
private void check(String[] aliases) {
if ( ! Arrays.equals( aliases, this.aliases ) ) {
throw new IllegalStateException(
"aliases are different from what is cached; aliases=" + Arrays.asList( aliases ) +
" cached=" + Arrays.asList( this.aliases ) );
}
}
@Override
public boolean equals(Object o) {
if ( this == o ) {
return true;
}
if ( o == null || getClass() != o.getClass() ) {
return false;
}
Xa3itAliasToBeanResultTransformer that = ( Xa3itAliasToBeanResultTransformer ) o;
if ( ! resultClass.equals( that.resultClass ) ) {
return false;
}
if ( ! Arrays.equals( aliases, that.aliases ) ) {
return false;
}
return true;
}
@Override
public int hashCode() {
int result = resultClass.hashCode();
result = 31 * result + ( aliases != null ? Arrays.hashCode( aliases ) : 0 );
return result;
}
}
就是 引數中有個 page 因為用的是 spring data:
@ResponseBody
@RequestMapping(value = "operationOrderr", method = RequestMethod.POST)
public XaResult<Page<OperationOrderCashierFlowingReportForAOuterVO>> operationOrderCashierFlowingReportForAOuter(
HttpServletRequest request,
@RequestParam(defaultValue = "0") Integer nextPage,
@RequestParam(defaultValue = "10") Integer pageSize,
@RequestParam(defaultValue = "[{property:'A.id',direction:'DESC'}]") String sortData,
@RequestParam(defaultValue = "{}") String jsonFilter)
throws BusinessException {
Pageable pageable = WebUitl.buildPageRequest(nextPage, pageSize,sortData);
Map<String, Object> filterParams = WebUitl.getParametersStartingWith(jsonFilter, "search_");
XaResult<Page<OperationOrderCashierFlowingReportForAOuterVO>> xa = new XaResult<>();
try
{
Page<OperationOrderCashierFlowingReportForAOuterVO> p = this.operationOrderCashierFlowingReportForAOuterService.getResult(pageable, filterParams);
xa.success(p);
}catch(Exception e)
{
xa.error("資料查詢出錯");
}
return xa;
}