spring data jpa 想使用EntityManager 对sql 进行处理四种方式（第四种本人改写的）

下面看看主体的一个类：

package com.chinait.service.impl;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.websocket.server.ServerEndpoint;

import org.hibernate.SQLQuery;
import org.hibernate.Session;
import org.hibernate.transform.Transformers;
import org.springframework.stereotype.Service;

import com.chinait.service.TestService;
import com.chinait.utils.Testtrans;
import com.chinait.vo.Test;

@Service
public class TestServiceImpl implements TestService{
@PersistenceContext
private EntityManager entityManager;
@Override
public void getTest(){
String sql = "select apps.appName,source.cutPath,sourcetype.sourceTypeName from apps join source on source.apps_id = apps.id join sourcetype on sourcetype.id = source.sourceType_id";
Session session = entityManager.unwrap(org.hibernate.Session.class);
//返回类型是List<map>
SQLQuery query2 = session.createSQLQuery(sql);
query2.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP);
System.out.println("查询数据返回map"+query2.list());
//返回数据是list<List<Object>>
SQLQuery query3 = session.createSQLQuery(sql);
query2.setResultTransformer(Transformers.TO_LIST);
System.out.println("查询数据返回map"+query2.list());
//返回类型是可定制化对象
SQLQuery query = session.createSQLQuery(sql);
Testtrans Testtrans = new Testtrans(Test.class);
query.setResultTransformer(Testtrans);
List<Test> list = (List<Test>)query.list();
System.out.println("查询数据返回对象"+list);
//返回数据是对象,首先这个方法有点坑，因为它需要去找寻bean 对应的对象是否是放在spring data jpa 的entity 如果不是的话回报错
/*SQLQuery query4 = session.createSQLQuery(sql);
query.setResultTransformer(Transformers.aliasToBean(Test.class));
List<Test> list3 = (List<Test>)query.list();
System.out.println("查询数据返回对象"+list);*/
}
}

下面则是：我重写的一个类的源码：

package com.chinait.utils;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;

import org.hibernate.transform.AliasToBeanResultTransformer;

public class Testtrans extends AliasToBeanResultTransformer{
private Class resultClass;
public Testtrans(Class resultClass) {
super(resultClass);
this.resultClass = resultClass;
}

private static final long serialVersionUID = 1L;

public List transformTuple(Object[] tuple, String[] aliases) {
List list = new ArrayList();
Object obj = null;
try {
obj = resultClass.newInstance();
} catch (InstantiationException e1) {
e1.printStackTrace();
} catch (IllegalAccessException e1) {
e1.printStackTrace();
}
Method[] methods = resultClass.getMethods();// 返回这个类里面方法的集合
for(int k=0;k<aliases.length;k++){
String aliase=aliases[k];
char[] ch = aliase.toCharArray();
ch[0] = Character.toUpperCase(ch[0]);
String s = new String(ch);
String[] names = new String[] { ("set" + s).intern(),
("get" + s).intern(), ("is" + s).intern(),
("read" + s).intern() };
Method setter = null;
Method getter = null;
int length = methods.length;
for (int i = 0; i < length; ++i) {
Method method = methods[i];
/**
* 检查该方法是否为公共方法,如果非公共方法就继续
*/
if (!Modifier.isPublic(method.getModifiers()))
continue;
String methodName = method.getName();

for (String name : names) {
if (name.equals(methodName)) {
if (name.startsWith("set") || name.startsWith("read"))
setter = method;
else if (name.startsWith("get") || name.startsWith("is"))
getter = method;

}
}
}
if(getter!=null){
Object[] param = buildParam(getter.getReturnType().getName(), tuple[k]);
try {
setter.invoke(obj, param);
} catch (Exception e) {
e.printStackTrace();
}
}
}
list.add(obj);
return list;
}
private final static Object[] buildParam(String paramType, Object value) {
Object[] param = new Object[1];
if (paramType.equalsIgnoreCase("java.lang.String")) {
param[0] = (String)(value);
} else if (paramType.equalsIgnoreCase("int")
|| paramType.equalsIgnoreCase("java.lang.Integer")) {
param[0] = (Integer)(value);
} else if (paramType.equalsIgnoreCase("long")|| paramType.equalsIgnoreCase("java.lang.Long")) {
param[0] = (Long)(value);
} else if (paramType.equalsIgnoreCase("double")|| paramType.equalsIgnoreCase("java.lang.Double")) {
param[0] = (Double)(value);
} else if (paramType.equalsIgnoreCase("float")|| paramType.equalsIgnoreCase("java.lang.Float")) {
param[0] = (Float)(value);
} else if (paramType.equalsIgnoreCase("char")
|| paramType.equalsIgnoreCase("Character")) {
param[0] = (char)(value);
}
return param;
}
}

注意Test 的实体类：

package com.chinait.vo;
//apps.appName,source.cutPath,sourcetype.sourceTypeName
public class Test {
private String appName;
private String cutPath;
private String sourceTypeName;
public String getAppName() {
return appName;
}
public void setAppName(String appName) {
this.appName = appName;
}
public String getCutPath() {
return cutPath;
}
public void setCutPath(String cutPath) {
this.cutPath = cutPath;
}
public String getSourceTypeName() {
return sourceTypeName;
}
public void setSourceTypeName(String sourceTypeName) {
this.sourceTypeName = sourceTypeName;
}
@Override
public String toString() {
return "Test [appName=" + appName + ", cutPath=" + cutPath + ", sourceTypeName=" + sourceTypeName + "]";
}
}

输出结果：



*注意这里还有一个bug，那就是select * 这里会报错，因为sqlquery 是按照字段的别名来判断数据与实体的对应关系。所以这里如果写成是select * 回报一个异常是指无法匹配

这边有兴趣的就是看这个源码。spring data jpa 想使用entityManager 对sql 进行处理四种方式（第四种本人改写的）。