这篇文章主要介绍“Spring Data JPA映射怎么自定义实体类”，在日常操作中，相信很多人在Spring Data JPA映射怎么自定义实体类问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”Spring Data JPA映射怎么自定义实体类”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
Spring Data JPA映射自定义实体类
这个问题困扰了我2天=-=，好像也能使用 jpql解决
先说下自己的功能：查询oracle最近sql执行记录
sql很简单：【如果需要分页，需要自己手动分页，因为你使用分页工具他第一页查询不会查询rownum，第二页查询就会查询rownum，然而这个返回的List<Object[]>中的参数必须要和实体类中一一对应，所以这就有一个不可控制的属性rownum，所以我们不能使用Pageable入参接口了，需要自定义pageSize pageNum参数】
SELECT t.SQL_ID AS SQL的ID, t.SQL_TEXT AS SQL语句, t.HASH_VALUE AS 完整SQL哈希值, t.ELAPSED_TIME AS 解析执行总共时间微秒, t.EXECUTIONS AS 执行总共次数, t.LAST_ACTIVE_TIME AS 执行最后时间, t.CPU_TIME AS CPU执行时间微秒 FROM v$sqlarea t WHERE t.PARSING_SCHEMA_NAME IN ( 'C##DBAAS' ) AND t.EXECUTIONS > 10 AND t.LAST_ACTIVE_TIME > TO_DATE('0001-01-01 01:01:01', 'yyyy-MM-dd hh34:mi:ss') AND t.ELAPSED_TIME > 0 AND t.CPU_TIME > 0 ORDER BY t.EXECUTIONS DESC;但是我用的是Spring Data JPA。。。。这个网上说不能将查询结果自动映射到自定义的实体类。。。。这就比较蛋疼了，在网上就找了个轮子。先上一下自己的Dao层，查出来的是集合数组，所以使用List< Object [ ] >接收【我将sql简化了一下，主要先测试能不能成功】
@Query(value="SELECT\r\n" + " t.SQL_ID,\r\n" + " t.ELAPSED_TIME,\r\n" + " t.EXECUTIONS,\r\n" + " t.LAST_ACTIVE_TIME, \r\n" + " t.CPU_TIME \r\n" + "FROM\r\n" + " v$sqlarea t \r\n" + "WHERE\r\n" + " t.PARSING_SCHEMA_NAME IN ( 'C##DBAAS' ) AND t.EXECUTIONS > 100 \r\n" + "ORDER BY\r\n" + " t.EXECUTIONS DESC",nativeQuery=true) public List<Object[]> findTopSQLS4();然后就是实体类了：注意实体类中 必须包含构造函数，而且构造函数中的参数必须和你SQL中 查询的参数 顺序保持一致
package com.befery.oams.entity; import java.io.Serializable;import java.math.BigInteger;import java.security.Timestamp;import java.util.Date; import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.Table; @Entity@Table(name = "v$sqlarea")public class V$sqlarea implements Serializable { @Id private String sqlId; private Number elapsedTime; // 解析+执行sql 总时间 微秒 private Number executions; // 执行次数 private Date lastActiveTime; private Number cpuTime; public String getSqlId() { return sqlId; } public void setSqlId(String sqlId) { this.sqlId = sqlId; } public Number getElapsedTime() { return elapsedTime; } public void setElapsedTime(Number elapsedTime) { this.elapsedTime = elapsedTime; } public Number getExecutions() { return executions; } public void setExecutions(Number executions) { this.executions = executions; } public Date getLastActiveTime() { return lastActiveTime; } public void setLastActiveTime(Date lastActiveTime) { this.lastActiveTime = lastActiveTime; } public Number getCpuTime() { return cpuTime; } public void setCpuTime(Number cpuTime) { this.cpuTime = cpuTime; } public V$sqlarea() { } public V$sqlarea(String sqlId, Number elapsedTime, Number executions, Date lastActiveTime,Number cpuTime) { this.sqlId = sqlId; this.elapsedTime = elapsedTime; this.executions = executions; this.lastActiveTime = lastActiveTime; this.cpuTime = cpuTime; } }然后就是网上的轮子了
package com.befery.oams.util; import org.slf4j.Logger;import org.slf4j.LoggerFactory; import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map; public class EntityUtils { private static Logger logger = LoggerFactory.getLogger(EntityUtils.class); public static <T> List<T> castEntity(List<Object[]> list, Class<T> clazz, Object model) { List<T> returnList = new ArrayList<T>(); if (list.isEmpty()) { return returnList; } //获取每个数组集合的元素个数 Object[] co = list.get(0); //获取当前实体类的属性名、属性值、属性类别 List<Map> attributeInfoList = getFiledsInfo(model); //创建属性类别数组 Class[] c2 = new Class[attributeInfoList.size()]; //如果数组集合元素个数与实体类属性个数不一致则发生错误 if (attributeInfoList.size() != co.length) { return returnList; } //确定构造方法 for (int i = 0; i < attributeInfoList.size(); i++) { c2[i] = (Class) attributeInfoList.get(i).get("type"); } try { for (Object[] o : list) { Constructor<T> constructor = clazz.getConstructor(c2); returnList.add(constructor.newInstance(o)); } } catch (Exception ex) { logger.error("实体数据转化为实体类发生异常：异常信息：{}", ex.getMessage()); return returnList; } return returnList; } private static Object getFieldValueByName(String fieldName, Object modle) { try { String firstLetter = fieldName.substring(0, 1).toUpperCase(); String getter = "get" + firstLetter + fieldName.substring(1); Method method = modle.getClass().getMethod(getter, new Class[]{}); Object value = method.invoke(modle, new Object[]{}); return value; } catch (Exception e) { return null; } } private static List<Map> getFiledsInfo(Object model) { Field[] fields = model.getClass().getDeclaredFields(); List<Map> list = new ArrayList(fields.length); Map infoMap = null; for (int i = 0; i < fields.length; i++) { infoMap = new HashMap(3); infoMap.put("type", fields[i].getType()); infoMap.put("name", fields[i].getName()); infoMap.put("value", getFieldValueByName(fields[i].getName(), model)); list.add(infoMap); } return list; }}最后的操作，调用 castEntity() 方法：
@GetMapping(value = "/list") @ResponseBody public List<V$sqlarea> selectTopSQLUntreated() { System.out.println("============================TOPSQL START================================="); List<Object[]> list = v$sqlareaDao.findTopSQLS4(); List<V$sqlarea> list1 =EntityUtils.castEntity(list, V$sqlarea.class,new V$sqlarea()); System.out.println("============================TOPSQL END================================="); return list1; }看一下日志的输出
============================TOPSQL START=================================
Hibernate:
SELECT
t.SQL_ID,
t.ELAPSED_TIME,
t.EXECUTIONS,
t.LAST_ACTIVE_TIME,
t.CPU_TIME
FROM
v$sqlarea t
WHERE
t.PARSING_SCHEMA_NAME IN (
'C##DBAAS'
)
AND t.EXECUTIONS > 100
ORDER BY
t.EXECUTIONS DESC
============================TOPSQL END=================================
2019-03-12 18:06:57.108 INFO 21076 --- [nio-8081-exec-7] com.befery.oams.config.LogAspectConfig : --------------返回内容----------------
2019-03-12 18:06:57.114 INFO 21076 --- [nio-8081-exec-7] com.befery.oams.config.LogAspectConfig : Response内容:[{"cpuTime":84731,"elapsedTime":183491,"executions":348,"lastActiveTime":1552385204000,"sqlId":"f05fn7j6rbcsj"},{"cpuTime":17827,"elapsedTime":33036,"executions":212,"lastActiveTime":1552385203000,"sqlId":"avc1jqzz04wpr"},{"cpuTime":9054,"elapsedTime":23874,"executions":174,"lastActiveTime":1552385204000,"sqlId":"b4xr1nw5vtk2v"},{"cpuTime":102017,"elapsedTime":97842,"executions":153,"lastActiveTime":1552313331000,"sqlId":"711b9thj3s4ug"},{"cpuTime":89011,"elapsedTime":90341,"executions":153,"lastActiveTime":1552313331000,"sqlId":"grqh2qs9ajypn"},{"cpuTime":58984,"elapsedTime":81214,"executions":135,"lastActiveTime":1552385214000,"sqlId":"d442vk7001fvw"},{"cpuTime":17260604818,"elapsedTime":41375561059,"executions":122,"lastActiveTime":1552297847000,"sqlId":"170am4cyckruf"},{"cpuTime":13194,"elapsedTime":31267,"executions":108,"lastActiveTime":1552383540000,"sqlId":"9q00dg3n0748y"}]
2019-03-12 18:06:57.114 INFO 21076 --- [nio-8081-exec-7] com.befery.oams.config.LogAspectConfig : --------------返回内容----------------
JPA 配置类实体映射示例
A: 两张表示例
@Entity@Table(name="apo_config")public class SiteConfig implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long ID; private String caption; @ElementCollection(fetch = FetchType.LAZY) @MapKeyColumn(name="name") @Column(name="value") @CollectionTable(name="apo_config_attributes", joinColumns=@JoinColumn(name="ca_id")) private Map<String, String> attributes = new HashMap<String, String>(); //GET/SET}测试代码
@Test public void test(){ SiteConfig sc=new SiteConfig(); sc.setID(1L); sc.setCaption("全局配置"); Map<String, String> data=new HashMap<>(); data.put("site", "csdn.net"); data.put("account", "xiaofanku"); sc.setAttributes(data); siteConfigDao.save(sc); } @Test public void getConfig(){ SiteConfig config=siteConfigDao.findOne(1L); assertEquals(config.getAttributes().get("site"), "csdn.net"); }apo_config:表结构
apo_config_attributes:表结构
B: 三张表示例
@Entity@Table(name="apo_config")public class SiteConfig implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long ID; private String caption; @OneToMany(cascade=CascadeType.ALL, orphanRemoval = true) @MapKey(name="name") @JoinTable(name = "apo_config_attributes") private Map<String, ConfigAttribute> attributes=new HashMap<>(); //GET/SET}@Entity@Table(name="apo_attributes")public class ConfigAttribute implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long ID; @Column(name="name") private String name; private String value; //GET/SET}测试代码
@Test @Ignore public void test(){ SiteConfig sc=new SiteConfig(); sc.setID(1L); sc.setCaption("全局配置"); Map<String, ConfigAttribute> data=new HashMap<>(); ConfigAttribute ca1=new ConfigAttribute(); ca1.setName("site");ca1.setValue("csdn.net"); data.put("site", ca1); ConfigAttribute ca2=new ConfigAttribute(); ca2.setName("account");ca2.setValue("xiaofanku"); data.put("account", ca2); sc.setAttributes(data); siteConfigDao.save(sc); } @Test @Ignore public void getConfig(){ SiteConfig config=siteConfigDao.findOne(1L); assertEquals(config.getAttributes().get("site").getValue(), "csdn.net"); }apo_config:表结构
apo_attributes:表结构
apo_config_attributes：中间表结构
C: 使用ASF Commons BeanUtils来构造一个Dynamic Class
import java.util.ArrayList;import java.util.List;import java.util.Map;import java.util.Objects;import java.util.Set;import org.apache.commons.beanutils.BasicDynaClass;import org.apache.commons.beanutils.ConvertUtils;import org.apache.commons.beanutils.DynaBean;import org.apache.commons.beanutils.DynaProperty;public class DynamicClass{ private final DynaBean config; public DynamicClass(Map<String,String> attributeMeta) throws IllegalAccessException, InstantiationException, ClassNotFoundException{ DynaProperty[] props=covert(attributeMeta).toArray(new DynaProperty[]{}); BasicDynaClass dynaClass = new BasicDynaClass("CustomConfig", null, props); this.config = dynaClass.newInstance(); } public DynamicClass(Set<Attribute> attributes) throws ClassNotFoundException, IllegalAccessException, InstantiationException{ DynaProperty[] props=covert(attributes).toArray(new DynaProperty[]{}); BasicDynaClass dynaClass = new BasicDynaClass("CustomConfig", null, props); this.config = dynaClass.newInstance(); load(attributes); } public Object getValue(String attributeName){ return config.get(attributeName); } public <T> T getValue(String attributeName, Class<T> classType) throws java.lang.ClassCastException{ return (T)getValue(attributeName); } public void setValue(String attributeName, String attributeValue){ DynaProperty dp = config.getDynaClass().getDynaProperty(attributeName); config.set(attributeName, ConvertUtils.convert(attributeValue, dp.getType())); } public void setValue(Attribute attribute) throws ClassNotFoundException { config.set(attribute.getName(), ConvertUtils.convert(attribute.getValue(), Class.forName(attribute.getClassName()))); } private void load(Set<Attribute> attributes){ for(Attribute attr : attributes){ try{ config.set(attr.getName(), ConvertUtils.convert(attr.getValue(), Class.forName(attr.getClassName()))); }catch(ClassNotFoundException e){ } } } private List<DynaProperty> covert(Set<Attribute> attributes) throws ClassNotFoundException{ List<DynaProperty> attres=new ArrayList<>(); for(Attribute attr : attributes){ attres.add(new DynaProperty(attr.getName(), Class.forName(attr.getClassName()))); } return attres; } private List<DynaProperty> covert(Map<String,String> attributeMeta) throws ClassNotFoundException{ List<DynaProperty> properties=new ArrayList<>(); Set<String> attrSet=attributeMeta.keySet(); for(String attrName : attrSet){ String className=attributeMeta.get(attrName); properties.add(new DynaProperty(attrName, Class.forName(className))); } return properties; } public static enum Type{ BOOLEAN("java.lang.Boolean"), INTEGER("java.lang.Integer"), LONG("java.lang.Long"), STRING("java.lang.String"), CHAR("java.lang.Character"), DOUBLE("java.lang.Double"), FLOAT("java.lang.Float"); private final String name; private Type(String className){ this.name=className; } public String getName() { return name; } } public static class Attribute{ //属性名,例:show private final String name; //属性名的值,例:"true" private final String value; //属性名的类型,例:java.lang.Boolean private final String className; public Attribute(String name, String value, String className) { this.name = name; this.value = value; this.className = className; } public String getName() { return name; } public String getValue() { return value; } public String getClassName() { return className; } @Override public int hashCode() { int hash = 5; hash = 97 * hash + Objects.hashCode(this.name); hash = 97 * hash + Objects.hashCode(this.className); return hash; } @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } final Attribute other = (Attribute) obj; if (!Objects.equals(this.name, other.name)) { return false; } if (!Objects.equals(this.className, other.className)) { return false; } return true; } }}测试代码:
@Test public void test(){ Set<Attribute> sas=new HashSet<>(); sas.add(new Attribute("logo", "logo.png", DynamicClass.Type.STRING.getName())); sas.add(new Attribute("pageSize", "50", DynamicClass.Type.INTEGER.getName())); sas.add(new Attribute("shortcut", "true", DynamicClass.Type.BOOLEAN.getName())); try{ DynamicClass dc=new DynamicClass(sas); Integer ps = dc.getValue("pageSize", Integer.class); System.out.println(ps); dc.setValue("pageSize", "150"); System.out.println(dc.getValue("pageSize")); }catch(Exception e){ e.printStackTrace(); } } @Test @Ignore public void base() { Map<String, String> am = new HashMap<>(); am.put("logo", DynamicClass.Type.STRING.getName()); am.put("pageSize", DynamicClass.Type.INTEGER.getName()); am.put("shortcut", DynamicClass.Type.BOOLEAN.getName()); try { DynamicClass dc = new DynamicClass(am); dc.setValue("pageSize", "150"); System.out.println(dc.getValue("pageSize")); dc.setValue(new Attribute("shortcut", "true", DynamicClass.Type.BOOLEAN.getName())); System.out.println(dc.getValue("shortcut")); } catch (IllegalAccessException | InstantiationException | ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } }到此，关于“Spring Data JPA映射怎么自定义实体类”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注编程网网站，小编会继续努力为大家带来更多实用的文章！
