手写 Hibernate 系列
手写 Hibernate ORM 框架 00-hibernate 简介
手写 Hibernate ORM 框架 02-实体 Bean 定义，建表语句自动生成
手写 Hibernate ORM 框架 03-配置文件读取, 数据库连接构建
手写 Hibernate ORM 框架 05-整体效果测试验证
从零手写组件系列
本节内容
实体 Bean 的定义。
根据实体 Bean 生成对应的建表语句。
定义实体 Bean
简单的用户实体信息定义
package com.ryo.hibernate.simulator.model;
import com.ryo.hibernate.simulator.hibernate.annotations.Column;
import com.ryo.hibernate.simulator.hibernate.annotations.Entity;
import com.ryo.hibernate.simulator.hibernate.annotations.GenerateValue;
import com.ryo.hibernate.simulator.hibernate.annotations.Id;
import java.util.Date;
/**
* 用户实体类
* Created by houbinbin on 16/6/5.
*/
@Entity("t_user")
public class User {
@Id
@GenerateValue
private Long id;
private String name;
private String password;
@Column("myAge")
private Integer age;
private Date createOn;
private Date modifiedOn;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Date getCreateOn() {
return createOn;
}
public void setCreateOn(Date createOn) {
this.createOn = createOn;
}
public Date getModifiedOn() {
return modifiedOn;
}
public void setModifiedOn(Date modifiedOn) {
this.modifiedOn = modifiedOn;
}
}
Table
实现
Table 核心类的实现
package com.ryo.hibernate.simulator.hibernate;
import com.ryo.hibernate.simulator.hibernate.annotations.Column;
import com.ryo.hibernate.simulator.hibernate.constants.HibernateConstant;
import com.ryo.hibernate.simulator.hibernate.util.FieldUtil;
import com.ryo.hibernate.simulator.hibernate.util.TableUtil;
import com.ryo.hibernate.simulator.util.ReflectionUtil;
import com.ryo.hibernate.simulator.util.StringBuilderUtil;
import java.lang.reflect.Field;
/**
* 表
* @author houbinbin
* Created by houbinbin on 16/6/5.
*/
public class Table {
/**
* 构建创建表的 SQL
* @param t 泛型入参
* @param <T> 泛型
* @return sql
*/
public <T> String buildCreateTableSQL(T t) {
String tableName = TableUtil.getTableName(t);
StringBuilder stringBuilder = new StringBuilder("create table ");
stringBuilder.append(tableName).append(" (");
for(Field field : ReflectionUtil.getFieldList(t)) {
stringBuilder.append(buildFieldSQL(t, field));
}
String result = StringBuilderUtil.removeLastStr(stringBuilder, ", ");
result = buildPrimaryKey(t, result);
return String.format("%s );", result);
}
/**
* 构建主键SQL
* @param t 入参
* @param result 结果
* @param <T> 泛型
* @return SQL
*/
private <T> String buildPrimaryKey(T t, String result) {
Field field = FieldUtil.getIdField(t);
if(field != null) {
String idFieldName = FieldUtil.getFieldName(field);
result = String.format("%s , PRIMARY KEY (`%s`)", result, idFieldName);
}
return result;
}
private <T> String buildFieldSQL(T t, Field field) {
String result;
String fieldName = FieldUtil.getFieldName(field);
String sqlType = FieldUtil.getSqlType(field);
result = String.format("%s %s", fieldName, sqlType);
Column column = FieldUtil.getFieldColumnAnnotation(field);
if(ReflectionUtil.isType(field, String.class)) {
int length = column != null ? column.length() : HibernateConstant.DEFAULT_STRING_SIZE;
result = String.format("%s(%d)", result, length);
}
if(column != null) {
result = String.format("%s %s", result, getNullAbleInfo(column));
}
if(FieldUtil.isGenerateValueField(t, field)) {
result = String.format("%s AUTO_INCREMENT", result);
}
return String.format("%s, ", result);
}
/**
* 获取是否可以为空的信息
* @param column 列信息
* @return 是否可以为空的结果
*/
private String getNullAbleInfo(Column column) {
return column.nullable() ? "" : "NOT NULL";
}
}
测试
- TableTest.java
/**
* 建表语句测试
*/
@Test
public void createTableSQLTest() {
Table table = new Table();
User user = new User();
System.out.println(table.buildCreateTableSQL(user));
}
测试结果：
create table t_user (id BIGINT AUTO_INCREMENT, name VARCHAR(255), password VARCHAR(255), myAge INTEGER , createOn DATETIME, modifiedOn DATETIME , PRIMARY KEY (`id`) );
Table 中涉及到的工具类
后面如有重复，将不再赘述
FieldUtil
package com.ryo.hibernate.simulator.hibernate.util;
import com.ryo.hibernate.simulator.hibernate.annotations.Column;
import com.ryo.hibernate.simulator.hibernate.annotations.GenerateValue;
import com.ryo.hibernate.simulator.hibernate.annotations.Id;
import com.ryo.hibernate.simulator.hibernate.constants.TypeMap;
import com.ryo.hibernate.simulator.util.CollectionUtil;
import com.ryo.hibernate.simulator.util.StringUtil;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;
import static com.ryo.hibernate.simulator.util.ReflectionUtil.getAnnotation;
import static com.ryo.hibernate.simulator.util.ReflectionUtil.getFieldList;
import static com.ryo.hibernate.simulator.util.ReflectionUtil.getFieldValueForce;
import static com.ryo.hibernate.simulator.util.ReflectionUtil.isType;
/**
*
* 字段工具类
* @author houbinbin
* @date 16/6/5
*/
public class FieldUtil {
/**
* 获取对应SQL字段类型
* @param field
* @return
*/
public static String getSqlType(Field field) {
return TypeMap.getTypeMap().get(field.getType().getTypeName());
}
/**
* 获取字段名称
* @param field
* @return
*/
public static String getFieldName(Field field) {
String fieldName = field.getName();
Annotation annotation = getAnnotation(field, Column.class);
Column column = getFieldColumnAnnotation(field);
if(column != null) {
String columnValue = column.value();
fieldName = StringUtil.isEmpty(columnValue) ? fieldName : columnValue;
}
return fieldName;
}
/**
* 获取子弹注解信息
* @param field
* @return
*/
public static Column getFieldColumnAnnotation(Field field) {
Annotation annotation = getAnnotation(field, Column.class);
if(annotation != null) {
return (Column) annotation;
}
return null;
}
/**
* 获取ID字段
* - 不存在则返回null
* @param t
* @param <T>
* @return
*/
public static <T> Field getIdField(T t) {
for (Field field : getFieldList(t)) {
Annotation annotation = getAnnotation(field, Id.class);
if(annotation != null) {
return field;
}
}
return null;
}
/**
* 获取自增长字段。
* @param <T>
* @return
*/
public static <T> Field getGenerateValueField(T t) {
for(Field field : getFieldList(t)) {
Annotation annotation = getAnnotation(field, GenerateValue.class);
if(annotation != null) {
return field;
}
}
return null;
}
/**
* 是否为 GenerateValue 字段
* @param t
* @param field
* @param <T>
* @return
*/
public static <T> boolean isGenerateValueField(T t, Field field) {
Field generateValueField = getGenerateValueField(t);
return generateValueField != null && field.equals(generateValueField);
}
/**
* 获取字段名称列表
* @param t
* @param <T>
* @return
*/
public static <T> List<String> getFieldNameList(T t) {
List<String> fieldNameList = new LinkedList<>();
for(Field field : getFieldList(t)) {
fieldNameList.add(getFieldName(field));
}
return fieldNameList;
}
/**
* 获取字段名称字符串形式
* @param t
* @param <T>
* @return
*/
public static <T> String getFieldNameString(T t) {
return CollectionUtil.concatCollection2Str(FieldUtil.getFieldNameList(t));
}
/**
* 获取字段值字符串形式
* @param t
* @param <T>
* @return
*/
public static <T> String getFieldValueString(T t) {
List<String> valueStrList = new LinkedList<>();
for(Field field : getFieldList(t)) {
valueStrList.add(String.format("'%s'", getValueString(t, field)));
}
return CollectionUtil.concatCollection2Str(valueStrList);
}
/**
* 获取指定字段值字符串
* @param t
* @param field
* @param <T>
* @return
*/
private static <T> String getValueString(T t, Field field) {
Object value = getFieldValueForce(t, field.getName());
String result = value.toString();
if(isType(field, Date.class)) {
result = dateToString((Date) value);
}
return result;
}
/**
* 日期转字符串
* @param dateTime 日期
* @return 字符串
*/
private static String dateToString(Date dateTime) {
return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(dateTime);
}
}
TableUtil
package com.ryo.hibernate.simulator.hibernate.util;
import com.ryo.hibernate.simulator.hibernate.annotations.Entity;
import com.ryo.hibernate.simulator.util.ReflectionUtil;
import com.ryo.hibernate.simulator.util.StringUtil;
import java.lang.annotation.Annotation;
/**
* 列表工具类
*
* @author houbinbin
* @date 16/6/5
*/
public class TableUtil {
private TableUtil() {
}
/**
* 获取表名称
*
* @param t
* @param <T>
* @return 表名称
*/
public static <T> String getTableName(T t) {
Annotation annotation = ReflectionUtil.getAnnotation(t, Entity.class);
String tableName = ReflectionUtil.getClassName(t);
if (annotation != null) {
Entity entity = (Entity) annotation;
String tableValue = entity.value();
tableName = StringUtil.isEmpty(tableValue) ? tableName : tableValue;
}
return tableName;
}
}
ReflectionUtil
package com.ryo.hibernate.simulator.util;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.LinkedList;
import java.util.List;
/**
*
* 反射工具类
* @author houbinbin
* @date 16/6/5
*/
public class ReflectionUtil {
/**
* 是否为某一类型
* @param field
* @param clazz
* @return
*/
public static Boolean isType(Field field, Class clazz) {
return field.getType().equals(clazz);
}
/**
* 获取类名
* @param t
* @param <T>
* @return
*/
public static <T> String getClassName(T t) {
Class clazz = t.getClass();
return clazz.getSimpleName();
}
/**
* 获取子弹列表
* @param t
* @param <T>
* @return
*/
public static <T> Field[] getFieldList(T t) {
Class clazz = t.getClass();
return clazz.getDeclaredFields();
}
/**
* 强制获取字段值
* @param t
* @param fieldName
* @param <T>
* @return
*/
public static <T> Object getFieldValueForce(T t, String fieldName) {
Class clazz = t.getClass();
Object value = null;
try {
Field field = clazz.getDeclaredField(fieldName);
value = getFieldValue(t, field);
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
return value;
}
/**
* 获取字段值
* @param t
* @param field
* @param <T>
* @return
*/
private static <T> Object getFieldValue(T t, Field field) {
Object value = null;
field.setAccessible(true);
try {
value = field.get(t);
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return value;
}
/**
* 获取注解信息
* @param t
* @param annotationClass
* @param <T>
* @return
*/
public static <T> Annotation getAnnotation(T t, Class annotationClass) {
Class clazz = t.getClass();
return clazz.getAnnotation(annotationClass);
}
/**
* 获取注解信息
* @param field
* @param annotationClass
* @return
*/
public static Annotation getAnnotation(Field field, Class annotationClass) {
return field.getAnnotation(annotationClass);
}
}
StringBuilderUtil
package com.ryo.hibernate.simulator.util;
/**
* 字符串Builder-工具类
*
* @author houbinbin
* @date 16/6/5
*/
public class StringBuilderUtil {
/**
* 移除最后一饿字符
*
* @param stringBuilder stringBuilder
* @param subStr 需要字符串
* @return 新的结果
*/
public static String removeLastStr(StringBuilder stringBuilder, String subStr) {
int lastIndex = stringBuilder.lastIndexOf(subStr);
return stringBuilder.substring(0, lastIndex);
}
}
StringUtil
package com.ryo.hibernate.simulator.util;
/**
* 字符串-工具类
* @author houbinbin
* @date 16/6/5
*/
public class StringUtil {
/**
* 空字符串
*/
public static final String EMPTY_STRING = "";
/**
* 是否为空
* @param string
* @return
*/
public static Boolean isEmpty(String string) {
return string == null || EMPTY_STRING.equals(string.trim());
}
}
CollectionUtil
package com.ryo.hibernate.simulator.util;
import java.util.Collection;
/**
* 集合工具类
* @author houbinbin
* @date 16/6/5
*/
public class CollectionUtil {
/**
* 默认连接符
*/
public static final String CONNECTER = ",";
/**
* 是否为空
*
* @param array
* @return
*/
public static boolean isEmpty(Object[] array) {
return (array == null) || (array.length <= 0);
}
/**
* Collection<String>,根据连接符转成字符串.
* 注意：如set 是无序的。。。
*
* @param collection
* @param connector //连接符默认为","
* @return
*/
public static String concatCollection2Str(Collection<String> collection, String... connector) {
String conn = isEmpty(connector) ? CollectionUtil.CONNECTER : connector[0];
StringBuilder stringBuilder = new StringBuilder();
for (String str : collection) {
if (stringBuilder.length() > 0) {
stringBuilder.append(conn);
}
stringBuilder.append(str);
}
return stringBuilder.toString();
}
}
