30 个类手写 Spring 核心原理之自定义 ORM（下）（7）
作者：Tom弹架构
- 2021 年 12 月 30 日
本文字数：18616 字
阅读完需：约 61 分钟
本文节选自《Spring 5 核心原理》
3 基于 Spring JDBC 实现关键功能
3.1 ClassMappings
ClassMappings 主要定义基础的映射类型，代码如下：
package com.tom.orm.framework;
import java.lang.reflect.Field;import java.lang.reflect.Method;import java.lang.reflect.Modifier;import java.math.BigDecimal;import java.sql.Date;import java.sql.Timestamp;import java.util.Arrays;import java.util.HashMap;import java.util.HashSet;import java.util.Map;import java.util.Set;
public class ClassMappings {
private ClassMappings(){} static final Set<Class<?>> SUPPORTED_SQL_OBJECTS = new HashSet<Class<?>>();
static { //只要这里写了，默认支持自动类型转换 Class<?>[] classes = { boolean.class, Boolean.class, short.class, Short.class, int.class, Integer.class, long.class, Long.class, float.class, Float.class, double.class, Double.class, String.class, Date.class, Timestamp.class, BigDecimal.class }; SUPPORTED_SQL_OBJECTS.addAll(Arrays.asList(classes)); }
static boolean isSupportedSQLObject(Class<?> clazz) { return clazz.isEnum() || SUPPORTED_SQL_OBJECTS.contains(clazz); }
public static Map<String, Method> findPublicGetters(Class<?> clazz) { Map<String, Method> map = new HashMap<String, Method>(); Method[] methods = clazz.getMethods(); for (Method method : methods) { if (Modifier.isStatic(method.getModifiers())) continue; if (method.getParameterTypes().length != 0) continue; if (method.getName().equals("getClass")) continue; Class<?> returnType = method.getReturnType(); if (void.class.equals(returnType)) continue; if(!isSupportedSQLObject(returnType)){ continue; } if ((returnType.equals(boolean.class) || returnType.equals(Boolean.class)) && method.getName().startsWith("is") && method.getName().length() > 2) { map.put(getGetterName(method), method); continue; } if ( ! method.getName().startsWith("get")) continue; if (method.getName().length() < 4) continue; map.put(getGetterName(method), method); } return map; } public static Field[] findFields(Class<?> clazz){ return clazz.getDeclaredFields(); }
public static Map<String, Method> findPublicSetters(Class<?> clazz) { Map<String, Method> map = new HashMap<String, Method>(); Method[] methods = clazz.getMethods(); for (Method method : methods) { if (Modifier.isStatic(method.getModifiers())) continue; if ( ! void.class.equals(method.getReturnType())) continue; if (method.getParameterTypes().length != 1) continue; if ( ! method.getName().startsWith("set")) continue; if (method.getName().length() < 4) continue; if(!isSupportedSQLObject(method.getParameterTypes()[0])){ continue; } map.put(getSetterName(method), method); } return map; }
public static String getGetterName(Method getter) { String name = getter.getName(); if (name.startsWith("is")) name = name.substring(2); else name = name.substring(3); return Character.toLowerCase(name.charAt(0)) + name.substring(1); }
private static String getSetterName(Method setter) { String name = setter.getName().substring(3); return Character.toLowerCase(name.charAt(0)) + name.substring(1); }}
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3.2 EntityOperation
EntityOperation 主要实现数据库表结构和对象类结构的映射关系，代码如下：
package com.tom.orm.framework;
import java.lang.reflect.Field;import java.lang.reflect.Method;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.util.HashMap;import java.util.Map;import java.util.TreeMap;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.Table;import javax.persistence.Transient;import org.apache.log4j.Logger;import org.springframework.jdbc.core.RowMapper;import javax.core.common.utils.StringUtils;
/** * 实体对象的反射操作 * * @param <T> */public class EntityOperation<T> { private Logger log = Logger.getLogger(EntityOperation.class); public Class<T> entityClass = null; // 泛型实体Class对象 public final Map<String, PropertyMapping> mappings; public final RowMapper<T> rowMapper; public final String tableName; public String allColumn = "*"; public Field pkField; public EntityOperation(Class<T> clazz,String pk) throws Exception{ if(!clazz.isAnnotationPresent(Entity.class)){ throw new Exception("在" + clazz.getName() + "中没有找到Entity注解，不能做ORM映射"); } this.entityClass = clazz; Table table = entityClass.getAnnotation(Table.class); if (table != null) { this.tableName = table.name(); } else { this.tableName = entityClass.getSimpleName(); } Map<String, Method> getters = ClassMappings.findPublicGetters(entityClass); Map<String, Method> setters = ClassMappings.findPublicSetters(entityClass); Field[] fields = ClassMappings.findFields(entityClass); fillPkFieldAndAllColumn(pk,fields); this.mappings = getPropertyMappings(getters, setters, fields); this.allColumn = this.mappings.keySet().toString().replace("[", "").replace("]",""). replaceAll(" ",""); this.rowMapper = createRowMapper(); } Map<String, PropertyMapping> getPropertyMappings(Map<String, Method> getters, Map<String, Method> setters, Field[] fields) { Map<String, PropertyMapping> mappings = new HashMap<String, PropertyMapping>(); String name; for (Field field : fields) { if (field.isAnnotationPresent(Transient.class)) continue; name = field.getName(); if(name.startsWith("is")){ name = name.substring(2); } name = Character.toLowerCase(name.charAt(0)) + name.substring(1); Method setter = setters.get(name); Method getter = getters.get(name); if (setter == null || getter == null){ continue; } Column column = field.getAnnotation(Column.class); if (column == null) { mappings.put(field.getName(), new PropertyMapping(getter, setter, field)); } else { mappings.put(column.name(), new PropertyMapping(getter, setter, field)); } } return mappings; } RowMapper<T> createRowMapper() { return new RowMapper<T>() { public T mapRow(ResultSet rs, int rowNum) throws SQLException { try { T t = entityClass.newInstance(); ResultSetMetaData meta = rs.getMetaData(); int columns = meta.getColumnCount(); String columnName; for (int i = 1; i <= columns; i++) { Object value = rs.getObject(i); columnName = meta.getColumnName(i); fillBeanFieldValue(t,columnName,value); } return t; }catch (Exception e) { throw new RuntimeException(e); } } }; }
protected void fillBeanFieldValue(T t, String columnName, Object value) { if (value != null) { PropertyMapping pm = mappings.get(columnName); if (pm != null) { try { pm.set(t, value); } catch (Exception e) { e.printStackTrace(); } } } }
private void fillPkFieldAndAllColumn(String pk, Field[] fields) { //设定主键 try { if(!StringUtils.isEmpty(pk)){ pkField = entityClass.getDeclaredField(pk); pkField.setAccessible(true); } } catch (Exception e) { log.debug("没找到主键列，主键列名必须与属性名相同"); } for (int i = 0 ; i < fields.length ;i ++) { Field f = fields[i]; if(StringUtils.isEmpty(pk)){ Id id = f.getAnnotation(Id.class); if(id != null){ pkField = f; break; } } } } public T parse(ResultSet rs) { T t = null; if (null == rs) { return null; } Object value = null; try { t = (T) entityClass.newInstance(); for (String columnName : mappings.keySet()) { try { value = rs.getObject(columnName); } catch (Exception e) { e.printStackTrace(); } fillBeanFieldValue(t,columnName,value); } } catch (Exception ex) { ex.printStackTrace(); } return t; }
public Map<String, Object> parse(T t) { Map<String, Object> _map = new TreeMap<String, Object>(); try { for (String columnName : mappings.keySet()) { Object value = mappings.get(columnName).getter.invoke(t); if (value == null) continue; _map.put(columnName, value);
} } catch (Exception e) { e.printStackTrace(); } return _map; }
public void println(T t) { try { for (String columnName : mappings.keySet()) { Object value = mappings.get(columnName).getter.invoke(t); if (value == null) continue; System.out.println(columnName + " = " + value); } } catch (Exception e) { e.printStackTrace(); } }}
class PropertyMapping {
final boolean insertable; final boolean updatable; final String columnName; final boolean id; final Method getter; final Method setter; final Class enumClass; final String fieldName;
public PropertyMapping(Method getter, Method setter, Field field) { this.getter = getter; this.setter = setter; this.enumClass = getter.getReturnType().isEnum() ? getter.getReturnType() : null; Column column = field.getAnnotation(Column.class); this.insertable = column == null || column.insertable(); this.updatable = column == null || column.updatable(); this.columnName = column == null ? ClassMappings.getGetterName(getter) : ("".equals(column.name()) ? ClassMappings.getGetterName(getter) : column.name()); this.id = field.isAnnotationPresent(Id.class); this.fieldName = field.getName(); }
@SuppressWarnings("unchecked") Object get(Object target) throws Exception { Object r = getter.invoke(target); return enumClass == null ? r : Enum.valueOf(enumClass, (String) r); }
@SuppressWarnings("unchecked") void set(Object target, Object value) throws Exception { if (enumClass != null && value != null) { value = Enum.valueOf(enumClass, (String) value); } //BeanUtils.setProperty(target, fieldName, value); try { if(value != null){ setter.invoke(target, setter.getParameterTypes()[0].cast(value)); } } catch (Exception e) { e.printStackTrace(); /** * 出错原因如果是boolean字段、mysql字段类型，设置tinyint(1) */ System.err.println(fieldName + "--" + value); } }}
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3.3 QueryRuleSqlBuilder
QueryRuleSqlBuilder 根据用户构建好的 QueryRule 来自动生成 SQL 语句，代码如下：
package com.tom.orm.framework;
import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.regex.Matcher;import java.util.regex.Pattern;import org.apache.commons.lang.ArrayUtils;import com.tom.orm.framework.QueryRule.Rule;import javax.core.common.utils.StringUtils;
/** * 根据QueryRule自动构建SQL语句 */public class QueryRuleSqlBuilder {
private int CURR_INDEX = 0; //记录参数所在的位置 private List<String> properties; //保存列名列表 private List<Object> values; //保存参数值列表 private List<Order> orders; //保存排序规则列表 private String whereSql = ""; private String orderSql = ""; private Object [] valueArr = new Object[]{}; private Map<Object,Object> valueMap = new HashMap<Object,Object>(); /** * 获得查询条件 * @return */ public String getWhereSql(){ return this.whereSql; } /** * 获得排序条件 * @return */ public String getOrderSql(){ return this.orderSql; } /** * 获得参数值列表 * @return */ public Object [] getValues(){ return this.valueArr; } /** * 获取参数列表 * @return */ public Map<Object,Object> getValueMap(){ return this.valueMap; } /** * 创建SQL构造器 * @param queryRule */ public QueryRuleSqlBuilder(QueryRule queryRule) { CURR_INDEX = 0; properties = new ArrayList<String>(); values = new ArrayList<Object>(); orders = new ArrayList<Order>(); for (QueryRule.Rule rule : queryRule.getRuleList()) { switch (rule.getType()) { case QueryRule.BETWEEN: processBetween(rule); break; case QueryRule.EQ: processEqual(rule); break; case QueryRule.LIKE: processLike(rule); break; case QueryRule.NOTEQ: processNotEqual(rule); break; case QueryRule.GT: processGreaterThen(rule); break; case QueryRule.GE: processGreaterEqual(rule); break; case QueryRule.LT: processLessThen(rule); break; case QueryRule.LE: processLessEqual(rule); break; case QueryRule.IN: processIN(rule); break; case QueryRule.NOTIN: processNotIN(rule); break; case QueryRule.ISNULL: processIsNull(rule); break; case QueryRule.ISNOTNULL: processIsNotNull(rule); break; case QueryRule.ISEMPTY: processIsEmpty(rule); break; case QueryRule.ISNOTEMPTY: processIsNotEmpty(rule); break; case QueryRule.ASC_ORDER: processOrder(rule); break; case QueryRule.DESC_ORDER: processOrder(rule); break; default: throw new IllegalArgumentException("type " + rule.getType() + " not supported."); } } //拼装where语句 appendWhereSql(); //拼装排序语句 appendOrderSql(); //拼装参数值 appendValues(); } /** * 去掉order * * @param sql * @return */ protected String removeOrders(String sql) { Pattern p = Pattern.compile("order\\s*by[\\w|\\W|\\s|\\S]*", Pattern.CASE_INSENSITIVE); Matcher m = p.matcher(sql); StringBuffer sb = new StringBuffer(); while (m.find()) { m.appendReplacement(sb, ""); } m.appendTail(sb); return sb.toString(); } /** * 去掉select * * @param sql * @return */ protected String removeSelect(String sql) { if(sql.toLowerCase().matches("from\\s+")){ int beginPos = sql.toLowerCase().indexOf("from"); return sql.substring(beginPos); }else{ return sql; } } /** * 处理like * @param rule */ private void processLike(QueryRule.Rule rule) { if (ArrayUtils.isEmpty(rule.getValues())) { return; } Object obj = rule.getValues()[0];
if (obj != null) { String value = obj.toString(); if (!StringUtils.isEmpty(value)) { value = value.replace('*', '%'); obj = value; } } add(rule.getAndOr(),rule.getPropertyName(),"like","%"+rule.getValues()[0]+"%"); }
/** * 处理between * @param rule */ private void processBetween(QueryRule.Rule rule) { if ((ArrayUtils.isEmpty(rule.getValues())) || (rule.getValues().length < 2)) { return; } add(rule.getAndOr(),rule.getPropertyName(),"","between",rule.getValues()[0],"and"); add(0,"","","",rule.getValues()[1],""); } /** * 处理 = * @param rule */ private void processEqual(QueryRule.Rule rule) { if (ArrayUtils.isEmpty(rule.getValues())) { return; } add(rule.getAndOr(),rule.getPropertyName(),"=",rule.getValues()[0]); }
/** * 处理 <> * @param rule */ private void processNotEqual(QueryRule.Rule rule) { if (ArrayUtils.isEmpty(rule.getValues())) { return; } add(rule.getAndOr(),rule.getPropertyName(),"<>",rule.getValues()[0]); }
/** * 处理 > * @param rule */ private void processGreaterThen( QueryRule.Rule rule) { if (ArrayUtils.isEmpty(rule.getValues())) { return; } add(rule.getAndOr(),rule.getPropertyName(),">",rule.getValues()[0]); }
/** * 处理>= * @param rule */ private void processGreaterEqual( QueryRule.Rule rule) { if (ArrayUtils.isEmpty(rule.getValues())) { return; } add(rule.getAndOr(),rule.getPropertyName(),">=",rule.getValues()[0]); }
/** * 处理< * @param rule */ private void processLessThen(QueryRule.Rule rule) { if (ArrayUtils.isEmpty(rule.getValues())) { return; } add(rule.getAndOr(),rule.getPropertyName(),"<",rule.getValues()[0]); }
/** * 处理<= * @param rule */ private void processLessEqual( QueryRule.Rule rule) { if (ArrayUtils.isEmpty(rule.getValues())) { return; } add(rule.getAndOr(),rule.getPropertyName(),"<=",rule.getValues()[0]); }
/** * 处理 is null * @param rule */ private void processIsNull(QueryRule.Rule rule) { add(rule.getAndOr(),rule.getPropertyName(),"is null",null); }
/** * 处理 is not null * @param rule */ private void processIsNotNull(QueryRule.Rule rule) { add(rule.getAndOr(),rule.getPropertyName(),"is not null",null); }
/** * 处理 <>'' * @param rule */ private void processIsNotEmpty(QueryRule.Rule rule) { add(rule.getAndOr(),rule.getPropertyName(),"<>","''"); }
/** * 处理 ='' * @param rule */ private void processIsEmpty(QueryRule.Rule rule) { add(rule.getAndOr(),rule.getPropertyName(),"=","''"); }
/** * 处理in和not in * @param rule * @param name */ private void inAndNotIn(QueryRule.Rule rule,String name){ if (ArrayUtils.isEmpty(rule.getValues())) { return; } if ((rule.getValues().length == 1) && (rule.getValues()[0] != null) && (rule.getValues()[0] instanceof List)) { List<Object> list = (List) rule.getValues()[0]; if ((list != null) && (list.size() > 0)){ for (int i = 0; i < list.size(); i++) { if(i == 0 && i == list.size() - 1){ add(rule.getAndOr(),rule.getPropertyName(),"",name + " (",list.get(i),")"); }else if(i == 0 && i < list.size() - 1){ add(rule.getAndOr(),rule.getPropertyName(),"",name + " (",list.get(i),""); } if(i > 0 && i < list.size() - 1){ add(0,"",",","",list.get(i),""); } if(i == list.size() - 1 && i != 0){ add(0,"",",","",list.get(i),")"); } } } } else { Object[] list = rule.getValues(); for (int i = 0; i < list.length; i++) { if(i == 0 && i == list.length - 1){ add(rule.getAndOr(),rule.getPropertyName(),"",name + " (",list[i],")"); }else if(i == 0 && i < list.length - 1){ add(rule.getAndOr(),rule.getPropertyName(),"",name + " (",list[i],""); } if(i > 0 && i < list.length - 1){ add(0,"",",","",list[i],""); } if(i == list.length - 1 && i != 0){ add(0,"",",","",list[i],")"); } } } } /** * 处理 not in * @param rule */ private void processNotIN(QueryRule.Rule rule){ inAndNotIn(rule,"not in"); } /** * 处理 in * @param rule */ private void processIN(QueryRule.Rule rule) { inAndNotIn(rule,"in"); } /** * 处理 order by * @param rule 查询规则 */ private void processOrder(Rule rule) { switch (rule.getType()) { case QueryRule.ASC_ORDER: //propertyName非空 if (!StringUtils.isEmpty(rule.getPropertyName())) { orders.add(Order.asc(rule.getPropertyName())); } break; case QueryRule.DESC_ORDER: //propertyName非空 if (!StringUtils.isEmpty(rule.getPropertyName())) { orders.add(Order.desc(rule.getPropertyName())); } break; default: break; } } /** * 加入SQL查询规则队列 * @param andOr and 或者 or * @param key 列名 * @param split 列名与值之间的间隔 * @param value 值 */ private void add(int andOr,String key,String split ,Object value){ add(andOr,key,split,"",value,""); } /** * 加入SQL查询规则队列 * @param andOr and 或则 or * @param key 列名 * @param split 列名与值之间的间隔 * @param prefix 值前缀 * @param value 值 * @param suffix 值后缀 */ private void add(int andOr,String key,String split,String prefix,Object value,String suffix){ String andOrStr = (0 == andOr ? "" :(QueryRule.AND == andOr ? " and " : " or ")); properties.add(CURR_INDEX, andOrStr + key + " " + split + prefix + (null != value ? " ? " : " ") + suffix); if(null != value){ values.add(CURR_INDEX,value); CURR_INDEX ++; } } /** * 拼装 where 语句 */ private void appendWhereSql(){ StringBuffer whereSql = new StringBuffer(); for (String p : properties) { whereSql.append(p); } this.whereSql = removeSelect(removeOrders(whereSql.toString())); } /** * 拼装排序语句 */ private void appendOrderSql(){ StringBuffer orderSql = new StringBuffer(); for (int i = 0 ; i < orders.size(); i ++) { if(i > 0 && i < orders.size()){ orderSql.append(","); } orderSql.append(orders.get(i).toString()); } this.orderSql = removeSelect(removeOrders(orderSql.toString())); } /** * 拼装参数值 */ private void appendValues(){ Object [] val = new Object[values.size()]; for (int i = 0; i < values.size(); i ++) { val[i] = values.get(i); valueMap.put(i, values.get(i)); } this.valueArr = val; }}
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3.4 BaseDaoSupport
BaseDaoSupport 主要是对 JdbcTemplate 的包装，下面讲一下其重要代码，请“小伙伴们” 关 注 公 众 号 『 Tom 弹架构 』，回复 " Spring " 可下载全部源代码。先看全局定义：
package com.tom.orm.framework;
...
/** * BaseDao 扩展类，主要功能是支持自动拼装SQL语句，必须继承方可使用 * @author Tom */public abstract class BaseDaoSupport<T extends Serializable, PK extends Serializable> implements BaseDao<T,PK> { private Logger log = Logger.getLogger(BaseDaoSupport.class);
private String tableName = "";
private JdbcTemplate jdbcTemplateWrite; private JdbcTemplate jdbcTemplateReadOnly;
private DataSource dataSourceReadOnly; private DataSource dataSourceWrite;
private EntityOperation<T> op;
@SuppressWarnings("unchecked") protected BaseDaoSupport(){ try{ Class<T> entityClass = GenericsUtils.getSuperClassGenricType(getClass(), 0); op = new EntityOperation<T>(entityClass,this.getPKColumn()); this.setTableName(op.tableName); }catch(Exception e){ e.printStackTrace(); } }
protected String getTableName() { return tableName; } protected DataSource getDataSourceReadOnly() { return dataSourceReadOnly; } protected DataSource getDataSourceWrite() { return dataSourceWrite; }
/** * 动态切换表名 */ protected void setTableName(String tableName) { if(StringUtils.isEmpty(tableName)){ this.tableName = op.tableName; }else{ this.tableName = tableName; } }
protected void setDataSourceWrite(DataSource dataSourceWrite) { this.dataSourceWrite = dataSourceWrite; jdbcTemplateWrite = new JdbcTemplate(dataSourceWrite); }
protected void setDataSourceReadOnly(DataSource dataSourceReadOnly) { this.dataSourceReadOnly = dataSourceReadOnly; jdbcTemplateReadOnly = new JdbcTemplate(dataSourceReadOnly); }
private JdbcTemplate jdbcTemplateReadOnly() { return this.jdbcTemplateReadOnly; }
private JdbcTemplate jdbcTemplateWrite() { return this.jdbcTemplateWrite; }
/** * 还原默认表名 */ protected void restoreTableName(){ this.setTableName(op.tableName); } /** * 获取主键列名称，建议子类重写 * @return */ protected abstract String getPKColumn(); protected abstract void setDataSource(DataSource dataSource);
//此处有省略
}
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为了照顾程序员的一般使用习惯，查询方法的前缀命名主要有 select、get、load，兼顾 Hibernate 和 MyBatis 的命名风格。
/** * 查询函数，使用查询规则 * 例如以下代码查询条件为匹配的数据 * * @param queryRule 查询规则 * @return 查询的结果List */ public List<T> select(QueryRule queryRule) throws Exception{ QueryRuleSqlBuilder bulider = new QueryRuleSqlBuilder(queryRule); String ws = removeFirstAnd(bulider.getWhereSql()); String whereSql = ("".equals(ws) ? ws : (" where " + ws)); String sql = "select " + op.allColumn + " from " + getTableName() + whereSql; Object [] values = bulider.getValues(); String orderSql = bulider.getOrderSql(); orderSql = (StringUtils.isEmpty(orderSql) ? " " : (" order by " + orderSql)); sql += orderSql; log.debug(sql); return (List<T>) this.jdbcTemplateReadOnly().query(sql, this.op.rowMapper, values); }
...
/** * 根据SQL语句执行查询，参数为Object数组对象 * @param sql 查询语句 * @param args 为Object数组 * @return 符合条件的所有对象 */ public List<Map<String,Object>> selectBySql(String sql,Object... args) throws Exception{ return this.jdbcTemplateReadOnly().queryForList(sql,args); }
...
/** * 分页查询函数，使用查询规则<br> * 例如以下代码查询条件为匹配的数据 * * @param queryRule 查询规则 * @param pageNo 页号，从1开始 * @param pageSize 每页的记录条数 * @return 查询的结果Page */ public Page<T> select(QueryRule queryRule,final int pageNo, final int pageSize) throws Exception{ QueryRuleSqlBuilder bulider = new QueryRuleSqlBuilder(queryRule); Object [] values = bulider.getValues(); String ws = removeFirstAnd(bulider.getWhereSql()); String whereSql = ("".equals(ws) ? ws : (" where " + ws)); String countSql = "select count(1) from " + getTableName() + whereSql; long count = (Long) this.jdbcTemplateReadOnly().queryForMap(countSql, values).get ("count(1)"); if (count == 0) { return new Page<T>(); } long start = (pageNo - 1) * pageSize; //在有数据的情况下，继续查询 String orderSql = bulider.getOrderSql(); orderSql = (StringUtils.isEmpty(orderSql) ? " " : (" order by " + orderSql)); String sql = "select " + op.allColumn +" from " + getTableName() + whereSql + orderSql + " limit " + start + "," + pageSize; List<T> list = (List<T>) this.jdbcTemplateReadOnly().query(sql, this.op.rowMapper, values); log.debug(sql); return new Page<T>(start, count, pageSize, list); }...
/** * 分页查询特殊SQL语句 * @param sql 语句 * @param param 查询条件 * @param pageNo 页码 * @param pageSize 每页内容 * @return */ public Page<Map<String,Object>> selectBySqlToPage(String sql, Object [] param, final int pageNo, final int pageSize) throws Exception { String countSql = "select count(1) from (" + sql + ") a";
long count = (Long) this.jdbcTemplateReadOnly().queryForMap(countSql,param).get("count(1)"); if (count == 0) { return new Page<Map<String,Object>>(); } long start = (pageNo - 1) * pageSize; sql = sql + " limit " + start + "," + pageSize; List<Map<String,Object>> list = (List<Map<String,Object>>) this.jdbcTemplateReadOnly(). queryForList(sql, param); log.debug(sql); return new Page<Map<String,Object>>(start, count, pageSize, list); }
/** * 获取默认的实例对象 * @param <T> * @param pkValue * @param rowMapper * @return */ private <T> T doLoad(Object pkValue, RowMapper<T> rowMapper){ Object obj = this.doLoad(getTableName(), getPKColumn(), pkValue, rowMapper); if(obj != null){ return (T)obj; } return null; }
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插入方法，均以 insert 开头：
/** * 插入并返回ID * @param entity * @return */ public PK insertAndReturnId(T entity) throws Exception{ return (PK)this.doInsertRuturnKey(parse(entity)); }
/** * 插入一条记录 * @param entity * @return */ public boolean insert(T entity) throws Exception{ return this.doInsert(parse(entity)); }/** * 批量保存对象.<br> * * @param list 待保存的对象List * @throws InvocationTargetException * @throws IllegalArgumentException * @throws IllegalAccessException */ public int insertAll(List<T> list) throws Exception { int count = 0 ,len = list.size(),step = 50000; Map<String, PropertyMapping> pm = op.mappings; int maxPage = (len % step == 0) ? (len / step) : (len / step + 1); for (int i = 1; i <= maxPage; i ++) { Page<T> page = pagination(list, i, step); String sql = "insert into " + getTableName() + "(" + op.allColumn + ") values ";// (" + valstr.toString() + ")"; StringBuffer valstr = new StringBuffer(); Object[] values = new Object[pm.size() * page.getRows().size()]; for (int j = 0; j < page.getRows().size(); j ++) { if(j > 0 && j < page.getRows().size()){ valstr.append(","); } valstr.append("("); int k = 0; for (PropertyMapping p : pm.values()) { values[(j * pm.size()) + k] = p.getter.invoke(page.getRows().get(j)); if(k > 0 && k < pm.size()){ valstr.append(","); } valstr.append("?"); k ++; } valstr.append(")"); } int result = jdbcTemplateWrite().update(sql + valstr.toString(), values); count += result; }
return count; }
private Serializable doInsertRuturnKey(Map<String,Object> params){ final List<Object> values = new ArrayList<Object>(); final String sql = makeSimpleInsertSql(getTableName(),params,values); KeyHolder keyHolder = new GeneratedKeyHolder(); final JdbcTemplate jdbcTemplate = new JdbcTemplate(getDataSourceWrite()); try {
jdbcTemplate.update(new PreparedStatementCreator() { public PreparedStatement createPreparedStatement(
Connection con) throws SQLException { PreparedStatement ps = con.prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);
for (int i = 0; i < values.size(); i++) { ps.setObject(i+1, values.get(i)==null?null:values.get(i));
} return ps; }
}, keyHolder); } catch (DataAccessException e) { log.error("error",e); }
if (keyHolder == null) { return ""; }
Map<String, Object> keys = keyHolder.getKeys(); if (keys == null || keys.size() == 0 || keys.values().size() == 0) { return ""; } Object key = keys.values().toArray()[0]; if (key == null || !(key instanceof Serializable)) { return ""; } if (key instanceof Number) { //Long k = (Long) key; Class clazz = key.getClass();// return clazz.cast(key); return (clazz == int.class || clazz == Integer.class) ? ((Number) key).intValue() : ((Number)key).longValue();
} else if (key instanceof String) { return (String) key; } else { return (Serializable) key; }
}
/** * 插入 * @param params * @return */ private boolean doInsert(Map<String, Object> params) { String sql = this.makeSimpleInsertSql(this.getTableName(), params); int ret = this.jdbcTemplateWrite().update(sql, params.values().toArray()); return ret > 0; }
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删除方法，均以 delete 开头：
/** * 删除对象.<br> * * @param entity 待删除的实体对象 */ public boolean delete(T entity) throws Exception { return this.doDelete(op.pkField.get(entity)) > 0; }
/** * 删除对象.<br> * * @param list 待删除的实体对象列表 * @throws InvocationTargetException * @throws IllegalArgumentException * @throws IllegalAccessException */ public int deleteAll(List<T> list) throws Exception { String pkName = op.pkField.getName(); int count = 0 ,len = list.size(),step = 1000; Map<String, PropertyMapping> pm = op.mappings; int maxPage = (len % step == 0) ? (len / step) : (len / step + 1); for (int i = 1; i <= maxPage; i ++) { StringBuffer valstr = new StringBuffer(); Page<T> page = pagination(list, i, step); Object[] values = new Object[page.getRows().size()];
for (int j = 0; j < page.getRows().size(); j ++) { if(j > 0 && j < page.getRows().size()){ valstr.append(","); } values[j] = pm.get(pkName).getter.invoke(page.getRows().get(j)); valstr.append("?"); }
String sql = "delete from " + getTableName() + " where " + pkName + " in (" + valstr.toString() + ")"; int result = jdbcTemplateWrite().update(sql, values); count += result; } return count; }
/** * 根据id删除对象。如果有记录则删之，没有记录也不报异常<br> * 例如：删除主键唯一的记录 * * @param id 序列化id */ protected void deleteByPK(PK id) throws Exception { this.doDelete(id); }
/** * 删除实例对象，返回删除记录数 * @param tableName * @param pkName * @param pkValue * @return */ private int doDelete(String tableName, String pkName, Object pkValue) { StringBuffer sb = new StringBuffer(); sb.append("delete from ").append(tableName).append(" where ").append(pkName).append(" = ?"); int ret = this.jdbcTemplateWrite().update(sb.toString(), pkValue); return ret; }
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修改方法，均以 update 开头：
/** * 更新对象.<br> * * @param entity 待更新对象 * @throws IllegalAccessException * @throws IllegalArgumentException */ public boolean update(T entity) throws Exception { return this.doUpdate(op.pkField.get(entity), parse(entity)) > 0; }
/** * 更新实例对象，返回删除记录数 * @param pkValue * @param params * @return */ private int doUpdate(Object pkValue, Map<String, Object> params){ String sql = this.makeDefaultSimpleUpdateSql(pkValue, params); params.put(this.getPKColumn(), pkValue); int ret = this.jdbcTemplateWrite().update(sql, params.values().toArray()); return ret; }
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至此一个完整的 ORM 框架就横空出世。当然，还有很多优化的地方，请小伙伴可以继续完善。
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发布于: 17 小时前
版权声明: 本文为 InfoQ 作者【Tom弹架构】的原创文章。
原文链接:【http://xie.infoq.cn/article/fd4e18eb7a2daf8eb97ccca35】。文章转载请联系作者。
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不只做一个技术者，更要做一个思考者 2021.10.22 加入
畅销书作者，代表作品：《Spring 5核心原理》、《Netty 4核心原理》、《设计模式就该这样学》
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