面试准备--持久层框架
在说到持久层框架，耳熟能详的有Hibernate和iBatis，他们最简单的区别是一个全自动的，一个是半自动的。但是归根结底他们的实现原理都差不多，他们都是引用了C3P0数据库连接池，使用ibatis 提供的orm机制，对业务逻辑实现人员而言，面对的是纯粹的java对象。这一层与通过hibernate 实现orm 而言基本一致，而对于具体的数据操作，hibernate会自动生成sql 语句，而ibatis 则要求开发者编写具体的sql 语句。相对hibernate而言，ibatis 以sql开发的工作量和数据库移植性上的让步，为系统设计提供了更大的自由空间。
以下是本人模仿写的持久层框架
当用户的业务逻辑处理中，需要对数据库进行操作，依照Hibernate的经验，我们需要自定义一些条件带入，所以这里创建了2个类：Criteria.java负责查询，Handler.java负责修改数据。
package com.qj.engine.sqlmap; import java.sql.SQLException; import java.util.HashMap; import java.util.List; import java.util.Map; import com.qj.engine.session.Session; import com.qj.engine.session.SessionImpl; import com.qj.engine.session.exception.SessionException; import com.qj.engine.sqlmap.util.FilterUtil; public class Criteria { private String tableName=""; private int custom = 0; private Map<String, String> filterMap = new HashMap<String, String>(); private Map<String, String> orderMap = new HashMap<String, String>(); private Session session = new SessionImpl(); public Criteria(String tableName) { this.tableName = tableName; } /** * 添加过滤条件 */ public void filter(CriteriaTypes type, String colName, Object value){ String filterStr = FilterUtil.getFilterStr(type, colName, value); this.filterMap.put(colName, filterStr); } /** * 添加过滤条件 between and */ public void filter(CriteriaTypes type, String colName, Object val1, Object val2){ String filterStr = FilterUtil.getFilterStr(type, colName, val1, val2); this.filterMap.put(colName, filterStr); } /** * 添加过滤条件 * @param filterStr:自定义过滤条件 */ public void filter(String filterStr){ this.custom=this.custom+1; this.filterMap.put("CUSTOM"+this.custom, filterStr); } /** * 添加排序条件 * @param type * @param colName */ public void order(OrderTypes type, String colName){ this.orderMap.put(colName, colName + " " + type.toString()); } /** * 查询一列数据，以Map形式返回 * @return */ public Map<String, Object> executeQueryForMap(){ String querySql = FilterUtil.getQuerySQL(this.tableName, this.filterMap, this.orderMap); Map<String, Object> resultMap = null; try { resultMap = this.session.executeQueryForMap(querySql); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return resultMap; } /** * 查询数据列表，list子集是以Map形式返回 * @return */ public List<Map<String, Object>> executeQueryForMapList(){ String querySql = FilterUtil.getQuerySQL(this.tableName, this.filterMap, this.orderMap); List<Map<String, Object>> resultList = null; try { resultList = this.session.executeQueryForMapList(querySql); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return resultList; } /** * 查询数据列表，以Object形式返回 * @param cls * @return */ public Object executeQueryForObject(Class<?> cls){ String querySql = FilterUtil.getQuerySQL(this.tableName, this.filterMap, this.orderMap); Object obj = null; try { obj = this.session.executeQueryForObject(querySql, cls); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return obj; } /** * 查询数据列表，list子集是以Object形式返回 * @param cls * @return */ public List<Object> executeQueryForList(Class<?> cls){ String querySql = FilterUtil.getQuerySQL(this.tableName, this.filterMap, this.orderMap); List<Object> objList = null; try { objList = this.session.executeQueryForList(querySql, cls); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return objList; } /** * 执行存储过程 * @param procName 存储过程名称 * @param map 传递的参数列表, 如key:in; value: param * @return 执行结果 */ public Object executeProcessQueryForObject(String procName, Map<String, Object> map){ Object result = null; try { result = this.session.executeProcessQueryForObject(procName, map); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return result; } /** * 执行存储过程 * @param procName 存储过程名称 * @param map 传递的参数列表, 如key:in; value: param * @return 执行结果 */ public Object[] executeProcessQueryForList(String procName, Map<String, Object> map){ Object[] results = null; try { results = this.session.executeProcessQueryForList(procName, map); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return results; } }
package com.qj.engine.sqlmap; import java.sql.SQLException; import java.util.Map; import com.qj.engine.session.Session; import com.qj.engine.session.SessionImpl; import com.qj.engine.session.exception.SessionException; import com.qj.engine.sqlmap.exception.SqlMappingException; import com.qj.engine.sqlmap.util.HandlerUtil; /** * * @author QJ * */ public class Handler { private String tableName=""; private Session session = new SessionImpl(); public Handler(String tableName) { this.tableName = tableName; } /** * 插入 * @param pkRow * @param pkVal * @param valsMap * @return */ public boolean insert(String pkRow, Object pkVal, Map<String, Object> valsMap){ if(this.tableName.equals("")){ try { throw new SqlMappingException("表的名称没有设定"); } catch (SqlMappingException e) { // TODO Auto-generated catch block e.printStackTrace(); } } String insertSql = HandlerUtil.getDmlSql(HandlerTypes.INSERT, this.tableName, pkRow, pkVal, valsMap); boolean result = false; try { result = session.insert(insertSql); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return result; } /** * 修改 * @param pkRow * @param pkVal * @param valsMap * @return */ public boolean update(String pkRow, Object pkVal, Map<String, Object> valsMap){ if(this.tableName.equals("")){ try { throw new SqlMappingException("表的名称没有设定"); } catch (SqlMappingException e) { // TODO Auto-generated catch block e.printStackTrace(); } } String updateSql = HandlerUtil.getDmlSql(HandlerTypes.UPDATE, this.tableName, pkRow, pkVal, valsMap); boolean result = false; try { result = session.insert(updateSql); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return result; } /** * 删除 * @param pkRow * @param pkVal * @return */ public boolean delete(String pkRow, Object pkVal){ if(this.tableName.equals("")){ try { throw new SqlMappingException("表的名称没有设定"); } catch (SqlMappingException e) { // TODO Auto-generated catch block e.printStackTrace(); } } String deleteSql = HandlerUtil.getDmlSql(HandlerTypes.DELETE, this.tableName, pkRow, pkVal, null); boolean result = false; try { result = session.insert(deleteSql); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return result; } /** * 自定义DML sql * @param userDefinedSql * @return */ public boolean userDefinedSql(String userDefinedSql){ boolean result = false; try { result = session.insert(userDefinedSql); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return result; } /** * 执行存储过程 * @param procName * @param map * @return */ public boolean executeProcess(String procName, Map<String, Object> map){ boolean result = false; try { result = this.session.executeProcess(procName, map); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SessionException e) { // TODO Auto-generated catch block e.printStackTrace(); } return result; } }