【郭林专刊】万能 dao 层

于 2011-09-12 23:18:00 发布 · 163 阅读 · 0
文章标签：

#数据库 #java

本文分享了对数据库操作类的改进，相较于Hibernate，该实现被认为在某些方面更易于使用。详细介绍了类的两个核心方法：操作对象和结果集转换为对象的方法，以及连接、预处理语句和结果集管理的简化流程。
2011-08-30 05:13 189人阅读 评论(3) 收藏 举报
view plain copy to clipboard print ?
  1. packageheima.shawn.utils;
  3. importjava.beans.Introspector;
  4. importjava.beans.PropertyDescriptor;
  5. importjava.sql.Connection;
  6. importjava.sql.PreparedStatement;
  7. importjava.sql.ResultSet;
  8. importjava.util.ArrayList;
  9. importjava.util.List;
  11. publicclassBaseDao<T>{
  12. publicObjectopreatorObj(Class<T>tClazz,Stringsql,Object...params)
  13. throwsException{
  14. Connectionconn=null;
  15. PreparedStatementpst=null;
  16. ResultSetrs=null;
  17. try{
  18. List<T>list=newArrayList<T>();
  19. conn=DBUtils.getInstance().getConnection();
  20. pst=conn.prepareStatement(sql);
  21. if(params!=null){
  22. for(inti=1;i<=params.length;i++){
  23. pst.setObject(i,params[i-1]);
  24. }
  25. }
  26. if(pst.execute()){
  27. rs=pst.getResultSet();
  28. while(rs.next()){
  29. Tt=resultSet2Bean(rs,tClazz);
  30. list.add(t);
  31. }
  32. returnlist;
  33. }else{
  34. introws=pst.getUpdateCount();
  35. if(rows>0)
  36. returntrue;
  37. returnfalse;
  38. }
  39. }finally{
  40. DBUtils.getInstance().release(conn,pst,rs);
  41. }
  42. }
  44. publicTresultSet2Bean(ResultSetrs,Class<T>clazz)throwsException{
  45. Tt=clazz.newInstance();
  46. PropertyDescriptor[]props=Introspector.getBeanInfo(clazz)
  47. .getPropertyDescriptors();
  48. for(inti=0;i<props.length;i++){
  49. if(props[i].getName().equals("class"))
  50. continue;
  51. props[i].getWriteMethod().invoke(t,
  52. rs.getObject(props[i].getName()));
  53. }
  54. returnt;
  55. }
  56. }
package heima.shawn.utils; import java.beans.Introspector; import java.beans.PropertyDescriptor; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList; import java.util.List; public class BaseDao<T> { public Object opreatorObj(Class<T> tClazz, String sql, Object... params) throws Exception { Connection conn = null; PreparedStatement pst = null; ResultSet rs = null; try { List<T> list = new ArrayList<T>(); conn = DBUtils.getInstance().getConnection(); pst = conn.prepareStatement(sql); if (params != null) { for (int i = 1; i <= params.length; i++) { pst.setObject(i, params[i - 1]); } } if (pst.execute()) { rs = pst.getResultSet(); while (rs.next()) { T t = resultSet2Bean(rs, tClazz); list.add(t); } return list; } else { int rows = pst.getUpdateCount(); if (rows > 0) return true; return false; } } finally { DBUtils.getInstance().release(conn, pst, rs); } } public T resultSet2Bean(ResultSet rs, Class<T> clazz) throws Exception { T t = clazz.newInstance(); PropertyDescriptor[] props = Introspector.getBeanInfo(clazz) .getPropertyDescriptors(); for (int i = 0; i < props.length; i++) { if (props[i].getName().equals("class")) continue; props[i].getWriteMethod().invoke(t, rs.getObject(props[i].getName())); } return t; } }


view plain copy to clipboard print ?
  1. packageheima.shawn.utils;
  3. importjava.io.IOException;
  4. importjava.sql.Connection;
  5. importjava.sql.DriverManager;
  6. importjava.sql.ResultSet;
  7. importjava.sql.SQLException;
  8. importjava.sql.Statement;
  9. importjava.util.Properties;
  11. importcom.mysql.jdbc.Driver;
  13. publicclassDBUtils{
  14. privatePropertiesprop=newProperties();
  16. privateDBUtils(){
  17. try{
  18. prop.load(DBUtils.class.getClassLoader().getResourceAsStream(
  19. "DB.properties"));
  20. }catch(IOExceptione){
  21. thrownewRuntimeException(e);
  22. }
  23. }
  25. privatestaticDBUtilsinstance=newDBUtils();
  27. publicstaticDBUtilsgetInstance(){
  28. returninstance;
  29. }
  31. publicConnectiongetConnection(){
  32. Connectionconn=null;
  33. try{
  34. Class.forName(prop.getProperty("driver"));
  35. //Driverdriver=newDriver();
  36. conn=DriverManager.getConnection(prop.getProperty("url"),prop
  37. .getProperty("user"),prop.getProperty("password"));
  38. }catch(Exceptione){
  39. thrownewRuntimeException(e);
  40. }
  41. returnconn;
  42. }
  44. publicvoidrelease(Connectionconn,Statementst,ResultSetrs){
  45. if(rs!=null)
  46. try{
  47. rs.close();
  48. }catch(SQLExceptione){
  49. thrownewRuntimeException(e);
  50. }
  51. if(st!=null)
  52. try{
  53. st.close();
  54. }catch(SQLExceptione){
  55. thrownewRuntimeException(e);
  56. }
  57. if(conn!=null)
  58. try{
  59. conn.close();
  60. }catch(SQLExceptione){
  61. thrownewRuntimeException(e);
  62. }
  63. }
  64. }
package heima.shawn.utils; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.Properties; import com.mysql.jdbc.Driver; public class DBUtils { private Properties prop = new Properties(); private DBUtils() { try { prop.load(DBUtils.class.getClassLoader().getResourceAsStream( "DB.properties")); } catch (IOException e) { throw new RuntimeException(e); } } private static DBUtils instance = new DBUtils(); public static DBUtils getInstance() { return instance; } public Connection getConnection() { Connection conn = null; try { Class.forName(prop.getProperty("driver")); //Driver driver = new Driver(); conn = DriverManager.getConnection(prop.getProperty("url"), prop .getProperty("user"), prop.getProperty("password")); } catch (Exception e) { throw new RuntimeException(e); } return conn; } public void release(Connection conn, Statement st, ResultSet rs) { if (rs != null) try { rs.close(); } catch (SQLException e) { throw new RuntimeException(e); } if (st != null) try { st.close(); } catch (SQLException e) { throw new RuntimeException(e); } if (conn != null) try { conn.close(); } catch (SQLException e) { throw new RuntimeException(e); } } }


还能改进，，，但是已经觉得比hibernate好用了！！！你懂的·········

view plain copy to clipboard print ?
  1. packageheima.shawn.utils;
  3. importjava.beans.Introspector;
  4. importjava.beans.PropertyDescriptor;
  5. importjava.sql.Connection;
  6. importjava.sql.PreparedStatement;
  7. importjava.sql.ResultSet;
  8. importjava.util.ArrayList;
  9. importjava.util.List;
  11. publicclassBaseDao<T>{
  12. publicObjectopreatorObj(Class<T>tClazz,Stringsql,Object...params)
  13. throwsException{
  14. Connectionconn=null;
  15. PreparedStatementpst=null;
  16. ResultSetrs=null;
  17. try{
  18. List<T>list=newArrayList<T>();
  19. conn=DBUtils.getInstance().getConnection();
  20. pst=conn.prepareStatement(sql);
  21. if(params!=null){
  22. for(inti=1;i<=params.length;i++){
  23. pst.setObject(i,params[i-1]);
  24. }
  25. }
  26. if(pst.execute()){
  27. rs=pst.getResultSet();
  28. while(rs.next()){
  29. Tt=resultSet2Bean(rs,tClazz);
  30. list.add(t);
  31. }
  32. returnlist;
  33. }else{
  34. introws=pst.getUpdateCount();
  35. if(rows>0)
  36. returntrue;
  37. returnfalse;
  38. }
  39. }finally{
  40. DBUtils.getInstance().release(conn,pst,rs);
  41. }
  42. }
  44. publicTresultSet2Bean(ResultSetrs,Class<T>clazz)throwsException{
  45. Tt=clazz.newInstance();
  46. PropertyDescriptor[]props=Introspector.getBeanInfo(clazz)
  47. .getPropertyDescriptors();
  48. for(inti=0;i<props.length;i++){
  49. if(props[i].getName().equals("class"))
  50. continue;
  51. props[i].getWriteMethod().invoke(t,
  52. rs.getObject(props[i].getName()));
  53. }
  54. returnt;
  55. }
  56. }
package heima.shawn.utils; import java.beans.Introspector; import java.beans.PropertyDescriptor; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList; import java.util.List; public class BaseDao<T> { public Object opreatorObj(Class<T> tClazz, String sql, Object... params) throws Exception { Connection conn = null; PreparedStatement pst = null; ResultSet rs = null; try { List<T> list = new ArrayList<T>(); conn = DBUtils.getInstance().getConnection(); pst = conn.prepareStatement(sql); if (params != null) { for (int i = 1; i <= params.length; i++) { pst.setObject(i, params[i - 1]); } } if (pst.execute()) { rs = pst.getResultSet(); while (rs.next()) { T t = resultSet2Bean(rs, tClazz); list.add(t); } return list; } else { int rows = pst.getUpdateCount(); if (rows > 0) return true; return false; } } finally { DBUtils.getInstance().release(conn, pst, rs); } } public T resultSet2Bean(ResultSet rs, Class<T> clazz) throws Exception { T t = clazz.newInstance(); PropertyDescriptor[] props = Introspector.getBeanInfo(clazz) .getPropertyDescriptors(); for (int i = 0; i < props.length; i++) { if (props[i].getName().equals("class")) continue; props[i].getWriteMethod().invoke(t, rs.getObject(props[i].getName())); } return t; } }


view plain copy to clipboard print ?
  1. packageheima.shawn.utils;
  3. importjava.io.IOException;
  4. importjava.sql.Connection;
  5. importjava.sql.DriverManager;
  6. importjava.sql.ResultSet;
  7. importjava.sql.SQLException;
  8. importjava.sql.Statement;
  9. importjava.util.Properties;
  11. importcom.mysql.jdbc.Driver;
  13. publicclassDBUtils{
  14. privatePropertiesprop=newProperties();
  16. privateDBUtils(){
  17. try{
  18. prop.load(DBUtils.class.getClassLoader().getResourceAsStream(
  19. "DB.properties"));
  20. }catch(IOExceptione){
  21. thrownewRuntimeException(e);
  22. }
  23. }
  25. privatestaticDBUtilsinstance=newDBUtils();
  27. publicstaticDBUtilsgetInstance(){
  28. returninstance;
  29. }
  31. publicConnectiongetConnection(){
  32. Connectionconn=null;
  33. try{
  34. Class.forName(prop.getProperty("driver"));
  35. //Driverdriver=newDriver();
  36. conn=DriverManager.getConnection(prop.getProperty("url"),prop
  37. .getProperty("user"),prop.getProperty("password"));
  38. }catch(Exceptione){
  39. thrownewRuntimeException(e);
  40. }
  41. returnconn;
  42. }
  44. publicvoidrelease(Connectionconn,Statementst,ResultSetrs){
  45. if(rs!=null)
  46. try{
  47. rs.close();
  48. }catch(SQLExceptione){
  49. thrownewRuntimeException(e);
  50. }
  51. if(st!=null)
  52. try{
  53. st.close();
  54. }catch(SQLExceptione){
  55. thrownewRuntimeException(e);
  56. }
  57. if(conn!=null)
  58. try{
  59. conn.close();
  60. }catch(SQLExceptione){
  61. thrownewRuntimeException(e);
  62. }
  63. }
  64. }
package heima.shawn.utils; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.Properties; import com.mysql.jdbc.Driver; public class DBUtils { private Properties prop = new Properties(); private DBUtils() { try { prop.load(DBUtils.class.getClassLoader().getResourceAsStream( "DB.properties")); } catch (IOException e) { throw new RuntimeException(e); } } private static DBUtils instance = new DBUtils(); public static DBUtils getInstance() { return instance; } public Connection getConnection() { Connection conn = null; try { Class.forName(prop.getProperty("driver")); //Driver driver = new Driver(); conn = DriverManager.getConnection(prop.getProperty("url"), prop .getProperty("user"), prop.getProperty("password")); } catch (Exception e) { throw new RuntimeException(e); } return conn; } public void release(Connection conn, Statement st, ResultSet rs) { if (rs != null) try { rs.close(); } catch (SQLException e) { throw new RuntimeException(e); } if (st != null) try { st.close(); } catch (SQLException e) { throw new RuntimeException(e); } if (conn != null) try { conn.close(); } catch (SQLException e) { throw new RuntimeException(e); } } }


还能改进，，，但是已经觉得比hibernate好用了！！！你懂的·········

iteye_10189
关注
评论
添加红包

请填写红包祝福语或标题

个

红包个数最小为10个

元

红包金额最低5元

当前余额3.43元 前往充值 >
需支付：10.00元
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付元
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明：

1.余额是钱包充值的虚拟货币，按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载，可以购买VIP、付费专栏及课程。

余额充值