请教评价java连接数据库的几种不方式

 

====1.

package common;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.sql.*;

public class PropertiesConnection extends Properties{
 
 private static PropertiesConnection instance=null;
 
 private PropertiesConnection() throws IOException{
  InputStream is=getClass().getResourceAsStream("/db.properties");
  try {
   this.load(is);
  } catch (IOException e) {
   throw e;
  }
 }
 
 private static PropertiesConnection getInstance() throws IOException{
  if(instance==null){
   makeInstance();
   return instance;
  }
  return instance;
 }
 
 private static synchronized void makeInstance() throws IOException{
  if(instance==null){
   instance=new PropertiesConnection();
  }
 }
 
 public static synchronized Connection getCon() throws IOException, ClassNotFoundException, SQLException {
  String Driver=PropertiesConnection.getInstance().getProperty("DRIVER");
  String Url=PropertiesConnection.getInstance().getProperty("URL");
  String User=PropertiesConnection.getInstance().getProperty("USER");
  String Pwd=PropertiesConnection.getInstance().getProperty("PWD");
  Class.forName(Driver);
  return DriverManager.getConnection(Url,User,Pwd);
 }
}

====2.

package common;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import java.sql.*;

public class PoolConnection {
 
 public static Connection getConnection() throws NamingException,SQLException{
   //context接口提供了查找JNDI Resource的接口
   Context ct=new InitialContext();
   //datasource对象由tomcat提供,所以不能在程序中实例化获得,需查找获取
   DataSource ds=(DataSource)ct.lookup("java:comp/env/addressBook");
   //获取datasource对象后,由对象的getConnection方法获取一个连接对象
   return ds.getConnection();
 }
 public static void close(Connection con,PreparedStatement ps,ResultSet rs) {
  try {
   if (rs != null) {
    rs.close();
    rs = null;
   }
   if(ps!=null){
    ps.close();
    ps=null;
   }
   if(con!=null){
    con.close();
    con=null;
   }
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
}

====3.

package common;

import java.sql.*;

public class DBConnection {
 
 private static final String DRIVER="com.microsoft.sqlserver.jdbc.SQLServerDriver";
 private static final String URL="jdbc:sqlserver://localhost:1433;DataBaseName=Book";
 private static final String USER="sa";
 private static final String PWD="sa";
 
 private static DBConnection instance=null;
 
 private DBConnection(){}
 
 public static DBConnection getInstance(){
  if(instance==null){
   makeInstance();
   return instance;
  }
  return instance;
 }
 
 private static synchronized void makeInstance() {
  if(instance==null){
   instance=new DBConnection();
  }
 }
 
 public Connection getCon() throws ClassNotFoundException,SQLException{
  Connection con=null;
  try {
   Class.forName(DRIVER);
   con=DriverManager.getConnection(URL,USER,PWD);
  } catch (ClassNotFoundException e) {
   throw e;
  }catch (SQLException e) {
   throw e;
  }
  return con;
 }
 
 public void close(ResultSet rs,PreparedStatement ps,Connection con) throws SQLException{
  try {
   if(rs!=null){
       rs.close();
    rs=null;
   }
   if(ps!=null){
       ps.close();
    ps=null;
   }
   if(con!=null){
    con.close();
    con=null;
   }
  } catch (SQLException e) {
   throw e;
  }
 }
}

====4.

package common;

import java.util.List;
import java.sql.*;

import javax.servlet.jsp.jstl.sql.Result;
import javax.servlet.jsp.jstl.sql.ResultSupport;

public class CommonDaoConnection {
 private String sqlValue;
 private List values;
 private Connection con;
 
 /*
  * 设定con
  */
 public void setConnection(Connection _con){
  this.con=_con;
 }
 
 /*
  * 设定sqlValue
  */
 public void setSqlValue(String _sqlValue){
  this.sqlValue=_sqlValue;
 }
 
 /*
  * 设定list(sql语句参数)
  */
 public void setList(List _values){
  this.values=_values;
 }
 
 /*
  * 执行Query
  * return Result
  */
 public Result executeQuery() throws SQLException{
  Result result=null;
  PreparedStatement ps=null;
  Statement st=null;
  ResultSet rs=null;
  try{
  //带参数的是执行的PreparedStatement
  if(this.values!=null||this.values.size()>0){
   con.prepareStatement(this.sqlValue);
   this.setValues(ps, values);
   rs=ps.executeQuery();   
  }else{
   con.createStatement();
   rs=st.executeQuery(sqlValue);
  }
   result=ResultSupport.toResult(rs);
  }finally{
   if(rs!=null){
    try{rs.close();}catch(SQLException e){}
   }
   if(st!=null){
    try{st.close();}catch(SQLException e){}
   }
   if(ps!=null){
    try{ps.close();}catch(SQLException e){}
   }
  } 
   return result;
 }
 
 /*
  * 执行Update
  */
 public int executeUpdate() throws SQLException{
  PreparedStatement ps=null;
  Statement st=null;
  int num=0;
  try{
  if(this.values!=null||this.values.size()>0){
   this.con.prepareStatement(sqlValue);
   this.setValues(ps, values);
   num=ps.executeUpdate();
  }else{
   this.con.createStatement();
   num=st.executeUpdate(sqlValue);
  }
  }finally{
   if(st!=null){
    try{st.close();}catch(SQLException e){}
   }
   if(ps!=null){
    try{ps.close();}catch(SQLException e){}
   }
  }
  return num;
 }
 /*
  * 设置参数
  */
 public void setValues(PreparedStatement ps,List values) throws SQLException{
  for(int i=0;i<values.size();i++){
   ps.setObject(i+1, values.get(i));
  }
 }
 
}