java连接mysql底层封装详解

package com.dao.db;

import java.sql.Connection;
import java.sql.SQLException;

/**
 * 数据库连接层MYSQL
 * @author Administrator
 *
 */
public class DBConnection {
 
 
 /**
  * 连接数据库
  * @return
  */
 public static Connection getDBConnection()
 {
  // 1. 注册驱动
  try {
   Class.forName("com.mysql.jdbc.Driver");
  } catch (ClassNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  // 获取数据库的连接
  try {
   Connection conn = java.sql.DriverManager.getConnection("jdbc:mysql://localhost/mysql?useUnicode=true&characterEncoding=utf-8", "root", "root");
   return conn;
  } catch (SQLException e1) {
   e1.printStackTrace();
  }
  return null;
 }
 
}

package com.dao.db;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Types;
import java.util.ArrayList;
import java.util.HashMap;

/**
 * MYSQL数据库底层封装
 * @author Administrator
 *
 */
public class DBManager {
 
 private PreparedStatement pstmt;
 private Connection conn;
 private ResultSet rs;
 

 /**
  * 打开数据库
  */
 public DBManager() {
  conn = DBConnection.getDBConnection();
 }
 
 /**
  * 执行修改添加操作
  * @param coulmn
  * @param type
  * @param sql
  * @return
  * @throws SQLException
  */
 public boolean updateOrAdd(String[] coulmn, int[] type, String sql) throws SQLException
 {
  if(!setPstmtParam(coulmn, type, sql))
   return false;
  boolean flag = pstmt.executeUpdate()>0?true:false;
  closeDB();
  return flag;
 }
 /**
  * 获取查询结果集
  * @param coulmn
  * @param type
  * @param sql
  * @throws SQLException
  */
 public DataTable getResultData(String[] coulmn, int[] type, String sql) throws SQLException
 {
  DataTable dt = new DataTable();
  
  ArrayList<HashMap<String, String>>list = new ArrayList<HashMap<String, String>>();
  
  if(!setPstmtParam(coulmn, type, sql))
   return null;
  rs = pstmt.executeQuery();
  ResultSetMetaData rsmd = rs.getMetaData();//取数据库的列名 
  int numberOfColumns = rsmd.getColumnCount();
  while(rs.next())
  {
   HashMap<String, String> rsTree = new HashMap<String, String>(); 
   for(int r=1;r<numberOfColumns+1;r++)
    {
    rsTree.put(rsmd.getColumnName(r),rs.getObject(r).toString());
    }
   list.add(rsTree);
  }
  closeDB();
  dt.setDataTable(list);
  return dt;
 }
 
 /**
  * 参数设置
  * @param coulmn
  * @param type
  * @throws SQLException 
  * @throws NumberFormatException 
  */
 private boolean setPstmtParam(String[] coulmn, int[] type, String sql) throws NumberFormatException, SQLException
 {
  if(sql== null) return false;
  pstmt = conn.prepareStatement(sql);
  if(coulmn != null && type != null && coulmn.length !=0 && type.length !=0 )
  {  
   for (int i = 0; i<type.length; i++) {
    switch (type[i]) {
    case Types.INTEGER:
     pstmt.setInt(i+1, Integer.parseInt(coulmn[i]));
     break;
    case Types.BOOLEAN:
     pstmt.setBoolean(i+1, Boolean.parseBoolean(coulmn[i]));
     break;
    case Types.CHAR:
     pstmt.setString(i+1, coulmn[i]);
     break;
    case Types.DOUBLE:
     pstmt.setDouble(i+1, Double.parseDouble(coulmn[i]));
     break;
    case Types.FLOAT:
     pstmt.setFloat(i+1, Float.parseFloat(coulmn[i]));
     break;
    default:
     break;
    }
   }
  }
  return true;
 }
 
 /**
  * 关闭数据库
  * @throws SQLException
  */
 private void closeDB() throws SQLException
 {
  if(rs != null)
  {
   rs.close();
  }
  if(pstmt != null)
  {
   pstmt.close();
  }
  if(conn != null)
  {
   conn.close();
  }
  
 }
}

package com.dao.db;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
 * 数据集封装
 * @author Administrator
 *
 */
public class DataTable {
 
 public String[] column;//列字段
 public String[][] row; //行值
 public int rowCount = 0;//行数
 public int colCoun = 0;//列数
 
 
 public DataTable() {
  super();
 }
 
 public DataTable(String[] column, String[][] row, int rowCount, int colCoun) {
  super();
  this.column = column;
  this.row = row;
  this.rowCount = rowCount;
  this.colCoun = colCoun;
 }


 public void setDataTable(ArrayList<HashMap<String, String>> list) {
  rowCount = list.size();
  colCoun = list.get(0).size();
  column = new String[colCoun];
  row = new String[rowCount][colCoun];
  for (int i = 0; i < rowCount; i++) {
   Set<Map.Entry<String, String>> set = list.get(i).entrySet();
   int j = 0;
   for (Iterator<Map.Entry<String, String>> it = set.iterator(); it
     .hasNext();) {
    Map.Entry<String, String> entry = (Map.Entry<String, String>) it
      .next();
    row[i][j] = entry.getValue();
    if (i == rowCount - 1) {
     column[j] = entry.getKey();
    }
    j++;
   }
  }
 }

 public String[] getColumn() {
  return column;
 }

 public void setColumn(String[] column) {
  this.column = column;
 }

 public String[][] getRow() {
  return row;
 }

 public void setRow(String[][] row) {
  this.row = row;
 }

 public int getRowCount() {
  return rowCount;
 }

 public void setRowCount(int rowCount) {
  this.rowCount = rowCount;
 }

 public int getColCoun() {
  return colCoun;
 }

 public void setColCoun(int colCoun) {
  this.colCoun = colCoun;
 }
 
 

}

package com.bussiness.test;

import java.sql.SQLException;
import java.sql.Types;

import com.dao.db.DBManager;
import com.dao.db.DataTable;

public class TestBusIness{
 
 static String searchSql = "select * from score";
 static String insertSql = "insert into score(name, age, score)values(?,?,?)";
 static String deleteSql = "delete from score where id = ?";
 static String updateSql = "update score set name = ? where id = ?";
 
 public static void main(String[] args) {
  intsertData();
  searchData();
 }
 
 private static void intsertData()
 { 
  DBManager dm = new DBManager();
  String[] coulmn = new String[]{"wyf2", "23", "89.5"};
  int[] type = new int[]{Types.CHAR, Types.INTEGER, Types.DOUBLE};
  
  try {
   boolean flag = dm.updateOrAdd(coulmn, type, insertSql);
   if(flag)
    System.out.println("插入成功");
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
 private static void searchData()
 { 
  DBManager dm = new DBManager();
  String[] coulmn = null;
  int[] type = null;
  
  try {
   DataTable dt = dm.getResultData(coulmn, type, searchSql);
   if(dt != null && dt.getRowCount()> 0){   
    for(int i = 0; i<dt.getRowCount(); i++)
    {
     for(int j = 0; j<dt.getColCoun(); j++)
     System.out.printf(dt.getRow()[i][j]+"\t");
     System.out.println();
    }
   }
   else
    System.out.println("查询失败");
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
}