JDBC连接MySQL 方法（封装方法，把增删改查操作封装在函数中）

package com.wanyifei.bean;


import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;




public class ConnectionDB {
 /**
  * 数据库驱动类名称
  */
 private static final String DRIVER = "com.mysql.jdbc.Driver";
 /**
  * 连接字符串
  */
 private static final String URLSTR = "jdbc:mysql://localhost:3306/BookStore";
 /**
  * 用户名
  */
 private static final String USERNAME = "root";
 /**
  * 密码
  */
 private static final String USERPASSWORD = "mysql";
 /**
  * 创建数据库连接类
  */
 private Connection connnection = null;
 private PreparedStatement preparedStatement = null;
 /**
  * 创建结果集对象
  */
 private ResultSet resultSet = null;
 
 static {
  try {
   // 加载数据库驱动程序
   Class.forName(DRIVER);
  } catch (ClassNotFoundException e) {
   System.out.println("加载驱动错误");
   System.out.println(e.getMessage());
  }
 }
 /**
  * 建立数据库连接
  *
  * @return
  */
 public Connection getConnection() {
  try {
   // 获取连接
   connnection = DriverManager.getConnection(URLSTR, USERNAME,
     USERPASSWORD);
  } catch (SQLException e) {
   System.out.println(e.getMessage());
  }
  return connnection;
 }
 
 public int executeUpdate(String sql, Object[] params) {
  int affectedLine = 0;
  try {
   connnection = this.getConnection();
   preparedStatement = connnection.prepareStatement(sql);
   for (int i = 0; i < params.length; i++) {
    preparedStatement.setObject(i + 1, params[i]);
   }
   affectedLine = preparedStatement.executeUpdate();
  } catch (SQLException e) {
   System.out.println(e.getMessage());
  } finally {
   closeAll();
  }
  return affectedLine;
 }
 
 /**
  * 查询语句   
  * @param sql SQL语句
  * @param params SQL语句
  * @return List结果集
  */
 private ResultSet executeQueryRS(String sql, Object[] params) {
  try {
   connnection = this.getConnection();
   preparedStatement = connnection.prepareStatement(sql);
   for (int i = 0; i < params.length; i++) {
    preparedStatement.setObject(i + 1, params[i]);
   }
   resultSet = preparedStatement.executeQuery();
  } catch (SQLException e) {
   System.out.println(e.getMessage());
 }  
  return resultSet;
 }
 
 /**
  * 获取结果集，并将结果放在List中
  * @param sql SQL语句
  * @return List结果集
  */
 public List<Object> excuteQuery(String sql, Object[] params) {
  ResultSet rs = executeQueryRS(sql,params);
  ResultSetMetaData rsmd = null;
  int columnCount = 0;
  try {
   rsmd = rs.getMetaData();
   columnCount = rsmd.getColumnCount();
  } catch (SQLException e1) {
   System.out.println(e1.getMessage());
  }
  
  List<Object> list = new ArrayList<Object>();
  
  try {
   while(rs.next()) {
    Map<String, Object> map = new HashMap<String, Object>();
    for(int i = 1; i <= columnCount; i++) {
     map.put(rsmd.getColumnLabel(i), rs.getObject(i));    
    }
    list.add(map);
   }
  } catch (SQLException e) {
   System.out.println(e.getMessage());
  } finally {
   closeAll();
  }
  
  return list;
 }
 
/**
 * 撤销链接
 */
 private void closeAll() {
  if (resultSet != null) {
   try {
    resultSet.close();
   } catch (SQLException e) {
    System.out.println(e.getMessage());
   }
  }
  if (preparedStatement != null) {
   try {
    preparedStatement.close();
   } catch (SQLException e) {
    System.out.println(e.getMessage());
   }
  }
  
  if (connnection != null) {
   try {
    connnection.close();
   } catch (SQLException e) {
    System.out.println(e.getMessage());
   }
  }
 }
 
 
 
 public static void main(String[] args) {  
     String[] params={"wanyifei"};
     ConnectionDB connDB = new ConnectionDB();  
     List<Object> list = connDB.excuteQuery("SELECT * FROM User_Information where username= ?", params);  
     for(int i=0;i<list.size();i++)
     {
    	 System.out.println(list.get(i));
     }
     connDB.closeAll();  
 }  
}