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();
}
}