java jdbc 连接mysql 数据库

JDBC连接MySQL

加载及注册JDBC驱动程序

Class.forName("com.mysql.jdbc.Driver");
Class.forName("com.mysql.jdbc.Driver").newInstance();

JDBC URL 定义驱动程序与数据源之间的连接

标准语法：

<protocol（主要通讯协议）>:<subprotocol（次要通讯协议，即驱动程序名称）>:<data source identifier（数据源）>

MySQL的JDBC URL格式：

jdbc:mysql//[hostname][:port]/[dbname][?param1=value1][&param2=value2]….

示例：

常见参数：

user                       用户名
password                   密码
autoReconnect              联机失败，是否重新联机（true/false）
maxReconnect               尝试重新联机次数
initialTimeout             尝试重新联机间隔
maxRows                    传回最大行数
useUnicode                 是否使用Unicode字体编码（true/false）
characterEncoding          何种编码（GB2312/UTF-8/…）
relaxAutocommit            是否自动提交（true/false）
capitalizeTypeNames        数据定义的名称以大写表示

package mysqlmanage;

import datastructures.QueueArray;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import tools.Time;

/**
 * 执行数据库操作之前的业务逻辑 主要执行jdbcUtils类中的命令
 *
 * @author timeless <834916321@qq.com>
 * 2015年2.26
 */
public class ExecCmd {

    /**
     * 获取 mysql 连接
     *
     * @return JdbcUtils对象
     */
    public static JdbcUtils getJdbcUtil() {
        //数据库用户名
        String USERNAME = "root";
        //数据库密码
        String PASSWORD = "xxxxxx";
        //驱动信息
        String URL = "jdbc:mysql://localhost:3306/mxManage";
        JdbcUtils jdbcUtils = new JdbcUtils(USERNAME, PASSWORD, URL);
        jdbcUtils.getConnection();
        return jdbcUtils;
    }
/**
     * 执行更新操作 前提是 sql 语句中的数值不为空
     *
     * @param sql 要执行的 insert 或者 update 语句
     */
    public static void updateInsertData(String sql, JdbcUtils jdbcUtils) {
        try {
            System.out.println(sql);
            jdbcUtils.updateByPreparedStatement(sql, null);
        } catch (Exception ex) {
            System.out.println("sql 语句问题：语句为" + sql + "异常为：" + ex.toString());
        } finally {
            jdbcUtils.releaseConn();
        }
    }

    /**
     * 执行更新操作 前提是 sql 语句中的数值不为空
     *
     * @param sql 要执行的 insert 或者 update 语句
     * @param table 批量出入的表
     * @param field 数据表格中的字段 格式为：示例 (`id`, `name`) 每一个字段都需要写上
     */
    public static String formInsertSql(ArrayList<String> list, String table, String field) {
        if (list.size() == 0) {
            return null;
        }
        String sql = "INSERT INTO `" + table + "`" + field + " VALUES ";//(null,'dsadsad'),(null,'dss')
        try {
            for (String perdomain : list) {
                sql = sql + "(null,'" + perdomain + "'),";
            }
            //把最后一个字符串","去掉
            int end = sql.length();
            sql = sql.substring(0, end - 1);
        } catch (Exception ex) {
            System.out.println("形成sql语句问题" + ex.toString());
        }
        return sql;
    }

}

package mysqlmanage;

import java.lang.reflect.Field;
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 JdbcUtils {

    //数据库用户名
    private String USERNAME = "";
    //数据库密码
    private String PASSWORD = "";
    //驱动信息
    private String DRIVER = "com.mysql.jdbc.Driver";
    //数据库地址
    private String URL = "";
    private Connection connection;
    private PreparedStatement pstmt;
    private ResultSet resultSet;

    public JdbcUtils(String username, String password, String url) {
        // TODO Auto-generated constructor stub
        this.USERNAME = username;
        this.PASSWORD = password;
        this.URL = url;
        try {
            Class.forName(DRIVER);
        } catch (Exception ex) {
            System.out.println("数据库连接失败！" + ex.toString());
        }
    }

    /**
     * 获得数据库的连接
     *
     * @return
     */
    public Connection getConnection() {
        try {
            connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return connection;
    }

    /**
     * 增加、删除、改
     *
     * @param sql
     * @param params
     * @return
     * @throws SQLException
     */
    public boolean updateByPreparedStatement(String sql, List<Object> params) throws SQLException {
        boolean flag = false;
        int result = -1;
        pstmt = connection.prepareStatement(sql);
        int index = 1;
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        result = pstmt.executeUpdate();
        flag = result > 0 ? true : false;
        return flag;
    }

    /**
     * 查询单条记录
     *
     * @param sql
     * @param params
     * @return
     * @throws SQLException
     */
    public Map<String, Object> findSimpleResult(String sql, List<Object> params) throws SQLException {
        Map<String, Object> map = new HashMap<String, Object>();
        int index = 1;
        pstmt = connection.prepareStatement(sql);
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        resultSet = pstmt.executeQuery();//返回查询结果
        ResultSetMetaData metaData = resultSet.getMetaData();
        int col_len = metaData.getColumnCount();
        while (resultSet.next()) {
            for (int i = 0; i < col_len; i++) {
                String cols_name = metaData.getColumnLabel(i + 1);
                Object cols_value = resultSet.getObject(cols_name);
                if (cols_value == null) {
                    cols_value = "";
                }
                map.put(cols_name, cols_value);
            }
        }
        return map;
    }

    /**
     * 查询单条记录
     *
     * @param sql
     * @param params
     * @return 是不是含有某条记录
     * @throws SQLException
     */
    public boolean verifyDataIsInDatabase(String sql, List<Object> params) throws SQLException {
        boolean status = false;
        int index = 1;
        pstmt = connection.prepareStatement(sql);
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        resultSet = pstmt.executeQuery();//返回查询结果
        if (resultSet.next()) {
            status = true;
        }
        return status;
    }

    /**
     * 查询多条记录
     *
     * @param sql
     * @param params
     * @return
     * @throws SQLException
     */
    public List<Map<String, Object>> findModeResult(String sql, List<Object> params) throws SQLException {
        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        int index = 1;
        pstmt = connection.prepareStatement(sql);
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        resultSet = pstmt.executeQuery();
        ResultSetMetaData metaData = resultSet.getMetaData();
        int cols_len = metaData.getColumnCount();
        while (resultSet.next()) {
            Map<String, Object> map = new HashMap<String, Object>();
            for (int i = 0; i < cols_len; i++) {
                String cols_name = metaData.getColumnLabel(i + 1);
                Object cols_value = resultSet.getObject(cols_name);
                if (cols_value == null) {
                    cols_value = "";
                }
                map.put(cols_name, cols_value);
            }
            list.add(map);
        }
        return list;
    }

    /**
     * 通过反射机制查询单条记录
     *
     * @param sql
     * @param params
     * @param cls
     * @return
     * @throws Exception
     */
    public <T> T findSimpleRefResult(String sql, List<Object> params, Class<T> cls) throws Exception {
        T resultObject = null;
        int index = 1;
        pstmt = connection.prepareStatement(sql);
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        resultSet = pstmt.executeQuery();
        ResultSetMetaData metaData = resultSet.getMetaData();
        int cols_len = metaData.getColumnCount();
        while (resultSet.next()) {
            //  通过反射机制创建一个实例
            //  cls.class;
            resultObject = cls.newInstance();
            for (int i = 0; i < cols_len; i++) {
                String cols_name = metaData.getColumnName(i + 1);
                Object cols_value = resultSet.getObject(cols_name);
                if (cols_value == null) {
                    cols_value = "";
                }
                Field field = cls.getDeclaredField(cols_name);
                field.setAccessible(true); //打开javabean的访问权限
                field.set(resultObject, cols_value);
            }
        }
        return resultObject;
    }

    /**
     * 通过反射机制查询多条记录
     *
     * @param sql
     * @param params
     * @param cls
     * @return
     * @throws Exception
     */
    public <T> List<T> findMoreRefResult(String sql, List<Object> params, Class<T> cls) throws Exception {
        List<T> list = new ArrayList<T>();
        int index = 1;
        pstmt = connection.prepareStatement(sql);
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        resultSet = pstmt.executeQuery();
        ResultSetMetaData metaData = resultSet.getMetaData();
        int cols_len = metaData.getColumnCount();
        while (resultSet.next()) {
            //通过反射机制创建一个实例
            T resultObject = cls.newInstance();
            for (int i = 0; i < cols_len; i++) {
                String cols_name = metaData.getColumnName(i + 1);
                Object cols_value = resultSet.getObject(cols_name);
                if (cols_value == null) {
                    cols_value = "";
                }
                Field field = cls.getDeclaredField(cols_name);
                field.setAccessible(true); //打开javabean的访问权限
                field.set(resultObject, cols_value);
            }
            list.add(resultObject);
        }
        return list;
    }

    /**
     * 释放数据库连接
     */
    public void releaseConn() {
        if (resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

}