结合properties配置文件优化jdbc连接工具类

把一些步骤抽取出来然后，从properties获取连接属性。

在项目下新建一个配置文件夹config和配置文件database.properties里面这样写，和map一样以键值对的形式存在，前面键后面值。因为我的密码为空所以不写。

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mydata?useUnicode=true&characterEncoding=UTF-8
user=root
password=

然后Properties加载配置文件，同时把读取配置文件写在静态代码块中方便只加载一次。

 1     static String driver;
    static String url;
    static String user;
    static String password;

    static {// 加载配置文件
        Properties properties = new Properties();
        try {
            BufferedReader br = new BufferedReader(new FileReader("config/database.properties"));
            properties.load(br);
            driver = properties.getProperty("driver");
            url = properties.getProperty("url");
            user = properties.getProperty("user");
            password = properties.getProperty("password");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

再把获取数据库连接抽取出来

/** 获取数据库连接 */
    public Connection getConnection() {
        Connection conn = null;
        try {
            // 1、加载驱动
            Class.forName(driver);
            // 2、建立连接
            conn = DriverManager.getConnection(url, user, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }

把增删改抽取出来（查询单独出来在上一个博客）

/**
     * 增删改
     */
    public int execute(String sql, Object... args) {
        Connection conn = null;
        int result = -1;
        PreparedStatement ps = null;
        try {
            conn = this.getConnection();
            ps = conn.prepareStatement(sql);
            if (args != null) {
                for (int i = 0; i < args.length; i++) {
                    ps.setObject(i + 1, args[i]);
                }
            }
            result = ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            this.closeAll(null, ps, conn);
        }

        return result;
    }

最后把关闭资源抽出来

/**
     * 关闭资源
     */

    public void closeAll(ResultSet rs, PreparedStatement ps, Connection conn) {
        try {
            if (rs != null)
                rs.close();
            if (ps != null)
                ps.close();
            if (conn != null)
                conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

最后代码就行这样

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

/**
 * 数据库连接工具类
 * 
 * @author W
 *
 */

public class JDBCUtils {
    static String driver;
    static String url;
    static String user;
    static String password;

    static {// 加载配置文件
        Properties properties = new Properties();
        try {
            BufferedReader br = new BufferedReader(new FileReader("config/database.properties"));
            properties.load(br);
            driver = properties.getProperty("driver");
            url = properties.getProperty("url");
            user = properties.getProperty("user");
            password = properties.getProperty("password");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /** 获取数据库连接 */
    public Connection getConnection() {
        Connection conn = null;
        try {
            // 1、加载驱动
            Class.forName(driver);
            // 2、建立连接
            conn = DriverManager.getConnection(url, user, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }

    /**
     * 关闭资源
     */

    public void closeAll(ResultSet rs, PreparedStatement ps, Connection conn) {
        try {
            if (rs != null)
                rs.close();
            if (ps != null)
                ps.close();
            if (conn != null)
                conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /**
     * 增删改
     */
    public int execute(String sql, Object... args) {
        Connection conn = null;
        int result = -1;
        PreparedStatement ps = null;
        try {
            conn = this.getConnection();
            ps = conn.prepareStatement(sql);
            if (args != null) {
                for (int i = 0; i < args.length; i++) {
                    ps.setObject(i + 1, args[i]);
                }
            }
            result = ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            this.closeAll(null, ps, conn);
        }

        return result;
    }

}