mysql学习笔记3

JDBC的API的详解：
DriverManager：
* 注册驱动：
* 获得连接：
Connection：
* 获得执行SQL语句对象.
* Statement createStatement();
* PreparedStatement prepareStatement(String sql);
* CallableStatement prepareCall(String sql);
* 进行事务管理:
* setAutoCommit(boolean flag);
* commit();
* rollback();
Statement:
* 执行SQL语句:
* int executeUpate(String sql); –执行insert update delete语句.
* ResultSet executeQuery(String sql); –执行select语句.
* boolean execute(String sql); –执行select返回true 执行其他的语句返回false.

ResultSet:
* 遍历结果集：next();
* 获得结果集中的数据.getXXX(int c); getXXX(String name);
抽取工具类：
package com.itheima.jdbc.utils;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

/**
* JDBC的工具类
* @author apple
*
*/
public class JDBCUtils {
public static final String DRIVERCLASS;
public static final String URL;
public static final String USERNAME;
public static final String PASSWORD;

static{
    // 获得属性文件中的数据.
    Properties properties = new Properties();
    try {
        properties.load(new FileInputStream("src/db.properties"));
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    DRIVERCLASS = properties.getProperty("jdbc.driverClass");
    URL = properties.getProperty("jdbc.url");
    USERNAME = properties.getProperty("jdbc.username");
    PASSWORD = properties.getProperty("jdbc.password");
}

// 加载驱动：
public static void loadDriver(){
    try {
        Class.forName(DRIVERCLASS);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

// 获得连接:
public static Connection getConnection(){
    loadDriver();
    Connection conn = null;
    try {
        conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return conn;
}

// 释放资源：
public static void release(Statement stmt,Connection conn){
    if(stmt != null){
        try {
            stmt.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        stmt = null;
    }

    if(conn != null){
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        conn = null;
    }
}

public static void release(ResultSet rs,Statement stmt,Connection conn){
    if(rs!= null){
        try {
            rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        rs = null;
    }
    if(stmt != null){
        try {
            stmt.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        stmt = null;
    }

    if(conn != null){
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        conn = null;
    }
}

}

分类的CRUD的操作详见JDBCDemo1.java
记得下载，mysql对应的数据库驱动包。