package jdbc;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;public class demo {public static void main(String[] args) throws Exception {//注册驱动Class.forName("com.mysql.cj.jdbc.Driver");//注册方法String url = "jdbc:mysql://127.0.0.1:3306/itcast?" +"useSSL=false&amp&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";String username = "root";String password = "gyx.l123";Connection conn = DriverManager.getConnection(url, username, password);//定义SQL语句String sql = "insert into users values(4,'张六',30,'1','男',2)";//获取statement对象Statement sm = conn.createStatement();//执行sqlint count = sm.executeUpdate(sql);//受影响的行数//处理结果System.out.println(count);//释放资源sm.close();conn.close();}
}

JDBC API详解

DriverManager

Connection

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;public class demo2 {public static void main(String[] args) throws Exception {//注册方法String url = "jdbc:mysql://127.0.0.1:3306/itcast?" +                "useSSL=false&amp&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";String username = "root";String password = "gyx.l123";Connection conn = DriverManager.getConnection(url, username, password);//定义SQL语句String sql1 = "update users set age = 30 where name = '张三'";String sql2 = "update users set age = 32 where name = '张四'";//获取statement对象Statement sm = conn.createStatement();try {//开启事务（手动提交）conn.setAutoCommit(false);//执行sql1，并处理结果int count1 = sm.executeUpdate(sql1);//受影响的行数System.out.println(count1);//执行sql2，并处理结果int count2 = sm.executeUpdate(sql1);//受影响的行数System.out.println(count1);//提交事务conn.commit();} catch (Exception e) {//回滚事务conn.rollback();}//释放资源sm.close();conn.close();}
}

Statement

DDL语句不能用count的值判断是否执行成功，如"drop database username"
DML语句可以用count的值判断是否执行成功

ResultSet

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;public class demo_ResultSet {public static void main(String[] args) throws Exception {//注册方法String url = "jdbc:mysql://127.0.0.1:3306/itcast?" +"useSSL=false&amp&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";String username = "root";String password = "gyx.l123";Connection conn = DriverManager.getConnection(url, username, password);//定义SQL语句//DDL语句不能用count的值判断是否执行成功，如"drop database username"//DML语句可以用count的值判断是否执行成功String sql = "select * from users";//获取statement对象Statement sm = conn.createStatement();//执行sqlResultSet res = sm.executeQuery(sql);//处理结果while (res.next()){int id = res.getInt(1);String name = res.getString(2);int age = res.getInt(3);String gender = res.getString(4);int dep = res.getInt(5);System.out.println(id+"\t"+name+"\t"+age+"\t"+gender+"\t"+dep);}//释放资源res.close();sm.close();conn.close();/*1 张三  30  男   12  张四  28  男   23  张五  22  女   34  张六  30  男   25  王六  28  男   16  王五  28  男   1*/}
}

import pojo.users;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;public class demo_ResultSet2 {public static void main(String[] args) throws Exception {//注册方法String url = "jdbc:mysql://127.0.0.1:3306/itcast?" +"useSSL=false&amp&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";String username = "root";String password = "gyx.l123";Connection conn = DriverManager.getConnection(url, username, password);//定义SQL语句String sql = "select * from users";//获取statement对象Statement sm = conn.createStatement();//执行sqlResultSet res = sm.executeQuery(sql);//处理结果ArrayList<users> arr = new ArrayList<users>();while (res.next()){//创建对象users u =new users();//获取数据int id = res.getInt(1);String name = res.getString(2);int age = res.getInt(3);String gender = res.getString(4);int dep = res.getInt(5);//给对象赋值u.setId(id);u.setName(name);u.setAge(age);u.setGender(gender);u.setDep(dep);//把对象加入集合arr.add(u);}//打印集合System.out.println(arr);//释放资源res.close();sm.close();conn.close();}
}public class users {private int id;private String name;private int age;private String gender;private int dep;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getGender() {return gender;}public void setGender(String gendert) {this.gender = gendert;}public int getDep() {return dep;}public void setDep(int dep) {this.dep = dep;}@Overridepublic String toString() {return "users{" +"id=" + id +", name='" + name + '\'' +", age=" + age +", gendert='" + gender + '\'' +", dep=" + dep +'}';}
}

PreparedStatement

登录案例：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;public class demo_PreparedStatement {public static void main(String[] args) throws Exception {//注册方法String url = "jdbc:mysql://127.0.0.1:3306/itcast?" +"useSSL=false&amp&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";String username = "root";String password = "gyx.l123";Connection conn = DriverManager.getConnection(url, username, password);//接收用户输入的用户名和密码String name = "小红";String psw = "123";//String name = "3326988";//String psw = "'or '1'='1";//定义SQL语句String sql = "select * from username_password where username = '" + name + "' and password='" + psw + "'";//获取statement对象Statement sm = conn.createStatement();//执行sqlResultSet res = sm.executeQuery(sql);//判断是否登陆成功if(res.next()){//res有数据，返回trueSystem.out.println("登陆成功");}else{System.out.println("登录失败");}//释放资源res.close();sm.close();conn.close();}
}

import java.sql.*;public class demo_PreparedStatement {public static void main(String[] args) throws Exception {//注册方法String url = "jdbc:mysql://127.0.0.1:3306/itcast?" +"useSSL=false&amp&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";String username = "root";String password = "gyx.l123";Connection conn = DriverManager.getConnection(url, username, password);//接收用户输入的用户名和密码String name = "小红";String psw = "123";//定义SQL语句String sql = "select * from username_password where username = ? and password = ?";//获取 PreparedStatement对象，并设置 ? 的值PreparedStatement ps = conn.prepareStatement(sql);ps.setString(1, name);ps.setString(2, psw);//执行sqlResultSet res = ps.executeQuery();//判断是否登陆成功if (res.next()) {//res有数据，返回trueSystem.out.println("登陆成功");} else {System.out.println("登录失败");}//释放资源res.close();ps.close();conn.close();}
}

数据库连接池Druid

import com.alibaba.druid.pool.DruidDataSourceFactory;import javax.sql.DataSource;
import java.io.FileInputStream;
import java.sql.Connection;
import java.util.Properties;public class druid_Demo {public static void main(String[] args) throws Exception {//1.导jar包//2.配置文件//3.加载配置文件Properties prop = new Properties();prop.load(new FileInputStream("jdbc-demo/src/druid.properties"));//System.out.println(System.getProperty("user.dir"));找当前路径的方法//4.获取连接池对象DataSource dataSource = DruidDataSourceFactory.createDataSource(prop);//5.获取数据库连接 ConnectionConnection conn = dataSource.getConnection();System.out.println(conn);}
}

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JavaWeb——JDBC

JDBC API详解

Statement

ResultSet

数据库连接池Druid

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