- JDBC
- 1.连接数据库
- 方式一
- 方式二
- 方式三
- 方式四
- 方式五
- 2.读数据库进行增删改操作
寻找url
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方式一package com.feng.connection;
import org.junit.Test;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.SQLException;
import java.util.Properties;
public class ConnectionTest {
// 方式一
@Test
public void testConnection1() throws SQLException {
Driver driver=new com.mysql.jdbc.Driver();
// url:http://localhost:8080/.... url为固定，可以直接拿来用
String url="jdbc:mysql://localhost:3306/test";
// 将用户名和密码封装在Properties中
Properties info=new Properties();
info.setProperty("user","root");
info.setProperty("password","root");
Connection conn=driver.connect(url,info);
System.out.println(conn);
}
}
报错：
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解决方法：修改驱动为cj.jdbc
package com.feng.connection;
import org.junit.Test;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.SQLException;
import java.util.Properties;
public class ConnectionTest {
// 方式一
@Test
public void testConnection1() throws SQLException {
Driver driver=new com.mysql.cj.jdbc.Driver();
// url:http://localhost:8080/.... url为固定，可以直接拿来用
String url="jdbc:mysql://localhost:3306/test?serverTimezone=UTC&useSSL=false";
// 将用户名和密码封装在Properties中
Properties info=new Properties();
info.setProperty("user","root");
info.setProperty("password","root");
Connection conn=driver.connect(url,info);
System.out.println(conn);
}
}
运行结果：
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方式二在方式一基础上获取驱动对象方式做修改，运用反射获取对象，保证了代码尽量少让第三方插件影响。
// 1.获取driver对象
Class clazz = Class.forName("com.mysql.cj.jdbc.Driver");
Driver diver=(Driver) clazz.newInstance();
// 2.提供要连接的数据库
String url="jdbc:mysql://localhost:3306/test?serverTimezone=UTC&userSSL=false";
// 3.提供连接需要的用户名和密码
Properties info=new Properties();
// 获取连接
info.setProperty("user","root");
info.setProperty("password","root");
Connection connection=diver.connect(url,info);
System.out.println(connection);
运行成功
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方式三使用系统提供的DriverManager类连接数据库。
// 1.获取driver对象
Class clazz = Class.forName("com.mysql.cj.jdbc.Driver");
Driver diver=(Driver) clazz.newInstance();
String url="jdbc:mysql://localhost:3306/test?serverTimezone=UTC&userSSL=false";
String user="root";
String password="root";
DriverManager.registerDriver(diver);
Connection connection=DriverManager.getConnection(url,user,password);
System.out.println(connection);
方式四
在方式三的基础上进行优化。将Diver获取对象，注册步骤减去。
因为在mysql的Diver实现类静态模块中声明了如下操作。
// 方式四
@Test
public void testConnection4() throws Exception{
// 1.加载驱动
Class clazz = Class.forName("com.mysql.cj.jdbc.Driver");
// Driver diver=(Driver) clazz.newInstance();
String url="jdbc:mysql://localhost:3306/test?serverTimezone=UTC&userSSL=false";
String user="root";
String password="root";
// DriverManager.registerDriver(diver);
Connection connection=DriverManager.getConnection(url,user,password);
System.out.println(connection);
}
方式五
// 最终方式,好处：1.实现代码、数据分离（解耦）2.如果需要修改配置文件信息需要重新打包
@Test
public void testConnection5() throws Exception{
InputStream is = ConnectionTest.class.getClassLoader().getResourceAsStream("jdbc.properties");
Properties pros = new Properties();
pros.load(is);
String user=pros.getProperty("user");
String password=pros.getProperty("password");
String url=pros.getProperty("url");
String driverClass=pros.getProperty("DriverClass");
Class.forName(driverClass);
Connection connection=DriverManager.getConnection(url,user,password);
System.out.println(connection);
}
配置文件中：jdbc.properties
url=jdbc:mysql://localhost:3306/test?serverTimezone=UTC&userSSL=false user=root password=root DriverClass=com.mysql.cj.jdbc.Driver2.读数据库进行增删改操作
InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("jdbc.properties");
Properties pros = new Properties();
pros.load(is);
String user=pros.getProperty("user");
String password=pros.getProperty("password");
String url=pros.getProperty("url");
String driverClass=pros.getProperty("DriverClass");
Class.forName(driverClass);
Connection connection= DriverManager.getConnection(url,user,password);
// System.out.println(connection);
String str="insert into customers(name,email,birth)values(?,?,?)";
PreparedStatement ps = connection.prepareStatement(str);
ps.setString(1,"哪吒");
ps.setString(2,"nezha@gmail.com");
// 格式转化
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
java.util.Date date=sdf.parse("1000-01-01");
ps.setDate(3,new Date(date.getTime()));
// 执行sql
ps.execute();
// 关闭资源
if (connection!=null)
connection.close();
if (ps!=null)
ps.close();
书写配置文件：
package com.feng.connection;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JDBCUtils {
public static Connection getConnection() throws Exception {
// 1.读取配置文件中的4个基本信息
InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("jdbc.properties");
Properties pros = new Properties();
pros.load(is);
String user = pros.getProperty("user");
String password = pros.getProperty("password");
String url = pros.getProperty("url");
String driverClass = pros.getProperty("driverClass");
// 2.加载驱动
Class.forName(driverClass);
// 3.获取连接
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
}
public static void closeRescource(Connection conn, Statement ps){
try {
if(ps != null)
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
ps != null)
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
