目录
前言：
本实验主要针对于在自己的JDBC实验中遇到的问题和整个实验中的注意事项和内容整理。
JDBC代码：
db.properties:连接配置
driver = com.mysql.jdbc.Driver
url = jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8&useSSL=true
username = root
password = Acad112625!
DButil:功能
package com.xjdx.utils;
import java.io.IOException;
import java.sql.*;
import java.io.InputStream;
import java.util.Properties;
import static java.lang.System.in;
public class DButil {
private static String driver = null;
private static String url = null;
private static String username = null;
private static String password = null;
static{
try {
InputStream in = DButil.class.getClassLoader().getResourceAsStream("db.properties");
Properties properties = new Properties();
properties.load(in);
driver = properties.getProperty("driver");
url = properties.getProperty("url");
username = properties.getProperty("username");
password = properties.getProperty("password");
//1.驱动只用加载一次
Class.forName(driver);
} catch (Exception e) {
e.printStackTrace();
}
}
//获取连接
public static Connection getConnection() throws SQLException{
return DriverManager.getConnection(url,username,password);
}
//释放资源
public static void release(Connection conn, Statement st, ResultSet rs){
if (rs!=null){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (st != null){
try {
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
DBTestInsert:插入功能
package com.xjdx.utils;
import com.xjdx.utils.DButil;
import java.sql.*;
public class DBTestInsert {
public static void main(String[] args) {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = DButil.getConnection();//获取数据库连接
st = conn.createStatement();//获得SQL的执行对象
String sql = "insert into users(id, name, password, email, birthday) values (5, 'Niko','123456','NIko@outlook.com','1997-12-21')";
int i = st.executeUpdate(sql);
if (i > 0){
System.out.println("Insert successfully");
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
DButil.release(conn,st,rs);
}
}
}
DBTestDelete:删除功能
package com.xjdx.utils;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DBTestDelete {
public static void main(String[] args) {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = DButil.getConnection();//获取数据库连接
st = conn.createStatement();//获得SQL的执行对象
String sql = "delete from users where id=2;";//删除SQL语句
int i = st.executeUpdate(sql);
if (i > 0){
System.out.println("Delete successfully");
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
DButil.release(conn,st,rs);
}
}
}
DBTestUpdate:修改功能
package com.xjdx.utils;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DBTestUpdate {
public static void main(String[] args) {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = DButil.getConnection();//获取数据库连接
st = conn.createStatement();//获得SQL的执行对象
String sql = "update users set name = 'electronic' , email = 'electronic@outlook.com' where id = 3";//UpdateSQL语句
int i = st.executeUpdate(sql);
if (i > 0){
System.out.println("Update successfully");
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
DButil.release(conn,st,rs);
}
}
}
DBTestSelect:查询功能
package com.xjdx.utils;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import com.xjdx.utils.DButil;
public class DBTestSelect {
public static void main(String[] args) {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = DButil.getConnection();
st = conn.createStatement();
//SQL
String sql = "select * from users";
rs = st.executeQuery(sql);//查询完毕会返回一个结果集
while(rs.next()){
System.out.print(rs.getInt("id"));
System.out.print(", "+rs.getString("name"));
System.out.print(", "+rs.getString("password"));
System.out.print(", "+rs.getString("email"));
System.out.println(", "+rs.getString("birthday"));
}
System.out.println("Select successfully");
} catch (SQLException e) {
e.printStackTrace();
}finally {
DButil.release(conn,st,rs);
}
}
}
小结：
1.数据库的连接注意事项
MySQL 8.0 以下版本 – JDBC 驱动名及数据库 URL
static final String JDBC_DRIVER = “com.mysql.jdbc.Driver”;
static final String DB_URL = “jdbc:mysql://localhost:3306/数据库名称”;
MySQL 8.0 以上版本 – JDBC 驱动名及数据库 URL
static final String JDBC_DRIVER = “com.mysql.cj.jdbc.Driver”;
static final String DB_URL=”jdbc:mysql://localhost:3306/数据库名称?useSSL=false &allowPublicKeyRetrieval=true&serverTimezone=UTC”;
2.增删改和查：executeUpdate方法用于向数据库发送增、删、改的SQL语句；executeQuery方法用于向数据库发送查询语句，executeQuery方法返回的是代表查询结果的ResultSet对象，executeQuery()查询完毕会返回一个结果集。
3.使用完数据库后一定要释放资源。
4.担心中文乱码的可以在url的？后加上useUnicode=true&characterEncoding=utf-8&useSSL=true。
版权声明：本文为RainsKianna原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。