你是否还在为每次新建项目连接数据库而烦恼???(教你一次代码,简单完成每次连接)
1.建立maven项目
还没下载安装或者不会建立maven项目的可以看这里哦:maven的下载安装与配置环境变量!!!(全网最详细)_明天更新的博客-CSDN博客
2.编写配置文件。
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.2</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!-- com.mysql/mysql-connector-j -->
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<version>8.1.0</version>
</dependency>
</dependencies>
3.在项目的src/main/resources文件下建立db.properties文件,并写入一下代码。
db.driver=com.mysql.cj.jdbc.Driver
db.url=jdbc:mysql:/book
db.username=root
db.password=
4.编写工具类。
/*
* Copyright (c) 2020, 2023, All rights reserved.
*
*/
package cn;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.*;
/**
* <p>Project: jdbcUnitls - Untils</p>
* <p>Powered by scl On 2023-08-15 19:12:41</p>
* <p>描述:<p>
*
* @author 孙臣龙 [1846080280@qq.com]
* @version 1.0
* @since 17
*/
public class Untils {
private String driver;
private String url;
private String username;
private String password;
private Connection con;
//初始化自动建立连接
public Untils() {
connect();
}
//初始化传参可以连接自定义数据库
public Untils(String url, String username, String password) {
this.url = url;
this.username = username;
this.password = password;
connect(url, username, password);
}
//建立连接,默认数据库
public void connect() {
Class<Untils> until = Untils.class;
InputStream db = until.getClassLoader().getResourceAsStream("db.properties");
Properties prop = new Properties();
try {
prop.load(db);
this.driver = prop.getProperty("db.driver", "com.mysql.cj.jdbc.Driver");
Class.forName(this.driver);
this.url = prop.getProperty("db.url", "jdbc:mysql:/mysql");
this.username = prop.getProperty("db.username", "root");
this.password = prop.getProperty("db.password", "");
con = DriverManager.getConnection(this.url, this.username, this.password);
} catch (Exception e) {
e.printStackTrace();
}
}
//建立连接,指定数据库
public void connect(String url, String username, String password) {
try {
Class.forName(driver);
con = DriverManager.getConnection(url, username, password);
} catch (Exception e) {
e.printStackTrace();
}
}
//获取版本号
public String version() {
String ver = "";
try {
ver = this.con.getMetaData().getDatabaseProductVersion();
} catch (Exception e) {
e.printStackTrace();
}
return ver;
}
//建立数据库
public void creatdatabase(String dbname) {
try {
String sql = "create database if not exists " + dbname;
PreparedStatement ps = con.prepareStatement(sql);
ps.execute();
} catch (Exception e) {
e.printStackTrace();
}
}
//删除数据库
public void deletedatabase(String dbname) {
try {
String sql = "drop database if exists " + dbname;
PreparedStatement ps = con.prepareStatement(sql);
ps.execute();
} catch (Exception e) {
e.printStackTrace();
}
}
//查看所有数据库(排除系统数据库)
public Set<String> showdatabase() {
Set<String> set = new HashSet<>();
try {
String sql = "show databases";
PreparedStatement ps = con.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
Set<String> exclude = new HashSet<>(List.of("information_schema", "performance_schema", "test", "sys", "mysql"));
while (rs.next()) {
String database = rs.getString(1);
if (exclude.contains(database)) continue;
set.add(rs.getString(1));
}
rs.close();
ps.close();
} catch (Exception e) {
e.printStackTrace();
}
return set;
}
//查看指定数据库的所有表
public List<String> showtables(String dbname) {
List<String> list = new ArrayList<>();
try {
String sql = "show tables ";
if (dbname != null && dbname.length() > 0) {
sql = "show tables from " + dbname;
}
PreparedStatement ps = con.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
while (rs.next()) {
list.add(rs.getString(1));
}
ps.close();
rs.close();
} catch (Exception e) {
e.printStackTrace();
}
return list;
}
//查看使用数据库的表
public List<String> showtables() {
String dbname = "";
try {
String sql = "select database()";
PreparedStatement ps = con.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
if (rs.isBeforeFirst()) {
rs.next();
dbname = rs.getString(1);
}
} catch (Exception e) {
e.printStackTrace();
}
return showtables(dbname);
}
//关闭连接
public void close() {
try {
con.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public String getDriver() {
return driver;
}
public void setDriver(String driver) {
this.driver = driver;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Connection getCon() {
return con;
}
public void setCon(Connection con) {
this.con = con;
}
}
5.将你写好的项目进行打包。
不会打包的可以作为参考:maven如何打包你会吗?_明天更新的博客-CSDN博客
6.将打包文件复制到常用架包文件夹中。
7.使用架包(一行代码连接数据库)
有小伙伴就有疑问啦: 这就结束了????多少是有点简单了
后续功能你可以根据自己所学进行添加。
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