JAVA maven项目 连接数据库 mysql8.0
查询，插入，删除，更新
1.在pom.xml加入mysql-connector-java依赖包，version要跟你的mysql版本对应
下面展示一些 内联代码片。
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.17</version>
</dependency>
2.创建java ,MySQLDemo.java
先连接数据库，要开启mysql
package demo;
import java.sql.*;
public class MySQLDemo {
// 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/runoob?characterEncoding=utf8&useSSL=true";
// 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";
Connection conn = null;
Statement stmt = null;
static final String DB_URL = "jdbc:mysql://localhost:3306/RUNOOB?useSSL=false&serverTimezone=UTC";
// 数据库的用户名与密码，需要根据自己的设置
static final String USER = "root";
static final String PASS = "123456";
public MySQLDemo() {
try {
Class.forName(JDBC_DRIVER);
System.out.println("加载数据库驱动成功");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
conn = DriverManager.getConnection(DB_URL, USER, PASS);
System.out.println("连接数据库驱动成功");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void main(String[] args) {
MySQLDemo demo=new MySQLDemo();
}}
代码中的String DB_URL = “jdbc:mysql://localhost:3306/RUNOOB?useSSL=false&serverTimezone=UTC”;
加粗的地方对应mysql这里，如图。还有用户名跟密码要改，其他不变。还有版本号不一也要改
3.加上查询，插入，删除，更新的完整代码，在基本上改就行
package demo;
import java.sql.*;
public class MySQLDemo {
// 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/runoob?characterEncoding=utf8&useSSL=true";
// 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";
Connection conn = null;
Statement stmt = null;
static final String DB_URL = "jdbc:mysql://localhost:3306/RUNOOB?useSSL=false&serverTimezone=UTC";
// 数据库的用户名与密码，需要根据自己的设置
static final String USER = "root";
static final String PASS = "ZJM199933";
public MySQLDemo() {
try {
Class.forName(JDBC_DRIVER);
System.out.println("加载数据库驱动成功");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
conn = DriverManager.getConnection(DB_URL, USER, PASS);
System.out.println("连接数据库驱动成功");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void query() {
try{
stmt = conn.createStatement();
String sql;
sql = "SELECT id, name, url FROM websites";
ResultSet rs = stmt.executeQuery(sql);
// 展开结果集数据库
while(rs.next()){
// 通过字段检索
int id = rs.getInt("id");
String name = rs.getString("name");
String url = rs.getString("url");
// 输出数据
System.out.print("ID: " + id);
System.out.print(", 站点名称: " + name);
System.out.print(", 站点 URL: " + url);
System.out.print("\n");
}
// 完成后关闭
rs.close();
stmt.close();
conn.close();
}catch(SQLException se){
// 处理 JDBC 错误
se.printStackTrace();
}catch(Exception e){
// 处理 Class.forName 错误
e.printStackTrace();
}finally{
// 关闭资源
try{
if(stmt!=null) stmt.close();
}catch(SQLException se2){
}// 什么都不做
try{
if(conn!=null) conn.close();
}catch(SQLException se){
se.printStackTrace();
}
}
System.out.println("");
}
public void insert() {
String sql1 = "insert into websites(id,name,url,alexa,country) values(6,'java','www.baidu',6,'hmoe')";
PreparedStatement ps = null;
try {
ps = conn.prepareStatement(sql1);
ps.executeUpdate();
System.out.println("插入成功！");
System.out.println("插入结束！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//查询
public void like(){
String sql = "select * from hot where name like '%zhang%'";
PreparedStatement ps = null;
ResultSet res = null;
try {
ps = (PreparedStatement) conn.prepareStatement(sql);
res = ps.executeQuery();
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
while(res.next()){
int num = res.getInt(1);
String name = res.getString(2);
String author = res.getString(3);
String style = res.getString(4);
String form = res.getString(5);
System.out.println("num: " + num + " ,name: " + name +" ,author: " + author + " ,style: " + style + " ,form: " + form);
System.out.println("模糊查询成功");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//更新
public int update(){
String sql = "update hot set name = '张军' where num=7";
PreparedStatement ps = null;
try {
ps = (PreparedStatement) conn.prepareStatement(sql);
ps.executeUpdate();
System.out.println("更新成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return 0;
}
//删除
public void delete(){
String sql = "delete from hot where num = 1";
String sql2 = "delete from hot where num = 2";
String sql3 = "delete from hot where num = 3";
String sql4 = "delete from hot where num = 4";
String sql5 = "delete from hot where num = 5";
PreparedStatement ps = null;
try {
ps = (PreparedStatement) conn.prepareStatement(sql);
ps.executeUpdate();
System.out.println("删除成功！");
ps = (PreparedStatement) conn.prepareStatement(sql2);
ps.executeUpdate();
System.out.println("删除成功！");
ps = (PreparedStatement) conn.prepareStatement(sql3);
ps.executeUpdate();
System.out.println("删除成功！");
ps = (PreparedStatement) conn.prepareStatement(sql4);
ps.executeUpdate();
System.out.println("删除成功！");
ps = (PreparedStatement) conn.prepareStatement(sql5);
ps.executeUpdate();
System.out.println("删除成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void main(String[] args){
MySQLDemo conn2 = new MySQLDemo();
conn2.insert();
System.out.println("--------------------");
conn2.like();
System.out.println("--------------------");
conn2.update();
System.out.println("--------------------");
// conn2.delete();
System.out.println("--------------------");
conn2.query();
System.out.println("--------------------");
}
}