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JavaWeb入门（二）：JDBC的基本使用

我们以java操作mysql为例

一、下载JDBC的驱动包

下载地址：https://downloads.mysql.com/archives/c-j/

二、把JDBC驱动包加载到项目中（如何加载第三方包:https://www.cnblogs.com/Infancy/p/12499208.html）

三、Java使用JDBC操作mysql数据库我们将之分为四步

加载驱动
获取连接
创建执行sql语句的对象
编写sql语句，执行sql语句并得到返回结果

四、JDBC操作数据示例代码（自己写的，亲测可以跑起来）

添加数据

@Test
    public void addData(){
        Connection conn = null;
        Statement statement = null;
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //获取连接
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web_test3", "root", "root");
            //创建执行sql的对象
            statement = conn.createStatement();
            //编写sql语句
            String sql  = "insert into user_baseinfo values(null,'1','老师','正常','fs')";
            //执行sql语句
            int num = statement.executeUpdate(sql);
            if(num>0){
                System.out.println("添加成功");
            }else{
                System.out.println("添加失败");
            }
        }catch(Exception e){
            e.printStackTrace();
        }finally {
            if(conn!=null){
                try {
                    conn.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                conn = null;
            }
            if(statement!=null){
                try {
                    statement.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                statement=null;
            }
        }
    }

删除数据

@Test
    public void deleteData(){
        Connection conn = null;
        Statement statement = null;
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //获取连接
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web_test3","root" , "root");
            //创建执行sql的对象
            statement = conn.createStatement();
            //编写sql语句
            String strSql = "delete from user_baseinfo where id = 9";
            //执行sql语句
            int num = statement.executeUpdate(strSql);
            if(num>0){
                System.out.println("删除成功");
            }else{
                System.out.println("删除失败");
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }finally {
            if(conn!=null){
                try {
                    conn.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                conn = null;
            }
            if(statement!=null){
                try {
                    statement.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                statement=null;
            }
        }
    }

修改数据

@Test
    public void modifyData(){
        Connection conn = null;
        Statement statement = null;
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //创建连接
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web_test3", "root", "root");
            //用连接获取执行sql对象
            statement = conn.createStatement();
            //编写sql语句
            String strSql = "update user_baseinfo set username = 'fs' where id = 9";
            //执行sql
            int num = statement.executeUpdate(strSql);
            if(num>0){
                System.out.println("修改成功");
            }else{
                System.out.println("修改失败");
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }finally {
            if(conn!=null){
                try {
                    conn.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                conn = null;
            }
            if(statement!=null){
                try {
                    statement.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                statement=null;
            }
        }
    }

查询数据

@Test
    public void selDate(){
        Connection conn = null;//数据库连接对象
        Statement statement = null;//执行sql对象
        ResultSet rs = null;//结果集
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //获取连接
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web_test3", "root", "root");
            //获取执行对象
            statement = conn.createStatement();
            //编写sql
            String strSql = "select * from user_baseinfo";
            //执行sql
            rs = statement.executeQuery(strSql);
            //遍历结果集
            while (rs.next()){
                System.out.println("id："+rs.getInt("id")+"    姓名"+rs.getString("username"));
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }finally {
            if(conn!=null) {
                try {
                    conn.close();
                }catch(Exception e) {
                    e.printStackTrace();
                }
                conn= null;
            }
            if(statement!=null) {
                try {
                    statement.close();
                }catch(Exception e) {
                    e.printStackTrace();
                }
                statement= null;
            }
            if(rs!=null) {
                try {
                    rs.close();
                }catch(Exception e) {
                    e.printStackTrace();
                }
                rs= null;
            }
        }
    }

完整代码如下：

package com.zhurouwangzi.com;

import org.junit.Test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class HelloTest {
    public static void main(String[] args){
        
    }

    @Test
    public void addData(){
        Connection conn = null;
        Statement statement = null;
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //获取连接
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web_test3", "root", "root");
            //创建执行sql的对象
            statement = conn.createStatement();
            //编写sql语句
            String sql  = "insert into user_baseinfo values(null,'1','老师','正常','fs')";
            //执行sql语句
            int num = statement.executeUpdate(sql);
            if(num>0){
                System.out.println("添加成功");
            }else{
                System.out.println("添加失败");
            }
        }catch(Exception e){
            e.printStackTrace();
        }finally {
            if(conn!=null){
                try {
                    conn.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                conn = null;
            }
            if(statement!=null){
                try {
                    statement.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                statement=null;
            }
        }
    }

    @Test
    public void deleteData(){
        Connection conn = null;
        Statement statement = null;
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //获取连接
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web_test3","root" , "root");
            //创建执行sql的对象
            statement = conn.createStatement();
            //编写sql语句
            String strSql = "delete from user_baseinfo where id = 9";
            //执行sql语句
            int num = statement.executeUpdate(strSql);
            if(num>0){
                System.out.println("删除成功");
            }else{
                System.out.println("删除失败");
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }finally {
            if(conn!=null){
                try {
                    conn.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                conn = null;
            }
            if(statement!=null){
                try {
                    statement.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                statement=null;
            }
        }
    }

    @Test
    public void modifyData(){
        Connection conn = null;
        Statement statement = null;
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //创建连接
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web_test3", "root", "root");
            //用连接获取执行sql对象
            statement = conn.createStatement();
            //编写sql语句
            String strSql = "update user_baseinfo set username = 'fs' where id = 9";
            //执行sql
            int num = statement.executeUpdate(strSql);
            if(num>0){
                System.out.println("修改成功");
            }else{
                System.out.println("修改失败");
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }finally {
            if(conn!=null){
                try {
                    conn.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                conn = null;
            }
            if(statement!=null){
                try {
                    statement.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
                statement=null;
            }
        }
    }

    @Test
    public void selDate(){
        Connection conn = null;//数据库连接对象
        Statement statement = null;//执行sql对象
        ResultSet rs = null;//结果集
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //获取连接
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web_test3", "root", "root");
            //获取执行对象
            statement = conn.createStatement();
            //编写sql
            String strSql = "select * from user_baseinfo";
            //执行sql
            rs = statement.executeQuery(strSql);
            //遍历结果集
            while (rs.next()){
                System.out.println("id："+rs.getInt("id")+"    姓名"+rs.getString("username"));
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }finally {
            if(conn!=null) {
                try {
                    conn.close();
                }catch(Exception e) {
                    e.printStackTrace();
                }
                conn= null;
            }
            if(statement!=null) {
                try {
                    statement.close();
                }catch(Exception e) {
                    e.printStackTrace();
                }
                statement= null;
            }
            if(rs!=null) {
                try {
                    rs.close();
                }catch(Exception e) {
                    e.printStackTrace();
                }
                rs= null;
            }
        }
    }
}

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转载请注明出处：https://www.cnblogs.com/Infancy/p/12499806.html

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原文地址：https://www.cnblogs.com/Infancy/p/12499806.html