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  • java连接MySql数据库

    package Dao;

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

    public class MySql {

    private String url = "jdbc:mysql://localhost:3306/jw?useUnicode=true&characterEncoding=utf-8";
    private String user = "root";
    private String password = "root";
    public Connection getCon(){
    Connection conn = null;
    try{
    Connection con = DriverManager.getConnection(url , user , password ) ;
    }catch(SQLException se){
    System.out.println("数据库连接失败!");
    se.printStackTrace() ;
    }
    return conn;
    }
    public void Query(String sql){
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    try {
    //建立数据库连接
    conn =getCon();
    stmt = conn.createStatement();//创建一个Statement对象
    System.out.println("成功连接到数据库~");

    /*在询数据表时,需要用到ResultSet接口,它类似于一个数据表,通过该接口的实例
    * 可以获得检索结果集,以及对应数据表的接口信息。*/
    rs = stmt.executeQuery(sql);//创建数据对象

    //遍历查询的结果集
    while (rs.next()) {
    System.out.print(rs.getInt(1)+" ");
    System.out.print(rs.getString(2)+" ");
    System.out.print(rs.getString(3)+" ");
    System.out.print(rs.getString(4)+" ");
    System.out.println();
    }
    //关闭连接
    rs.close();
    stmt.close();
    conn.close();
    } catch (SQLException e) {
    e.printStackTrace();
    }
    }
    public void insert(String sql){
    Connection conn = null;
    PreparedStatement pstm = null;
    ResultSet rt = null;
    Statement stmt = null;
    //建立数据库连接
    try {
    conn =getCon();
    //String sql = "INSERT INTO comments(MovieName,Mid,Mnum,url,content,date,star,usefulnum) VALUES(?,?,?,?,?,?,?,?)";
    //pstm.setString(1, n.getMovieName());
    //pstm.setString(2, n.getMid());
    pstm = conn.prepareStatement(sql);
    pstm.executeUpdate();

    String sql3 = "select * from users";//要执行的SQL

    /*在询数据表时,需要用到ResultSet接口,它类似于一个数据表,通过该接口的实例
    * 可以获得检索结果集,以及对应数据表的接口信息。*/
    ResultSet rs = stmt.executeQuery(sql3);//创建数据对象

    System.out.println("编 号"+" "+"姓 名"+" "+"密 码"+" "+"邮 箱");
    //遍历查询的结果集
    while (rs.next()) {
    System.out.print(rs.getInt(1)+" ");
    System.out.print(rs.getString(2)+" ");
    System.out.print(rs.getString(3)+" ");
    System.out.print(rs.getString(4)+" ");
    System.out.println();
    }
    //关闭连接
    rs.close();
    stmt.close();
    conn.close();
    } catch (SQLException e) {
    e.printStackTrace();
    }
    }
    public void Delete(String sql){
    Connection conn = null;
    PreparedStatement psql = null;
    //建立数据库连接
    try {
    conn =getCon();
    psql = conn.prepareStatement(sql);
    psql.executeUpdate();
    psql.close();
    }catch(SQLException e){
    e.printStackTrace();
    }catch (Exception e) {
    e.printStackTrace();
    }finally{
    System.out.println("数据库数据删除成功!"+" ");
    }
    }

    }

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  • 原文地址:https://www.cnblogs.com/altlb/p/9048380.html
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