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  • 2020年11月22日Java学习日记

    DaoTest.java

    复制代码
    package 人口普查系统;
    
    import static org.junit.Assert.*;
    
    import java.sql.SQLException;
    
    import org.junit.Test;
    
    public class DaoTest {
    
        @Test
        public void test() throws SQLException {
            Dao dao=new Dao();
            System.out.print(dao.searchByName("2").size());
        }
    }
    复制代码

    DBUtil.java

    复制代码
    package 人口普查系统;
    
    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 DBUtil {
        private static String url = "jdbc:mysql://localhost:3306/course?useUnicode=true&characterEncoding=utf8";
        private static String user = "root";
        private static String password = "123";
        private static String jdbcName="com.mysql.jdbc.Driver";
        private Connection con=null;
        public static  Connection getConnection() {
            Connection con=null;
            try {
                Class.forName(jdbcName);
                con=DriverManager.getConnection(url, user, password);
                //System.out.println("数据库连接成功");
            } catch (Exception e) {
                // TODO Auto-generated catch block
                //System.out.println("数据库连接失败");
                e.printStackTrace();
            }
            try {
                con = DriverManager.getConnection(url,user,password);
                System.out.println("连接成功");
    
    
            } catch (SQLException e) {
                // TODO: handle exception
                e.printStackTrace();
            }
            return con;
        }
        public static void main(String[] args)throws SQLException { 
            Connection conn = getConnection();
            PreparedStatement pstmt = null;
            ResultSet rs = null;
            String sql ="select * from person";
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            System.out.println(getConnection());
            while(rs.next()){
                System.out.println("成功");
            }
    
            }
    
           // return con;
            
        
        public static void close(Connection con) {
            if(con!=null)
                try {
                    con.close();
                } catch (SQLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            
        }
        public static void close(Statement state, Connection conn) {
            if(state!=null) {
                try {
                    state.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(conn!=null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        
        public static void close(ResultSet rs, Statement state, Connection conn) {
            if(rs!=null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(state!=null) {
                try {
                    state.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(conn!=null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    
    }
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  • 原文地址:https://www.cnblogs.com/9635741zly/p/14176480.html
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