培训第四天-----jdbc连接oracle

• oracle链接数据库并向tableone插入中一条数据

package com.zjw.db;

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

public class mydbbase {

    private  Connection conn;
    private  String oracleUrl="jdbc:oracle:thin:@localhost:1521:orcl";
    //private String mysqlUrl="jdbc:mysql://localhost:3306//mysql";
    private  String username = "u1";
    private  String password = "Admin123";
    public mydbbase(){
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            DriverManager.setLoginTimeout(0);
            conn = DriverManager.getConnection(oracleUrl,username,password);

            Statement stmt =  conn.createStatement();
            String sql = "insert into tableone(id,name,sex,age) values(1,'jiewei','男','23') ";
            stmt.executeUpdate(sql);
            conn.commit();
            stmt.close();
            conn.close();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        mydbbase mb = new mydbbase();
    }

}

• 查询数据库中tableone的数据

package com.zjw.db;

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

public class mydbbase {

    private  Connection conn;
    private  String oracleUrl="jdbc:oracle:thin:@localhost:1521:orcl";
    //private String mysqlUrl="jdbc:mysql://localhost:3306//mysql";
    private  String username = "u1";
    private  String password = "Admin123";
    public mydbbase(){
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            DriverManager.setLoginTimeout(0);
            conn = DriverManager.getConnection(oracleUrl,username,password);

            Statement stmt =  conn.createStatement();
            //插入语句
            //String sql = "insert into tableone(id,name,sex,age) values(1,'jiewei','男','23') ";
            //String sql = "delete from tableone where id=1";
            //stmt.executeUpdate(sql);
            //查询语句
            String sqlSelect = "select * from tableone";
            ResultSet rs = stmt.executeQuery(sqlSelect);
            while(rs.next()){
                System.out.print(rs.getInt("id")+" ");
                System.out.print(rs.getString("name")+" ");
                System.out.print(rs.getString("sex")+" ");
                System.out.print(rs.getString("age")+" ");
            }
            conn.commit();
            stmt.close();
            conn.close();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        mydbbase mb = new mydbbase();
    }

}

• 用 preparedStatement来进行增删改查

  //用preparedStatement来进行增删改查
      public static boolean auth(String name,String password){
          conn = getConnection();
          try {
              PreparedStatement pstmt = conn.prepareStatement("select * from tableone " + "where name=? and password = ?");
              pstmt.setString(1, name);
              pstmt.setString(2, password);
              ResultSet rs = pstmt.executeQuery();
              if(rs.next()){
                  return true;
              }
          } catch (SQLException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          }
          return false;
      }

  解决了当对象没有被NEW 的时候，去setid会出现空指针。

  public userTableDaoBean selector(String where) {
          PreparedStatement ps;
          userTableDaoBean ub = new userTableDaoBean();
          try {
              String sql = "select * from usertable where id=?";
              ps = conn.prepareStatement(sql);
              ps.setInt(1, Integer.parseInt(where));
              ResultSet rs = ps.executeQuery();
              if(rs.next()){
                  ub.setId(rs.getInt("id"));
                  ub.setName(rs.getString("name"));
                  ub.setSex(rs.getString("sex"));
                  ub.setAge(rs.getString("age"));
              }
              rs.close();
              ps.close();
          } catch (SQLException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          }
          return ub;
      }
  像这个方法，new userTableDaoBean()如果写成null,容易出现空指针。