day17 11.JdbcUtils工具抽取

连接数据库的四个必要条件:driverclass、url、username、password。

package cn.itcast.utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ResourceBundle;
//使用配置文件

public class JdbcUtils {
    private static final String DRIVERCLASS;
	private static final String URL;
	private static final String USERNAME;
	private static final String PASSWORD;
	static{
		DRIVERCLASS=ResourceBundle.getBundle("jdbc").getString("driverClass");
		URL=ResourceBundle.getBundle("jdbc").getString("url");
		USERNAME=ResourceBundle.getBundle("jdbc").getString("username");
		PASSWORD=ResourceBundle.getBundle("jdbc").getString("password");
	}
	static{//静态块只执行一次驱动就加载了
		try {
			//将加载驱动操作,放置在静态代码块中,这样就保证了只加载一次。
			Class.forName(DRIVERCLASS);
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
    public static Connection getConnectin() throws SQLException{//连接就抛SQLException最靠谱

    	//Class.forName("com.mysql.jdbc.Driver");//在开发中用哪个Statement人家有选择的权利,你不能给它抽取

		//2.获取连接
	  //Connection		 con = DriverManager.getConnection("jdbc:mysql:///day17", "root", "");
		Connection		 con = DriverManager.getConnection(URL,USERNAME, PASSWORD);

		return con;
}

    //如果再完善一点,可以写关闭操作
    public static void closeConnection(Connection con) throws SQLException{
    	if(con!=null){
    		con.close();
    	}
    }
    public static void closeStatement(Statement st) throws SQLException{
    	if(st!=null){
    		st.close();
    	}
    }
    public static void closeResultSet(ResultSet rs) throws SQLException{
    	if(rs!=null){
    		rs.close();
    	}
    }

}

driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql:///day17
username=root
password=

#driverClass=oracle.jdbc.driver.OracleDriver
#url=jdbc:oracle:thin:@localhost:1521:MFC
#username=scott
#password=scott

package cn.itcast.jdbc;

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

import org.junit.Test;

import cn.itcast.utils.JdbcUtils;
import cn.itcast.utils.JdbcUtils1;

//jdbc的crud操作
public class JdbcDemo6 {

    @Test
    public void findByIdTest(){
    //1.定义sql
    String sql = "select * from user where id= 1";
    Connection con = null;
       Statement st = null;
       ResultSet rs = null;

       try {

        //1.注册驱动  

        Class.forName("com.mysql.jdbc.Driver");

        //2.获取连接
        try {
             con = DriverManager.getConnection("jdbc:mysql:///day17", "root", "");

            //3.获取操作sql语句对象Statement
             st =   con.createStatement();

           //4.执行sql
             rs = st.executeQuery(sql);

           //5.遍历结果集
            while(rs.next()){
                int id = rs.getInt("id");
                //String id = rs.getString("id");//虽然用getString()行,但是用getInt()比较合适
                String username = rs.getString("username");
                String password = rs.getString("password");
                String email = rs.getString("email");
                System.out.println(id+"   "+username+"   "+password+"   "+email);
            }

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }finally{
          //6.释放资源
          try {
              if(rs !=null ){
            rs.close();
              }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
          try {
              if(st!=null){
            st.close();
              }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
       try {
           if(con!=null){
            con.close();
           }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
     }
}
    //添加操作
    @Test
    public void addTest(){
        //定义sql
        String sql = "insert into user values(null,'张三','123','zs@163.com')";
        Connection con = null;
           Statement st = null;
           ResultSet rs = null;

           try {

            //1.注册驱动  

            Class.forName("com.mysql.jdbc.Driver");

            //2.获取连接
            try {
                 con = DriverManager.getConnection("jdbc:mysql:///day17", "root", "");

                //3.获取操作sql语句对象Statement
                 st =   con.createStatement();

               //4.执行sql
                 int row = st.executeUpdate(sql);
                 System.out.println(row);
                 if(row!=0){
                     System.out.println("添加成功");
                 }

            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
              //6.释放资源
              try {
                  if(rs !=null ){
                rs.close();
                  }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
              try {
                  if(st!=null){
                st.close();
                  }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
           try {
               if(con!=null){
                con.close();
               }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
         }
    }

    //update操作
    @Test
    public void updateTest(){
        //将id=3的人的password修改为456
        String password = "456";
        String sql = "update user set password='"+password+"' where id=3";

        //1.得到Connection
        Connection con = null;
        Statement st = null;
        try {
            con = JdbcUtils1.getConnectin();

            //3.获取操作sql语句对象Statement
             st =   con.createStatement();

           //4.执行sql
             int row = st.executeUpdate(sql);
             System.out.println(row);
             if(row!=0){
                 System.out.println("添加成功");
             }

        }catch(ClassNotFoundException e){
            e.printStackTrace();
        }
        catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
             //关闭资源
              try {
                  if(st!=null){
                st.close();
                  }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
           try {
               if(con!=null){
                con.close();
               }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }

    //delete测试
    @Test
    public void deleteTest(){
        //将id=3的人删除
                //String sql = "delete from user where id=3";
                //将id=2的人删除
                String sql = "delete from user where id=2";
                //1.得到Connection
                Connection con = null;
                Statement st = null;
                try {
                    con = JdbcUtils.getConnectin();

                    //3.获取操作sql语句对象Statement
                     st =   con.createStatement();

                   //4.执行sql
                     int row = st.executeUpdate(sql);
                     System.out.println(row);
                     if(row!=0){
                         System.out.println("删除成功");
                     }

                }/*catch(ClassNotFoundException e){
                    e.printStackTrace();
                }*/
                catch (SQLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }finally{
                     //关闭资源
            /*          try {
                          if(st!=null){
                        st.close();
                          }
                    } catch (SQLException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }*/
                 /*  try {
                       if(con!=null){
                        con.close();
                       }
                    } catch (SQLException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }    */
                try {
                    JdbcUtils.closeStatement(st);
                    JdbcUtils.closeConnection(con);
                } catch (SQLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                }
    }

}