Callablestatement與JavaBean及其實例

時間 2020-01-18

標籤 callablestatement javabean 及其實例欄目 Java 简体版

原文原文鏈接

1、html

Callablestatement：調用數據庫中的存儲過程、存儲函數

connection.prepareCall(參數：存儲過程/存儲函數名)
參數格式：
存儲過程：(無返回值return，用Out參數代替返回值)
      {call 存儲過程名(參數列表)}
存儲函數：(有返回值return)
       { ？=call 存儲函數名(參數列表)}

存儲過程：
create or replace procedure addTwoNum( num1 in number,num2 in number,result out number) --1+2-->3
as
begin
       result :=num1+num2;
end;
/     --/結束

強調：
若是經過sqlplus訪問數據庫，只須要開啓：OracleServiceSID
經過其它程序訪問數據(Sqldevelop、Navicat、JDBC),須要開啓：OracleServiceSID、XxxListener

JDBC調用存儲過程的步驟
a.產生調用存儲過程的對象(CallableStatement )cstmt=connection.prepareCall("{call addTwoNum(?,?,?)}");
b.利用setXXX()進行處理           cstmt.setInt(1, 10)
c.經過registerOutParameter()處理輸出參數類型          cstmt.registerOutParameter(3, Types.INTEGER);//必須放在execute()前面
d.cstmt.execute();//execute()進行執行
e.接受返回值int result=cstmt.getInt(3);java

package JDBCDemo;

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



public class JDBCcallablestatementDemo {
    private static final String URL="jdbc:mysql://localhost:3306/mysql?serverTimezone=UTC&characterEncoding=utf-8";
    private static final String USERNAME="root";
    private static final String PWD="vayne";
        public static void update()
        {
            CallableStatement cstmt=null;
            Connection connection=null;
            try {
                
            //a.導入驅動，加載具體的驅動類
            Class.forName("com.mysql.cj.jdbc.Driver");
            //b.與數據庫創建鏈接
            connection = DriverManager.getConnection(URL,USERNAME,PWD);
            //使用Ctrl+1，快速生成值來獲取Connection
            //c.發送SQL，執行(增刪改、查)
             cstmt=connection.prepareCall("{call addTwoNum(?,?,?)}");
             cstmt.setInt(1, 10);
             cstmt.setInt(2, 20);
             
             
             cstmt.registerOutParameter(3, Types.INTEGER);//必須放在execute()前面
             cstmt.execute();//execute()前處理輸入值及輸出參數類型，execute()後處理輸出值
             //設置輸出參數的類型
             int result=cstmt.getInt(3);
            //處理結果
            System.out.println(result+"操做成功！！！");
            
            }catch(ClassNotFoundException e) {
                e.printStackTrace();
            }catch(SQLException e) {
                e.printStackTrace();
            }catch(Exception e){
                e.printStackTrace();
            }finally {
                try {
                    //先開的後關，後開的先關
                if(cstmt!=null)cstmt.close();
                if(connection !=null)connection.close();
                }catch(SQLException e) {
                    e.printStackTrace();
                }finally {
                    
                }
            }
        }
        public static void main(String[] args) {
            update();
            
        }
}

2、JavaBean
將java代碼和jsp代碼分開存放
做用：
一、減輕jsp頁面的負擔，便於開發人員進行分塊管理代碼
二、提升代碼複用率，封裝成類，使用時直接調用便可。

定義
一、public修飾的類以及public修飾的無參構造
二、全部的屬性都是private，而且還提供set/get (boolean類型提供set/is)

使用層面，分爲兩類：
一、封裝業務邏輯的JavaBean (LoginDao.java封裝了登陸邏輯)            即邏輯
    能夠將jsp中的JDBC代碼，封裝到Dao.java類中（Dao.java）

二、封裝數據的JavaBean   （實體類，Student.java Person.java ）    即數據
    對應於數據庫中的一張表
    User user=new User(name,pwd);//即用User對象封裝了2個數據（用戶名和密碼）

封裝數據的JavaBean 對應於數據庫中的一張表   (User(name,pwd))
封裝業務邏輯的JavaBean 用於操做一個封裝數據的JavaBean

能夠發現，JavaBean能夠簡化代碼(jsp->jsp+java)、提供代碼複用(Dao.java)
mysql

登陸實例sql

Navicat中建表以下數據庫

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
       <form action="check.jsp" method="post">
                     用戶名<input type="text" name="uname"><br/>
                     密碼<input type="password" name="upwd"><br/>
            <input type="submit" value="登陸"><br/>
       </form>
</body>
</html>

check.jsp函數

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
  <%@ page import="Dao.*"%>  
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
      <%
          request.setCharacterEncoding("utf-8");
          String name=request.getParameter("uname");
          String pwd=request.getParameter("upwd");
          User user=new User(name,pwd);
          Dao dao =new Dao();
          int result=Dao.login(user);
          if(result>0){
              out.print("登陸成功");
          }else{
              out.print("用戶名或密碼錯誤");
          }%>
</body>
</html>

DBUtil.DBUtil.javapost

package DBUtil;

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

import Dao.User;

public class DBUtil {

    public static String db_url = "jdbc:mysql://localhost:3306/system?serverTimezone=UTC&characterEncoding=utf-8";
    public static String db_user = "root";
    public static String db_pass = "vayne";
    
    public static Connection getConn () {
        Connection conn = null;
        
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            conn = DriverManager.getConnection(db_url, db_user, db_pass);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }
    
    
    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();
            }
        }
        
    }
}

Dao.User.javathis

package Dao;

public class User {
    private int id;
    private static String name;
    private static String pwd;
    private static String hobby;

    public User() {

    }
    public User( String name, String pwd) {
        this.name = name;
        this.pwd = pwd;
    }
    

    public User(int id, String name, String pwd, String hobby) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
        this.hobby = hobby;
    }
    

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public static String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public static String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public static String getHobby() {
        return hobby;
    }

    public void setHobby(String hobby) {
        this.hobby = hobby;
    }

}

Dao.Dao.javaurl

package Dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import Dao.User;
import DBUtil.DBUtil;
public class Dao {
    public static int login(User user) {
               int f=-1;
                String sql = "select * from JDBCjsp where name = '" + User.getName() + "' and password = '"+User.getPwd()+"'";
                //
                Connection conn = DBUtil.getConn();
                Statement state = null;
                ResultSet rs = null;       
                try {
                    state = conn.createStatement();
                    rs = state.executeQuery(sql);
                    if (rs.next()) {
                        f = rs.getInt(1);
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                } finally {
                    DBUtil.close(rs, state, conn);
                }
                return f;
            }
      
}