JAVA JDBC连接SQL Server数据库进阶(一)---ConnectionFactory

在上一阶段每次执行操作时，都需要建立连接，然后在关闭连接。这就产生了很多冗余的代码，这和我们应用的复用性是违背的。因此，我们需要创建一些简单工厂类来帮助我们提高代码的复用性。简单的说就是将重复的代码封装起来以便复用。

一、ConnectionFactory

1.1 ConnectionFactory的作用

利用工厂模式提高代码的重用性。

封装注册数据库的驱动和获得数据库的连接。

利用配置文件减少硬编码，便于维护。

1.2 配置文件jdbcinfo.properties

jdbc.driver=com.microsoft.sqlserver.jdbc.SQLServerDriver
jdbc.url=jdbc:sqlserver://127.0.0.1:1433;databaseName=Student
jdbc.user=sa
jdbc.password=123

配置文件信息的获取

ConnectionFactory.class.getResourceAsStream("jdbcinfo.properties");//参数jdbcinfo.properties：指定了配置文件的路径，这里在一个目录下所以使用相对路径，

getResourceAsStream()方法返回的是一个输入流。

数据库连接Connection的获取

public static Connection getConnection();

首先在SQL Server数据库中创建一个Student表，表模型如下：

具体代码如下：

创建一个配置文件后缀名为.properties ：jdbcinfo.properties

jdbc.driver=com.microsoft.sqlserver.jdbc.SQLServerDriver
jdbc.url=jdbc:sqlserver://127.0.0.1:1433;databaseName=UserInfo
jdbc.user=sa
jdbc.password=123

简单工厂：ConnectionFactory.java

package com.mao.common;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
//简单工厂
public class ConnectionFactory {
    public static String DRIVER;
    public static String URL;
    public static String USER;
    public static String PASSWORD;
    static {
    	Properties props=new Properties();
    	InputStream is=ConnectionFactory.class.getResourceAsStream("jdbcinfo.properties");
    	try {
    		//从流中读取相应的配置文件信息将其加载到props中，将键值对封装进其中
			props.load(is);
			//通过键获取相应的值
			DRIVER=props.getProperty("jdbc.driver");
			URL=props.getProperty("jdbc.url");
			USER=props.getProperty("jdbc.user");
			PASSWORD=props.getProperty("jdbc.password");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
    }
    //获取数据库连接
    public static Connection getConnection() {
    	Connection conn=null;
    	try {
    		//加载驱动
    		Class.forName(DRIVER);
    		//获取连接
    	    conn=DriverManager.getConnection(URL, USER, PASSWORD);
    	}catch(Exception e) {
    		e.printStackTrace();
    	}
    	return conn;
    } 

}

实体类：Student.java

package com.mao.common;

import java.io.Serializable;
//实体类
public class Student implements Serializable {
     private String id;
     private String name;
     private String sex;
    public Student() {
    	
    }

	public Student(String id, String name, String sex) {
		super();
		this.id = id;
		this.name = name;
		this.sex = sex;
	}

	public String getId() {
		return id;
	}

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

	public String getName() {
		return name;
	}

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

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}
     
}

封装关闭连接的工具类：CloseDbUtils.java

package com.mao.common;

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

public class CloseDbUtils {
    public static void closeConn(Connection conn,Statement state,ResultSet rs) {
    	if(rs!=null) {
    		try {
				rs.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
    	}
    	if(state!=null) {
    		try {
				state.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
    	}
    	if(conn!=null) {
    		try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
    	}
    }
    public static void closeConn(Connection conn,Statement state) {
    	if(state!=null) {
    		try {
				state.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
    	}
    	if(conn!=null) {
    		try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
    	}
    }
    public static void closeConn(Connection conn) {
    	if(conn!=null) {
    		try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
    	}
    } 
}

封装具体操作的类：StudentJDBC.java

package com.mao.common;

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

public class StudentJDBC {
	  //插入一条记录
    public static void insertItem(Student stu) {
       Connection conn=null;
       PreparedStatement state=null;
       try {
    	   conn=ConnectionFactory.getConnection();
    	   //？表示占位符
       	   String sql="INSERT INTO Student VALUES(?,?,?)";
       	   state=conn.prepareStatement(sql);
       	   //表示第1个占位符的值为stu.getId()
       	   state.setString(1, stu.getId());
       	 //表示第2个占位符的值为stu.getName()
       	   state.setString(2, stu.getName());
       	   state.setString(3, stu.getSex());
       	   int rows=state.executeUpdate();
       	   System.out.println("成功插入："+rows+"条记录");
       }catch(Exception e) {
    	   try {
    		   //出现异常则事务回滚
			conn.rollback();
		} catch (SQLException e1) {
			
		}
       }finally {
    		CloseDbUtils.closeConn(conn, state);
       }
    }
    public static void deleteItem(Student stu) {
    	Connection conn=null;
    	PreparedStatement state=null;
    	try {
    		conn=ConnectionFactory.getConnection();
    		String sql="DELETE FROM Student WHERE ID=?";
    		state=conn.prepareStatement(sql);
    		state.setString(1, stu.getId());
    		int rows=state.executeUpdate();
    		System.out.println("成功删除："+rows+"条记录");
    	}catch(Exception e) {
    		
    	}finally {
    		CloseDbUtils.closeConn(conn, state);
    	}
    }
    //修改数据
    public static void updateItem(Student stu) {
    	Connection conn=null;
    	PreparedStatement state = null;
    	try {
    		conn=ConnectionFactory.getConnection();
    		String sql="UPDATE Student SET NAME=?,SEX=? WHERE ID=?";
    		state=conn.prepareStatement(sql);
    		state.setString(1, stu.getName());
    		state.setString(2, stu.getSex());
    		state.setString(3, stu.getId());
    		int rows=state.executeUpdate();
    		System.out.println("成功更新："+rows+"条记录");
    	}catch(Exception e) {
    		e.printStackTrace();
    	}finally{
    		CloseDbUtils.closeConn(conn, state);
    	}
    }
    //查询所有
    public static void selectAll() {
    	Connection conn=null;
    	Statement state=null;
    	ResultSet rs=null;
    	try {
		conn=ConnectionFactory.getConnection();
		state=conn.createStatement();
		String sql="SELECT * FROM Student";
		rs=state.executeQuery(sql);
		while(rs.next()) {
			System.out.println("ID:"+rs.getString("ID")+"  NAME:"+rs.getString("NAME")+"  SEX:"+rs.getString("SEX"));
		}
		state.executeQuery(sql);
		} catch (Exception e) {
			
		}finally {
			CloseDbUtils.closeConn(conn, state, rs);
			}
		}
    //查询单个记录
    public static void selectItem(Student stu) {
    	Connection conn=null;
    	PreparedStatement state=null;
    	ResultSet rs=null;
    	try {
    		conn=ConnectionFactory.getConnection();
    		String sql="SELECT NAME,SEX FROM Student WHERE ID=?";
    		state=conn.prepareStatement(sql);
    		state.setString(1, stu.getId());
    		rs=state.executeQuery();
    		if(rs.next()) {
    			System.out.println("NAME:"+rs.getString("NAME")+"  SEX:"+rs.getString("SEX"));
    		}
    	}catch(Exception e) {
    		e.printStackTrace();
    	}finally {
    		CloseDbUtils.closeConn(conn, state, rs);
    	}
    }
    	
    }

测试类：MainActivity.java

import com.mao.common.ConnectionFactory;
import com.mao.common.Student;
import com.mao.common.StudentJDBC;

public class MainActivity {

	public static void main(String[] args) {
      Student  stu=new Student("4","mao4","男");
        StudentJDBC stujdbc=new StudentJDBC();
       stujdbc.insertItem(stu);//增
       // stujdbc.deleteItem(stu);//删
       // stujdbc.updateItem(stu);//更新数据
     stujdbc.selectAll();//查所有记录
     //stujdbc.selectItem(stu);//查单个记录
	}
}

JAVA JDBC连接SQL Server数据库进阶(一)---ConnectionFactory

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