java 中JDBC实现查询数据表的功能

预备工作：

               a.建立java工程，并在工程中建立Source Folder,在资源夹下创建两个包分别为cn.jdbc.test和cn.jdbc.utils

                 在test包下创建java类LastTest,在utils包下创建java类JDBCUtils.

               b.连接数据库的jar包(本机安装的是sql server 2000,需要的jar包msbase.jar  mssqlserver.jar msutil.jar)

1.创建JDBCUtils类代码

package cn.jdbc.utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public  class JDBCUtils {
	private static final String DRIVER="com.microsoft.jdbc.sqlserver.SQLServerDriver";
	private static final String URL="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=news";
	private static final String USER="sa";
	private static final String PASSWORD="water";
	public static Connection con=null;
	static PreparedStatement pst=null;
	static ResultSet rs=null;
	static {
		try {
			Class.forName(DRIVER);	
			try {
				con=DriverManager.getConnection(URL, USER, PASSWORD);
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static PreparedStatement getpst(String sql){
		try {
			pst=con.prepareStatement(sql);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return pst;
	}
	public static ResultSet getrs(PreparedStatement p){
		try {
			rs=p.executeQuery();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return rs;
	}
    public static int getquery(){
    	int a=0;
    	try {
			a=pst.executeUpdate();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return a;
    }
    public static void closeObject(Connection c,PreparedStatement p,ResultSet r){
    	if(r!=null)
			try {
				r.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			if(p!=null)
				try {
					p.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				if(c!=null)
					try {
						c.close();
					} catch (SQLException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
    }
    public static void closeObject(Connection c,PreparedStatement p){
    	if(p!=null)
			try {
				p.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			if(c!=null)
				try {
					c.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
    }
}

 

 2.创建实现查询的java代码

 

package cn.jdbc.test;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import cn.jdbc.utils.*;
public class LastTest {
public static void main(String[] args){
	//Connection con1=null;
	String sql="select * from users where username=?";
	PreparedStatement pst1=null;
	ResultSet rs1=null;
	pst1=JDBCUtils.getpst(sql);
	try {
		pst1.setString(1, "飞鸟");
	} catch (SQLException e1) {
		// TODO Auto-generated catch block
		e1.printStackTrace();
	}
	rs1=JDBCUtils.getrs(pst1);
	try {
		while(rs1.next()){
			
			String id=rs1.getString(1);
			String username=rs1.getString(2);
			String password=rs1.getString(3);
			String nickname=rs1.getString(4);
			System.out.println(id+"  "+username+""+password+""+nickname);
		}
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}finally{
		JDBCUtils.closeObject(JDBCUtils.con, pst1,rs1);
	}
	
	
}
}