增删改查 公共代码

##DBUtil

package org.lizhenhua.util;

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

public class DBUtil {

	static {
		try {
			Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static Connection getConn() {
		Connection conn = null;
		try {
			conn = DriverManager.getConnection(
					"jdbc:sqlserver://localhost:1433;databaseName=school", "sa",
					"1");
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}

	public static void close(Connection conn, PreparedStatement ps, ResultSet rs) {
		try {
			if (conn != null)
				conn.close();
			if (ps != null)
				ps.close();
			if (rs != null)
				rs.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
//增删改查  公共代码
	public static int updata(String sql, Object[] objs) {
		int count = 0;
		PreparedStatement ps = null;
		Connection conn = null;
		conn = getConn();
		try {
			ps = conn.prepareStatement(sql);
			for (int i = 0; i < objs.length; i++) {
				ps.setObject(i + 1, objs[i]);
			}
			count = ps.executeUpdate();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		return count;

	}
}

```java
package org.lizhenhua.action;

import java.awt.image.DataBufferUShort;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;

import org.lizhenhua.isBean.Book;
import org.lizhenhua.util.DBHelper;

public class Login {
// 获取指定ID的信息
	public static Book getId(Integer id) {
		String message = "";
		Book book = null;
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;

		conn = DBHelper.getconn();

		String sql = "select * from Book where id =?";

		try {
			ps = conn.prepareStatement(sql);
			ps.setObject(1, id);
			rs = ps.executeQuery();

			if (rs.next()) {
				book = new Book();
				book.setId(rs.getInt(1));
				book.setUserName(rs.getString(2));
				book.setPwd(rs.getString(3));

			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return book;
	}
//获取全部表数据信息
	public static ArrayList<Book> getSelect() {
		ArrayList<Book> bookList = new ArrayList<Book>();

		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;

		conn = DBHelper.getconn();

		String sql = "select * from  book ";

		try {
			ps = conn.prepareStatement(sql);

			rs = ps.executeQuery();

			while (rs.next()) {
				Book book = new Book();
				book.setId(rs.getInt(1));
				book.setUserName(rs.getString(2));
				book.setPwd(rs.getString(3));
				bookList.add(book);
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		DBHelper.close(conn, ps, rs);
		return bookList;
	}
// 登录查询
	public static Book getLogin(String userName, String pwd) {
		
		Book book = null;
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;

		conn = DBHelper.getconn();

		String sql = "select * from Book where user_name = ? and pwd = ?";

		try {
			ps = conn.prepareStatement(sql);
			System.out.println("----------");
			ps.setObject(1, userName);
			ps.setObject(2, pwd);
			System.out.println("===============");
			rs = ps.executeQuery();

			if (rs.next()) {
				book = new Book();
				book.setId(rs.getInt(1));
				book.setUserName(rs.getString(2));
				book.setPwd(rs.getString(3));
				
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return book;
	}
}