JDBC模板CRUD

创建一个Util工具类

创建工具类为了方便后期管理，例如对数据库做出修改的时候只需要在工具类里修改一处即可！

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

public final class JdbcUtils {
	private static String url = "jdbc:mysql://localhost:3306/mydb";
	private static String user = "root";
	private static String password = "000000";
	private JdbcUtils() {
	}
	static {    //静态代码块，加载jdbc驱动一次
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			throw new ExceptionInInitializerError(e);
		}
	}
	public static Connection getConnection() throws SQLException {
		return DriverManager.getConnection(url, user, password);
	}
	//释放资源进行判断
	public static void free(ResultSet rs, PreparedStatement ps, Connection conn) {
		try {
			if (rs != null)
				rs.close();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				if (ps != null)
					ps.close();
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				if (conn != null)
					try {
						conn.close();
					} catch (SQLException e) {
						e.printStackTrace();
					}
			}
		}
	}
}

创建一个测试类

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

public class Base {
	public static void main(String[] args) throws Exception {
		template("张三");
	}
	static void template(String name) throws SQLException, ClassNotFoundException {
		Connection conn = null;
		//Statement st = null;
		PreparedStatement ps = null; // 比上一种解决了SQL注入的问题 安全！还快
		ResultSet rs = null;
		try {
			// 2.建立连接
			conn = JdbcUtils.getConnection();
			// 3.创建语句
			//st = conn.createStatement();
			String sql = "select * from user where name = ?";
		ps = conn.prepareStatement(sql);
		ps.setString(1, name);
			// 4.执行语句
			//rs = st.executeQuery("select * from user");
			rs = ps.executeQuery();
			// 5.处理结果
			while (rs.next()) {
				// 参数中的1,2,3,4是指sql中的列索引
				System.out.println(rs.getObject(1) + "\t" + rs.getObject(2)
						);
			}
		} finally {
			JdbcUtils.free(rs, ps, conn);
		}
	}
}

实现简单增删改查

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

public class CRUD {
	public static void main(String[] args) throws SQLException {
		// create();
		read();
		// update();
		// delete();
	}
	static void delete() throws SQLException {
		Connection conn = null;
		Statement st = null;
		ResultSet rs = null;
		try {
			// 2.建立连接
			conn = JdbcUtils.getConnection();
			// 3.创建语句
			st = conn.createStatement();
			String sql = "delete from user where id>4";
			// 4.执行语句
			int i = st.executeUpdate(sql);
			System.out.println("i=" + i);
		} finally {
			JdbcUtils.free(rs, st, conn);
		}
	}
	static void update() throws SQLException {
		Connection conn = null;
		Statement st = null;
		ResultSet rs = null;
		try {
			// 2.建立连接
			conn = JdbcUtils.getConnection();
			// 3.创建语句
			st = conn.createStatement();
			String sql = "update user set money=money+10 ";
			// 4.执行语句
			int i = st.executeUpdate(sql);
			System.out.println("i=" + i);
		} finally {
			JdbcUtils.free(rs, st, conn);
		}
	}
	static void create() throws SQLException {
		Connection conn = null;
		Statement st = null;
		ResultSet rs = null;
		try {
			// 2.建立连接
			conn = JdbcUtils.getConnection();
			// conn = JdbcUtilsSing.getInstance().getConnection();
			// 3.创建语句
			st = conn.createStatement();
			String sql = "insert into user(name,birthday, money) values ('name1', '1987-01-01', 400) ";
			// 4.执行语句
			int i = st.executeUpdate(sql);
			System.out.println("i=" + i);
		} finally {
			JdbcUtils.free(rs, st, conn);
		}
	}

	static void read() throws SQLException {
		Connection conn = null;
		Statement st = null;
		ResultSet rs = null;
		try {
			// 2.建立连接
			conn = JdbcUtils.getConnection();
			// 3.创建语句
			st = conn.createStatement();
			// 4.执行语句
			rs = st.executeQuery("select id, name, money, birthday  from user");
			// 5.处理结果
			while (rs.next()) {
				System.out.println(rs.getObject("id") + "\t"
						+ rs.getObject("name") + "\t"
						+ rs.getObject("birthday") + "\t"
						+ rs.getObject("money"));
			}
		} finally {
			JdbcUtils.free(rs, st, conn);
		}
	}
}