import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import org.junit.Test;import util.JdbcUtil;/** * PreparedStatement執行sql語句 * @author APPle * */public class Demo1 {    /**     * 增加     */    @Test    public void testInsert() {        Connection conn = null;        PreparedStatement stmt = null;        try {            //1.获取连接            conn = JdbcUtil.getConnection();                        //2.准备预编译的sql            String sql = "INSERT INTO student2(NAME,gender) VALUES(?,?)"; //?表示一个参数的占位符                        //3.执行预编译sql语句(检查语法)            stmt = conn.prepareStatement(sql);                        //4.设置参数值            /**             * 参数一： 参数位置  从1开始             */            stmt.setString(1, "李四");            stmt.setString(2, "男");                        //5.发送参数，执行sql            int count = stmt.executeUpdate();                        System.out.println("影响了"+count+"行");                    } catch (Exception e) {            e.printStackTrace();            throw new RuntimeException(e);        } finally {            JdbcUtil.close(conn, stmt);        }    }        /**     * 修改     */    @Test    public void testUpdate() {        Connection conn = null;        PreparedStatement stmt = null;        try {            //1.获取连接            conn = JdbcUtil.getConnection();                        //2.准备预编译的sql            String sql = "UPDATE student2 SET NAME=? WHERE id=?"; //?表示一个参数的占位符                        //3.执行预编译sql语句(检查语法)            stmt = conn.prepareStatement(sql);                        //4.设置参数值            /**             * 参数一： 参数位置  从1开始             */            stmt.setString(1, "王五");            stmt.setInt(2, 9);                        //5.发送参数，执行sql            int count = stmt.executeUpdate();                        System.out.println("影响了"+count+"行");                    } catch (Exception e) {            e.printStackTrace();            throw new RuntimeException(e);        } finally {            JdbcUtil.close(conn, stmt);        }    }        /**     * 删除     */    @Test    public void testDelete() {        Connection conn = null;        PreparedStatement stmt = null;        try {            //1.获取连接            conn = JdbcUtil.getConnection();                        //2.准备预编译的sql            String sql = "DELETE FROM student2 WHERE id=?"; //?表示一个参数的占位符                        //3.执行预编译sql语句(检查语法)            stmt = conn.prepareStatement(sql);                        //4.设置参数值            /**             * 参数一： 参数位置  从1开始             */            stmt.setInt(1, 9);                        //5.发送参数，执行sql            int count = stmt.executeUpdate();                        System.out.println("影响了"+count+"行");                    } catch (Exception e) {            e.printStackTrace();            throw new RuntimeException(e);        } finally {            JdbcUtil.close(conn, stmt);        }    }        /**     * 查询     */    @Test    public void testQuery() {        Connection conn = null;        PreparedStatement stmt = null;        ResultSet rs = null;        try {            //1.获取连接            conn = JdbcUtil.getConnection();                        //2.准备预编译的sql            String sql = "SELECT * FROM student2";                         //3.预编译            stmt = conn.prepareStatement(sql);                        //4.执行sql            rs = stmt.executeQuery();                        //5.遍历rs            while(rs.next()){                int id = rs.getInt("id");                String name = rs.getString("name");                String gender = rs.getString("gender");                System.out.println(id+","+name+","+gender);            }                    } catch (Exception e) {            e.printStackTrace();            throw new RuntimeException(e);        } finally {            //关闭资源            JdbcUtil.close(conn,stmt,rs);        }    }}