JDBC1利用Statement对数据库进行增删改查

　　private int id; private String name;private String pwd;        set&＃xff0c;get方法省略

public class UserDao {private static String jdbcDriver &＃61; "com.mysql.jdbc.Driver";private static String jdbcUrl&＃61;"jdbc:mysql://localhost:3306/homework";private static String jdbcuser&＃61;"root";private static String jdbcpwd&＃61;"123";public boolean ChaRu(User user){ //插入数据boolean flag&＃61;true;return flag;}public boolean XiuGai(User user){ //修改数据boolean flag&＃61;true;return flag;}public boolean ShanChu(int id){ //删除数据boolean flag&＃61;true;return flag;}public List ChanZhao(){ // 查找数据List list&＃61; new ArrayList();return list;}}

public boolean ChaRu(User user){boolean flag&＃61;true;Connection conn&＃61; null;Statement st&＃61;null;String sql&＃61;"insert into user(name,pwd) values(&＃39;"&＃43;user.getName()&＃43;"&＃39;,&＃39;"&＃43;user.getPwd()&＃43;"&＃39;)"; //插入数据的SQL语句 try {Class.forName(jdbcDriver); // 加载驱动器conn&＃61;DriverManager.getConnection(jdbcUrl, jdbcuser, jdbcpwd); // 驱动利用驱动地址&＃xff0c;数据库用户名&＃xff0c;密码创建连接st&＃61;conn.createStatement(); // 连接创建数据库操作对象,Statement是执行数据库的重要方法int i&＃61;st.executeUpdate(sql); // Statement 对象利用executeUpdate()方法执行sql。if(i&＃61;&＃61;0){ flag&＃61;false; // 后面测试用到flag变量&＃xff0c;前面执行sql语句&＃xff0c;如果成功i不为0&＃xff0c;true代表执行成功&＃xff0c;false代表失败。}} catch (ClassNotFoundException e) { //加载驱动器失败异常// TODO Auto-generated catch block
e.printStackTrace();} catch (SQLException e) { //创建链接失败异常// TODO Auto-generated catch block
e.printStackTrace();}finally{if(conn!&＃61;null){ // 最后关闭连接try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}}if(st!&＃61;null){ //关闭Statementtry {st.close();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}}}return flag; // 返回flag}

public static void main(String[] args) {User user&＃61;new User(); //初始化 User类 对象user可以调用set&＃xff0c;get方法设置或者获得数据。UserDao userDao &＃61; new UserDao(); //初始化UserDao 类&＃xff0c;可以调用增删改差的各种方法。
user.setName("lbzz"); // 设置姓名user.setPwd("123"); // 设置密码boolean flag&＃61;userDao.ChaRu(user); //执行插入操作&＃xff0c;返回值赋给flagif(flag){ //根据flag判断执行是否成功。System.out.println("插入成功");}else{System.out.println("插入失败");}}

public boolean XiuGai(User user){boolean flag&＃61;true;Connection conn&＃61; null;Statement st&＃61; null;String sql&＃61; "update user set pwd&＃61;&＃39;"&＃43;user.getPwd()&＃43;"&＃39; where name&＃61;&＃39;"&＃43;user.getName()&＃43;"&＃39;";System.out.println(sql);try {Class.forName(jdbcDriver);conn&＃61;DriverManager.getConnection(jdbcUrl, jdbcuser, jdbcpwd);st&＃61;conn.createStatement();int i&＃61;st.executeUpdate(sql);if(i&＃61;&＃61;0){flag&＃61;false;}} catch (ClassNotFoundException e) {// TODO Auto-generated catch block
e.printStackTrace();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}finally{if(conn!&＃61;null){try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}}if(st!&＃61;null){try {st.close();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}}}return flag;}

public static void main(String[] args) {User user&＃61; new User();UserDao userDao&＃61; new UserDao();user.setName("lbzz");user.setPwd("lbzz");boolean flag&＃61;userDao.XiuGai(user);if(flag){System.out.println("修改成功");}else{System.out.println("修改失败");}}

public boolean ShanChu(int id){boolean flag&＃61;true;Connection conn&＃61; null;Statement st&＃61; null;String sql&＃61;"delete from user where id&＃61;"&＃43;id;try {Class.forName(jdbcDriver);conn&＃61;DriverManager.getConnection(jdbcUrl, jdbcuser, jdbcpwd);st&＃61;conn.createStatement();int i&＃61;st.executeUpdate(sql);if(i&＃61;&＃61;0){flag&＃61;false;}} catch (ClassNotFoundException e) {// TODO Auto-generated catch block
e.printStackTrace();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}finally{if(conn!&＃61;null){try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}}if(st!&＃61;null){try {st.close();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}}}return flag;}

public static void main(String[] args) {UserDao userDao &＃61; new UserDao();boolean flag&＃61; userDao.ShanChu(1);if(flag){System.out.println("删除成功");}else{System.out.println("删除失败");}

}

public List ChanZhao(){ // 查询出来的数据不止一条&＃xff0c;所以使用集合List list&＃61; new ArrayList(); // 对集合进行初始化Connection conn&＃61; null;Statement st&＃61;null;ResultSet rs&＃61;null; // ResultSet 返回的是一个结果集String sql&＃61;"select * from user";try {Class.forName(jdbcDriver);conn&＃61; DriverManager.getConnection(jdbcUrl, jdbcuser, jdbcpwd);st&＃61;conn.createStatement();rs&＃61;st.executeQuery(sql); // 查询时使用 executeQuery()方法while(rs.next()){ // 对结果集进行遍历User user &＃61; new User();user.setName(rs.getString("name")); // 需要查询什么就要像这样设置什么list.add(user); //添加到集合}} catch (ClassNotFoundException e) {// TODO Auto-generated catch block
e.printStackTrace();} catch (SQLException e) {// TODO Auto-generated catch block
e.printStackTrace();}finally{

关闭conn,st,rs

　　　　}return list; //返回list}

public static void main(String[] args) {UserDao userDao &＃61; new UserDao();List list&＃61;userDao.ChanZhao();for(User user:list){System.out.println(user.getName());}}