JAVA增删改查 代码范例

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


 public class DBTools {
 // 定义一个方法，用来得到一个"新的"连接对象
 public static Connection getConnection()
 {
 Connection conn = null;
 String driverName = "oracle.jdbc.driver.OracleDriver";
 String url = "jdbc:oracle:thin:@localhost:1521:ora9i";
 String userName = "scott";
 String passWord = "tiger";
 try {
 Class.forName(driverName);
 conn = DriverManager.getConnection(url,userName,passWord );
 } catch (Exception e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 return conn;
 }


 public static void closeConn(Connection conn)
 {
 try {
 if(conn != null)
 {
 conn.close();
 }
 } catch (SQLException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 }


 public static void closeState(Statement state)
 {
 try {
 if(state != null)
 {
 state.close();
 }
 } catch (SQLException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 }


 public static void closeRs(ResultSet rs)
 {
 try {
 if(rs != null)
 {
 rs.close();
 }
 } catch (SQLException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 }
 }






 import java.sql.ResultSet;
 import java.sql.Statement;
 import java.util.ArrayList;


 import com.tianyitime.notebook.support.userPO.UserPO;
 import com.tianyitime.notebook.support.util.DBTools;




 public class UserDAO {


 // 新增user
 public void saveUserInfo(UserPO upo)
 {
 Connection conn = null;
 Statement state = null;
 try {
 conn = DBTools.getConnection();
 state = conn.createStatement();
 String sql = "insert into notebook_user values ("+getMaxId()+",'"+upo.getYhm()+"','"+upo.getEmail()+"','"+upo.getContent()+"')";
 //System.out.println(sql);
 state.executeUpdate(sql);


 } catch (Exception ex) {
 // TODO Auto-generated catch block
 ex.printStackTrace();
 }
 finally
 {
 DBTools.closeState(state);
 DBTools.closeConn(conn);
 }
 }


 //得到一个数据库中当前Id的最大值
 private int getMaxId()
 {
 Connection conn = null;
 Statement state = null;
 ResultSet rs = null;
 int maxId = 0;
 try {
 conn = DBTools.getConnection();
 state = conn.createStatement();
 String sql = "select max(id) maxId from notebook_user";
 rs = state.executeQuery(sql);
 //从resultset对象中将数据取出
 if(rs.next())
 {
 maxId = rs.getInt("maxId");
 }
 } catch (Exception ex) {
 // TODO Auto-generated catch block
 ex.printStackTrace();
 }


 return ++maxId;
 }


 // 得到所有的记录
 public ArrayList getUserInfo()
 {
 Connection conn = null;
 Statement state = null;
 ResultSet rs = null;
 UserPO upo = null;
 ArrayList al = new ArrayList();
 try {
 conn = DBTools.getConnection();
 state = conn.createStatement();
 String sql = "select * from notebook_user";
 rs = state.executeQuery(sql);
 //从resultset对象中将数据取出


 while(rs.next())
 {
 upo = new UserPO();
 int id = rs.getInt("id");
 String yhm = rs.getString("yhm");
 String email = rs.getString("email");
 String content = rs.getString("content");


 upo.setId(id);
 upo.setYhm(yhm);
 upo.setEmail(email);
 upo.setContent(content);


 //将改对象放入已经创建好的集合类对象ArrauyList
 al.add(upo);
 }
 } catch (Exception ex) {
 // TODO Auto-generated catch block
 ex.printStackTrace();
 }
 finally
 {
 DBTools.closeRs(rs);
 DBTools.closeState(state);
 DBTools.closeConn(conn);
 }
 return al;
 }


 // 删除一条user记录
 public void deleteUserInfo(int id)
 {
 Connection conn = null;
 Statement state = null;
 try {
 conn = DBTools.getConnection();
 state = conn.createStatement();
 String sql = "delete from notebook_user where id="+id;
 //System.out.println(sql);
 state.executeUpdate(sql);


 } catch (Exception ex) {
 // TODO Auto-generated catch block
 ex.printStackTrace();
 }
 finally
 {
 DBTools.closeState(state);
 DBTools.closeConn(conn);
 }
 }


 // 根据给定的信息得到记录
 public ArrayList getUserInfoByInfo(String name,String email,String content)
 {
 Connection conn = null;
 Statement state = null;
 ResultSet rs = null;
 UserPO upo = null;
 ArrayList al = new ArrayList();
 try {
 conn = DBTools.getConnection();
 state = conn.createStatement();
 String sql = "select * from notebook_user where 1=1 ";
 if(!"".equals(name) && name != null)
 {
 sql += " and yhm like '%"+name+"%'";
 }
 if(!"".equals(email) && email != null)
 {
 sql += " and email = '"+email+"'";
 }
 if(!"".equals(content) && content != null)
 {
 sql += " and content like '%"+content+"%'";
 }
 sql+=" order by id desc";
 rs = state.executeQuery(sql);
 //从resultset对象中将数据取出


 while(rs.next())
 {
 upo = new UserPO();
 int id = rs.getInt("id");
 String yhm = rs.getString("yhm");
 String femail = rs.getString("email");
 String fcontent = rs.getString("content");


 upo.setId(id);
 upo.setYhm(yhm);
 upo.setEmail(femail);
 upo.setContent(fcontent);


 //将改对象放入已经创建好的集合类对象ArrauyList
 al.add(upo);
 }
 } catch (Exception ex) {
 // TODO Auto-generated catch block
 ex.printStackTrace();
 }
 finally
 {
 DBTools.closeRs(rs);
 DBTools.closeState(state);
 DBTools.closeConn(conn);
 }
 return al;
 }


 }