statement和Prestatement的区别

public class StatementCRUDtest {   /**     * 操作表jdbc_users     * @param args     */   public static void main(String[] args) {     User u=new User();     u.setId(45);     u.setName("statement");     u.setPasswd("yf123");     u.setPhone("13821930");     u.setEmail("[e-mail]");     //insert(u);     //delete(2);     //reset(u);     System.out.println(getById(45));   }   /**增*/   public static void insert(User user){     Connection conn=null;     Statement stmt=null;     try {       Class.forName("oracle.jdbc.driver.OracleDriver");       //conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL10","scott","yf123");       conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:ORCL10", "SCOTT", "yf123");       stmt=conn.createStatement();//Statement创建时就是一个空的执行器       /**在execute或者executeQuery时执行死的sql语句*/       /**这只能是拼好的字符串,而不能动态的传参数,并且在数据库中每次肯定穿的是不同的sql语句，因此每次都要解析编译*/       stmt.execute("insert into jdbc_users values ("+user.getId()+",'"+user.getName()+"','"+user.getPasswd()+"','"+user.getPhone()+"','"+user.getEmail()+"')");     } catch (Exception e) {       e.printStackTrace();     }finally{       if(stmt!=null){try{stmt.close();}catch(Exception e){}}       if(conn!=null){try{conn.close();}catch(Exception e){}}     }   }   /**删*/   public static void delete(Integer id){     Connection conn=null;     Statement stmt=null;     try {       Class.forName("oracle.jdbc.driver.OracleDriver");       //conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL10","scott","yf123");       conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:ORCL10", "SCOTT", "yf123");       stmt=conn.createStatement();//Statement创建时就是一个空的执行器       /**在execute或者executeQuery时执行死的sql语句*/       /**这只能是拼好的字符串,而不能动态的传参数,并且在数据库中每次肯定穿的是不同的sql语句，因此每次都要解析编译*/       stmt.execute("delete from jdbc_users where id="+id);     } catch (Exception e) {       e.printStackTrace();     }finally{       if(stmt!=null){try{stmt.close();}catch(Exception e){}}       if(conn!=null){try{conn.close();}catch(Exception e){}}     }   }   /**改*/   public static void reset(User user){     Connection conn=null;     Statement stmt=null;     try {       Class.forName("oracle.jdbc.driver.OracleDriver");       //conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL10","scott","yf123");       conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:ORCL10", "SCOTT", "yf123");       stmt=conn.createStatement();//Statement创建时就是一个空的执行器       /**在execute或者executeQuery时执行死的sql语句*/       /**这只能是拼好的字符串,而不能动态的传参数,并且在数据库中每次肯定穿的是不同的sql语句，因此每次都要解析编译*/       String sql="update jdbc_users set name='"+user.getName()+"',passwd='"+user.getPasswd()+"',phone='"+user.getPhone()+"',email='"+user.getEmail()+"' where id="+user.getId();       System.out.println(sql);       stmt.execute(sql);     } catch (Exception e) {       e.printStackTrace();     }finally{       if(stmt!=null){try{stmt.close();}catch(Exception e){}}       if(conn!=null){try{conn.close();}catch(Exception e){}}     }   }   /**查*/   public static User getById(Integer id){     Connection conn=null;     Statement stmt=null;     ResultSet rs=null;     User u=null;     try {       Class.forName("oracle.jdbc.driver.OracleDriver");       //conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL10","scott","yf123");       conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:ORCL10", "SCOTT", "yf123");       stmt=conn.createStatement();//Statement创建时就是一个空的执行器       /**在execute或者executeQuery时执行死的sql语句*/       /**这只能是拼好的字符串,而不能动态的传参数,并且在数据库中每次肯定穿的是不同的sql语句，因此每次都要解析编译*/       String sql="select * from jdbc_users where id="+id;       System.out.println(sql);       rs=stmt.executeQuery(sql);       while(rs.next()){         u=new User();         u.setId(rs.getInt("id"));         u.setName(rs.getString("name"));         u.setPhone(rs.getString("phone"));         u.setPasswd(rs.getString("passwd"));         u.setEmail(rs.getString("email"));       }     } catch (Exception e) {       e.printStackTrace();     }finally{       if(stmt!=null){try{stmt.close();}catch(Exception e){}}       if(conn!=null){try{conn.close();}catch(Exception e){}}     }     return u;   } } /** * PreparedStatement是在创建pstm的时候就给它传一个动态的sql，参数是通过pstm设置的。执行时，只需要空执行一下就可以. * @author Administrator * */ public class PreparedStatementCRUDtest {   /**     * 操作表jdbc_users     * @param args     */   public static void main(String[] args) {     User u=new User();     u.setId(21);     u.setName("statement");     u.setPasswd("yf123");     u.setPhone("13821930");     u.setEmail("[e-mail]");     //insert(u);     //delete(42);     //reset(u);     System.out.println(getById(21));   }   /**增*/   public static void insert(User user){     Connection conn=null;     PreparedStatement pstmt=null;     try {       Class.forName("oracle.jdbc.driver.OracleDriver");       //conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL10","scott","yf123");       conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:ORCL10", "SCOTT", "yf123");       String sql="insert into jdbc_users values(?,?,?,?,?)";       pstmt=conn.prepareStatement(sql);//PreparedStatement创建时就传过去一个sql语句,这样就可以预编译       /**然后设置sql中好占位符的值,这里是动态的传参数*/       pstmt.setInt(1, user.getId());       pstmt.setString(2, user.getName());       pstmt.setString(3, user.getPasswd());       pstmt.setString(4, user.getPhone());       pstmt.setString(5, user.getEmail());       /**设置好后，就全封装到pstm里了,只要空执行就可以了*/       pstmt.execute();     } catch (Exception e) {       e.printStackTrace();     }finally{       if(pstmt!=null){try{pstmt.close();}catch(Exception e){}}       if(conn!=null){try{conn.close();}catch(Exception e){}}     }   }   /**删*/   public static void delete(Integer id){     Connection conn=null;     PreparedStatement pstmt=null;     try {       Class.forName("oracle.jdbc.driver.OracleDriver");       //conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL10","scott","yf123");       conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:ORCL10", "SCOTT", "yf123");       String sql="delete from jdbc_users where id=?";       /**PreparedStatement创建时就传过去一个sql语句,这样就可以预编译*/       pstmt=conn.prepareStatement(sql);       /**然后设置sql中好占位符的值,这里是动态的传参数*/       pstmt.setInt(1, id);       /**设置好后，就全封装到pstm里了,只要空执行就可以了*/       pstmt.execute();     } catch (Exception e) {       e.printStackTrace();     }finally{       if(pstmt!=null){try{pstmt.close();}catch(Exception e){}}       if(conn!=null){try{conn.close();}catch(Exception e){}}     }   }   /**改*/   public static void reset(User u){     Connection conn=null;     PreparedStatement pstmt=null;     try {       Class.forName("oracle.jdbc.driver.OracleDriver");       //conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL10","scott","yf123");       conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:ORCL10", "SCOTT", "yf123");       String sql="update jdbc_users set name=?,passwd=?,phone=?,email=? where id=?";       /**PreparedStatement创建时就传过去一个sql语句,这样就可以预编译*/       pstmt=conn.prepareStatement(sql);       /**然后设置sql中好占位符的值,这里是动态的传参数*/       pstmt.setString(1, u.getName());       pstmt.setString(2, u.getPasswd());       pstmt.setString(3, u.getPhone());       pstmt.setString(4, u.getEmail());       pstmt.setInt(5, u.getId());       /**设置好后，就全封装到pstm里了,只要空执行就可以了*/       pstmt.execute();     } catch (Exception e) {       e.printStackTrace();     }finally{       if(pstmt!=null){try{pstmt.close();}catch(Exception e){}}       if(conn!=null){try{conn.close();}catch(Exception e){}}     }   }   /**查*/   public static User getById(Integer id){     Connection conn=null;     PreparedStatement pstmt=null;     ResultSet rs=null;     User u=null;     try {       Class.forName("oracle.jdbc.driver.OracleDriver");       //conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL10","scott","yf123");       conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:ORCL10", "SCOTT", "yf123");       String sql="select * from jdbc_users where id=?";       pstmt=conn.prepareStatement(sql);//Statement创建时就是一个空的执行器       /**在execute或者executeQuery时执行死的sql语句*/       /**这只能是拼好的字符串,而不能动态的传参数,并且在数据库中每次肯定穿的是不同的sql语句，因此每次都要解析编译*/       pstmt.setInt(1, id);       rs=pstmt.executeQuery();       while(rs.next()){         u=new User();         u.setId(rs.getInt("id"));         u.setName(rs.getString("name"));         u.setPhone(rs.getString("phone"));         u.setPasswd(rs.getString("passwd"));         u.setEmail(rs.getString("email"));       }     } catch (Exception e) {       e.printStackTrace();     }finally{       if(pstmt!=null){try{pstmt.close();}catch(Exception e){}}       if(conn!=null){try{conn.close();}catch(Exception e){}}     }     return u;   } }