JDBC 笔记3 通过PreparedStatement 对数据库进行增删改查 （转载）

　　之前MVC时一直用它，学了框架后就没怎么用了。这里转载一位同学的博客，以后可能也会用到的。

　　转自：https://www.cnblogs.com/zilong882008/archive/2011/11/13/2247065.html

1 插入数据

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public boolean ChaRu3(User user){         boolean flag=true;         Connection conn=null;         PreparedStatement ps=null;    //创建PreparedStatement 对象         String sql= "insert into user (name,pwd) values(?,?)";  //sql语句不再采用拼接方式，应用占位符问号的方式写sql语句。         conn=DBConnUtil.getConn();         try {             ps=conn.prepareStatement(sql);             ps.setString(1, user.getName()); //对占位符设置值，占位符顺序从1开始，第一个参数是占位符的位置，第二个参数是占位符的值。             ps.setString(2, user.getPwd());             int i=ps.executeUpdate();             if(i==0){                 flag=false;             }         } catch (SQLException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }finally{             DBConnUtil.closeAll(null, ps, conn);         }         return flag;               }

　　2.修改数据

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public boolean XiuGai3(User user){         boolean flag=true;         Connection conn=null;         PreparedStatement ps=null;         String sql="update user set pwd=? where name=?";         conn=DBConnUtil.getConn();         try {             ps=conn.prepareStatement(sql);             ps.setString(1, user.getPwd());             ps.setString(2, user.getName());             int i= ps.executeUpdate();             if(i==0){                 flag=false;             }                       } catch (SQLException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }finally{             DBConnUtil.closeAll(null, ps, conn);         }         return flag;     }

　　3.删除数据

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public boolean ShanChu3(int id){         boolean flag=true;         Connection conn=null;         PreparedStatement ps=null;         String sql="delete from user where id=?";         conn=DBConnUtil.getConn();         try {             ps=conn.prepareStatement(sql);             ps.setInt(1, id);             int i=ps.executeUpdate();             if(i==0){                 flag=false;             }         } catch (SQLException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }finally{             DBConnUtil.closeAll(null, ps, conn);         }                   return flag;     }

　　4.查看数据

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public List<User> ChaKan3(){          List<User> list= new ArrayList<User>();          Connection conn=null;          PreparedStatement ps=null;          ResultSet rs=null;          String sql="select * from user";          conn=DBConnUtil.getConn();          try {                ps=conn.prepareStatement(sql);              rs=ps.executeQuery();              while(rs.next()){                 User user= new User();                 user.setName(rs.getString("name"));                 list.add(user);              }         } catch (SQLException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }finally{             DBConnUtil.closeAll(rs, ps, conn);         }                    return list;      }