JDBC mysql 相关内容笔记

解决乱码： url字符串加上?useUnicode=true&characterEncoding=utf-8;

mysql数据库无法插入中文数据问题：将mysql数据库的编码改为utf-8;

ResultSet中get(列名)方法不一定获取的是数据库字段名，也有可能是自定义的别名，例如：select id,name,password pwd from user 此时resultSet.get("password")会抛出异常！

反射封装JDBC：

  1 package com.jdbc;
  2 
  3 import java.lang.reflect.Field;
  4 import java.sql.Connection;
  5 import java.sql.DriverManager;
  6 import java.sql.PreparedStatement;
  7 import java.sql.ResultSet;
  8 import java.sql.ResultSetMetaData;
  9 import java.sql.SQLException;
 10 import java.util.ArrayList;
 11 import java.util.List;
 12 
 13 public class TestReflectionJDBC<T> {
 14 
 15     private static Connection connection = null;
 16 
 17     private static ResultSet resultSet = null;
 18 
 19     private static PreparedStatement preparedStatement = null;
 20 
 21     public static void main(String[] args) {
 22 
 23     }
 24 
 25     public Connection getConnection() throws Exception {
 26         Class.forName("com.mysql.jdbc.Driver");
 27         if (connection != null) {
 28             connection = DriverManager.getConnection(
 29                     "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8", "root", "123456");
 30         }
 31         return connection;
 32     }
 33 
 34     public List<T> query(String sql, Class<T> clzz, Object... obj) throws Exception {
 35         List<T> list = new ArrayList<T>();
 36         preparedStatement = getConnection().prepareStatement(sql);
 37         for (int i = 0; i < obj.length; i++) {
 38             preparedStatement.setObject(i + 1, obj[i]);
 39         }
 40         resultSet = preparedStatement.executeQuery();
 41         if (resultSet != null) {
 42             ResultSetMetaData resultSetMetaData = null;
 43             while (resultSet.next()) {
 44                 if (resultSetMetaData == null) {
 45                     resultSetMetaData = resultSet.getMetaData();
 46                     int count = resultSetMetaData.getColumnCount();
 47                     T t = clzz.newInstance();
 48                     for (int i = 0; i < count; i++) {
 49                         String name = resultSetMetaData.getColumnName(i + 1);
 50                         Field field = clzz.getDeclaredField(name);
 51                         field.setAccessible(true);
 52                         Object value = resultSet.getObject(name);
 53                         field.set(t, value);
 54                     }
 55                     list.add(t);
 56                 }
 57             }
 58         }
 59         return list;
 60     }
 61 
 62     public int update(String sql, Object... obj) {
 63         int result = 0;
 64         try {
 65             preparedStatement = getConnection().prepareStatement(sql);
 66             for (int i = 0; i < obj.length; i++) {
 67                 preparedStatement.setObject(i + 1, obj[i]);
 68             }
 69             result = preparedStatement.executeUpdate();
 70         } catch (SQLException e) {
 71             e.printStackTrace();
 72         } catch (Exception e) {
 73             e.printStackTrace();
 74         } finally {
 75             if (preparedStatement != null) {
 76                 try {
 77                     preparedStatement.close();
 78                 } catch (SQLException e) {
 79                     e.printStackTrace();
 80                 }
 81             }
 82             if (resultSet != null) {
 83                 try {
 84                     resultSet.close();
 85                 } catch (SQLException e) {
 86                     e.printStackTrace();
 87                 }
 88             }
 89             if (connection != null) {
 90                 try {
 91                     connection.close();
 92                 } catch (SQLException e) {
 93                     e.printStackTrace();
 94                 }
 95             }
 96         }
 97         return result;
 98     }
 99 
100 }