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 }