JDBC(Java DataBase Connectivity)是使用 Java 存取数据库系统的标准解决方案，它将不同数据库间各自差异API与标准 SQL语句分开看待，实现数据库无关的 Java操作接口。
JDBC程序访问数据库的步骤
步骤一：加载JDBC驱动程序:Class.forName("com.mysql.jdbc.Driver");Oracle10g：oracle.jdbc.driver.OracleDriver;MySQL5：com.mysql.jdbc.Driver;SQLServer2005：com.microsoft.sqlserver.jdbc.SQLServerDriver
步骤二：提供连接参数:URL,USERNAME, PASSWORD:不同数据库产品的连接URL不同
Oracle10g：jdbc:oracle:thin:@主机名:端口:数据库SID
jdbc:oracle:thin:@localhost:1521:ORCL
MySQL5：jdbc:mysql://主机名:端口/数据库名
jdbc:mysql://localhost:3306/test
SQLServer2005：jdbc:sqlserver://主机名:端口:DatabaseName=库名
jdbc:sqlserver://localhost:1433:DatabaseName=BookDB
步骤三：建立一个数据库的连接:connection=DriverManager.getConnection(URL,USERNAME, PASSWORD);
步骤四：创建一个statement:preparedStatement=connection.prepareStatement(sql);
步骤五：执行SQL语句:result=preparedStatement.executeUpdate();
步骤六：处理结果:flag=result>0?true:false;return flag;
步骤七：关闭JDBC对象:if(resultSet!=null){resultSet.close();}if(preparedStatement!=null){preparedStatement.close();}if(connection!=null){connection.close();}
package com.jdbc.dbUtils; import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map; import com.jdbc.dbUtils.dormain.UserInfo; public class JDBCutils { private final String USERNAME="root";
private final String PASSWORD="admin";
private final String DRIVER="com.mysql.jdbc.Driver";
private final String URL="jdbc:mysql://localhost:3306/mydb"; private Connection connection;
private PreparedStatement preparedStatement;
private ResultSet resultSet; public JDBCutils() {
try {
Class.forName(DRIVER);//注册驱动
System.out.println("成功注册驱动"); } catch (Exception e) {
// TODO: handle exception
}
} public Connection getConnection(){
try {
connection=DriverManager.getConnection(URL,USERNAME, PASSWORD);
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
return connection;
}
//增删改
public boolean updateByPreparedStatement(String sql,List<Object> params)throws SQLException {
boolean flag=false;
int result=-;//执行增删改操作的时候所影响的行数
int index=;//占位符的第一个位置
preparedStatement=connection.prepareStatement(sql);
if(params!=null&&!params.isEmpty()){
for (int i = ; i < params.size(); i++) {
preparedStatement.setObject(index++, params.get(i));
}
}
result=preparedStatement.executeUpdate();
flag=result>?true:false;
return flag;
}
//查询 返回单条记录
public Map<String,Object> findSimpleResult(String sql,List<Object> params) throws SQLException{
Map<String,Object> map=new HashMap<String,Object>();
int index=;//占位符的第一个位置
preparedStatement=connection.prepareStatement(sql);
if(params!=null&&!params.isEmpty()){
for (int i = ; i < params.size(); i++) {
preparedStatement.setObject(index++, params.get(i));
}
}
resultSet=preparedStatement.executeQuery();
ResultSetMetaData resultSetMetaData=resultSet.getMetaData();
int col_len=resultSetMetaData.getColumnCount();//得到数据库表的列
while(resultSet.next()){
for (int i = ; i < col_len; i++) {
String col_name=resultSetMetaData.getColumnName(i+);
Object col_val=resultSet.getObject(col_name);
if(col_val==null){
col_val="";
}
map.put(col_name,col_val);
}
}
return map; }
//查询 返回多条记录
public List<Map<String,Object>> findMultiResult(String sql,List<Object> params) throws SQLException{
List<Map<String,Object>> list=new ArrayList<Map<String,Object>>();
int index=;//占位符的第一个位置
preparedStatement=connection.prepareStatement(sql);
if(params!=null&&!params.isEmpty()){
for (int i = ; i < params.size(); i++) {
preparedStatement.setObject(index++, params.get(i));
}
}
resultSet=preparedStatement.executeQuery();
ResultSetMetaData resultSetMetaData=resultSet.getMetaData();
int col_len=resultSetMetaData.getColumnCount();//得到数据库表的列名
while(resultSet.next()){
Map<String,Object>map=new HashMap<String,Object>();
for (int i = ; i < col_len; i++) {
String col_name=resultSetMetaData.getColumnName(i+);
Object col_val=resultSet.getObject(col_name);
if(col_val==null){
col_val="";
}
map.put(col_name,col_val);
}
list.add(map);
}
return list; }
//jdbc的封装也可以采用反射机制
public <T> T findSimpReflectResult(String sql,List<Object> params,Class<T> cls) throws Exception{
T resObj=null;
int index=;//占位符的第一个位置
preparedStatement=connection.prepareStatement(sql);
if(params!=null&&!params.isEmpty()){
for (int i = ; i < params.size(); i++) {
preparedStatement.setObject(index++, params.get(i));
}
}
resultSet=preparedStatement.executeQuery();
ResultSetMetaData resultSetMetaData=resultSet.getMetaData();
int col_len=resultSetMetaData.getColumnCount();//得到数据库表的列名
while(resultSet.next()){
resObj=cls.newInstance();//通过反射机制创建实例
for (int i = ; i < col_len; i++) {
String col_name=resultSetMetaData.getColumnName(i+);
Object col_val=resultSet.getObject(col_name);
if(col_val==null){
col_val="";
}
Field field=cls.getDeclaredField(col_name);
field.setAccessible(true);//打开访问javabean的私有权限
field.set(resObj, col_val);
}
}
return resObj;
}
public <T> List<T> findMultiReflectResult(String sql,List<Object> params,Class<T> cls) throws Exception{
List<T> list=new ArrayList<T>();
int index=;//占位符的第一个位置
preparedStatement=connection.prepareStatement(sql);
if(params!=null&&!params.isEmpty()){
for (int i = ; i < params.size(); i++) {
preparedStatement.setObject(index++, params.get(i));
}
}
resultSet=preparedStatement.executeQuery();
ResultSetMetaData resultSetMetaData=resultSet.getMetaData();
int col_len=resultSetMetaData.getColumnCount();//得到数据库表的列名
while(resultSet.next()){
T resObj=cls.newInstance();//通过反射机制创建实例
for (int i = ; i < col_len; i++) {
String col_name=resultSetMetaData.getColumnName(i+);
Object col_val=resultSet.getObject(col_name);
if(col_val==null){
col_val="";
}
Field field=cls.getDeclaredField(col_name);
field.setAccessible(true);//打开访问javabean的私有权限
field.set(resObj, col_val);
}
list.add(resObj);
}
return list;
}
public void releaseConnection() throws SQLException{
if(resultSet!=null){
resultSet.close();
}
if(preparedStatement!=null){
preparedStatement.close();
}
if(connection!=null){
connection.close();
}
}
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
JDBCutils jdbc=new JDBCutils();
jdbc.getConnection();
List<Object> params=new ArrayList<Object>(); /* params.add("fjf");
params.add("123");
params.add("fanjingfang");
String sql="insert into userinfo(username,password,realname)values(?,?,?)";
boolean flag=jdbc.updateByPreparedStatement(sql, params);
System.out.println(flag);
params.add(1);
String sql="select * from userinfo where id=?";
Map<String,Object> m=jdbc.findSimpleResult(sql, params);
System.out.println(m);*/ /*String sql2="select * from userinfo ";
List<Map<String,Object>> list=jdbc.findMultiResult(sql2, null);
System.out.println(list);*/ /* params.add(1);
String sql3="select * from userinfo where id=? ";
UserInfo u=jdbc.findSimpReflectResult(sql3, params,UserInfo.class);
System.out.println(u);*/ String sql4="select * from userinfo ";
List<UserInfo> list=jdbc.findMultiReflectResult(sql4, null,UserInfo.class);
System.out.println(list);
} }