内容简介：JDBC基本的代码结构，一定要记住！！！
JDBC 要处理的事情，一共有七步：
- 连接数据库
- 注册驱动
- 获取连接
- 获取数据库操作对象
- 执行 SQL
- 处理结果集
- 释放资源
这个是没有对输入结果进行预先处理的代码，会发生 sql 注入。
package Demo000.demo001;
import java.sql.*;
import java.util.*;
public class JDBCTest001 {
public static void main(String[] args) {
ResourceBundle bundle = ResourceBundle.getBundle("jdbc");
String driver = bundle.getString("driver");
String url = bundle.getString("url");
String user = bundle.getString("user");
String password = bundle.getString("password");
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try{
Class.forName(driver);
conn = DriverManager.getConnection(url,user,password);
stmt = conn.createStatement();
rs = stmt.executeQuery("select deptno,ename,sal from emp");
while(rs.next()){
String deptno = rs.getString("deptno");
String ename = rs.getString("ename");
String sal = rs.getString("sal");
System.out.println(deptno + " " + ename + " " + sal);
}
}catch(Exception e){
e.printStackTrace();
}finally{
if(rs != null){
try{
rs.close();
}catch(SQLException e){
e.printStackTrace();
}
}
if(stmt != null){
try{
stmt.close();
}catch(SQLException e){
e.printStackTrace();
}
}
if(conn != null){
try{
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
}
}
}
}
为了避免 sql 注入的发生，可以使用下面的代码
package JDBCTest07;
import java.sql.*;
import java.util.ResourceBundle;
public class JDBCTest07 {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try{
ResourceBundle bundle = ResourceBundle.getBundle("jdbc");
String driver = bundle.getString("driver");
String url = bundle.getString("url");
String user = bundle.getString("user");
String password = bundle.getString("password");
Class.forName(driver);
conn = DriverManager.getConnection(url,user,password);
String sql = "select * from t_student";
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
while(rs.next()){
String no = rs.getString("no");
String name = rs.getString("name");
System.out.println(no + " " + name);
}
}catch(Exception e){
e.printStackTrace();
}finally{
if(rs != null){
try{
rs.close();
}catch(Exception e){
e.printStackTrace();
}
}
if(ps != null){
try{
ps.close();
}catch(Exception e){
e.printStackTrace();
}
}
if(conn != null){
try{
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
}
}
}