<span style="font-family: 'Microsoft YaHei'; font-size: 18px;">package com.myit.util;
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.List;
public class DBHelper {
private static final String DRIVER="com.mysql.jdbc";
private static final String URL="jdbc:mysql://localhost:3306/dvd";
private static final String USER="root";
private static final String PASSWORD="root";
/**
* 连接数据库
* @return 链接数据库对象
*/
public Connection getConnection(){
Connection conn=null;
try {
Class.forName(DRIVER);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
try {
conn=DriverManager.getConnection(URL, USER, PASSWORD);
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
/**
* 释放相应的资源
* @param rs
* @param pstmt
* @param conn
*/
public void closeAll(ResultSet rs,PreparedStatement pstmt,Connection conn){
try {
if(rs!=null){
rs.close();
}
if(pstmt!=null){
pstmt.close();
}
if(conn!=null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
* 此方法可以完成增删改所有的操作
* @param sql
* @param params
* @return true or false
*/
public boolean excuteUpdate(String sql,List<Object> params){
int res=0;
Connection conn=null;
PreparedStatement pstmt = null;
ResultSet rs=null;
try {
conn=getConnection();
pstmt=conn.prepareStatement(sql);
if(params!=null){
for(int i=0;i<params.size();i++){
pstmt.setObject(i+1, params.get(i));
}
}
res=pstmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}finally{
closeAll(rs, pstmt, conn);
}
return res>0?true:false;
}
/**
* 使用泛型方法和反射机制进行封装
* @param sql
* @param params
* @param cls
* @return
*/
public <T> List<T> executeQuery(String sql,List<Object> params,Class<T> cls) throws Exception{
Connection conn=null;
PreparedStatement pstmt = null;
ResultSet rs=null;
List<T> data=new ArrayList<T>();
try {
conn=getConnection();
pstmt=conn.prepareStatement(sql);
if(params!=null){
for(int i=0;i<params.size();i++){
pstmt.setObject(i+1, params.get(i));
}
}
rs=pstmt.executeQuery();
ResultSetMetaData rsd=rs.getMetaData();
while(rs.next()){
T m=cls.newInstance();
for(int i=0;i<rsd.getColumnCount();i++){
String col_name=rsd.getColumnName(i+1);
Object value=rs.getObject(col_name);
Field field=cls.getDeclaredField(col_name);
field.setAccessible(true);
field.set(m, value);
}
data.add(m);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
closeAll(rs, pstmt, conn);
}
return data;
}
}
</span>
