模仿DBUtils里面的一些用法,下面是一些简单的实现数据集的操作的方法
下面使用到的两个bean。首先是userbean
package bean;
public class user {
String username;
String password;
public user(){
username=null;
password=null;
}
@Override
public String toString() {
return "user [username=" + username + ", password=" + password + "]";
}
public user(String username, String password) {
super();
this.username = username;
this.password = password;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
接下来是itemsbean的代码,都很简单
package bean;
public class Items {
String title;
String contents;
public Items(){
title=null;
contents=null;
}
public Items(String title, String contents) {
super();
this.title = title;
this.contents = contents;
}
@Override
public String toString() {
return "Items [title=" + title + ", contents=" + contents + "]";
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getContents() {
return contents;
}
public void setContents(String contents) {
this.contents = contents;
}
}
接下来就是重头戏了,也即是我们的DBHelper类,主要的思想是其中对bean的操作,还有是如何将数据集进行封装的
package DBUtils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import bean.Items;
import bean.user;
/**
* 易错点:
* 需要注意的是items表中有一项在数据库中为content,而bean里设置出错,设置成了contents,尤其应该注意;
* @author Summer
*
*/
public class Dbutiler {
static String DRIVER="com.mysql.jdbc.Driver";
static String CONNECTIONURL="jdbc:mysql://127.0.0.1:3306/summer";
static String ROOT="root";
static String PASSWORD="mysql";
Connection conn=null;
PreparedStatement ps=null;
ResultSet result=null;
public Dbutiler(){
try {
Class.forName(DRIVER);
conn=(Connection) DriverManager.getConnection(CONNECTIONURL, ROOT, PASSWORD);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
if(conn!=null){
System.out.println("Connected!");
}
}
//下面是获得用户信息数据集
public List getUserInfo(String sql){
user tempUser=null;
List userList=new ArrayList();
try {
ps=conn.prepareStatement(sql);
result=ps.executeQuery();
while(result.next()){
tempUser=new user();
String userName=result.getString("username");
String passWord=result.getString("password");
tempUser.setUsername(userName);
tempUser.setPassword(passWord);
userList.add(tempUser);
//感悟就是,每次invoke之后,都要及时的进行置空,否则可能得不到新值
tempUser=null;
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
if(ps!=null){
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
ps=null;
}
if(result!=null){
try {
result.close();
} catch (SQLException e) {
e.printStackTrace();
}
result=null;
}
}
return userList;
}
//下面是插入用户的方法
public boolean addUser(user userInfo){
int flag=0;
try {
String sql="insert into user(username,password) values(?,?);";
ps=(PreparedStatement) conn.prepareStatement(sql);
ps.setString(1,userInfo.getUsername());
ps.setString(2, userInfo.getPassword());
flag=ps.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}finally{
if(ps!=null){
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
ps=null;
}
if(result!=null){
try {
result.close();
} catch (SQLException e) {
e.printStackTrace();
}
result=null;
}
}
if(flag!=0){
return true;
}else{
return false;
}
}
public List getItemsInfo(String sql){
Items tempItem=null;
List ItemsInfo=new ArrayList();
try {
ps=conn.prepareStatement(sql);
result=ps.executeQuery();
while(result.next()){
tempItem=new Items();
String Title=result.getString("title");
String Contents=result.getString("content");
tempItem.setTitle(Title);
tempItem.setContents(Contents);
ItemsInfo.add(tempItem);
//感悟就是,每次invoke之后,都要及时的进行置空,否则可能得不到新值
tempItem=null;
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
if(ps!=null){
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
ps=null;
}
if(result!=null){
try {
result.close();
} catch (SQLException e) {
e.printStackTrace();
}
result=null;
}
}
return ItemsInfo;
}
//下面是添加数据信息的方法
public boolean addOneItem(Items item){
int flag=0;
try {
String sql="insert into items(title,content) values(?,?);";
ps=(PreparedStatement) conn.prepareStatement(sql);
ps.setString(1,item.getTitle());
ps.setString(2, item.getContents());
flag=ps.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}finally{
if(ps!=null){
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
ps=null;
}
if(result!=null){
try {
result.close();
} catch (SQLException e) {
e.printStackTrace();
}
result=null;
}
}
if(flag!=0){
return true;
}else{
return false;
}
}
public static void main(String []args){
Dbutiler helper=new Dbutiler();
//对存储的用户信息进行测试
user one=new user("Rui","Tiger");
helper.addUser(one);
List res=new ArrayList();
res=helper.getUserInfo("select * from user;");
for(int i=0;iitemsList=new ArrayList();
itemsList=helper.getItemsInfo("select * from items;");
if(itemsList.isEmpty()){
System.out.println("This resultSet is empty!");
}else{
for(int i=0;i
相应的我们运行完程序之后,是可以在MySQL的数据库下进行查看的,确实是插入进去了,而查找的时候也会返回我们想要查找的并且符合要求的值。