import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JDBCUtil {
// 驱动包名和数据库url
private static String url = null;
private static String driverClass = null;
// 数据库用户名和密码
private static String userName = null;
private static String password = null;
/**
* 初始化驱动程序
* 静态代码块中（只加载一次）
*/
static{
try {
//读取db.properties文件
Properties prop = new Properties();
/**
* 使用类路径的读取方式
* / : 斜杠表示classpath的根目录
* 在java项目下，classpath的根目录从bin目录开始
* 在web项目下，classpath的根目录从WEB-INF/classes目录开始
*/
InputStream in = JDBCUtil.class.getResourceAsStream("/db.properties");
//加载文件
prop.load(in);
//读取信息
url = prop.getProperty("url");
driverClass = prop.getProperty("driverClass");
userName = prop.getProperty("user");
password = prop.getProperty("password");
//注册驱动程序
Class.forName(driverClass);
} catch (Exception e) {
e.printStackTrace();
System.out.println("驱程程序注册出错");
}
}
/**
* 打开数据库驱动连接
*/
public static Connection getConnection(){
try {
Connection conn = DriverManager.getConnection(url, userName, password);
return conn;
} catch (SQLException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
/**
* 清理环境，关闭连接(顺序:后打开的先关闭)
*/
public static void close(Connection conn,Statement stmt,ResultSet rs){
if(rs!=null)
try {
rs.close();
} catch (SQLException e1) {
e1.printStackTrace();
throw new RuntimeException(e1);
}
if(stmt!=null){
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
}
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
conn=JDBCUtil.getConnection();
try {
stmt=conn.createStatement();
//准备sql操作语句
String sql= "SELECT cid,name,address FROM client";
rs = stmt.executeQuery(sql);
//从结果集中提取数据
while(rs.next()){
int cid = rs.getInt("cid");
String name = rs.getString("name");
String address = rs.getString("address");
System.out.print("CID: " + cid);
System.out.print(", name: " + name);
System.out.println(", address: " + address);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
JDBCUtil.close(conn, stmt, rs);
}
}
}
// db.properties文件
url=jdbc:mysql://localhost/fdb
user=root
password=root
driverClass=com.mysql.jdbc.Driver
package db;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import entity.Client;
public class ClientDao {
private Connection conn = JDBCUtil.getConnection();
private ResultSet rs = null;
/**
* 添加一个Client
* @param c
* @return
*/
public int addClient(Client c){
String sql= "insert into client(name,address) values(?,?)";
int i = 0;
try{
PreparedStatement ptmt=conn.prepareStatement(sql);
ptmt.setString(1, c.getName());
ptmt.setString(2, c.getAddress());
i = ptmt.executeUpdate();
ptmt.close();
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
return i;
}
/**
* 更新Client的Name字段
* @param c
* @return
*/
public int updateClientName(Client c){
String sql = "update client set name='"+c.getName()+"' where cid="+c.getCid();
int i=0;
try{
PreparedStatement pstmt = (PreparedStatement) conn.prepareStatement(sql);
i = pstmt.executeUpdate();
pstmt.close();
conn.close();
}catch (SQLException e) {
e.printStackTrace();
}
return i;
}
/**
*
* @param c
* @return
*/
public int updateClientAddress(Client c){
String sql = "update client set address='"+c.getAddress()+"' where cid="+c.getCid();
int i=0;
try{
PreparedStatement pstmt = (PreparedStatement) conn.prepareStatement(sql);
i = pstmt.executeUpdate();
pstmt.close();
conn.close();
}catch (SQLException e) {
e.printStackTrace();
}
return i;
}
/**
* 根据cid删除Client
* @param c
* @return
*/
public int delClientById(Client c){
String sql= "delete from client where cid=?";
int i = 0;
try{
PreparedStatement ptmt=conn.prepareStatement(sql);
ptmt.setInt(1, c.getCid());
i = ptmt.executeUpdate();
ptmt.close();
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
return i;
}
/**
* 根据Cid查询Client
* @param c
* @return 返回一个Client
*/
public Client selClientById(Client c){
String sql= "select cid,name,address from client where cid=?";
Client client = new Client();
try{
PreparedStatement ptmt=conn.prepareStatement(sql);
ptmt.setInt(1, c.getCid());
ResultSet rs =ptmt.executeQuery();
while(rs.next()){
int cid = rs.getInt(1);
String name = rs.getString(2);
String addr = rs.getString(3);
client.setCid(cid);
client.setName(name);
client.setAddress(addr);
}
ptmt.close();
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
return client;
}
/**
* 根据Address查询Client
* @param c
* @return Client的列表
*/
public List<Client> selClientByAddress(Client c){
String sql= "select cid,name,address from client where address=?";
List<Client> list = new ArrayList<Client>();
try{
PreparedStatement ptmt=conn.prepareStatement(sql);
ptmt.setString(1, c.getAddress());
ResultSet rs =ptmt.executeQuery();
while(rs.next()){
int cid = rs.getInt(1);
String name = rs.getString(2);
String addr = rs.getString(3);
Client client = new Client();
client.setCid(cid);
client.setName(name);
client.setAddress(addr);
list.add(client);
}
ptmt.close();
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
return list;
}
/**
* 根据Name查询Client
* @param c
* @return
*/
public List<Client> selClientByName(Client c){
String sql= "select cid,name,address from client where name=?";
List<Client> list = new ArrayList<Client>();
try{
PreparedStatement ptmt=conn.prepareStatement(sql);
ptmt.setString(1, c.getName());
ResultSet rs =ptmt.executeQuery();
while(rs.next()){
int cid = rs.getInt(1);
String name = rs.getString(2);
String addr = rs.getString(3);
Client client = new Client();
client.setCid(cid);
client.setName(name);
client.setAddress(addr);
list.add(client);
}
ptmt.close();
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
return list;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
}
}