java之操作mysql常用方法

package DBManager;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashSet;
import java.util.Set;

import MyClient.ArrivalCities;
import MyClient.LineInfos;
import MyClient.TrainLineInfo;

public class DBHelper {

private static final String DRIVER = "com.mysql.jdbc.Driver";
private static final String URL = "jdbc:mysql://localhost:3306/traininfo";
private static final String USERNAME = "root";
private static final String PASSWORD = "123abcd";
Connection conn = null;
ResultSet result = null;
PreparedStatement statement = null;
PreparedStatement stateInsert = null;
PreparedStatement stateUnlock = null;

public Connection getConnection() {
try {
Class.forName(DRIVER);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}

public ResultSet executeQuery(String sql) {
conn = this.getConnection();
try {
statement = conn.prepareStatement(sql);
result = statement.executeQuery();
return result;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("query data failed");
}
return null;
}

public ResultSet findTrainLinesByDate(String start_city, String date) {
String dateStr = dateToString(date);
ResultSet result = this.executeQuery("select name,start_time from "
+ "line_" + dateStr + "_info " + "where start_city='"
+ start_city + "' and date='" + date + "'");
return result;
}

public ResultSet findArrivalCities(String city, String line) {
ResultSet result = this
.executeQuery("select distinct arrival_city from " + city
+ "_city_info where line_num='" + line + "'");
return result;
}

public ArrivalCities getAllArrivalCities(String startCity, String date) {
ArrivalCities cities = new ArrivalCities();
Set<String> list = new HashSet<String>();
ResultSet lines = this.findTrainLinesByDate(startCity, date);
try {
while (lines.next()) {
ResultSet arrivals = this.findArrivalCities(startCity,
lines.getString("name"));
while (arrivals.next()) {
list.add(arrivals.getString("arrival_city"));
}
}
if (list.size() > 0) {
cities.setCities(list);
return cities;
}
return null;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}

public LineInfos getAllLineInfos(String startCity, String arrivalCity,
String date) {
LineInfos lineinfos = new LineInfos();
ResultSet lines = this.findTrainLinesByDate(startCity, date);
if (lines != null) {
try {
while (lines.next()) {
String name = lines.getString("name");
ResultSet result = this.executeQuery("select price from "
+ startCity + "_city_info where arrival_city="
+ '"' + arrivalCity + '"' + " and line_num=" + '"'
+ name + '"');
if (result.next()) {
TrainLineInfo train = new TrainLineInfo(name,
result.getInt("price"),
lines.getLong("start_time"));
lineinfos.getList().add(train);
}
}
return lineinfos;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return null;
}

public ResultSet findNumOfSellSeats(String date, String line) {
String dateStr = dateToString(date);
ResultSet result = this.executeQuery("SELECT count(id) as num from "
+ line + "_" + dateStr + "_info where is_out=1");
return result;
}

public String dateToString(String date) {
String[] result = date.split("-");
StringBuilder sb = new StringBuilder();
for (String ss : result) {
sb.append(ss);
}
return sb.toString();
}

//购票，更新数据库信息
public void getBuyTicket(String dep_city,String arr_city, String date, String line){
String seat = getProperSeat(dep_city, line, date);
String sql = "update ";

}

public boolean executeDelete(String sql) {
conn = this.getConnection();
try {
statement = conn.prepareStatement(sql);
if (statement.executeUpdate() > 0) {
return true;
}
} catch (SQLException e) {
// TODO Auto-generated catch block
System.out.println("delete data failed");
e.printStackTrace();
}
return false;
}

public boolean executeUpdate(String sql) {
conn = this.getConnection();
try {
statement = conn.prepareStatement(sql);
if (statement.executeUpdate() > 0) {
return true;
}
} catch (SQLException e) {
// TODO Auto-generated catch block
System.out.println("update data failed");
e.printStackTrace();
}
return false;
}

public boolean executeInsert(String sql, String date, String line) {
conn = this.getConnection();
String lockSql = "lock tables " + line + "_" + date + "_info write";
String unlockSql = "unlock tables";
try {
stateInsert = conn.prepareStatement(lockSql);
statement = conn.prepareStatement(sql);
stateUnlock = conn.prepareStatement(unlockSql);
stateInsert.executeQuery();
if (statement.executeUpdate() > 0) {
stateUnlock.executeQuery();
return true;
}
stateUnlock.executeQuery();
} catch (SQLException e) {
// TODO Auto-generated catch block
System.out.println("insert data failed");
e.printStackTrace();
}
return false;
}

}