import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.mysql.jdbc.PreparedStatement;


public class JdbcUtils {
// 獲取資料庫的連線
public static Connection getConnection() {
String driver = "com.mysql.jdbc.Driver";// 驅動，固定寫法
String url = "jdbc:mysql://localhost:3306/test?characterEncoding=utf-8";// 不加字元編碼中文會亂碼，親測
String userName = "admin";
String password = "7758258";
Connection conn = null;
try {
Class.forName(driver);
conn = DriverManager.getConnection(url, userName, password);
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}


// 增加
public static void getAllUser() {
Connection conn = JdbcUtils.getConnection();
String sql = "select * from user";
PreparedStatement pstmt;
try {
pstmt = (PreparedStatement) conn.prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();
int col = rs.getMetaData().getColumnCount();


while (rs.next()) {
for (int i = 1; i <= col; i++) {
System.out.print(rs.getString(i) + "\t");
}
System.out.println("");
}


} catch (SQLException e) {
e.printStackTrace();
}
}


// 插入
public static int insertUser(User user) {
Connection conn = JdbcUtils.getConnection();
int i = 0;
String sql = "insert into user (name,sex,age) values(?,?,?)";
PreparedStatement pstmt;
try {
pstmt = (PreparedStatement) conn.prepareStatement(sql);
pstmt.setString(1, user.getName());
pstmt.setString(2, user.getSex());
pstmt.setInt(3, user.getAge());
i = pstmt.executeUpdate();
pstmt.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
return i;
}


// 修改
public static int updateUser(User user) {
Connection conn = JdbcUtils.getConnection();
int i = 0;
String sql = "update user set age='" + user.getAge() + "' where name='"
+ user.getName() + "'";
PreparedStatement pstmt;
try {
pstmt = (PreparedStatement) conn.prepareStatement(sql);
i = pstmt.executeUpdate();
pstmt.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
return i;
}


// 刪除
public static int deleteUser(User user) {
Connection conn = JdbcUtils.getConnection();
   int i = 0;
   String sql = "delete from user where name='" + user.getName() + "'";
   PreparedStatement pstmt;
   try {
       pstmt = (PreparedStatement) conn.prepareStatement(sql);
       i = pstmt.executeUpdate();
       pstmt.close();
       conn.close();
   } catch (SQLException e) {
       e.printStackTrace();
   }
   return i;
}


// 用於測試的main方法
public static void main(String[] args) {
// 測試查詢方法
JdbcUtils.getAllUser();


// 測試插入方法
User user = new User();
user.setName("張三");
user.setSex("男");
user.setAge(55);
int i = JdbcUtils.insertUser(user);
System.out.print(i);


// 測試更新方法
user.setAge(100);
user.setName("zhangsan");
i = JdbcUtils.updateUser(user);

//測試刪除方法
user.setName("zhangsan");
i = JdbcUtils.deleteUser(user);
}
}