java 连接数据库测试类
时间：2021-07-01 10:21:17
帮助过：20人阅读
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.HashMap;
import java.util.List;
public class ConnectionTest {
public static Connection getConnection() {
// 定义连接
Connection connection =
null;
try {
// 加载驱动
Class.forName("com.mysql.jdbc.Driver"
);
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "123456"
);
} catch (Exception e) {
e.printStackTrace();
}
return connection;
}
public static List<HashMap<String, Object>>
getMysqlData() {
Connection connection =
null;
// 预执行加载
PreparedStatement preparedStatement =
null;
// 结果集
ResultSet resultSet =
null;
connection =
getConnection();
String sqlString = "select * from user"
;
List<HashMap<String, Object>> list =
new ArrayList<HashMap<String,Object>>
();
try {
preparedStatement =
connection.prepareStatement(sqlString);
resultSet =
preparedStatement.executeQuery();
HashMap<String, Object> map =
null;
while (resultSet.next()) {
map =
new HashMap<String, Object>
();
map.put("name", resultSet.getString("user_name"
));
list.add(map);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (resultSet !=
null) {
resultSet.close();
}
if (preparedStatement !=
null) {
preparedStatement.close();
}
if (connection !=
null) {
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
return list;
}
public static void main(String[] args) {
List<HashMap<String, Object>> mysqlData =
getMysqlData();
for(HashMap<String, Object>
map : mysqlData) {
System.out.println(map.get("name"
));
}
}
}
java 连接数据库测试类
标签：exec 连接数 sql port java print com ret stat
