java 每日习题（九）从数据库中取数据

题目：连接数据库，取出数据。

用到的类：

Connection：连接数据库

Statement:The object used for executing a static SQL statement and returning the results it produces.

ResultSet:A table of data representing a database result set, which is usually generated by executing a statement that queries the database.

package everyDay;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

public class GetData {

    @Test
    public void mysqlconnection() {
        try {
            String url = "jdbc:mysql://10.255.255.148:3306/testresults";
            String user = "user";
            String password = "pwd";
            Connection conn = DriverManager.getConnection(url, user, password);
            Statement stmt = conn.createStatement();
            //conn.setAutoCommit(false);

            String sql = "select timeStamp, elapsed from cpuInfo order by timeStamp";

            ResultSet rs = stmt.executeQuery(sql);
            //conn.commit();
            //conn.setAutoCommit(true);

            List<String> list = new ArrayList<String>();

            while (rs.next()) {
                list.add(rs.getString(1));//添加其中一列

            }
            if (list != null && list.size() > 0) {// 如果list中存入了数据，转化为数组
                String[] arr = new String[list.size()];// 创建一个和list长度一样的数组
                for (int i = 0; i < list.size(); i++) {
                    arr[i] = list.get(i);// 数组赋值。
                }
                // 输出数组
                for (int i = 0; i < arr.length; i++) {
                    System.out.println(arr[i]);
                }
            }

        } catch (Exception e) {
            // TODO: handle exception
        }

    }
}