本文已参与「新人创作礼」活动，一起开启掘金创作之路。
编写一个 JDBC 的使用程序，对商品表 gds_goods 进行操作，要求 1.编写一个 JDBC 联接的单例模式，用于联接数据库 2.编写测试类，使用编好联接类，取出商品表中的全部数据，输出内容
实现代码：
package com.zhangyufan.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class TestDbConn {
public static void main(String[] args) throws Exception {
String sql = "select * from gds_goods";
ResultSet rs = DbConn.exeQuery(sql, null);
System.out.println("商品表中的内容：");
while (rs.next()) {
System.out.println(rs.getInt("gds_id") + "\t" + rs.getString("gds_no") + "\t" + rs.getString("gds_name")
+ "\t" + rs.getDouble("gds_price") + "\t" + rs.getString("gds_memo"));
}
rs.close();
DbConn.close();
}
}
class DbConn {
private static String driver = "com.mysql.jdbc.Driver";
private static String dbname = "zyf";
private static String userName = "root";
private static String passWord = "root";
private static String url = "jdbc:mysql://localhost:3306/" + dbname;
private static Connection conn = null;
static {
try {
Class.forName(driver);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
private DbConn() {
}
public static Connection getConn() {
if (conn == null) {
try {
conn = DriverManager.getConnection(url, userName, passWord);
} catch (SQLException e) {
e.printStackTrace();
}
}
return conn;
}
public static void close() throws Exception {
if (conn != null) {
try {
conn.close();
} catch (Exception e) {
throw e;
}
}
}
public static ResultSet exeQuery(String sql, Object[] params) {
try {
Connection conn = getConn();
PreparedStatement ps = conn.prepareStatement(sql);
if (params != null) {
for (int i = 0; i < params.length; i++) {
ps.setObject(i + 1, params[i]);
}
}
ResultSet rs = ps.executeQuery();
return rs;
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
public static int execUpdate(String sql, Object[] params) {
try {
Connection conn = getConn();
PreparedStatement ps = conn.prepareStatement(sql);
if (params != null) {
for (int i = 0; i < params.length; i++) {
ps.setObject(i + 1, params[i]);
}
}
return ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
}
return -1;
}
}
运行结果：
