4、在MyJDBCUtils中加入Properties保存数据库的配置信息

1、为了程序更好的解耦合,在MyJDBCUtils中加入Properties保存数据库的配置信息.

2、db.properties文件的内容如下

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/testdatabase
username=root
password=1234

3、MyJDBCUtils的代码如下

package com.jdbc.utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class MyJDBCUtils {
// 为了程序的更好的解耦合,利用Properties文件保存连接Mysql的配置文件
private static Properties config = new Properties();
static {
try {
config.load(MyJDBCUtils.class.getClassLoader().getResourceAsStream(
"db.properties"));
Class.forName(config.getProperty("driver"));
} catch (Exception e) {
throw new ExceptionInInitializerError(e);
}
}

public static Connection getConnection() {
Connection conn = null;
try {
conn = DriverManager.getConnection(config.getProperty("url"),
config.getProperty("username"),
config.getProperty("password"));
} catch (SQLException e) {
throw new RuntimeException("获取连接Mysql数据库连接失败");
}
return conn;
}

public static void release(Connection conn, Statement st, ResultSet rs) {

if (rs != null) {
try {
rs.close();
} catch (Exception e) {
throw new RuntimeException("ResultSet关闭异常");
}
rs = null;
}
if (st != null) {
try {
st.close();
} catch (Exception e) {
throw new RuntimeException("Statement关闭异常");
}
st = null;
}
if (conn != null) {
try {
conn.close();
} catch (Exception e) {
throw new RuntimeException("Connection关闭异常");
}
conn = null;
}

}

}

4、利用MyJDBCUtils连接数据库的代码如下

package com.jdbc.utils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

import org.junit.Test;

public class TestMyJDBCUtils {

@Test
public void testMyJDBCUtils() {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = MyJDBCUtils.getConnection();
st = conn.createStatement();
rs = st.executeQuery("select * from user  ");

while (rs.next()) {
int id = rs.getInt(rs.findColumn("id"));
String uname = rs.getString(rs.findColumn("uname"));
int age = rs.getInt(rs.findColumn("age"));
// 遍历输出
System.out.println("id " + id + " " + "uname " + uname + " "
+ "age " + age + " ");
}

} catch (Exception e) {
throw new RuntimeException(e);
}
}
}