feat：统一数据库信息

README.md

@@ -93,9 +93,9 @@
 
 下载压缩包，或者使用`git clone`下载（使用`git checkout maven`可以更换为分支maven，其使用maven进行依赖管理，更便于运行部署）
 
-将**library.sql文件导入mysql数据库**，并需要修改以下两个数据库连接相关属性（数据库账号密码、数据库表名）
+将**library.sql文件导入mysql数据库**，并修改以下文件的数据库连接相关属性（数据库账号密码、数据库表名）
 
-![](https://ming-edu.oss-cn-beijing.aliyuncs.com/image-20201117122227215.png)
+![](https://ming-edu.oss-cn-beijing.aliyuncs.com/1630034271536.png)
 
 # 三、项目演示
 

src/javabean/Base.java

@@ -7,10 +7,10 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 
 public class Base {
-	private static String driver = "com.mysql.cj.jdbc.Driver";
+	private static final String driver = DBConstants.driver;
-	private static String url = "jdbc:mysql://localhost:3306/library?&useSSL=false&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";
+	private static final String url = DBConstants.url;
-	private static String username = "root";
+	private static final String username = DBConstants.username;
-	private static String password = "root";
+	private static final String password = DBConstants.password;
 
 	/**
 	 * 获取数据库连接

src/javabean/DBConstants.java

@@ -0,0 +1,8 @@
+package javabean;
+
+public class DBConstants {
+    public static final String driver = "com.mysql.cj.jdbc.Driver";
+    public static final String url = "jdbc:mysql://localhost:3306/library?&useSSL=false&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";
+    public static final String username = "root";
+    public static final String password = "root";
+}

src/javabean/JDBCBean.java

@@ -6,10 +6,10 @@ import java.sql.ResultSet;
 import java.sql.Statement;
 
 public class JDBCBean {
-	private static String driver = "com.mysql.cj.jdbc.Driver";
+	private static final String driver = DBConstants.driver;
-	private static String url = "jdbc:mysql://localhost:3306/library?&useSSL=false&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8";
+	private static final String url = DBConstants.url;
-	private static String username = "root";
+	private static final String username = DBConstants.username;
-	private static String password = "root";
+	private static final String password = DBConstants.password;
 	private Connection conn = null;
 	private Statement stmt = null;