把一些步骤抽取出来然后，从properties获取连接属性。

在项目下新建一个配置文件夹config和配置文件database.properties里面这样写，和map一样以键值对的形式存在，前面键后面值。因为我的密码为空所以不写。

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mydata?useUnicode=true&characterEncoding=UTF-8
user=root
password=

然后Properties加载配置文件，同时把读取配置文件写在静态代码块中方便只加载一次。

 1     static String driver;
 2     static String url;
 3     static String user;
 4     static String password;
 5 
 6     static {// 加载配置文件
 7         Properties properties = new Properties();
 8         try {
 9             BufferedReader br = new BufferedReader(new FileReader("config/database.properties"));
10             properties.load(br);
11             driver = properties.getProperty("driver");
12             url = properties.getProperty("url");
13             user = properties.getProperty("user");
14             password = properties.getProperty("password");
15         } catch (FileNotFoundException e) {
16             e.printStackTrace();
17         } catch (IOException e) {
18             e.printStackTrace();
19         }
20     }

再把获取数据库连接抽取出来

 1 /** 获取数据库连接 */
 2     public Connection getConnection() {
 3         Connection conn = null;
 4         try {
 5             // 1、加载驱动
 6             Class.forName(driver);
 7             // 2、建立连接
 8             conn = DriverManager.getConnection(url, user, password);
 9         } catch (ClassNotFoundException e) {
10             e.printStackTrace();
11         } catch (SQLException e) {
12             e.printStackTrace();
13         }
14         return conn;
15     }

把增删改抽取出来（查询单独出来在上一个博客）

 1 /**
 2      * 增删改
 3      */
 4     public int execute(String sql, Object... args) {
 5         Connection conn = null;
 6         int result = -1;
 7         PreparedStatement ps = null;
 8         try {
 9             conn = this.getConnection();
10             ps = conn.prepareStatement(sql);
11             if (args != null) {
12                 for (int i = 0; i < args.length; i++) {
13                     ps.setObject(i + 1, args[i]);
14                 }
15             }
16             result = ps.executeUpdate();
17         } catch (SQLException e) {
18             e.printStackTrace();
19         } finally {
20             this.closeAll(null, ps, conn);
21         }
22 
23         return result;
24     }

最后把关闭资源抽出来

 1 /**
 2      * 关闭资源
 3      */
 4 
 5     public void closeAll(ResultSet rs, PreparedStatement ps, Connection conn) {
 6         try {
 7             if (rs != null)
 8                 rs.close();
 9             if (ps != null)
10                 ps.close();
11             if (conn != null)
12                 conn.close();
13         } catch (SQLException e) {
14             e.printStackTrace();
15         }
16     }

最后代码就行这样

 1 import java.io.BufferedReader;
 2 import java.io.FileNotFoundException;
 3 import java.io.FileReader;
 4 import java.io.IOException;
 5 import java.sql.Connection;
 6 import java.sql.DriverManager;
 7 import java.sql.PreparedStatement;
 8 import java.sql.ResultSet;
 9 import java.sql.SQLException;
10 import java.util.Properties;
11 
12 /**
13  * 数据库连接工具类
14  * 
15  * @author W
16  *
17  */
18 
19 public class JDBCUtils {
20     static String driver;
21     static String url;
22     static String user;
23     static String password;
24 
25     static {// 加载配置文件
26         Properties properties = new Properties();
27         try {
28             BufferedReader br = new BufferedReader(new FileReader("config/database.properties"));
29             properties.load(br);
30             driver = properties.getProperty("driver");
31             url = properties.getProperty("url");
32             user = properties.getProperty("user");
33             password = properties.getProperty("password");
34         } catch (FileNotFoundException e) {
35             e.printStackTrace();
36         } catch (IOException e) {
37             e.printStackTrace();
38         }
39     }
40 
41     /** 获取数据库连接 */
42     public Connection getConnection() {
43         Connection conn = null;
44         try {
45             // 1、加载驱动
46             Class.forName(driver);
47             // 2、建立连接
48             conn = DriverManager.getConnection(url, user, password);
49         } catch (ClassNotFoundException e) {
50             e.printStackTrace();
51         } catch (SQLException e) {
52             e.printStackTrace();
53         }
54         return conn;
55     }
56 
57     /**
58      * 关闭资源
59      */
60 
61     public void closeAll(ResultSet rs, PreparedStatement ps, Connection conn) {
62         try {
63             if (rs != null)
64                 rs.close();
65             if (ps != null)
66                 ps.close();
67             if (conn != null)
68                 conn.close();
69         } catch (SQLException e) {
70             e.printStackTrace();
71         }
72     }
73 
74     /**
75      * 增删改
76      */
77     public int execute(String sql, Object... args) {
78         Connection conn = null;
79         int result = -1;
80         PreparedStatement ps = null;
81         try {
82             conn = this.getConnection();
83             ps = conn.prepareStatement(sql);
84             if (args != null) {
85                 for (int i = 0; i < args.length; i++) {
86                     ps.setObject(i + 1, args[i]);
87                 }
88             }
89             result = ps.executeUpdate();
90         } catch (SQLException e) {
91             e.printStackTrace();
92         } finally {
93             this.closeAll(null, ps, conn);
94         }
95 
96         return result;
97     }
98 
99 }

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