1 package com.homewoek3_4.dao;
2
3 import java.io.IOException;
4 import java.io.InputStream;
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 * 数据库连接通用类
14 * @author Administrator
15 */
16 public abstract class BaseDao {
17 private static final String path = "database.properties";
18 private static String DB_DRIVER;
19 private static String DB_URL;
20 private static String DB_USER;
21 private static String DB_PWD;
22
23 protected Connection conn = null;
24 protected PreparedStatement ps = null;
25 protected ResultSet rs = null;
26
27 static {
28 Properties pro = new Properties();
29 InputStream io = BaseDao.class.getClassLoader().getResourceAsStream(path);
30 try {
31 //读取配置文件
32 pro.load(io);
33 } catch (IOException e) {
34 e.printStackTrace();
35 }
36 DB_DRIVER = pro.getProperty("DB_DRIVER");
37 DB_URL = pro.getProperty("DB_URL");
38 DB_USER = pro.getProperty("DB_USER");
39 DB_PWD = pro.getProperty("DB_PWD");
40 try {
41 //加载驱动类
42 Class.forName(DB_DRIVER);
43 } catch (ClassNotFoundException e) {
44 e.printStackTrace();
45 }
46 }
47 /**
48 * 打开数据库连接
49 */
50 protected void openConn() {
51 try {
52 conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PWD);
53 } catch (SQLException e) {
54 e.printStackTrace();
55 }
56 }
57 /**
58 * 关闭数据库连接
59 */
60 protected void closeConn() {
61 try {
62 if (rs != null) {
63 rs.close();
64 }
65 if (ps != null) {
66 ps.close();
67 }
68 if (conn != null) {
69 conn.close();
70 }
71 } catch (SQLException e) {
72 e.printStackTrace();
73 }
74 }
75 /**
76 * 增删改
77 * @param sql
78 * @param obj
79 * @return
80 */
81 protected int executeUpdate(String sql, Object...obj) {
82 int result = -1;
83 this.openConn();
84 try {
85 ps = conn.prepareStatement(sql);
86 if (obj != null) {
87 for (int i = 0; i < obj.length; i++) {
88 ps.setObject(i+1, obj[i]);
89 }
90 }
91 result = ps.executeUpdate();
92 } catch (SQLException e) {
93 e.printStackTrace();
94 }
95 return result;
96 }
97 /**
98 * 查询
99 * @param sql
100 * @param obj
101 * @return
102 */
103 protected void executeQuery(String sql, Object...obj) {
104 this.openConn();
105 try {
106 ps = conn.prepareStatement(sql);
107 if (obj != null) {
108 for (int i = 0; i < obj.length; i++) {
109 ps.setObject(i+1, obj[i]);
110 }
111 }
112 rs = ps.executeQuery();
113 } catch (SQLException e) {
114 e.printStackTrace();
115 }
116 }
117 }
创建database.properties文件，注意：后缀名一定是properties。此格式的文件在MyEclipse中图标会变，这点很容易写错，要注意。
1 DB_DRIVER=com.mysql.jdbc.Driver
2 DB_URL=jdbc:mysql://localhost:3306/Pet?useUnicode=true&characterEncoding=utf8&useSSL=true
3 DB_USER=root
4 DB_PWD=111111