使用动态代理实现数据库事务
数据库sql：
1 create table T_USER
2 (
3 USER_ID VARCHAR(10) not null,
4 USER_NAME VARCHAR(30) not null,
5 PASSWORD VARCHAR(20) not null,
6 CONTACT_TEL VARCHAR(30),
7 EMAIL VARCHAR(30),
8 CREATE_DATE DATE,
9 constraint P_KEY_1 primary key (USER_ID)
10 );
11
12 insert into t_user(user_id, user_name, password) values('root', '系统管理员', 'root');
ConnectionManager.java(数据库连接管理)
1 package dynamicProxyTransaction;
2
3 import java.sql.Connection;
4 import java.sql.DriverManager;
5 import java.sql.SQLException;
6
7 public class ConnectionManager {
8 private ConnectionManager() {
9 }
10
11 private static ThreadLocal<Connection> threadConn = new ThreadLocal<Connection>();
12
13 // 获取数据库连接
14 public static Connection getConnection() {
15 Connection conn = threadConn.get();
16 if (conn == null) {
17 try {
18 Class.forName("com.ibm.db2.jcc.DB2Driver");
19 conn = DriverManager.getConnection(
20 "jdbc:db2://127.0.0.1:50000/DRP", "db2admin", "619100");
21 } catch (ClassNotFoundException e) {
22 e.printStackTrace();
23 } catch (SQLException e) {
24 e.printStackTrace();
25 }
26 threadConn.set(conn);
27 }
28 return conn;
29 }
30
31 // 设置事务手动提交
32 public static void benigTransction(Connection conn) {
33 try {
34 if (conn != null) {
35 if (conn.getAutoCommit()) {
36 conn.setAutoCommit(false);
37 }
38 }
39 } catch (SQLException e) {
40 e.printStackTrace();
41 }
42 }
43
44 // 提交事务
45 public static void endTransction(Connection conn) {
46 try {
47 if (conn != null) {
48 if (!conn.getAutoCommit()) {
49 conn.commit();
50 }
51 }
52 } catch (SQLException e) {
53 e.printStackTrace();
54 }
55 }
56
57 // 设置Connection的原始状态
58 public static void recoverTransction(Connection conn) {
59 try {
60 if (conn != null) {
61 if (conn.getAutoCommit()) {
62 conn.setAutoCommit(false);
63 } else {
64 conn.setAutoCommit(true);
65 }
66 }
67 } catch (SQLException e) {
68 e.printStackTrace();
69 }
70 }
71
72 // 发生异常回滚事务
73 public static void rollback(Connection conn) {
74 try {
75 if (conn != null) {
76 conn.rollback();
77 }
78 } catch (SQLException e) {
79 e.printStackTrace();
80 }
81 }
82
83 // 关闭连接,并将其从当前线程删除
84 public static void close() {
85 Connection conn = threadConn.get();
86 if (conn != null) {
87 try {
88 conn.close();
89 conn = null;
90 threadConn.remove();
91 } catch (SQLException e) {
92 e.printStackTrace();
93 }
94 }
95 }
96 }
User.java(实体类)
1 package dynamicProxyTransaction;
2
3 import java.util.Date;
4
5 public class User {
6 // 用户ID
7 private String id;
8 // 用户名称
9 private String name;
10 // 登陆密码
11 private String password;
12 // 联系电话
13 private String contact_tel;
14 // 电子邮件
15 private String email;
16 // 用户创建日期
17 private Date create_date;
18
19 public String getId() {
20 return id;
21 }
22
23 public void setId(String id) {
24 this.id = id;
25 }
26
27 public String getName() {
28 return name;
29 }
30
31 public void setName(String name) {
32 this.name = name;
33 }
34
35 public String getPassword() {
36 return password;
37 }
38
39 public void setPassword(String password) {
40 this.password = password;
41 }
42
43 public String getContact_tel() {
44 return contact_tel == null ? "" : contact_tel;
45 }
46
47 public void setContact_tel(String contact_tel) {
48 this.contact_tel = contact_tel;
49 }
50
51 public String getEmail() {
52 return email == null ? "" : email;
53 }
54
55 public void setEmail(String email) {
56 this.email = email;
57 }
58
59 public Date getCreate_date() {
60 return create_date;
61 }
62
63 public void setCreate_date(Date create_date) {
64 this.create_date = create_date;
65 }
66 }
UserDAO.java(用户相关的数据库操作)
1 package dynamicProxyTransaction;
2
3 import java.sql.SQLException;
4
5 public interface UserDAO {
6 public User selUser(String id ) throws SQLException ;
7 }
UserDAOImpl.java(UserDAO实现类)
1 package dynamicProxyTransaction;
2
3 import java.sql.Connection;
4 import java.sql.PreparedStatement;
5 import java.sql.ResultSet;
6 import java.sql.SQLException;
7
8 public class UserDAOImpl implements UserDAO {
9 @Override
10 public User selUser(String id) throws SQLException {
11 ResultSet resu = null;
12 String sql = "SELECT * FROM DB2ADMIN.T_USER WHERE USER_ID = ?";
13 Connection conn = ConnectionManager.getConnection();
14 PreparedStatement pstat = conn.prepareStatement(sql);
15 User user = null;
16 try {
17 pstat.setString(1, id);
18 resu = pstat.executeQuery();
19 if (resu.next()) {
20 user = getUser(resu);
21 }
22 } finally {
23 if (resu != null) {
24 resu.close();
25 }
26 if (pstat != null) {
27 pstat.close();
28 }
29 }
30 return user;
31 }
32 // 获取用户
33 private User getUser(ResultSet resu) throws SQLException {
34 User user = new User();
35 user.setId(resu.getString("USER_ID"));
36 user.setName(resu.getString("USER_NAME"));
37 user.setPassword(resu.getString("PASSWORD"));
38 user.setContact_tel(resu.getString("CONTACT_TEL"));
39 user.setEmail(resu.getString("EMAIL"));
40 user.setCreate_date(resu.getTimestamp("CREATE_DATE"));
41 return user;
42 }
43 }
UserManager.java(用户管理功能定义)
1 package dynamicProxyTransaction;
2
3 public interface UserManager {
4 public User findUser(String id ) throws Exception ;
5 }
UserManagerImpl.java(UserManager实现类)
1 package dynamicProxyTransaction;
2
3 import java.sql.SQLException;
4
5 public class UserManagerImpl implements UserManager {
6 // 这个和我以前写的不一样： 我都是写在每个方法中，写成属性应该好一点，减少创建对象的次数
7 private UserDAO userDAO = null;
8
9 public UserManagerImpl() {
10 userDAO = new UserDAOImpl();
11 }
12
13 public User findUser(String id) throws SQLException {
14 return userDAO.selUser(id);
15 }
16 }
TransactionProxy.java(代理实现)
1 package dynamicProxyTransaction;
2
3 import java.lang.reflect.InvocationHandler;
4 import java.lang.reflect.InvocationTargetException;
5 import java.lang.reflect.Method;
6 import java.lang.reflect.Proxy;
7 import java.sql.Connection;
8
9 public class TransactionProxy implements InvocationHandler {
10 private Object obj = null;
11
12 // obj:需要代理的类
13 public Object newProxyInstance(Object obj) {
14 this.obj = obj;
15 return Proxy.newProxyInstance(this.obj.getClass().getClassLoader(),
16 this.obj.getClass().getInterfaces(), this);
17 }
18
19 @Override
20 public Object invoke(Object proxy, Method method, Object[] args)
21 throws Throwable {
22 // 用于接收参数
23 Object param = null;
24 // 如果是以下方法开头,则代理事务
25 if (method.getName().startsWith("add")
26 || method.getName().startsWith("modify")
27 || method.getName().startsWith("find")
28 || method.getName().startsWith("del")) {
29 Connection conn = ConnectionManager.getConnection();
30 try {
31 // 手动提交事务
32 ConnectionManager.benigTransction(conn);
33 param = method.invoke(obj, args);
34 // 提交事务
35 ConnectionManager.endTransction(conn);
36 } catch (Exception e) {
37 // 回滚事务
38 ConnectionManager.rollback(conn);
39 if (e instanceof InvocationTargetException) {
40 InvocationTargetException inv = (InvocationTargetException) e;
41 throw inv.getTargetException();
42 } else {
43 throw new Exception("操作失败!");
44 }
45 } finally {
46 // 还原状态
47 ConnectionManager.recoverTransction(conn);
48 ConnectionManager.close();
49 }
50 }
51 return param;
52 }
53 }
Test.java(测试)
1 package dynamicProxyTransaction;
2
3 public class Test {
4 public static void main(String[] args) throws Exception {
5 TransactionProxy transctionProxy = new TransactionProxy();
6
7 // //产生代理对象
8 UserManager userManager = (UserManager) transctionProxy
9 .newProxyInstance(new UserManagerImpl());
10 User user = userManager.findUser("root");
11 System.out.println("用户名:" + user.getName());
12 }
13
14 }
