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44
45 import java.sql.Connection  ;
46 import java.sql.PreparedStatement ;
47 import java.sql.ResultSet ;
48 import java.sql.Statement ;
49
50 import javax.naming.Context ;
51 import javax.naming.InitialContext ;
52 import javax.transaction.UserTransaction ;
53
54
59 public class JdbcExample {
60
61 private static final String USAGE = "usage: java JdbcExample [database] [commit|rollback] [number]";
62 private static final String SQL_REQUEST = "select id, foo from testdata";
63 private static final String SQL_QUERY = "update testdata set foo = ? where id=1";
64 private static final String USER_TRANSACTION_JNDI_NAME = "UserTransaction";
65 private static Connection conn = null;
66
67 private static void printTable() {
68 try {
69 Statement stmt = conn.createStatement();
70 ResultSet rset = stmt.executeQuery(SQL_REQUEST);
71 int numcols = rset.getMetaData().getColumnCount();
72 for (int i = 1; i <= numcols; i++) {
73 System.out.print("\t" + rset.getMetaData().getColumnName(i));
74 }
75 System.out.println();
76 while (rset.next()) {
77 for (int i = 1; i <= numcols; i++) {
78 System.out.print("\t" + rset.getString(i));
79 }
80 System.out.println("");
81 }
82 } catch (Exception e) {
83 e.printStackTrace();
84 }
85 }
86
87 private static void updateTable(int newValue) {
88 try {
89 PreparedStatement pstmt = conn.prepareStatement(SQL_QUERY);
90 pstmt.setInt(1, newValue);
91 pstmt.executeUpdate();
92 } catch (Exception e) {
93 e.printStackTrace();
94 }
95 }
96
97 public static void main(String [] args) {
98
99 if (args.length != 3 || (!args[1].equals("commit") && !args[1].equals("rollback"))) {
100 System.out.println(USAGE + "\n");
101 System.exit(1);
102 }
103
104 String completion = args[1];
105
106 int newValue = 0;
107 try {
108 newValue = Integer.parseInt(args[2]);
109 } catch (NumberFormatException e) {
110 System.out.println(USAGE);
111 System.out.println("[number] has to be an integer\n");
112 System.exit(1);
113 }
114
115 System.out.println("start server");
116 DatabaseHelper dbHelper = new DatabaseHelper(args[0]);
117
118 UserTransaction utx = null;
119 try {
120 System.out.println("create initial context");
121 Context ictx = new InitialContext ();
122 System.out.println("lookup UserTransaction at : " + USER_TRANSACTION_JNDI_NAME);
123 utx = (UserTransaction ) ictx.lookup(USER_TRANSACTION_JNDI_NAME);
124 } catch (Exception e) {
125 System.out.println("Exception of type :" + e.getClass().getName() + " has been thrown");
126 System.out.println("Exception message :" + e.getMessage());
127 e.printStackTrace();
128 System.exit(1);
129 }
130
131 try {
132 System.out.println("get a connection");
133 conn = dbHelper.getConnection();
134 } catch (Exception e) {
135 e.printStackTrace();
136 }
137
138 System.out.println("before transaction, table is:");
139 printTable();
140
141 try {
142 System.out.println("begin a transaction");
143 utx.begin();
144
145 System.out.println("update the table");
146 updateTable(newValue);
147
148 if (completion.equals("commit")) {
149 System.out.println("*commit* the transaction");
150 utx.commit();
151 } else {
152 System.out.println("*rollback* the transaction");
153 utx.rollback();
154 }
155 } catch (Exception e) {
156 System.out.println("Exception of type :" + e.getClass().getName() + " has been thrown");
157 System.out.println("Exception message :" + e.getMessage());
158 e.printStackTrace();
159 System.exit(1);
160 }
161
162 utx = null;
163
164 System.out.println("after transaction, table is:");
165 printTable();
166
167 try {
168 System.out.println("close connection");
169 conn.close();
170
171 } catch (Exception e) {
172 e.printStackTrace();
173 } finally {
174 conn = null;
175 }
176
177 System.out.println("stop server");
178 dbHelper.stop();
179
180 System.out.println("JDBC example is ok.\n");
181 System.exit(0);
182 }
183 }
184 |
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