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1 package net.innig.macker.example.layering.persistence;
2
3 import java.sql.*;
4 import java.util.*;
5
6 public class ThingerPersistence
7 {
8 public ThingerPersistence()
9 throws PersistenceException
10 {
11 Properties connProps = new Properties();
12 try
13 { connProps.load(getClass().getClassLoader().getResourceAsStream("db.properties")); }
14 catch(Exception  e)
15 { throw new PersistenceException("Unable to load db.properties", e); }
16
17 try
18 { Class.forName(connProps.getProperty("db.driver")); }
19 catch(ClassNotFoundException cnfe)
20 { throw new PersistenceException("Unable to load DB driver", cnfe); }
21
22 try
23 {
24 conn = DriverManager.getConnection(
25 connProps.getProperty("db.url"),
26 connProps.getProperty("db.user"),
27 connProps.getProperty("db.pass"));
28 conn.setAutoCommit(false);
29 }
30 catch(SQLException sqle)
31 { throw new PersistenceException("Unable to connect to database", sqle); }
32
33 try
34 {
35 selStmt = conn.prepareStatement("select name from thinger");
36 insStmt = conn.prepareStatement("insert into thinger (name) values (?)");
37 delStmt = conn.prepareStatement("delete from thinger where name = ?");
38 }
39 catch(SQLException sqle)
40 { throw new PersistenceException("Unable to prepare statements", sqle); }
41 }
42
43 public Set selectAll()
44 throws PersistenceException
45 {
46 Set thingers = new HashSet();
47 try
48 {
49 ResultSet rs = selStmt.executeQuery();
50 while(rs.next())
51 thingers.add(rs.getString(1));
52 rs.close();
53 }
54 catch(SQLException sqle)
55 { throw new PersistenceException("Unable to select thingers", sqle); }
56 return thingers;
57 }
58
59 public void insert(String name)
60 throws PersistenceException
61 {
62 boolean done = false;
63 try
64 {
65 insStmt.clearParameters();
66 insStmt.setString(1, name);
67 insStmt.execute();
68 conn.commit();
69 done = true;
70 }
71 catch(SQLException sqle)
72 { throw new PersistenceException("Unable to insert thinger", sqle); }
73 finally
74 { quietRollback(done); }
75 }
76
77 public void delete(String name)
78 throws PersistenceException
79 {
80 boolean done = false;
81 try
82 {
83 if(delStmt.executeUpdate(name) == 0)
84 throw new PersistenceException("No such thinger: \"" + name + '"');
85 conn.commit();
86 done = true;
87 }
88 catch(SQLException sqle)
89 { throw new PersistenceException("Unable to delete thinger", sqle); }
90 finally
91 { quietRollback(done); }
92 }
93
94 private void quietRollback(boolean doit)
95 {
96 if(doit)
97 try { conn.rollback(); }
98 catch(Exception e) { }
99 }
100
101 private Connection conn;
102 private PreparedStatement selStmt, insStmt, delStmt;
103 }
104 |
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