Mercurial > hg > LightPIT / file comparison

comparison: src/java/de/uapcore/lightpit/DatabaseFacade.java

src/java/de/uapcore/lightpit/DatabaseFacade.java

changeset 29
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parent 28
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child 30
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equal deleted inserted replaced
28:cfc3d11884ad 29:27a0fdd7bca7
1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2018 Mike Becker. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 *
28 */
29 package de.uapcore.lightpit;
30
31 import java.sql.Connection;
32 import java.sql.DatabaseMetaData;
33 import java.sql.SQLException;
34 import java.util.Optional;
35 import javax.naming.Context;
36 import javax.naming.InitialContext;
37 import javax.naming.NamingException;
38 import javax.servlet.ServletContext;
39 import javax.servlet.ServletContextEvent;
40 import javax.servlet.ServletContextListener;
41 import javax.servlet.annotation.WebListener;
42 import javax.sql.DataSource;
43 import org.slf4j.Logger;
44 import org.slf4j.LoggerFactory;
45
46 /**
47 * Provides access to different privilege layers within the database.
48 */
49 @WebListener
50 public final class DatabaseFacade implements ServletContextListener {
51
52 private static final Logger LOG = LoggerFactory.getLogger(DatabaseFacade.class);
53
54 /**
55 * Timeout in seconds for the validation test.
56 */
57 private static final int DB_TEST_TIMEOUT = 10;
58
59 public static enum Dialect {
60 Postgres;
61 }
62
63 /**
64 * The database dialect to use.
65 *
66 * May be override by context parameter.
67 *
68 * @see Constants#CTX_ATTR_DB_DIALECT
69 */
70 private Dialect dialect = Dialect.Postgres;
71
72 /**
73 * The default schema to test against when validating the connection.
74 *
75 * May be overridden by context parameter.
76 *
77 * @see Constants#CTX_ATTR_DB_SCHEMA
78 */
79 private static final String DB_DEFAULT_SCHEMA = "lightpit";
80
81 /**
82 * The attribute name in the Servlet context under which an instance of this class can be found.
83 */
84 public static final String SC_ATTR_NAME = DatabaseFacade.class.getName();
85 private ServletContext sc;
86
87 private static final String DS_JNDI_NAME = "jdbc/lightpit/app";
88 private Optional<DataSource> dataSource;
89
90 /**
91 * Returns the data source.
92 *
93 * The Optional returned should never be empty. However, if something goes
94 * wrong during initialization, the data source might be absent.
95 * Hence, users of this data source are forced to check the existence.
96 *
97 * @return a data source
98 */
99 public Optional<DataSource> getDataSource() {
100 return dataSource;
101 }
102
103 public Dialect getSQLDialect() {
104 return dialect;
105 }
106
107 private static void checkConnection(DataSource ds, String testSchema, String errMsg) {
108 try (Connection conn = ds.getConnection()) {
109 if (!conn.isValid(DB_TEST_TIMEOUT)) {
110 throw new SQLException("Validation check failed.");
111 }
112 if (conn.isReadOnly()) {
113 throw new SQLException("Connection is read-only and thus unusable.");
114 }
115 if (!conn.getSchema().equals(testSchema)) {
116 throw new SQLException(String.format("Connection is not configured to use the schema %s.", testSchema));
117 }
118 DatabaseMetaData metaData = conn.getMetaData();
119 LOG.info("Connections as {} to {}/{} ready to go.", metaData.getUserName(), metaData.getURL(), conn.getSchema());
120 } catch (SQLException ex) {
121 LOG.error(errMsg, ex);
122 }
123 }
124
125 private static Optional<DataSource> retrieveDataSource(Context ctx) {
126 DataSource ret = null;
127 try {
128 ret = (DataSource)ctx.lookup(DS_JNDI_NAME);
129 LOG.info("Data source retrieved.");
130 } catch (NamingException ex) {
131 LOG.error("Data source {} not available.", DS_JNDI_NAME);
132 LOG.error("Reason for the missing data source: ", ex);
133 }
134 return Optional.ofNullable(ret);
135 }
136
137 @Override
138 public void contextInitialized(ServletContextEvent sce) {
139 sc = sce.getServletContext();
140
141 dataSource = null;
142
143 final String contextName = Optional
144 .ofNullable(sc.getInitParameter(Constants.CTX_ATTR_JNDI_CONTEXT))
145 .orElse("java:comp/env");
146 final String dbSchema = Optional
147 .ofNullable(sc.getInitParameter(Constants.CTX_ATTR_DB_SCHEMA))
148 .orElse(DB_DEFAULT_SCHEMA);
149 final String dbDialect = sc.getInitParameter(Constants.CTX_ATTR_DB_DIALECT);
150 if (dbDialect != null) {
151 try {
152 dialect = Dialect.valueOf(dbDialect);
153 } catch (IllegalArgumentException ex) {
154 LOG.error("Unknown or unsupported database dialect {}. Defaulting to {}.", dbDialect, dialect);
155 }
156 }
157
158 try {
159 LOG.debug("Trying to access JNDI context {}...", contextName);
160 Context initialCtx = new InitialContext();
161 Context ctx = (Context) initialCtx.lookup(contextName);
162
163 dataSource = retrieveDataSource(ctx);
164
165 dataSource.ifPresent((ds) -> checkConnection(ds, dbSchema, "Checking database connection failed"));
166 } catch (NamingException | ClassCastException ex) {
167 LOG.error("Cannot access JNDI resources.", ex);
168 }
169
170 sc.setAttribute(SC_ATTR_NAME, this);
171 LOG.info("Database facade injected into ServletContext.");
172 }
173
174 @Override
175 public void contextDestroyed(ServletContextEvent sce) {
176 dataSource = null;
177 }
178 }

Mercurial Repository: LightPIT

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