databasejournal.java

来自「jsr170接口的java实现。是个apache的开源项目。」· Java 代码 · 共 534 行 · 第 1/2 页

    /**
     * {@inheritDoc}
     */
    protected void doUnlock(boolean successful) {
        if (!successful) {
            rollback(con);
        }
        try {
            con.setAutoCommit(true);
        } catch (SQLException e) {
            String msg = "Unable to set autocommit to true.";
            log.warn(msg, e);
        }
    }

    /**
     * {@inheritDoc}
     * <p/>
     * Save away the locked revision inside the newly appended record.
     */
    protected void appending(AppendRecord record) {
        record.setRevision(lockedRevision);
    }

    /**
     * {@inheritDoc}
     * <p/>
     * We have already saved away the revision for this record.
     */
    protected void append(AppendRecord record, InputStream in, int length)
            throws JournalException {

        try {
            try {
                insertRevisionStmt.clearParameters();
                insertRevisionStmt.clearWarnings();
                insertRevisionStmt.setLong(1, record.getRevision());
                insertRevisionStmt.setString(2, getId());
                insertRevisionStmt.setString(3, record.getProducerId());
                insertRevisionStmt.setBinaryStream(4, in, length);
                insertRevisionStmt.execute();

                con.commit();
            } finally {
                try {
                    con.setAutoCommit(true);
                } catch (SQLException e) {
                    String msg = "Unable to set autocommit to true.";
                    log.warn(msg, e);
                }
            }
        } catch (SQLException e) {
            String msg = "Unable to append revision " + lockedRevision + ".";
            throw new JournalException(msg, e);
        }
    }

    /**
     * {@inheritDoc}
     */
    public void close() {
        try {
            con.close();
        } catch (SQLException e) {
            String msg = "Error while closing connection: " + e.getMessage();
            log.warn(msg);
        }
    }

    /**
     * Close some input stream.
     *
     * @param in input stream, may be <code>null</code>.
     */
    private void close(InputStream in) {
        try {
            if (in != null) {
                in.close();
            }
        } catch (IOException e) {
            String msg = "Error while closing input stream: " + e.getMessage();
            log.warn(msg);
        }
    }

    /**
     * Close some statement.
     *
     * @param stmt statement, may be <code>null</code>.
     */
    private void close(Statement stmt) {
        try {
            if (stmt != null) {
                stmt.close();
            }
        } catch (SQLException e) {
            String msg = "Error while closing statement: " + e.getMessage();
            log.warn(msg);
        }
    }

    /**
     * Close some resultset.
     *
     * @param rs resultset, may be <code>null</code>.
     */
    private void close(ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
            }
        } catch (SQLException e) {
            String msg = "Error while closing result set: " + e.getMessage();
            log.warn(msg);
        }
    }

    /**
     * Rollback a connection.
     *
     * @param con connection.
     */
    private void rollback(Connection con) {
        try {
            con.rollback();
        } catch (SQLException e) {
            String msg = "Error while rolling back connection: " + e.getMessage();
            log.warn(msg);
        }
    }

    /**
     * Checks if the required schema objects exist and creates them if they
     * don't exist yet.
     *
     * @throws Exception if an error occurs
     */
    private void checkSchema() throws Exception {
        DatabaseMetaData metaData = con.getMetaData();
        String tableName = schemaObjectPrefix + "JOURNAL";
        if (metaData.storesLowerCaseIdentifiers()) {
            tableName = tableName.toLowerCase();
        } else if (metaData.storesUpperCaseIdentifiers()) {
            tableName = tableName.toUpperCase();
        }

        ResultSet rs = metaData.getTables(null, null, tableName, null);
        boolean schemaExists;
        try {
            schemaExists = rs.next();
        } finally {
            rs.close();
        }

        if (!schemaExists) {
            // read ddl from resources
            InputStream in = DatabaseJournal.class.getResourceAsStream(schema + ".ddl");
            if (in == null) {
                String msg = "No schema-specific DDL found: '" + schema + ".ddl" +
                        "', falling back to '" + DEFAULT_DDL_NAME + "'.";
                log.info(msg);
                in = DatabaseJournal.class.getResourceAsStream(DEFAULT_DDL_NAME);
                if (in == null) {
                    msg = "Unable to load '" + DEFAULT_DDL_NAME + "'.";
                    throw new JournalException(msg);
                }
            }
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));
            Statement stmt = con.createStatement();
            try {
                String sql = reader.readLine();
                while (sql != null) {
                    // Skip comments and empty lines
                    if (!sql.startsWith("#") && sql.length() > 0) {
                        // replace prefix variable
                        sql = Text.replace(sql, SCHEMA_OBJECT_PREFIX_VARIABLE, schemaObjectPrefix);
                        // execute sql stmt
                        stmt.executeUpdate(sql);
                    }
                    // read next sql stmt
                    sql = reader.readLine();
                }
            } finally {
                close(in);
                close(stmt);
            }
        }
    }

    /**
     * Builds and prepares the SQL statements.
     *
     * @throws SQLException if an error occurs
     */
    private void prepareStatements() throws SQLException {
        selectRevisionsStmt = con.prepareStatement(
                "select REVISION_ID, JOURNAL_ID, PRODUCER_ID, REVISION_DATA " +
                "from " + schemaObjectPrefix + "JOURNAL " +
                "where REVISION_ID > ?");
        updateGlobalStmt = con.prepareStatement(
                "update " + schemaObjectPrefix + "GLOBAL_REVISION " +
                "set revision_id = revision_id + 1");
        selectGlobalStmt = con.prepareStatement(
                "select revision_id " +
                "from " + schemaObjectPrefix + "GLOBAL_REVISION");
        insertRevisionStmt = con.prepareStatement(
                "insert into " + schemaObjectPrefix + "JOURNAL" +
                "(REVISION_ID, JOURNAL_ID, PRODUCER_ID, REVISION_DATA) " +
                "values (?,?,?,?)");
    }

    /**
     * Bean getters
     */
    public String getDriver() {
        return driver;
    }

    public String getUrl() {
        return url;
    }

    public String getSchema() {
        return schema;
    }

    public String getSchemaObjectPrefix() {
        return schemaObjectPrefix;
    }

    public String getUser() {
        return user;
    }

    public String getPassword() {
        return password;
    }

    /**
     * Bean setters
     */
    public void setDriver(String driver) {
        this.driver = driver;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public void setSchema(String schema) {
        this.schema = schema;
    }

    public void setSchemaObjectPrefix(String schemaObjectPrefix) {
        this.schemaObjectPrefix = schemaObjectPrefix.toUpperCase();
    }

    public void setUser(String user) {
        this.user = user;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}