1 | /*
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2 | * TDBWrapper.java
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3 | * Copyright (C) 2015 New Zealand Digital Library, http://www.nzdl.org
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4 | *
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5 | * This program is free software; you can redistribute it and/or modify
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6 | * it under the terms of the GNU General Public License as published by
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7 | * the Free Software Foundation; either version 2 of the License, or
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8 | * (at your option) any later version.
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9 | *
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10 | * This program is distributed in the hope that it will be useful,
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11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 | * GNU General Public License for more details.
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14 | *
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15 | * You should have received a copy of the GNU General Public License
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16 | * along with this program; if not, write to the Free Software
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17 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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18 | */
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19 | package org.greenstone.gsdl3.util;
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20 |
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21 | import java.net.URLEncoder;
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22 | import java.util.Enumeration;
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23 |
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24 | import org.apache.log4j.Logger;
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25 | import org.greenstone.gsdl3.util.DBHelper;
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26 | import org.greenstone.gsdl3.util.FlatDatabaseWrapper;
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27 |
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28 | import org.greenstone.tdbjava.TDBJava;
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29 |
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30 | /**
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31 | * Java wrapper class for TDB - uses TDBJava (a JNI wrapper to TDB)
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32 | */
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33 | public class TDBWrapper
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34 | implements FlatDatabaseWrapper
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35 | {
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36 | // A logger for messaging (mostly error)
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37 | static Logger logger = Logger.getLogger(org.greenstone.gsdl3.util.TDBWrapper.class.getName());
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38 |
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39 | /** Register this Wrapper with the DBHelper */
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40 | static
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41 | {
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42 | DBHelper.registerDBTypeExt("tdb",".tdb");
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43 | logger.info("Registered TDB database type with file extension .tdb");
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44 | }
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45 |
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46 | // The open database (if any)
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47 | protected TDBJava db_ = null;
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48 |
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49 |
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50 | /** @function openDatabase(String, int)
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51 | * Open the database filename, with mode mode
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52 | */
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53 | public boolean openDatabase(String filename, int mode)
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54 | {
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55 | // convert mode to TDBJava open mode
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56 | if (mode == this.READ) {
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57 | mode = TDBJava.O_READONLY;
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58 | }
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59 | else if (mode == this.WRITE) {
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60 | mode = TDBJava.O_DEFAULT;
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61 | }
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62 | else {
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63 | logger.error("invalid mode, " + mode + ", opening db for reading only");
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64 | mode = TDBJava.O_READONLY;
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65 | }
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66 |
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67 | try {
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68 | if (this.db_ != null) {
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69 | this.db_.close();
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70 | }
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71 | this.db_ = new TDBJava(filename, TDBJava.TDB_DEFAULT, mode);
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72 | }
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73 | catch (Exception e) {
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74 | logger.error("couldn't open database: " + filename);
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75 | logger.error(" Exception: " + e.toString());
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76 | return false;
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77 | }
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78 | logger.info("opened with tdb_flags=" + TDBJava.TDB_DEFAULT + " and mode=" + mode);
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79 | return true;
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80 | }
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81 | /** openDatabase(String, int) **/
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82 |
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83 |
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84 | /** @function closeDatabase
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85 | * Close the database associated with this wrapper
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86 | */
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87 | public void closeDatabase()
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88 | {
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89 | if (this.db_ != null) {
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90 | try {
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91 | this.db_.close();
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92 | this.db_ = null;
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93 | // Hack: force Windows to let go of the gdb file
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94 | if (System.getProperty("os.name").startsWith("Windows")) {
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95 | System.gc();
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96 | }
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97 | }
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98 | catch (Exception e) {
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99 | logger.error("error on close()");
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100 | logger.error(" Exception: " + e.toString());
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101 | }
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102 | }
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103 | }
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104 | /** closeDatabase() **/
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105 |
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106 | /** @function getValue(String)
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107 | */
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108 | public String getValue(String key)
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109 | {
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110 | String value = null;
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111 | if (null != this.db_) {
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112 | try {
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113 | value = this.db_.fetch(key);
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114 | }
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115 | catch (Exception e) {
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116 | logger.error("error on getValue(" + key + ")");
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117 | logger.error(" Exception: " + e.toString());
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118 | }
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119 | }
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120 | if (null == value) {
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121 | logger.error("key " + key + " not present in db");
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122 | }
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123 | return value;
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124 | }
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125 | /** getValue(String) **/
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126 |
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127 | /** @function setValue(String, String)
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128 | * Sets the given key to the given value in the database
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129 | */
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130 | public boolean setValue(String key, String value)
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131 | {
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132 | boolean result = false;
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133 | if (this.db_ == null) {
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134 | logger.error("database is not open");
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135 | }
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136 | else if (!this.db_.isWritable()) {
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137 | logger.error("database is read-only");
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138 | }
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139 | else {
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140 | try {
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141 | this.db_.store(key, value);
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142 | result = true;
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143 | }
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144 | catch (Exception e) {
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145 | logger.error("error storing " + key + " = " + value);
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146 | logger.error(" Exception: " + e.toString());
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147 | }
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148 | }
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149 | return result;
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150 | }
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151 | /** setValue(String, String) **/
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152 |
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153 | /** @function deleteKey(String key)
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154 | * Deletes the entry for given key
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155 | */
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156 | public boolean deleteKey(String key)
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157 | {
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158 | boolean result = false;
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159 | if (null == this.db_) {
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160 | logger.error("database is not open");
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161 | }
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162 | else if (!this.db_.isWritable()) {
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163 | logger.error("database is read-only");
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164 | }
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165 | else {
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166 | try {
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167 | this.db_.delete(key);
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168 | result = true;
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169 | }
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170 | catch (Exception e) {
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171 | logger.error("error deleting key " + key);
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172 | logger.error(" Exception: " + e.toString());
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173 | }
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174 | }
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175 | return result;
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176 | }
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177 | /** deleteKey(String) **/
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178 |
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179 | /** @function displayAllEntries()
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180 | * Returns a string of key-value entries that can be printed for debugging
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181 | * purposes.
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182 | */
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183 | public String displayAllEntries()
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184 | {
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185 | StringBuffer output = new StringBuffer();
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186 | if (null == this.db_) {
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187 | logger.error("database is not open");
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188 | }
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189 | else {
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190 | try {
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191 | Enumeration keys = this.db_.keys();
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192 | while (keys.hasMoreElements()) {
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193 | String key = (String) keys.nextElement();
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194 | String value = this.db_.fetch(key);
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195 | String urlkey = URLEncoder.encode((String) key, "UTF8");
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196 | output.append("key href: ");
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197 | output.append(key);
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198 | output.append("\tvalue ID: ");
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199 | output.append(value);
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200 | output.append("\n");
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201 | output.append("URL encoded key: " + urlkey);
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202 | }
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203 | }
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204 | catch (Exception e) {
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205 | logger.error("error when trying to display all entries");
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206 | logger.error(" Exception: " + e.toString());
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207 | }
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208 | }
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209 | return output.toString();
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210 | }
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211 | /** displayAllEntries() **/
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212 |
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213 | }
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214 | /** Class: TDBWrapper **/
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