1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>ExampleInventoryRead.class</title> 7 <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.62.4" /> 9 <link rel="home" href="index.html" title="Getting Started with Berkeley DB" /> 10 <link rel="up" href="dpl_example.html" title="Chapter 6. A DPL Example" /> 11 <link rel="previous" href="dpl_exampledatabaseput.html" title="ExampleDatabasePut.class" /> 12 <link rel="next" href="baseapi.html" title="Part II. Programming with the Base API" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">ExampleInventoryRead.class</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="dpl_exampledatabaseput.html">Prev</a> </td> 22 <th width="60%" align="center">Chapter 6. A DPL Example</th> 23 <td width="20%" align="right"> <a accesskey="n" href="baseapi.html">Next</a></td> 24 </tr> 25 </table> 26 <hr /> 27 </div> 28 <div class="sect1" lang="en" xml:lang="en"> 29 <div class="titlepage"> 30 <div> 31 <div> 32 <h2 class="title" style="clear: both"><a id="dpl_exampleinventoryread"></a>ExampleInventoryRead.class</h2> 33 </div> 34 </div> 35 <div></div> 36 </div> 37 <p> 38 <tt class="classname">ExampleInventoryRead</tt> 39 retrieves 40 inventory information from our entity store and 41 displays it. When it displays each inventory item, it 42 also displays the related vendor contact information. 43 </p> 44 <p> 45 <tt class="classname">ExampleInventoryRead</tt> 46 can do one of two things. If you provide no search 47 criteria, it displays all of the inventory items in the 48 store. If you provide an item name (using the 49 <tt class="literal">-s</tt> command line switch), then just 50 those inventory items using that name are displayed. 51 </p> 52 <p> 53 The beginning of our example is almost identical to our 54 <tt class="classname">ExampleDatabasePut</tt> 55 example program. We 56 repeat that example code here for the sake of 57 completeness. For a complete walk-through of it, see 58 the previous section (<a href="dpl_exampledatabaseput.html">ExampleDatabasePut.class</a>). 59 </p> 60 <pre class="programlisting">package persist.gettingStarted; 61 62import java.io.File; 63import java.io.IOException; 64 65import com.sleepycat.db.DatabaseException; 66import com.sleepycat.persist.EntityCursor; 67 68public class ExampleInventoryRead { 69 70 private static File myDbEnvPath = 71 new File("/tmp/JEDB"); 72 73 private DataAccessor da; 74 75 // Encapsulates the database environment. 76 private static MyDbEnv myDbEnv = new MyDbEnv(); 77 78 // The item to locate if the -s switch is used 79 private static String locateItem; 80 81 private static void usage() { 82 System.out.println("ExampleInventoryRead [-h <env directory>]" + 83 "[-s <item to locate>]"); 84 System.exit(-1); 85 } 86 87 public static void main(String args[]) { 88 ExampleInventoryRead eir = new ExampleInventoryRead(); 89 try { 90 eir.run(args); 91 } catch (DatabaseException dbe) { 92 System.err.println("ExampleInventoryRead: " + dbe.toString()); 93 dbe.printStackTrace(); 94 } finally { 95 myDbEnv.close(); 96 } 97 System.out.println("All done."); 98 } 99 100 private void run(String args[]) 101 throws DatabaseException { 102 // Parse the arguments list 103 parseArgs(args); 104 105 myDbEnv.setup(myDbEnvPath, // path to the environment home 106 true); // is this environment read-only? 107 108 // Open the data accessor. This is used to retrieve 109 // persistent objects. 110 da = new DataAccessor(myDbEnv.getEntityStore()); 111 112 // If a item to locate is provided on the command line, 113 // show just the inventory items using the provided name. 114 // Otherwise, show everything in the inventory. 115 if (locateItem != null) { 116 showItem(); 117 } else { 118 showAllInventory(); 119 } 120 } </pre> 121 <p> 122 The first method that we provide is used to show inventory 123 items related to a given inventory name. This method is called 124 only if an inventory name is passed to 125 <tt class="classname">ExampleInventoryRead</tt> 126 via the <tt class="literal">-s</tt> option. Given the sample data 127 that we provide with this example, each matching inventory name 128 will result in the display of three inventory objects. 129 </p> 130 <p> 131 To display these objects we use the 132 <tt class="classname">Inventory</tt> class' 133 <tt class="literal">inventoryByName</tt> secondary index to retrieve 134 an <tt class="classname">EntityCursor</tt>, and then we iterate 135 over the resulting objects using the cursor. 136 </p> 137 <p> 138 Notice that this method calls 139 <tt class="methodname">displayInventoryRecord()</tt> 140 to display each individual object. We show this 141 method a little later in the example. 142 </p> 143 <pre class="programlisting"> // Shows all the inventory items that exist for a given 144 // inventory name. 145 private void showItem() throws DatabaseException { 146 147 // Use the inventory name secondary key to retrieve 148 // these objects. 149 EntityCursor<Inventory> items = 150 da.inventoryByName.subIndex(locateItem).entities(); 151 try { 152 for (Inventory item : items) { 153 displayInventoryRecord(item); 154 } 155 } finally { 156 items.close(); 157 } 158 } </pre> 159 <p> 160 Next we implement <tt class="methodname">showAllInventory()</tt>, 161 which shows all of the <tt class="classname">Inventory</tt> 162 objects in the store. To do this, we 163 obtain an <tt class="classname">EntityCursor</tt> 164 from the <tt class="classname">Inventory</tt> class' 165 primary index and, again, we iterate using that cursor. 166 </p> 167 <pre class="programlisting"> // Displays all the inventory items in the store 168 private void showAllInventory() 169 throws DatabaseException { 170 171 // Get a cursor that will walk every 172 // inventory object in the store. 173 EntityCursor<Inventory> items = 174 da.inventoryBySku.entities(); 175 176 try { 177 for (Inventory item : items) { 178 displayInventoryRecord(item); 179 } 180 } finally { 181 items.close(); 182 } 183 } </pre> 184 <p> 185 Now we implement 186 <tt class="methodname">displayInventoryRecord()</tt>. This 187 uses the getter methods on the <tt class="classname">Inventory</tt> 188 class to obtain the information that we want to display. 189 The only thing interesting about this method is that we 190 obtain <tt class="classname">Vendor</tt> objects within. 191 The vendor objects are retrieved <tt class="classname">Vendor</tt> 192 objects using their primary index. We get the key 193 for the retrieval from the <tt class="classname">Inventory</tt> 194 object that we are displaying at the time. 195 </p> 196 <pre class="programlisting"> private void displayInventoryRecord(Inventory theInventory) 197 throws DatabaseException { 198 199 System.out.println(theInventory.getSku() + ":"); 200 System.out.println("\t " + theInventory.getItemName()); 201 System.out.println("\t " + theInventory.getCategory()); 202 System.out.println("\t " + theInventory.getVendor()); 203 System.out.println("\t\tNumber in stock: " + 204 theInventory.getVendorInventory()); 205 System.out.println("\t\tPrice per unit: " + 206 theInventory.getVendorPrice()); 207 System.out.println("\t\tContact: "); 208 209 Vendor theVendor = 210 da.vendorByName.get(theInventory.getVendor()); 211 assert theVendor != null; 212 213 System.out.println("\t\t " + theVendor.getAddress()); 214 System.out.println("\t\t " + theVendor.getCity() + ", " + 215 theVendor.getState() + " " + theVendor.getZipcode()); 216 System.out.println("\t\t Business Phone: " + 217 theVendor.getBusinessPhoneNumber()); 218 System.out.println("\t\t Sales Rep: " + 219 theVendor.getRepName()); 220 System.out.println("\t\t " + 221 theVendor.getRepPhoneNumber()); 222 } </pre> 223 <p> 224 The last remaining parts of the example are used to parse 225 the command line. This is not very 226 interesting for our purposes here, but we show it anyway 227 for the sake of completeness. 228 </p> 229 <pre class="programlisting"> protected ExampleInventoryRead() {} 230 231 private static void parseArgs(String args[]) { 232 for(int i = 0; i < args.length; ++i) { 233 if (args[i].startsWith("-")) { 234 switch(args[i].charAt(1)) { 235 case 'h': 236 myDbEnvPath = new File(args[++i]); 237 break; 238 case 's': 239 locateItem = args[++i]; 240 break; 241 default: 242 usage(); 243 } 244 } 245 } 246 } 247} </pre> 248 </div> 249 <div class="navfooter"> 250 <hr /> 251 <table width="100%" summary="Navigation footer"> 252 <tr> 253 <td width="40%" align="left"><a accesskey="p" href="dpl_exampledatabaseput.html">Prev</a> </td> 254 <td width="20%" align="center"> 255 <a accesskey="u" href="dpl_example.html">Up</a> 256 </td> 257 <td width="40%" align="right"> <a accesskey="n" href="baseapi.html">Next</a></td> 258 </tr> 259 <tr> 260 <td width="40%" align="left" valign="top">ExampleDatabasePut.class </td> 261 <td width="20%" align="center"> 262 <a accesskey="h" href="index.html">Home</a> 263 </td> 264 <td width="40%" align="right" valign="top"> Part II. 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