src/be/nikiroo/utils/serial/Importer.java

   1 package be.nikiroo.utils.serial;
   2
   3 import java.io.IOException;
   4 import java.lang.reflect.Field;
   5 import java.util.HashMap;
   6 import java.util.Map;
   7 import java.util.Scanner;
   8
   9 import be.nikiroo.utils.StringUtils;
  10
  11 /**
  12  * A simple class that can accept the output of {@link Exporter} to recreate
  13  * objects as they were sent to said exporter.
  14  * <p>
  15  * This class requires the objects (and their potential enclosing objects) to
  16  * have an empty constructor, and does not support inner classes (it does
  17  * support nested classes, though).
  18  *
  19  * @author niki
  20  */
  21 public class Importer {
  22         private Boolean link;
  23         private Object me;
  24         private Importer child;
  25         private Map<String, Object> map;
  26
  27         private String currentFieldName;
  28
  29         /**
  30          * Create a new {@link Importer}.
  31          */
  32         public Importer() {
  33                 map = new HashMap<String, Object>();
  34                 map.put("NULL", null);
  35         }
  36
  37         private Importer(Map<String, Object> map) {
  38                 this.map = map;
  39         }
  40
  41         /**
  42          * Read some data into this {@link Importer}: it can be the full serialised
  43          * content, or a number of lines of it (any given line <b>MUST</b> be
  44          * complete though) and accumulate it with the already present data.
  45          *
  46          * @param data
  47          *            the data to parse
  48          *
  49          * @return itself so it can be chained
  50          *
  51          * @throws NoSuchFieldException
  52          *             if the serialised data contains information about a field
  53          *             which does actually not exist in the class we know of
  54          * @throws NoSuchMethodException
  55          *             if a class described in the serialised data cannot be created
  56          *             because it is not compatible with this code
  57          * @throws ClassNotFoundException
  58          *             if a class described in the serialised data cannot be found
  59          * @throws IOException
  60          *             if the content cannot be read (for instance, corrupt data)
  61          */
  62         public Importer read(String data) throws NoSuchFieldException,
  63                         NoSuchMethodException, ClassNotFoundException, IOException {
  64
  65                 Scanner scan = new Scanner(data);
  66                 try {
  67                         scan.useDelimiter("\n");
  68                         while (scan.hasNext()) {
  69                                 String line = scan.next();
  70
  71                                 if (line.startsWith("ZIP:")) {
  72                                         try {
  73                                                 line = StringUtils.unzip64(line.substring("ZIP:"
  74                                                                 .length()));
  75                                         } catch (IOException e) {
  76                                                 throw new IOException(
  77                                                                 "Internal error when decoding ZIP content: input may be corrupt");
  78                                         }
  79                                         read(line);
  80                                 } else {
  81                                         processLine(line);
  82                                 }
  83                         }
  84                 } finally {
  85                         scan.close();
  86                 }
  87
  88                 return this;
  89         }
  90
  91         /**
  92          * Read a single (whole) line of serialised data into this {@link Importer}
  93          * and accumulate it with the already present data.
  94          *
  95          * @param line
  96          *            the line to parse
  97          *
  98          * @return TRUE if we are just done with one object or sub-object
  99          *
 100          * @throws NoSuchFieldException
 101          *             if the serialised data contains information about a field
 102          *             which does actually not exist in the class we know of
 103          * @throws NoSuchMethodException
 104          *             if a class described in the serialised data cannot be created
 105          *             because it is not compatible with this code
 106          * @throws ClassNotFoundException
 107          *             if a class described in the serialised data cannot be found
 108          * @throws IOException
 109          *             if the content cannot be read (for instance, corrupt data)
 110          */
 111         private boolean processLine(String line) throws NoSuchFieldException,
 112                         NoSuchMethodException, ClassNotFoundException, IOException {
 113                 // Defer to latest child if any
 114                 if (child != null) {
 115                         if (child.processLine(line)) {
 116                                 if (currentFieldName != null) {
 117                                         setField(currentFieldName, child.getValue());
 118                                         currentFieldName = null;
 119                                 }
 120                                 child = null;
 121                         }
 122
 123                         return false;
 124                 }
 125
 126                 if (line.equals("{")) { // START: new child if needed
 127                         if (link != null) {
 128                                 child = new Importer(map);
 129                         }
 130                 } else if (line.equals("}")) { // STOP: report self to parent
 131                         return true;
 132                 } else if (line.startsWith("REF ")) { // REF: create/link self
 133                         String[] tab = line.substring("REF ".length()).split("@");
 134                         String type = tab[0];
 135                         tab = tab[1].split(":");
 136                         String ref = tab[0];
 137
 138                         link = map.containsKey(ref);
 139                         if (link) {
 140                                 me = map.get(ref);
 141                         } else {
 142                                 if (line.endsWith(":")) {
 143                                         // construct
 144                                         me = SerialUtils.createObject(type);
 145                                 } else {
 146                                         // direct value
 147                                         int pos = line.indexOf(":");
 148                                         String encodedValue = line.substring(pos + 1);
 149                                         me = SerialUtils.decode(encodedValue);
 150                                 }
 151                                 map.put(ref, me);
 152                         }
 153                 } else { // FIELD: new field *or* direct simple value
 154                         if (line.endsWith(":")) {
 155                                 // field value is compound
 156                                 currentFieldName = line.substring(0, line.length() - 1);
 157                         } else if (line.startsWith(":") || !line.contains(":")) {
 158                                 // not a field value but a direct value
 159                                 me = SerialUtils.decode(line);
 160                         } else {
 161                                 // field value is direct
 162                                 int pos = line.indexOf(":");
 163                                 String fieldName = line.substring(0, pos);
 164                                 String encodedValue = line.substring(pos + 1);
 165                                 Object value = null;
 166                                 value = SerialUtils.decode(encodedValue);
 167
 168                                 // To support simple types directly:
 169                                 if (me == null) {
 170                                         me = value;
 171                                 } else {
 172                                         setField(fieldName, value);
 173                                 }
 174                         }
 175                 }
 176
 177                 return false;
 178         }
 179
 180         private void setField(String name, Object value)
 181                         throws NoSuchFieldException {
 182
 183                 try {
 184                         Field field = me.getClass().getDeclaredField(name);
 185
 186                         field.setAccessible(true);
 187                         field.set(me, value);
 188                 } catch (NoSuchFieldException e) {
 189                         throw new NoSuchFieldException(String.format(
 190                                         "Field \"%s\" was not found in object of type \"%s\".",
 191                                         name, me.getClass().getCanonicalName()));
 192                 } catch (Exception e) {
 193                         throw new NoSuchFieldException(String.format(
 194                                         "Internal error when setting \"%s.%s\": %s", me.getClass()
 195                                                         .getCanonicalName(), name, e.getMessage()));
 196                 }
 197         }
 198
 199         /**
 200          * Return the current deserialised value.
 201          *
 202          * @return the current value
 203          */
 204         public Object getValue() {
 205                 return me;
 206         }
 207 }