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1
2
12 package com.versant.core.jdo.externalizer;
13
14 import com.versant.core.common.BindingSupportImpl;
15 import com.versant.core.common.Utils;
16
17 import javax.jdo.PersistenceManager;
18 import java.lang.reflect.Constructor  ;
19 import java.lang.reflect.Method ;
20 import java.io.*;
21
22
30 public class TypeAsBytesExternalizer implements Externalizer, Externalizable {
31
32 public static final String SHORT_NAME = "BYTES";
33
34 private Class type;
35 private Constructor constructor;
36 private Method toBytes;
37
38 public TypeAsBytesExternalizer(Class type) {
39 this.type = type;
40 init();
41 }
42
43 public TypeAsBytesExternalizer() {
44 }
45
46 private void init() {
47 try {
48 constructor = type.getConstructor(new Class []{byte[].class});
49 } catch (NoSuchMethodException e) {
50 throw BindingSupportImpl.getInstance().runtime(type + " does not have a " +
51 "constructor that accepts a byte[]", e);
52 }
53 try {
54 toBytes = type.getMethod("toBytes", null);
55 } catch (NoSuchMethodException e) {
56 throw BindingSupportImpl.getInstance().runtime(type + " does not have a " +
57 "public toBytes() method", e);
58 }
59 if (toBytes.getReturnType() != byte[].class) {
60 throw BindingSupportImpl.getInstance().runtime(type + ".toBytes() does not " +
61 "return byte[]");
62 }
63 }
64
65 public Object toExternalForm(PersistenceManager pm, Object o) {
66 if (o == null) return null;
67 try {
68 return toBytes.invoke(o, null);
69 } catch (Throwable x) {
70 throw BindingSupportImpl.getInstance().fatalDatastore("Unable to convert instance of " +
71 type.getName() + " '" + Utils.toString(o) + "' to byte[]: " + x, x);
72 }
73 }
74
75 public Object fromExternalForm(PersistenceManager pm, Object o) {
76 if (o == null) return null;
77 if (!(o instanceof byte[])) {
78 throw BindingSupportImpl.getInstance().runtime(
79 "Expected byte[] to create instance of " +
80 type.getName() + ", got: " + Utils.toString(o));
81 }
82 try {
83 return constructor.newInstance(new Object []{o});
84 } catch (Throwable x) {
85 throw BindingSupportImpl.getInstance().runtime(
86 "Unable to create instance of " +
87 type.getName() + " from " + Utils.toString(o) + ": " + x, x);
88 }
89 }
90
91 public Class getExternalType() {
92 return byte[].class;
93 }
94
95 public void writeExternal(ObjectOutput out) throws IOException {
96 out.writeObject(type);
97 }
98
99 public void readExternal(ObjectInput in) throws IOException,
100 ClassNotFoundException {
101 type = (Class )in.readObject();
102 init();
103 }
104 }
105
106 |
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