1 /*
2  * Copyright (C) 2010 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef JNI_CONSTANTS_H_included
18 #define JNI_CONSTANTS_H_included
19 
20 #include "JNIHelp.h"
21 
22 /**
23  * A cache to avoid calling FindClass at runtime.
24  *
25  * Class lookup is relatively expensive, so we do these lookups at startup. This means that code
26  * that never uses, say, java.util.zip.Deflater still has to pay for the lookup, but it means that
27  * on device the cost is paid during boot and amortized. A central cache also removes the temptation
28  * to dynamically call FindClass rather than add a small cache to each file that needs one. Another
29  * cost is that each class cached here requires a global reference, though in practice we save
30  * enough by not having a global reference for each file that uses a class such as java.lang.String
31  * which is used in several files.
32  *
33  * FindClass is still called in a couple of situations: when throwing exceptions, and in some of
34  * the serialization code. The former is clearly not a performance case, and we're currently
35  * assuming that neither is the latter.
36  *
37  * TODO: similar arguments hold for field and method IDs; we should cache them centrally too.
38  */
39 struct JniConstants {
40     static void init(JNIEnv* env);
41 
42     static jclass bigDecimalClass;
43     static jclass booleanClass;
44     static jclass byteArrayClass;
45     static jclass byteClass;
46     static jclass calendarClass;
47     static jclass characterClass;
48     static jclass charsetICUClass;
49     static jclass constructorClass;
50     static jclass deflaterClass;
51     static jclass doubleClass;
52     static jclass errnoExceptionClass;
53     static jclass fieldClass;
54     static jclass fileDescriptorClass;
55     static jclass floatClass;
56     static jclass gaiExceptionClass;
57     static jclass inet6AddressClass;
58     static jclass inetAddressClass;
59     static jclass inetAddressHolderClass;
60     static jclass inetSocketAddressClass;
61     static jclass inetSocketAddressHolderClass;
62     static jclass inflaterClass;
63     static jclass inputStreamClass;
64     static jclass integerClass;
65     static jclass localeDataClass;
66     static jclass longClass;
67     static jclass methodClass;
68     static jclass mutableIntClass;
69     static jclass mutableLongClass;
70     static jclass netlinkSocketAddressClass;
71     static jclass objectClass;
72     static jclass objectArrayClass;
73     static jclass outputStreamClass;
74     static jclass packetSocketAddressClass;
75     static jclass parsePositionClass;
76     static jclass patternSyntaxExceptionClass;
77     static jclass referenceClass;
78     static jclass shortClass;
79     static jclass socketClass;
80     static jclass socketImplClass;
81     static jclass socketTaggerClass;
82     static jclass stringClass;
83     static jclass structAddrinfoClass;
84     static jclass structFlockClass;
85     static jclass structGroupReqClass;
86     static jclass structGroupSourceReqClass;
87     static jclass structLingerClass;
88     static jclass structPasswdClass;
89     static jclass structPollfdClass;
90     static jclass structStatClass;
91     static jclass structStatVfsClass;
92     static jclass structTimevalClass;
93     static jclass structUcredClass;
94     static jclass structUtsnameClass;
95     static jclass unixSocketAddressClass;
96     static jclass zipEntryClass;
97 };
98 
99 #define NATIVE_METHOD(className, functionName, signature) \
100     { #functionName, signature, reinterpret_cast<void*>(className ## _ ## functionName) }
101 
102 #endif  // JNI_CONSTANTS_H_included
103