1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
/*
* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef WEBRTC_MODULES_UTILITY_SOURCE_JVM_H_
#define WEBRTC_MODULES_UTILITY_SOURCE_JVM_H_
#include <jni.h>
#include <string>
#include "webrtc/base/scoped_ptr.h"
#include "webrtc/base/thread_checker.h"
#include "webrtc/modules/utility/interface/helpers_android.h"
namespace webrtc {
// The JNI interface pointer (JNIEnv) is valid only in the current thread.
// Should another thread need to access the Java VM, it must first call
// AttachCurrentThread() to attach itself to the VM and obtain a JNI interface
// pointer. The native thread remains attached to the VM until it calls
// DetachCurrentThread() to detach.
class AttachCurrentThreadIfNeeded {
public:
AttachCurrentThreadIfNeeded();
~AttachCurrentThreadIfNeeded();
private:
rtc::ThreadChecker thread_checker_;
bool attached_;
};
// This class is created by the NativeRegistration class and is used to wrap
// the actual Java object handle (jobject) on which we can call methods from
// C++ in to Java. See example in JVM for more details.
// TODO(henrika): extend support for type of function calls.
class GlobalRef {
public:
GlobalRef(JNIEnv* jni, jobject object);
~GlobalRef();
jboolean CallBooleanMethod(jmethodID methodID, ...);
jint CallIntMethod(jmethodID methodID, ...);
void CallVoidMethod(jmethodID methodID, ...);
private:
JNIEnv* const jni_;
const jobject j_object_;
};
// Wraps the jclass object on which we can call GetMethodId() functions to
// query method IDs.
class JavaClass {
public:
JavaClass(JNIEnv* jni, jclass clazz) : jni_(jni), j_class_(clazz) {}
~JavaClass() {}
jmethodID GetMethodId(const char* name, const char* signature);
jmethodID GetStaticMethodId(const char* name, const char* signature);
jobject CallStaticObjectMethod(jmethodID methodID, ...);
protected:
JNIEnv* const jni_;
jclass const j_class_;
};
// Adds support of the NewObject factory method to the JavaClass class.
// See example in JVM for more details on how to use it.
class NativeRegistration : public JavaClass {
public:
NativeRegistration(JNIEnv* jni, jclass clazz);
~NativeRegistration();
rtc::scoped_ptr<GlobalRef> NewObject(
const char* name, const char* signature, ...);
private:
JNIEnv* const jni_;
};
// This class is created by the JVM class and is used to expose methods that
// needs the JNI interface pointer but its main purpose is to create a
// NativeRegistration object given name of a Java class and a list of native
// methods. See example in JVM for more details.
class JNIEnvironment {
public:
explicit JNIEnvironment(JNIEnv* jni);
~JNIEnvironment();
// Registers native methods with the Java class specified by |name|.
// Note that the class name must be one of the names in the static
// |loaded_classes| array defined in jvm_android.cc.
// This method must be called on the construction thread.
rtc::scoped_ptr<NativeRegistration> RegisterNatives(
const char* name, const JNINativeMethod *methods, int num_methods);
// Converts from Java string to std::string.
// This method must be called on the construction thread.
std::string JavaToStdString(const jstring& j_string);
private:
rtc::ThreadChecker thread_checker_;
JNIEnv* const jni_;
};
// Main class for working with Java from C++ using JNI in WebRTC.
//
// Example usage:
//
// // At initialization (e.g. in JNI_OnLoad), call JVM::Initialize.
// JNIEnv* jni = ::base::android::AttachCurrentThread();
// JavaVM* jvm = NULL;
// jni->GetJavaVM(&jvm);
// jobject context = ::base::android::GetApplicationContext();
// webrtc::JVM::Initialize(jvm, context);
//
// // Header (.h) file of example class called User.
// rtc::scoped_ptr<JNIEnvironment> env;
// rtc::scoped_ptr<NativeRegistration> reg;
// rtc::scoped_ptr<GlobalRef> obj;
//
// // Construction (in .cc file) of User class.
// User::User() {
// // Calling thread must be attached to the JVM.
// env = JVM::GetInstance()->environment();
// reg = env->RegisterNatives("org/webrtc/WebRtcTest", ,);
// obj = reg->NewObject("<init>", ,);
// }
//
// // Each User method can now use |reg| and |obj| and call Java functions
// // in WebRtcTest.java, e.g. boolean init() {}.
// bool User::Foo() {
// jmethodID id = reg->GetMethodId("init", "()Z");
// return obj->CallBooleanMethod(id);
// }
//
// // And finally, e.g. in JNI_OnUnLoad, call JVM::Uninitialize.
// JVM::Uninitialize();
class JVM {
public:
// Stores global handles to the Java VM interface and the application context.
// Should be called once on a thread that is attached to the JVM.
static void Initialize(JavaVM* jvm, jobject context);
// Clears handles stored in Initialize(). Must be called on same thread as
// Initialize().
static void Uninitialize();
// Gives access to the global Java VM interface pointer, which then can be
// used to create a valid JNIEnvironment object or to get a JavaClass object.
static JVM* GetInstance();
// Creates a JNIEnvironment object.
// This method returns a NULL pointer if AttachCurrentThread() has not been
// called successfully. Use the AttachCurrentThreadIfNeeded class if needed.
rtc::scoped_ptr<JNIEnvironment> environment();
// Returns a JavaClass object given class |name|.
// Note that the class name must be one of the names in the static
// |loaded_classes| array defined in jvm_android.cc.
// This method must be called on the construction thread.
JavaClass GetClass(const char* name);
// TODO(henrika): can we make these private?
JavaVM* jvm() const { return jvm_; }
jobject context() const { return context_; }
protected:
JVM(JavaVM* jvm, jobject context);
~JVM();
private:
JNIEnv* jni() const { return GetEnv(jvm_); }
rtc::ThreadChecker thread_checker_;
JavaVM* const jvm_;
jobject context_;
};
} // namespace webrtc
#endif // WEBRTC_MODULES_UTILITY_SOURCE_JVM_H_
|
