Android 多进程开发 - FileDescriptor、Uri、AIDL 接口定义不能抛出异常

FileDescriptor

1、AIDL

• IMyAidlInterface.aidl，这里是位于 src/main/java/com/my/common 包下

package com.my.common;

import android.os.ParcelFileDescriptor;

interface IMyAidlInterface {
ParcelFileDescriptor getFileDescriptor();
void setFileDescriptor(in ParcelFileDescriptor parcelFileDescriptor);
}

2、Server

private final IMyAidlInterface.Stub binder = new IMyAidlInterface.Stub() {

@Override
public ParcelFileDescriptor getFileDescriptor() throws RemoteException {
File filesDir = getFilesDir();
File file = new File(filesDir, "shared_file.dat");

// 如果示例文件不存在，则创建，并写入一些数据
if (!file.exists()) {
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
try {
FileOutputStream fileOutputStream = new FileOutputStream(file);
fileOutputStream.write("server content".getBytes());
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}

try {
return ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
} catch (FileNotFoundException e) {
e.printStackTrace();
return null;
}
}

@Override
public void setFileDescriptor(ParcelFileDescriptor parcelFileDescriptor) throws RemoteException {
if (parcelFileDescriptor != null) {
try (FileInputStream fileInputStream = new FileInputStream(parcelFileDescriptor.getFileDescriptor())) {
byte[] content = new byte[fileInputStream.available()];
int read = fileInputStream.read(content);
Log.i(TAG, "read " + read + " bytes from file");
Log.i(TAG, "file content: " + new String(content));
} catch (IOException e) {
Log.i(TAG, "open file error: " + e.getMessage());
} finally {
try {
parcelFileDescriptor.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
};

3、Client

try {
ParcelFileDescriptor parcelFileDescriptor = myAidlInterface.getFileDescriptor();
Log.i(TAG, "getFileDescriptor method success");

if (parcelFileDescriptor != null) {
try (FileInputStream fileInputStream = new FileInputStream(parcelFileDescriptor.getFileDescriptor())) {
byte[] content = new byte[fileInputStream.available()];
int read = fileInputStream.read(content);
Log.i(TAG, "read " + read + " bytes from file");
Log.i(TAG, "file content: " + new String(content));
} catch (IOException e) {
Log.i(TAG, "open file error: " + e.getMessage());
} finally {
try {
parcelFileDescriptor.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
} catch (RemoteException e) {
e.printStackTrace();
Log.e(TAG, "getFileDescriptor method error: " + e.getMessage());
}

File filesDir = getFilesDir();
File file = new File(filesDir, "shared_file.dat");

// 如果示例文件不存在，则创建，并写入一些数据
if (!file.exists()) {
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
try {
FileOutputStream fileOutputStream = new FileOutputStream(file);
fileOutputStream.write("client content".getBytes());
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}

try {
ParcelFileDescriptor parcelFileDescriptor = ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
try {
myAidlInterface.setFileDescriptor(parcelFileDescriptor);
Log.i(TAG, "setFileDescriptor method success");
} catch (RemoteException e) {
e.printStackTrace();
Log.e(TAG, "setFileDescriptor method error: " + e.getMessage());
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}

4、Test

getFileDescriptor method success
read 14 bytes from file
file content: server content

read 14 bytes from file
file content: client content
setFileDescriptor method success

Uri

1、AIDL

• IMyAidlInterface.aidl，这里是位于 src/main/java/com/my/common 包下

package com.my.common;

import android.net.Uri;

interface IMyAidlInterface {
Uri getUri();
void setUri(in Uri uri);
}

2、Server

private final IMyAidlInterface.Stub binder = new IMyAidlInterface.Stub() {

@Override
public Uri getUri() throws RemoteException {
File filesDir = getFilesDir();
File file = new File(filesDir, "shared_file.dat");

// 如果示例文件不存在，则创建，并写入一些数据
if (!file.exists()) {
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
try {
FileOutputStream fileOutputStream = new FileOutputStream(file);
fileOutputStream.write("server content".getBytes());
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}

Uri uri = FileProvider.getUriForFile(ServerService.this, getApplicationContext().getPackageName() + ".fileprovider", file);

// 授予临时权限
// 第一个参数是客户端应用包名
grantUriPermission("com.my.client", uri, Intent.FLAG_GRANT_READ_URI_PERMISSION);

return uri;
}

@Override
public void setUri(Uri uri) throws RemoteException {
if (uri != null) {
try (InputStream inputStream = getContentResolver().openInputStream(uri)) {
byte[] content = new byte[inputStream.available()];
int read = inputStream.read(content);
Log.i(TAG, "read " + read + " bytes from uri");
Log.i(TAG, "uri content: " + new String(content));
} catch (IOException e) {
e.printStackTrace();
}
}
}
};

3、Client

try {
Uri uri = myAidlInterface.getUri();
Log.i(TAG, "getUri method success");

if (uri != null) {
try (InputStream inputStream = getContentResolver().openInputStream(uri)) {
byte[] content = new byte[inputStream.available()];
int read = inputStream.read(content);
Log.i(TAG, "read " + read + " bytes from uri");
Log.i(TAG, "uri content: " + new String(content));
} catch (IOException e) {
e.printStackTrace();
}
}
} catch (RemoteException e) {
e.printStackTrace();
Log.e(TAG, "getUri method error: " + e.getMessage());
}

File filesDir = getFilesDir();
File file = new File(filesDir, "shared_file.dat");

// 如果示例文件不存在，则创建，并写入一些数据
if (!file.exists()) {
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
try {
FileOutputStream fileOutputStream = new FileOutputStream(file);
fileOutputStream.write("client content".getBytes());
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}

Uri uri = FileProvider.getUriForFile(this, getPackageName() + ".fileprovider", file);
grantUriPermission("com.my.server", uri, Intent.FLAG_GRANT_READ_URI_PERMISSION);
try {
myAidlInterface.setUri(uri);
Log.i(TAG, "setUri method success");
} catch (RemoteException e) {
e.printStackTrace();
Log.e(TAG, "setUri method error: " + e.getMessage());
}

4、Test

getUri method success
read 14 bytes from uri
uri content: server content

read 14 bytes from uri
uri content: client content
setUri method success

AIDL 接口定义不能抛出异常

• 在 AIDL 接口定义中，方法签名本身不能包含 throws 关键字来声明抛出异常，会导致编译错误

int add(int a, int b) throws RemoteException;

# 输出结果

syntax error, unexpected identifier, expecting '=' or ';'

oneway void doSomething() throws RemoteException;

# 输出结果

syntax error, unexpected identifier, expecting '=' or ';'

• 将光标移动到 throws 关键字上，会出现如下提示信息

AidlTokenTypes. ASSIGN expected, got 'throws'