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

java 复制代码

package com.my.common;

import android.os.ParcelFileDescriptor;

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

2、Server

java 复制代码

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

调用 getFileDescriptor 方法

java 复制代码

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());
}

调用 setFileDescriptor 方法

java 复制代码

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

调用 getFileDescriptor 方法，输出结果如下

getFileDescriptor method success
read 14 bytes from file
file content: server content
调用 setFileDescriptor 方法，输出结果如下

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

java 复制代码

package com.my.common;

import android.net.Uri;

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

2、Server

java 复制代码

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

调用 getUri 方法

java 复制代码

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());
}

调用 setUri 方法

java 复制代码

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

调用 getUri 方法，输出结果如下

getUri method success
read 14 bytes from uri
uri content: server content
调用 setUri 方法，输出结果如下

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

java 复制代码

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

复制代码

# 输出结果

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

java 复制代码

oneway void doSomething() throws RemoteException;

复制代码

# 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'