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
|
/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.messaging.datamodel;
import android.content.ContentProvider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.ParcelFileDescriptor;
import android.text.TextUtils;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Random;
/**
* A very simple content provider that can serve files.
*/
public abstract class FileProvider extends ContentProvider {
// Object to generate random id for temp images.
private static final Random RANDOM_ID = new Random();
abstract File getFile(final String path, final String extension);
private static final String FILE_EXTENSION_PARAM_KEY = "ext";
/**
* Check if filename conforms to requirement for our provider
* @param fileId filename (optionally starting with path character
* @return true if filename consists only of digits
*/
protected static boolean isValidFileId(final String fileId) {
// Ignore initial "/"
for (int index = (fileId.startsWith("/") ? 1 : 0); index < fileId.length(); index++) {
final Character c = fileId.charAt(index);
if (!Character.isDigit(c)) {
return false;
}
}
return true;
}
/**
* Create a temp file (to allow writing to that one particular file)
* @param file the file to create
* @return true if file successfully created
*/
protected static boolean ensureFileExists(final File file) {
try {
final File parentDir = file.getParentFile();
if (parentDir.exists() || parentDir.mkdirs()) {
return file.createNewFile();
}
} catch (final IOException e) {
// fail on exceptions creating the file
}
return false;
}
/**
* Build uri for a new temporary file (creating file)
* @param authority authority with which to populate uri
* @param extension optional file extension
* @return unique uri that can be used to write temporary files
*/
protected static Uri buildFileUri(final String authority, final String extension) {
final long fileId = Math.abs(RANDOM_ID.nextLong());
final Uri.Builder builder = (new Uri.Builder()).authority(authority).scheme(
ContentResolver.SCHEME_CONTENT);
builder.appendPath(String.valueOf(fileId));
if (!TextUtils.isEmpty(extension)) {
builder.appendQueryParameter(FILE_EXTENSION_PARAM_KEY, extension);
}
return builder.build();
}
@Override
public boolean onCreate() {
return true;
}
@Override
public int delete(final Uri uri, final String selection, final String[] selectionArgs) {
final String fileId = uri.getPath();
if (isValidFileId(fileId)) {
final File file = getFile(fileId, getExtensionFromUri(uri));
return file.delete() ? 1 : 0;
}
return 0;
}
@Override
public ParcelFileDescriptor openFile(final Uri uri, final String fileMode)
throws FileNotFoundException {
final String fileId = uri.getPath();
if (isValidFileId(fileId)) {
final File file = getFile(fileId, getExtensionFromUri(uri));
final int mode =
(TextUtils.equals(fileMode, "r") ? ParcelFileDescriptor.MODE_READ_ONLY :
ParcelFileDescriptor.MODE_WRITE_ONLY | ParcelFileDescriptor.MODE_TRUNCATE);
return ParcelFileDescriptor.open(file, mode);
}
return null;
}
protected static String getExtensionFromUri(final Uri uri) {
return uri.getQueryParameter(FILE_EXTENSION_PARAM_KEY);
}
@Override
public Cursor query(final Uri uri, final String[] projection, final String selection,
final String[] selectionArgs, final String sortOrder) {
// Don't support queries.
return null;
}
@Override
public Uri insert(final Uri uri, final ContentValues values) {
// Don't support inserts.
return null;
}
@Override
public int update(final Uri uri, final ContentValues values, final String selection,
final String[] selectionArgs) {
// Don't support updates.
return 0;
}
@Override
public String getType(final Uri uri) {
// No need for mime types.
return null;
}
}
|
