1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.io.input;
18
19 import java.io.InputStream;
20
21 /**
22 * Proxy stream that prevents the underlying input stream from being closed.
23 * <p>
24 * This class is typically used in cases where an input stream needs to be
25 * passed to a component that wants to explicitly close the stream even if more
26 * input would still be available to other components.
27 * </p>
28 *
29 * @since 1.4
30 */
31 public class CloseShieldInputStream extends ProxyInputStream {
32
33 /**
34 * Constructs a proxy that only shields {@link System#in} from closing.
35 *
36 * @param inputStream the candidate input stream.
37 * @return the given stream or a proxy on {@link System#in}.
38 * @since 2.17.0
39 */
40 public static InputStream systemIn(final InputStream inputStream) {
41 return inputStream == System.in ? wrap(inputStream) : inputStream;
42 }
43
44 /**
45 * Constructs a proxy that shields the given input stream from being closed.
46 *
47 * @param inputStream the input stream to wrap
48 * @return the created proxy
49 * @since 2.9.0
50 */
51 public static CloseShieldInputStream wrap(final InputStream inputStream) {
52 return new CloseShieldInputStream(inputStream);
53 }
54
55 /**
56 * Constructs a proxy that shields the given input stream from being closed.
57 *
58 * @param inputStream underlying input stream
59 * @deprecated Using this constructor prevents IDEs from warning if the
60 * underlying input stream is never closed. Use
61 * {@link #wrap(InputStream)} instead.
62 */
63 @Deprecated
64 public CloseShieldInputStream(final InputStream inputStream) {
65 super(inputStream);
66 }
67
68 /**
69 * Replaces the underlying input stream with a {@link ClosedInputStream}
70 * sentinel. The original input stream will remain open, but this proxy will
71 * appear closed.
72 */
73 @Override
74 public void close() {
75 in = ClosedInputStream.INSTANCE;
76 }
77
78 }