Coverage Summary for Class: MultiInputStream (com.google.common.io)

1 /*
2  * Copyright (C) 2007 The Guava Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5  * in compliance with the License. You may obtain a copy of the License at
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software distributed under the License
10  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11  * or implied. See the License for the specific language governing permissions and limitations under
12  * the License.
13  */
14 
15 package com.google.common.io;
16 
17 import static com.google.common.base.Preconditions.checkNotNull;
18 
19 import com.google.common.annotations.GwtIncompatible;
20 import java.io.IOException;
21 import java.io.InputStream;
22 import java.util.Iterator;
23 import javax.annotation.CheckForNull;
24 
25 /**
26  * An {@link InputStream} that concatenates multiple substreams. At most one stream will be open at
27  * a time.
28  *
29  * @author Chris Nokleberg
30  * @since 1.0
31  */
32 @GwtIncompatible
33 @ElementTypesAreNonnullByDefault
34 final class MultiInputStream extends InputStream {
35 
36   private Iterator<? extends ByteSource> it;
37   @CheckForNull private InputStream in;
38 
39   /**
40    * Creates a new instance.
41    *
42    * @param it an iterator of I/O suppliers that will provide each substream
43    */
44   public MultiInputStream(Iterator<? extends ByteSource> it) throws IOException {
45     this.it = checkNotNull(it);
46     advance();
47   }
48 
49   @Override
50   public void close() throws IOException {
51     if (in != null) {
52       try {
53         in.close();
54       } finally {
55         in = null;
56       }
57     }
58   }
59 
60   /** Closes the current input stream and opens the next one, if any. */
61   private void advance() throws IOException {
62     close();
63     if (it.hasNext()) {
64       in = it.next().openStream();
65     }
66   }
67 
68   @Override
69   public int available() throws IOException {
70     if (in == null) {
71       return 0;
72     }
73     return in.available();
74   }
75 
76   @Override
77   public boolean markSupported() {
78     return false;
79   }
80 
81   @Override
82   public int read() throws IOException {
83     while (in != null) {
84       int result = in.read();
85       if (result != -1) {
86         return result;
87       }
88       advance();
89     }
90     return -1;
91   }
92 
93   @Override
94   public int read(byte[] b, int off, int len) throws IOException {
95     checkNotNull(b);
96     while (in != null) {
97       int result = in.read(b, off, len);
98       if (result != -1) {
99         return result;
100       }
101       advance();
102     }
103     return -1;
104   }
105 
106   @Override
107   public long skip(long n) throws IOException {
108     if (in == null || n <= 0) {
109       return 0;
110     }
111     long result = in.skip(n);
112     if (result != 0) {
113       return result;
114     }
115     if (read() == -1) {
116       return 0;
117     }
118     return 1 + in.skip(n - 1);
119   }
120 }