Import code from internal repository to git

java/com/google/domain/registry/util/TeeOutputStream.java

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+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// 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.google.domain.registry.util;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkState;
+
+import com.google.common.collect.ImmutableList;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+import javax.annotation.WillNotClose;
+
+/**
+ * {@link OutputStream} delegate that writes simultaneously to multiple other output streams.
+  */
+public final class TeeOutputStream extends OutputStream {
+
+  private final ImmutableList<? extends OutputStream> outputs;
+  private boolean isClosed;
+  
+  public TeeOutputStream(@WillNotClose Iterable<? extends OutputStream> outputs) {
+    this.outputs = ImmutableList.copyOf(outputs);
+    checkArgument(!this.outputs.isEmpty(), "must provide at least one output stream");
+  }
+
+  /** @see java.io.OutputStream#write(int) */
+  @Override
+  public void write(int b) throws IOException {
+    checkState(!isClosed, "outputstream closed");
+    for (OutputStream out : outputs) {
+      out.write(b);
+    }
+  }
+
+  /** @see #write(byte[], int, int) */
+  @Override
+  public void write(byte[] b) throws IOException {
+    this.write(b, 0, b.length);
+  }
+
+  /** @see java.io.OutputStream#write(byte[], int, int) */
+  @Override
+  public void write(byte[] b, int off, int len) throws IOException {
+    checkState(!isClosed, "outputstream closed");
+    for (OutputStream out : outputs) {
+      out.write(b, off, len);
+    }
+  }
+
+  /** Closes the stream.  Any calls to a {@code write()} method after this will throw. */
+  @Override
+  public void close() throws IOException {
+    isClosed = true;
+  }
+}