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8032020: Update try-with-resources demo

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Reviewed-by: darcy, alanb, smarks
This commit is contained in:
Andrey Nazarov 2014-01-31 11:57:38 +01:00
parent 7bdf4708b2
commit a7acbb1cb7
4 changed files with 339 additions and 0 deletions
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36
jdk/src/share/sample/try-with-resources/index.html Normal file
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<!DOCTYPE html>
<html>
<head>
<title>Try-with-Resources Feature Demo</title>
</head>
<body>
<h2>Try-with-Resources Feature Demo</h2>
<p>
This demo shows how to use the try-with-resources feature introduced in JDK7.
</p>
<ul>
<li><h3>Custom AutoCloseable.</h3>
<p>
Shows how to use a custom resource with the try-with-resources construct.
For more information, see the source file.
</p>
Source: <a href="src/CustomAutoCloseableSample.java">src/CustomAutoCloseableSample.java</a>
<li><h3>Unzip</h3>
<p>
Extracts archived files. For more information, see the source file.
</p>
Source: <a href="src/Unzip.java">src/Unzip.java</a>
<li><h3>ZipCat</h3>
<p>Prints data about a specified file from an archive. For more information, see the source file.</p>
Source: <a href="src/ZipCat.java">src/ZipCat.java</a>
</ul>
</body>
</html>

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jdk/src/share/sample/try-with-resources/src/CustomAutoCloseableSample.java Normal file
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/*
* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This source code is provided to illustrate the usage of a given feature
* or technique and has been deliberately simplified. Additional steps
* required for a production-quality application, such as security checks,
* input validation, and proper error handling, might not be present in
* this sample code.
*/
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
/**
* This sample demonstrates the ability to create custom resource that
* implements the {@code AutoCloseable} interface. This resource can be used in
* the try-with-resources construct.
*/
public class CustomAutoCloseableSample {
/**
* The main method for the CustomAutoCloseableSample program.
*
* @param args is not used.
*/
public static void main(String[] args) {
/*
* TeeStream will be closed automatically after the try block.
*/
try (TeeStream teeStream = new TeeStream(System.out, Paths.get("out.txt"));
PrintStream out = new PrintStream(teeStream)) {
out.print("Hello, world");
} catch (Exception e) {
e.printStackTrace();
System.exit(1);
}
}
/**
* Passes the output through to the specified output stream while copying it into a file.
* The TeeStream functionality is similar to the Unix tee utility.
* TeeStream implements AutoCloseable interface. See OutputStream for details.
*/
public static class TeeStream extends OutputStream {
private final OutputStream fileStream;
private final OutputStream outputStream;
/**
* Creates a TeeStream.
*
* @param outputStream an output stream.
* @param outputFile an path to file.
* @throws IOException If an I/O error occurs.
*/
public TeeStream(OutputStream outputStream, Path outputFile) throws IOException {
this.fileStream = new BufferedOutputStream(Files.newOutputStream(outputFile));
this.outputStream = outputStream;
}
/**
* Writes the specified byte to the specified output stream
* and copies it to the file.
*
* @param b the byte to be written.
* @throws IOException If an I/O error occurs.
*/
@Override
public void write(int b) throws IOException {
fileStream.write(b);
outputStream.write(b);
}
/**
* Flushes this output stream and forces any buffered output bytes
* to be written out.
* The <code>flush</code> method of <code>TeeStream</code> flushes
* the specified output stream and the file output stream.
*
* @throws IOException if an I/O error occurs.
*/
@Override
public void flush() throws IOException {
outputStream.flush();
fileStream.flush();
}
/**
* Closes underlying streams and resources.
* The external output stream won't be closed.
* This method is the member of AutoCloseable interface and
* it will be invoked automatically after the try-with-resources block.
*
* @throws IOException If an I/O error occurs.
*/
@Override
public void close() throws IOException {
try (OutputStream file = fileStream) {
flush();
}
}
}
}

83
jdk/src/share/sample/try-with-resources/src/Unzip.java Normal file
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/*
* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This source code is provided to illustrate the usage of a given feature
* or technique and has been deliberately simplified. Additional steps
* required for a production-quality application, such as security checks,
* input validation, and proper error handling, might not be present in
* this sample code.
*/
import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.file.*;
import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;
/**
* Extract (unzip) a file to the current directory.
*/
public class Unzip {
/**
* The main method for the Unzip program. Run the program with an empty
* argument list to see possible arguments.
*
* @param args the argument list for {@code Unzip}.
*/
public static void main(String[] args) {
if (args.length != 1) {
System.out.println("Usage: Unzip zipfile");
}
final Path destDir = Paths.get(".");
/*
* Create AutoCloseable FileSystem. It will be closed automatically
* after the try block.
*/
try (FileSystem zipFileSystem = FileSystems.newFileSystem(Paths.get(args[0]), null)) {
Path top = zipFileSystem.getPath("/");
Files.walk(top).skip(1).forEach(file -> {
Path target = destDir.resolve(top.relativize(file).toString());
System.out.println("Extracting " + target);
try {
Files.copy(file, target, REPLACE_EXISTING);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
});
} catch (UncheckedIOException | IOException e) {
e.printStackTrace();
System.exit(1);
}
}
}

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jdk/src/share/sample/try-with-resources/src/ZipCat.java Normal file
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/*
* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This source code is provided to illustrate the usage of a given feature
* or technique and has been deliberately simplified. Additional steps
* required for a production-quality application, such as security checks,
* input validation, and proper error handling, might not be present in
* this sample code.
*/
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Paths;
/**
* Prints data of the specified file to standard output from a zip archive.
*/
public class ZipCat {
/**
* The main method for the ZipCat program. Run the program with an empty
* argument list to see possible arguments.
*
* @param args the argument list for ZipCat
*/
public static void main(String[] args) {
if (args.length != 2) {
System.out.println("Usage: ZipCat zipfile fileToPrint");
}
/*
* Creates AutoCloseable FileSystem and BufferedReader.
* They will be closed automatically after the try block.
* If reader initialization fails, then zipFileSystem will be closed
* automatically.
*/
try (FileSystem zipFileSystem
= FileSystems.newFileSystem(Paths.get(args[0]),null);
InputStream input
= Files.newInputStream(zipFileSystem.getPath(args[1]))) {
byte[] buffer = new byte[1024];
int len;
while ((len = input.read(buffer)) != -1) {
System.out.write(buffer, 0, len);
}
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
}
}