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Merge pull request #5 from caffinc/development
Adding JSON Iterator and removing unnecessary imports
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132 changes: 132 additions & 0 deletions
132
jaggr/jaggr-utils/src/main/java/com/caffinc/jaggr/utils/JsonIterator.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,132 @@ | ||
| package com.caffinc.jaggr.utils; | ||
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| import com.google.gson.Gson; | ||
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| import java.io.*; | ||
| import java.util.HashMap; | ||
| import java.util.Iterator; | ||
| import java.util.Map; | ||
| import java.util.NoSuchElementException; | ||
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| /** | ||
| * Iterates a JSON file | ||
| * | ||
| * @author Sriram | ||
| * @since 11/27/2016 | ||
| */ | ||
| public class JsonIterator implements Iterator<Map<String, Object>>, Closeable { | ||
| private final BufferedReader bufferedReader; | ||
| private String cachedLine; | ||
| private boolean finished = false; | ||
| private Gson gson = new Gson(); | ||
|
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| /** | ||
| * Constructs an iterator of the lines for a <code>fileName</code>. | ||
| * | ||
| * @param fileName the <code>fileName</code> to read from | ||
| * @throws IOException thrown if there is a problem accessing the file | ||
| */ | ||
| public JsonIterator(final String fileName) throws IOException { | ||
| this(new BufferedReader(new FileReader(fileName))); | ||
| } | ||
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| /** | ||
| * Constructs an iterator of the lines for a <code>Reader</code>. | ||
| * | ||
| * @param reader the <code>Reader</code> to read from, not null | ||
| * @throws IllegalArgumentException if the reader is null | ||
| */ | ||
| public JsonIterator(final Reader reader) throws IllegalArgumentException { | ||
| if (reader == null) { | ||
| throw new IllegalArgumentException("Reader must not be null"); | ||
| } | ||
| if (reader instanceof BufferedReader) { | ||
| bufferedReader = (BufferedReader) reader; | ||
| } else { | ||
| bufferedReader = new BufferedReader(reader); | ||
| } | ||
| } | ||
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| /** | ||
| * Indicates whether the <code>Reader</code> has more lines. | ||
| * If there is an <code>IOException</code> then {@link #close()} will | ||
| * be called on this instance. | ||
| * | ||
| * @return {@code true} if the Reader has more lines | ||
| * @throws IllegalStateException if an IO exception occurs | ||
| */ | ||
| public boolean hasNext() { | ||
| if (cachedLine != null) { | ||
| return true; | ||
| } else if (finished) { | ||
| return false; | ||
| } else { | ||
| try { | ||
| while (true) { | ||
| final String line = bufferedReader.readLine(); | ||
| if (line == null) { | ||
| finished = true; | ||
| return false; | ||
| } | ||
| cachedLine = line; | ||
| return true; | ||
| } | ||
| } catch (final IOException ioe) { | ||
| close(); | ||
| throw new IllegalStateException(ioe); | ||
| } | ||
| } | ||
| } | ||
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| /** | ||
| * Returns the next object in the file or wrapped <code>Reader</code>. | ||
| * | ||
| * @return the next JSON object from the input | ||
| * @throws NoSuchElementException if there is no object to return | ||
| */ | ||
| public Map<String, Object> next() { | ||
| return nextObject(); | ||
| } | ||
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| /** | ||
| * Returns the next object in the file or wrapped <code>Reader</code>. | ||
| * | ||
| * @return the next JSON object from the input | ||
| * @throws NoSuchElementException if there is no object to return | ||
| */ | ||
| public Map<String, Object> nextObject() { | ||
| if (!hasNext()) { | ||
| throw new NoSuchElementException("No more objects"); | ||
| } | ||
| final String currentLine = cachedLine; | ||
| cachedLine = null; | ||
| return gson.fromJson(currentLine, HashMap.class); | ||
| } | ||
|
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| /** | ||
| * Closes the underlying <code>Reader</code> quietly. | ||
| * This method is useful if you only want to process the first few | ||
| * lines of a larger file. If you do not close the iterator | ||
| * then the <code>Reader</code> remains open. | ||
| * This method can safely be called multiple times. | ||
| */ | ||
| public void close() { | ||
| finished = true; | ||
| try { | ||
| bufferedReader.close(); | ||
| } catch (final IOException ioe) { | ||
| // ignore | ||
| } | ||
| cachedLine = null; | ||
| } | ||
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| /** | ||
| * Unsupported. | ||
| * | ||
| * @throws UnsupportedOperationException always | ||
| */ | ||
| public void remove() { | ||
| throw new UnsupportedOperationException("Remove unsupported on JsonIterator"); | ||
| } | ||
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| } |
50 changes: 50 additions & 0 deletions
50
jaggr/jaggr-utils/src/test/java/com/caffinc/jaggr/utils/JsonIteratorTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,50 @@ | ||
| package com.caffinc.jaggr.utils; | ||
|
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| import com.google.gson.Gson; | ||
| import org.junit.Assert; | ||
| import org.junit.Test; | ||
|
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| import java.io.BufferedWriter; | ||
| import java.io.FileWriter; | ||
| import java.nio.file.Files; | ||
| import java.nio.file.Path; | ||
| import java.nio.file.Paths; | ||
| import java.util.*; | ||
|
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| /** | ||
| * Tests for the JsonIterator | ||
| * | ||
| * @author Sriram | ||
| * @since 11/27/2016 | ||
| */ | ||
| public class JsonIteratorTest { | ||
| private static final String TEMP_DIR = System.getProperty("java.io.tmpdir"); | ||
| private static final Random RANDOM = new Random(); | ||
| private static final Gson GSON = new Gson(); | ||
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| @Test | ||
| public void testJsonFileIterator() throws Exception { | ||
| Path tempFilePath = Paths.get(TEMP_DIR, "jsontest" + RANDOM.nextInt() + ".json"); | ||
| try { | ||
| List<Map<String, Object>> expectedData = new ArrayList<>(); | ||
| try (BufferedWriter br = new BufferedWriter(new FileWriter(tempFilePath.toFile())) | ||
| ) { | ||
| for (int i = 0; i < 10; i++) { | ||
| Map<String, Object> json = new HashMap<>(); | ||
| json.put("_id", (double) i); | ||
| json.put("val", RANDOM.nextDouble()); | ||
| expectedData.add(json); | ||
| br.write(GSON.toJson(json) + "\n"); | ||
| } | ||
| } | ||
| try (JsonIterator jsonIterator = new JsonIterator(tempFilePath.toString())) { | ||
| for (Map<String, Object> expected : expectedData) { | ||
| Map<String, Object> actual = jsonIterator.next(); | ||
| Assert.assertEquals("Value should match value written to file", expected, actual); | ||
| } | ||
| } | ||
| } finally { | ||
| Files.delete(tempFilePath); | ||
| } | ||
| } | ||
| } |
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