High -performance bitmap compression: a practical guide for the Javaewah framework
High -performance bitmap compression: a practical guide for the Javaewah framework
Overview:
Bit diagram compression is a commonly used data compression technology that is used to compress the sparse position in the data.The Javaewah framework is a high -performance bitmap compression library, which provides fast and efficient data compression and decompression functions.This article will introduce the use of the Javaewah framework and provide the corresponding example code and configuration description.
1. Javaewah framework brief introduction:
Javaewah is an open source Java library that is used to process large -scale diagram compression.It uses a bit diagram compression algorithm called "non -ambiguity wide hash", which achieves data compression and decompression by storing multiple continuous empty caves (zero value) inside a bitmap.This framework supports efficient bitmap operations, such as logical operations, aggregation statistics and iteration traversal.
2. Installation and configuration of javaewah:
You can use it by adding the javaewah library to your project dependence.You can download the latest Javaewah version from Maven central warehouse and add it to your project's pom.xml file.Below is a maven dependency example:
<dependency>
<groupId>com.googlecode.javaewah</groupId>
<artifactId>JavaEWAH</artifactId>
<version>1.1.6</version>
</dependency>
3. The creation and access of the compression position diagram:
First of all, you need to create a new compression level diagram.It can be implemented by using the EWAHCOMPRESEDBITMAP class:
EWAHCompressedBitmap bitmap = new EWAHCompressedBitmap();
Then, you can use the set method to set the specified position to 1:
bitmap.set (3); // Set 4th place to 1
bitmap.set (5); // Set the 6th place to 1
You can also use the get method to access the bit graph value of the specified position:
if (bitmap.get(3)) {
System.out.println ("4th place is 1");
}
4. Pickup compression and decompression:
Javaewah provides a method of compression and decompression.You can use Bitmap's Bitmapof method to convert the normal position diagram to compression position:
BitSet normalBitmap = new BitSet();
normalBitmap.set(2);
normalBitmap.set(4);
normalBitmap.set(6);
EWAHCompressedBitmap compressedBitmap = EWAHCompressedBitmap.bitmapOf(normalBitmap);
Conversely, you can use Bitmap's TOBITSET method to convert the compressed bitmap back to the normal position:
BitSet decompressedBitmap = compressedBitmap.toBitSet();
5. Bit diagram operation:
The Javaewah framework supports various position diagrams, such as logical operations, aggregation statistics and iteration traversal.Here are some common example diagrams operation examples:
- logic operation:
EWAHCompressedBitmap bitmap1 = new EWAHCompressedBitmap();
bitmap1.set(3);
bitmap1.set(5);
EWAHCompressedBitmap bitmap2 = new EWAHCompressedBitmap();
bitmap2.set(5);
bitmap2.set(7);
// Pitch diagram parallel
EWAHCompressedBitmap union = bitmap1.or(bitmap2);
// The intersection of the bitmap
EWAHCompressedBitmap intersection = bitmap1.and(bitmap2);
// The difference in the bitmap
EWAHCompressedBitmap difference = bitmap1.andNot(bitmap2);
-Cacline statistics:
EWAHCompressedBitmap bitmap = new EWAHCompressedBitmap();
bitmap.set(3);
bitmap.set(5);
bitmap.set(7);
// The number of 1 in the statistical level diagram
int count = bitmap.cardinality();
// minimum value
int minValue = bitmap.min();
// maximum value
int maxValue = bitmap.max();
-This traversal:
EWAHCompressedBitmap bitmap = new EWAHCompressedBitmap();
bitmap.set(3);
bitmap.set(5);
bitmap.set(7);
// Each bit in the iteration traversal diagram
bitmap.forEach(new IntConsumer() {
@Override
public void accept(int value) {
System.out.println ("No." + Value + "bit as 1");
}
});
The above is a brief introduction and usage guide for the Javaewah framework. I hope it will help you understand and use high -performance position compression technology.The detailed Javaewah API document and example code can be found on the official website.
