极客教程Java Deflater deflate()函数及示例
java.util.zip中 Deflater类 的 deflate() 函数用于压缩输入数据并将压缩后的数据填充到给定的缓冲区中。该函数返回压缩后的数据的字节数。
函数签名
public int deflate(byte[] b)
public int deflate(byte[] b, int offset, int length, int flush)
public int deflate(byte[] b, int offset, int length)
语法
d.deflate(byte[])
d.deflate(byte[], int, int, int)
d.deflate(byte[], int, int )
参数： 这些重载函数所接受的各种参数是。
- byte[] b : 这是要被解压的输入数组。
- int offset : 这是在给定数组中读取数值的起始偏移量。
- int length : 这是从起始偏移量开始要压缩的最大长度。
- int flush : 这是作为参数传递的冲洗模式。
返回类型： 该函数返回一个整数值，该值是压缩数据的大小。
异常： 如果冲洗模式无效，该函数会抛出IllegalArgumentException。有三种有效的刷新模式：NO_FLUSH, SYNC_FLUSH, FULL_FLUSH。
下面的例子演示了上述函数的使用。
例1： 演示deflate(byte[] b)函数的使用
// Java program to demonstrate
// the use of deflate(byte[] b) function
import java.util.zip.*;
import java.io.UnsupportedEncodingException;
class GFG {
public static void main(String args[])
throws UnsupportedEncodingException
{
// deflater
Deflater d = new Deflater();
// get the text
String pattern = "GeeksforGeeks", text = "";
// generate the text
for (int i = 0; i < 4; i++)
text += pattern;
// set the input for deflator
d.setInput(text.getBytes("UTF-8"));
// finish
d.finish();
// output bytes
byte output[] = new byte[1024];
// compress the data
int size = d.deflate(output);
// compressed String
System.out.println("Compressed String :"
+ new String(output)
+ "\n Size " + size);
// original String
System.out.println("Original String :"
+ text + "\n Size "
+ text.length());
// end
d.end();
}
}
输出
Compressed String :x?sOM?.N?/r???q??
Size 21
Original String :GeeksforGeeksGeeksforGeeksGeeksforGeeksGeeksforGeeks
Size 52
例2： 演示deflate(byte[] b, int offset, int length)函数的使用。
// Java program to demonstrate the use
// of deflate(byte[] b, int offset, int length) function
import java.util.zip.*;
import java.io.UnsupportedEncodingException;
class GFG {
public static void main(String args[])
throws UnsupportedEncodingException
{
// deflater
Deflater d = new Deflater();
// get the text
String pattern = "GeeksforGeeks", text = "";
// generate the text
for (int i = 0; i < 4; i++)
text += pattern;
// set the input for deflator
d.setInput(text.getBytes("UTF-8"));
// finish
d.finish();
// output bytes
byte output[] = new byte[1024];
// compress the data, with given offset and
// set maximum size of compressed string
int size = d.deflate(output, 2, 13);
// compressed String
System.out.println("Compressed String :"
+ new String(output)
+ "\n Size " + size);
// original String
System.out.println("Original String :"
+ text + "\n Size "
+ text.length());
// end
d.end();
}
}
输出
Compressed String :x?sOM?.N?/r?
Size 13
Original String :GeeksforGeeksGeeksforGeeksGeeksforGeeksGeeksforGeeks
Size 52
例3： 演示deflate(byte[] b, int offset, int length, int flush)函数的使用。
// Java program to demonstrate the use of
// deflate(byte[] b, int offset, int length, int flush) function
import java.util.zip.*;
import java.io.UnsupportedEncodingException;
class GFG {
public static void main(String args[])
throws UnsupportedEncodingException
{
// deflater
Deflater d = new Deflater();
// get the text
String pattern = "GeeksforGeeks", text = "";
// generate the text
for (int i = 0; i < 4; i++)
text += pattern;
// set the input for deflator
d.setInput(text.getBytes("UTF-8"));
// finish
d.finish();
// output bytes
byte output[] = new byte[1024];
// compress the data, with given offset and
// set maximum size of compressed string
// and specified Flush
int size = d.deflate(output, 2, 13, Deflater.FULL_FLUSH);
// compressed String
System.out.println("Compressed String :"
+ new String(output)
+ "\n Size " + size);
// original String
System.out.println("Original String :" + text
+ "\n Size " + text.length());
// end
d.end();
}
}
输出
Compressed String :x?sOM?.N?/r?
Size 13
Original String :GeeksforGeeksGeeksforGeeksGeeksforGeeksGeeksforGeeks
Size 52
参考资料
- https://docs.oracle.com/javase/9/docs/api/java/util/zip/Deflater.html#deflate-byte:A-
- https://docs.oracle.com/javase/9/docs/api/java/util/zip/Deflater.html#deflate-byte:A-int-int-
- https://docs.oracle.com/javase/9/docs/api/java/util/zip/Deflater.html#deflate-byte:A-int-int-int-