boolean needsInput()
描述 (Description)
如果输入数据缓冲区为空并且应调用setInput（）以提供更多输入，则java.util.zip.Deflater.needsInput()方法返回true。
声明 (Declaration)
以下是java.util.zip.Deflater.needsInput()方法的声明。
public boolean needsInput()
返回值 (Returns)
如果输入数据缓冲区为空并且应调用setInput（）以提供更多输入，则返回true。
例子 (Example)
以下示例显示了java.util.zip.Deflater.needsInput（）方法的用法。
package com.iowiki;
import java.io.UnsupportedEncodingException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;
public class DeflaterDemo {
public static void main(String[] args)
throws DataFormatException, UnsupportedEncodingException {
String message = "Welcome to iowiki.com;"
+"Welcome to iowiki.com;"
+"Welcome to iowiki.com;"
+"Welcome to iowiki.com;"
+"Welcome to iowiki.com;"
+"Welcome to iowiki.com;"
+"Welcome to iowiki.com;"
+"Welcome to iowiki.com;"
+"Welcome to iowiki.com;"
+"Welcome to iowiki.com;";
System.out.println("Original Message length : " + message.length());
byte[] input = message.getBytes("UTF-8");
// Compress the bytes
byte[] output = new byte[1024];
Deflater deflater = new Deflater();
int inCount = input.length;
int inPosition = 0;
int outPosition = 0;
int MAX_BUFFER_SIZE = 10;
while(!deflater.finished()){
int want = -1;
int got;
if (deflater.needsInput() && inCount != 0) {
want = (inCount < MAX_BUFFER_SIZE) ? inCount : MAX_BUFFER_SIZE;
deflater.setInput(input, inPosition, want);
inCount -= want;
inPosition += want;
if (inCount == 0) {
deflater.finish();
}
}
// deflate to current position in output buffer
int compCount;
compCount = deflater.deflate(output, outPosition, MAX_BUFFER_SIZE);
outPosition += compCount;
}
System.out.println("Total uncompressed bytes output :" + deflater.getTotalOut());
System.out.println("Compressed Message Checksum :" + deflater.getAdler());
deflater.finished();
System.out.println("Compressed Message length : " + outPosition);
// Decompress the bytes
Inflater inflater = new Inflater();
inflater.setInput(output, 0, outPosition);
byte[] result = new byte[1024];
int resultLength = inflater.inflate(result);
inflater.finished();
// Decode the bytes into a String
message = new String(result, 0, resultLength, "UTF-8");
System.out.println("UnCompressed Message Checksum :" + inflater.getAdler());
System.out.println("UnCompressed Message length : " + message.length());
}
}
让我们编译并运行上面的程序，这将产生以下结果 -
Original Message length : 300
Total uncompressed bytes output :42
Compressed Message Checksum :368538129
Compressed Message length : 42
UnCompressed Message Checksum :368538129
UnCompressed Message length : 300
