boolean needsInput()

描述 (Description)

如果输入缓冲区中没有数据，则java.util.zip.Inflater.needsInput()方法返回true。 这可用于确定是否应调用#setInput以提供更多输入。

声明 (Declaration)

以下是java.util.zip.Inflater.needsInput()方法的声明。

public boolean needsInput()

返回值 (Returns)

如果输入缓冲区中没有数据，则为true。

例子 (Example)

以下示例显示了java.util.zip.Inflater.needsInput（）方法的用法。

package cn.xnip;
import java.io.UnsupportedEncodingException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;
public class InflaterDemo {
   public static void main(String[] args) 
      throws DataFormatException, UnsupportedEncodingException {
      String message = "Welcome to xnip.cn;"
         +"Welcome to xnip.cn;"
         +"Welcome to xnip.cn;"
         +"Welcome to xnip.cn;"
         +"Welcome to xnip.cn;"
         +"Welcome to xnip.cn;"
         +"Welcome to xnip.cn;"
         +"Welcome to xnip.cn;"
         +"Welcome to xnip.cn;"
         +"Welcome to xnip.cn;";
      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();
      deflater.setInput(input);
      deflater.finish();
      int compressedDataLength = deflater.deflate(output,0,output.length);
      deflater.end();
      System.out.println("Compressed Message length : " + compressedDataLength);
      // Decompress the bytes
      Inflater inflater = new Inflater();
      inflater.setInput(output, 0, 10);
      byte[] result = new byte[1024];
      int resultLength = inflater.inflate(result, 0 , 10);
      if(inflater.needsInput()){
         inflater.setInput(output, 10, compressedDataLength - resultLength);    
         resultLength += inflater.inflate(result, resultLength , result.length - resultLength);
      }
      inflater.end();
      // Decode the bytes into a String
      message = new String(result, 0, resultLength, "UTF-8");
      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
Compressed Message length : 42
UnCompressed Message length : 300