Java内容重新整理删除过期的东西

Java/JavaDemo/codedemo/nio/MemoryMapper.java

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+package cn.aofeng.demo.nio;
+
+import java.io.Closeable;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.MappedByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.channels.FileChannel.MapMode;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * IO-内存映射。
+ * 
+ * @author 聂勇 <a href="mailto:aofengblog@163.com">aofengblog@163.com</a>
+ */
+public class MemoryMapper {
+
+    private static Logger logger = Logger.getLogger("bufferio");
+    
+    // 缓冲区大小
+    private final static int BUFFER_SIZE = 4096;
+    
+    public static void close(Closeable c) {
+        if (null != c) {
+            try {
+                c.close();
+            } catch (IOException e) {
+                // ingore
+            }
+        }
+    }
+    
+    /**
+     * @param args [0]：读取文件的完整路径
+     */
+    public static void main(String[] args) {
+        String filename = args[0];
+        File file = new File(filename);
+        FileChannel channel = null;
+        try {
+            channel = new FileInputStream(file).getChannel();
+             MappedByteBuffer buffer = channel.map(MapMode.READ_ONLY, 0, channel.size());
+             long startTime = System.currentTimeMillis();
+             long total = 0;
+             long len = file.length();
+             byte[] bs = new byte[BUFFER_SIZE];
+             for (int index = 0; index < len; index+=BUFFER_SIZE) {
+                 int readSize = BUFFER_SIZE;
+                 if (len-index < BUFFER_SIZE) {
+                    readSize = (int) len-index;
+                    buffer.get(new byte[readSize]);
+                 } else {
+                    buffer.get(bs);
+                 }
+                 
+                 total += readSize;
+             }
+             long endTime = System.currentTimeMillis();
+             logger.info("内存映射读取文件耗时：" + (endTime-startTime)+"毫秒，文件长度："+total+"字节");
+        } catch (FileNotFoundException e) {
+            logger.log(Level.SEVERE, "找不到文件："+filename, e);
+        } catch (IOException e) {
+            logger.log(Level.SEVERE, "读取文件出错", e);
+        } finally{
+            close(channel);
+        }
+        
+    }
+
+}