新增：google Collection 的MapMaker使用

Author: JeffLi1993

src/org/javacore/colgoogle/MapMakerT0.java

@@ -0,0 +1,48 @@
+package org.javacore.colgoogle;
+
+import com.google.common.base.Function;
+import com.google.common.collect.MapMaker;
+
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Created by 子木 on 2016/2/20.
+ */
+public class MapMakerT0 {
+    public static void main(String[] args) {
+        /**
+         * expiration(3, TimeUnit.SECONDS)设置超时时间为3秒
+         */
+        ConcurrentMap<String , String> map = new MapMaker().concurrencyLevel(32).softKeys().weakValues()
+                .expiration(3, TimeUnit.SECONDS).makeComputingMap(
+                        /**
+                         * 提供当Map里面不包含所get的项，可以自动加入到Map的功能
+                         * 可以将这里的返回值放到对应的key的value中
+                         */
+                        new Function<String, String>() {
+                            public String apply(String s) {
+                                return "creating " + s + " -> Object";
+                            }
+                        }
+                );
+
+        map.put("a","testa");
+        map.put("b","testb");
+
+        System.out.println(map.get("a"));
+        System.out.println(map.get("b"));
+        System.out.println(map.get("c"));
+
+        try {
+            // 4秒后，大于超时时间，缓存失效。
+            Thread.sleep(4000);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+
+        System.out.println(map.get("a"));
+        System.out.println(map.get("b"));
+        System.out.println(map.get("c"));
+    }
+}