Common class

src/java_common/CommonMethod.java

@@ -0,0 +1,28 @@
+package java_common;
+
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+/**
+ * Common methods
+ *
+ * @author ÌÆÁú
+ */
+public class CommonMethod {
+	/**get current time in the form of "yyyy-MM-dd HH:mm:ss"*/
+	public static final String TIME_NOW = getTimeNow();
+	private static String getTimeNow(){
+		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+		return sdf.format(new Date());
+	}
+
+	/**get current time in the form of nanosecond*/
+	public static long nano() {
+		return System.nanoTime();
+	}
+
+	/**get current time in the form of millisecond*/
+	public static long milli() {
+		return System.currentTimeMillis();
+	}
+}

src/java_common/CommonUtils.java

@@ -4,6 +4,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Random;
 
 /**
  * Common utilities for all classes
@@ -12,7 +13,12 @@
  *
  */
 public class CommonUtils {
-	/**Generate a List*/
+	/**
+	 * Generate a List
+	 *
+	 * @param size
+	 * @return
+	 */
 	public static List<String> getList(int size){
 		List<String> list = new ArrayList<String>();
 		for(int i=1;i<=size;i++){
@@ -21,12 +27,50 @@ public static List<String> getList(int size){
 		return list;
 	}
 
-	/**Generate a Map*/
+	/**
+	 * Generate a Map
+	 *
+	 * @param size
+	 * @return
+	 */
 	public static Map<String,String> getMap(int size){
 		Map<String,String> map = new HashMap<String,String>();
 		for(int i=1;i<=size;i++){
 			map.put("K"+i,"V"+i);
 		}
 		return map;
 	}
+
+	/**
+	 * Generate a String
+	 *
+	 * @param size
+	 * @return
+	 */
+	public static String getString(int length){
+		StringBuilder sb = new StringBuilder();
+		if(length <=0) {
+			return sb.toString();
+		}
+		Random r = new Random();
+		sb.append((char)(r.nextInt(26) + 65));          // first letter is upper case
+		for(int i=1;i<length;i++) {
+			switch(r.nextInt(4)) {
+			case 0:
+				sb.append(r.nextInt(10));              // number
+				break;
+			case 1:
+				sb.append((char)(r.nextInt(26) + 65)); // upper case
+				break;
+			case 2:
+				sb.append((char)(r.nextInt(26) + 97)); // lower case
+				break;
+			case 3:
+				sb.append((char)(r.nextInt(1) + 95)); // underline
+				break;
+			default:break;
+			}
+		}
+		return sb.toString();
+	}
 }

src/java_common/CommonBool.java → src/java_common/CommonValue.java

@@ -5,7 +5,7 @@
  *
  * @author ÌÆÁú
  */
-public class CommonBool {
+public class CommonValue {
 	public final static boolean TRUE = true;
 	public final static boolean FALSE = false;
 }

src/java_common/JVMMemory.java

@@ -0,0 +1,13 @@
+package java_common;
+
+/**
+ * The memory of JVM(M)
+ *
+ * @author ÌÆÁú
+ *
+ */
+public class JVMMemory {
+	private final static int M = 1024*1024;
+	static long maxMemory       = Runtime.getRuntime().maxMemory()/M;
+	static long totalUsedMemory = Runtime.getRuntime().totalMemory()/M;
+}