From bd8b4b72d0304d158f01cb64a0d0bf9bb0b31c9c Mon Sep 17 00:00:00 2001
From: Tanglong <13685759344@163.com>
Date: Fri, 12 Jan 2018 10:58:29 +0800
Subject: [PATCH] Common class

---
 src/java_common/CommonMethod.java             | 28 +++++++++++
 src/java_common/CommonUtils.java              | 48 ++++++++++++++++++-
 .../{CommonBool.java => CommonValue.java}     |  2 +-
 src/java_common/JVMMemory.java                | 13 +++++
 src/java_common/TimeNow.java                  | 17 -------
 5 files changed, 88 insertions(+), 20 deletions(-)
 create mode 100644 src/java_common/CommonMethod.java
 rename src/java_common/{CommonBool.java => CommonValue.java} (80%)
 create mode 100644 src/java_common/JVMMemory.java
 delete mode 100644 src/java_common/TimeNow.java

diff --git a/src/java_common/CommonMethod.java b/src/java_common/CommonMethod.java
new file mode 100644
index 0000000..cc44b00
--- /dev/null
+++ b/src/java_common/CommonMethod.java
@@ -0,0 +1,28 @@
+package java_common;
+
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+/**
+ * Common methods
+ *
+ * @author 唐龙
+ */
+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();
+	}
+}
\ No newline at end of file
diff --git a/src/java_common/CommonUtils.java b/src/java_common/CommonUtils.java
index 9d0b27d..e01d5f0 100644
--- a/src/java_common/CommonUtils.java
+++ b/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++){
@@ -21,7 +27,12 @@ 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++){
@@ -29,4 +40,37 @@ public static Map<String,String> getMap(int size){
 		}
 		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();
+	}
 }
\ No newline at end of file
diff --git a/src/java_common/CommonBool.java b/src/java_common/CommonValue.java
similarity index 80%
rename from src/java_common/CommonBool.java
rename to src/java_common/CommonValue.java
index fb56789..a3fd713 100644
--- a/src/java_common/CommonBool.java
+++ b/src/java_common/CommonValue.java
@@ -5,7 +5,7 @@
  *
  * @author 唐龙
  */
-public class CommonBool {
+public class CommonValue {
 	public final static boolean TRUE = true;
 	public final static boolean FALSE = false;
 }
\ No newline at end of file
diff --git a/src/java_common/JVMMemory.java b/src/java_common/JVMMemory.java
new file mode 100644
index 0000000..7e71764
--- /dev/null
+++ b/src/java_common/JVMMemory.java
@@ -0,0 +1,13 @@
+package java_common;
+
+/**
+ * The memory of JVM(M)
+ *
+ * @author 唐龙
+ *
+ */
+public class JVMMemory {
+	private final static int M = 1024*1024;
+	static long maxMemory       = Runtime.getRuntime().maxMemory()/M;
+	static long totalUsedMemory = Runtime.getRuntime().totalMemory()/M;
+}
\ No newline at end of file
diff --git a/src/java_common/TimeNow.java b/src/java_common/TimeNow.java
deleted file mode 100644
index c151181..0000000
--- a/src/java_common/TimeNow.java
+++ /dev/null
@@ -1,17 +0,0 @@
-package java_common;
-
-import java.text.SimpleDateFormat;
-import java.util.Date;
-
-/**
- * 获取系统当前时间
- * 以yyyy-MM-dd HH:mm:ss格式返回
- * @author 唐龙
- */
-public class TimeNow {
-	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());
-	}
-}
\ No newline at end of file