diff --git a/ProgressOfTesting.txt b/ProgressOfTesting.txt
index 1895c4d..0af1f01 100644
--- a/ProgressOfTesting.txt
+++ b/ProgressOfTesting.txt
@@ -1,6 +1,6 @@
-[ ] 未开始测试 - 8 (11.94%)
+[ ] 未开始测试 - 7 (10.45%)
 [-] 测试未完成 - 8 (11.94%)
-[Y] 测试完成 - 29 (43.28%)
+[Y] 测试完成 - 30 (44.78%)
 [x] 无需测试 - 22 (32.84%)
 
 xyz.zhouxy.plusone.commons
@@ -91,7 +91,7 @@ xyz.zhouxy.plusone.commons
             IdWorker.java                         [Y]
             Numbers.java                          [Y]
             OptionalTools.java                    [Y]
-            RandomTools.java                      [ ]
+            RandomTools.java                      [Y]
             RegexTools.java                       [ ]
             SnowflakeIdGenerator.java             [Y]
             StringTools.java                      [Y]
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/RandomTools.java b/src/main/java/xyz/zhouxy/plusone/commons/util/RandomTools.java
index f9bc4a2..07f54bf 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/RandomTools.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/RandomTools.java
@@ -16,6 +16,7 @@
 
 package xyz.zhouxy.plusone.commons.util;
 
+import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
 import java.util.Objects;
 import java.util.Random;
@@ -23,14 +24,40 @@ import java.util.concurrent.ThreadLocalRandom;
 
 import javax.annotation.Nonnull;
 
+/**
+ * 随机工具类
+ * <p>
+ * 建议调用方自行维护 Random 对象
+ * </p>
+ * @author <a href="http://zhouxy.xyz:3000/ZhouXY108}">ZhouXY</a>
+ */
 public final class RandomTools {
 
-    public static final SecureRandom DEFAULT_SECURE_RANDOM = new SecureRandom();
+    private static final SecureRandom DEFAULT_SECURE_RANDOM;
+
+    static {
+        SecureRandom secureRandom = null;
+        try {
+            secureRandom = SecureRandom.getInstanceStrong(); // 获取高强度安全随机数生成器
+        }
+        catch (NoSuchAlgorithmException e) {
+            secureRandom = new SecureRandom(); // 获取普通的安全随机数生成器
+        }
+        DEFAULT_SECURE_RANDOM = secureRandom;
+    }
 
     public static final String CAPITAL_LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
     public static final String LOWERCASE_LETTERS = "abcdefghijklmnopqrstuvwxyz";
     public static final String NUMBERS = "0123456789";
 
+    public static SecureRandom defaultSecureRandom() {
+        return DEFAULT_SECURE_RANDOM;
+    }
+
+    public static ThreadLocalRandom currentThreadLocalRandom() {
+        return ThreadLocalRandom.current();
+    }
+
     /**
      * 使用传入的随机数生成器，生成指定长度的字符串
      *
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/RandomToolsTests.java b/src/test/java/xyz/zhouxy/plusone/commons/util/RandomToolsTests.java
new file mode 100644
index 0000000..fcf5f44
--- /dev/null
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/RandomToolsTests.java
@@ -0,0 +1,89 @@
+package xyz.zhouxy.plusone.commons.util;
+
+import static org.junit.jupiter.api.Assertions.assertAll;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.security.SecureRandom;
+import java.util.Random;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+@SuppressWarnings("null")
+public class RandomToolsTests {
+
+    private static Random random;
+    private static SecureRandom secureRandom;
+    private static char[] sourceCharactersArray;
+    private static String sourceCharactersString;
+
+    @BeforeAll
+    public static void setUp() {
+        random = new Random();
+        secureRandom = new SecureRandom();
+        sourceCharactersArray = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
+        sourceCharactersString = "abcdefghijklmnopqrstuvwxyz";
+    }
+
+    @Test
+    public void randomStr_NullRandom_ThrowsException() {
+        assertThrows(IllegalArgumentException.class,
+                () -> RandomTools.randomStr(null, sourceCharactersArray, 5));
+        assertThrows(IllegalArgumentException.class,
+                () -> RandomTools.randomStr(null, sourceCharactersString, 5));
+    }
+
+    @Test
+    public void randomStr_NullSourceCharacters_ThrowsException() {
+        assertThrows(IllegalArgumentException.class, () -> RandomTools.randomStr(random, (char[]) null, 5));
+        assertThrows(IllegalArgumentException.class, () -> RandomTools.randomStr(random, (String) null, 5));
+    }
+
+    @Test
+    public void randomStr_NegativeLength_ThrowsException() {
+        assertThrows(IllegalArgumentException.class, () -> RandomTools.randomStr(random, sourceCharactersArray, -1));
+    }
+
+    @Test
+    public void randomStr_ZeroLength_ReturnsEmptyString() {
+        assertAll(
+                () -> assertEquals("", RandomTools.randomStr(random, sourceCharactersArray, 0)),
+                () -> assertEquals("", RandomTools.randomStr(random, sourceCharactersString, 0)),
+                () -> assertEquals("", RandomTools.randomStr(secureRandom, sourceCharactersArray, 0)),
+                () -> assertEquals("", RandomTools.randomStr(secureRandom, sourceCharactersString, 0)));
+    }
+
+    @Test
+    public void randomStr_PositiveLength_ReturnsRandomString() {
+        assertAll(
+                () -> assertEquals(5, RandomTools.randomStr(random, sourceCharactersArray, 5).length()),
+                () -> assertEquals(5, RandomTools.randomStr(random, sourceCharactersString, 5).length()),
+                () -> assertEquals(5, RandomTools.randomStr(secureRandom, sourceCharactersArray, 5).length()),
+                () -> assertEquals(5, RandomTools.randomStr(secureRandom, sourceCharactersString, 5).length()));
+    }
+
+    @Test
+    public void randomStr_ReturnsRandomString() {
+        String result = RandomTools.randomStr(sourceCharactersArray, 5);
+        assertEquals(5, result.length());
+    }
+
+    @Test
+    public void randomStr_StringSourceCharacters_ReturnsRandomString() {
+        String result = RandomTools.randomStr(sourceCharactersString, 5);
+        assertEquals(5, result.length());
+    }
+
+    @Test
+    public void secureRandomStr_ReturnsRandomString() {
+        String result = RandomTools.secureRandomStr(sourceCharactersArray, 5);
+        assertEquals(5, result.length());
+    }
+
+    @Test
+    public void secureRandomStr_StringSourceCharacters_ReturnsRandomString() {
+        String result = RandomTools.secureRandomStr(sourceCharactersString, 5);
+        assertEquals(5, result.length());
+    }
+}