getName() -返回由class对象表示的实体(类、接口、数组类、基本类型或void)的名称，作为字符串。

getCanonicalName()——返回由Java语言规范定义的底层类的规范名称。

getSimpleName() -返回底层类的简单名称，即源代码中给出的名称。

package com.practice;

public class ClassName {
public static void main(String[] args) {

  ClassName c = new ClassName();
  Class cls = c.getClass();

  // returns the canonical name of the underlying class if it exists
  System.out.println("Class = " + cls.getCanonicalName());    //Class = com.practice.ClassName
  System.out.println("Class = " + cls.getName());             //Class = com.practice.ClassName
  System.out.println("Class = " + cls.getSimpleName());       //Class = ClassName
  System.out.println("Class = " + Map.Entry.class.getName());             // -> Class = java.util.Map$Entry
  System.out.println("Class = " + Map.Entry.class.getCanonicalName());    // -> Class = java.util.Map.Entry
  System.out.println("Class = " + Map.Entry.class.getSimpleName());       // -> Class = Entry 
  }
}

一个不同之处在于，如果使用匿名类，则在尝试使用getCanonicalName()获取类名时可以得到空值。

另一个事实是，对于内部类，getName()方法的行为与getCanonicalName()方法不同。getName()使用美元作为外围类规范名和内部类简单名之间的分隔符。

了解有关在Java中检索类名的更多信息。

    public void printReflectionClassNames(){
    StringBuffer buffer = new StringBuffer();
    Class clazz= buffer.getClass();
    System.out.println("Reflection on String Buffer Class");
    System.out.println("Name: "+clazz.getName());
    System.out.println("Simple Name: "+clazz.getSimpleName());
    System.out.println("Canonical Name: "+clazz.getCanonicalName());
    System.out.println("Type Name: "+clazz.getTypeName());
}

outputs:
Reflection on String Buffer Class
Name: java.lang.StringBuffer
Simple Name: StringBuffer
Canonical Name: java.lang.StringBuffer
Type Name: java.lang.StringBuffer

如果您对某些事情不确定，请先尝试编写一个测试。

我是这样做的:

class ClassNameTest {
    public static void main(final String... arguments) {
        printNamesForClass(
            int.class,
            "int.class (primitive)");
        printNamesForClass(
            String.class,
            "String.class (ordinary class)");
        printNamesForClass(
            java.util.HashMap.SimpleEntry.class,
            "java.util.HashMap.SimpleEntry.class (nested class)");
        printNamesForClass(
            new java.io.Serializable(){}.getClass(),
            "new java.io.Serializable(){}.getClass() (anonymous inner class)");
    }

    private static void printNamesForClass(final Class<?> clazz, final String label) {
        System.out.println(label + ":");
        System.out.println("    getName():          " + clazz.getName());
        System.out.println("    getCanonicalName(): " + clazz.getCanonicalName());
        System.out.println("    getSimpleName():    " + clazz.getSimpleName());
        System.out.println("    getTypeName():      " + clazz.getTypeName()); // added in Java 8
        System.out.println();
    }
}

打印:

int.class (primitive):
    getName():          int
    getCanonicalName(): int
    getSimpleName():    int
    getTypeName():      int

String.class (ordinary class):
    getName():          java.lang.String
    getCanonicalName(): java.lang.String
    getSimpleName():    String
    getTypeName():      java.lang.String

java.util.HashMap.SimpleEntry.class (nested class):
    getName():          java.util.AbstractMap$SimpleEntry
    getCanonicalName(): java.util.AbstractMap.SimpleEntry
    getSimpleName():    SimpleEntry
    getTypeName():      java.util.AbstractMap$SimpleEntry

new java.io.Serializable(){}.getClass() (anonymous inner class):
    getName():          ClassNameTest$1
    getCanonicalName(): null
    getSimpleName():    
    getTypeName():      ClassNameTest$1

在最后一个块中有一个空条目，其中getSimpleName返回一个空字符串。

这样做的结果是:

the name is the name that you'd use to dynamically load the class with, for example, a call to Class.forName with the default ClassLoader. Within the scope of a certain ClassLoader, all classes have unique names. the canonical name is the name that would be used in an import statement. It might be useful during toString or logging operations. When the javac compiler has complete view of a classpath, it enforces uniqueness of canonical names within it by clashing fully qualified class and package names at compile time. However JVMs must accept such name clashes, and thus canonical names do not uniquely identify classes within a ClassLoader. (In hindsight, a better name for this getter would have been getJavaName; but this method dates from a time when the JVM was used solely to run Java programs.) the simple name loosely identifies the class, again might be useful during toString or logging operations but is not guaranteed to be unique. the type name returns "an informative string for the name of this type", "It's like toString: it's purely informative and has no contract value". (as written by sir4ur0n)

你也可以参考Java语言规范文档来了解这些类型的Java API技术细节:

下面是关于这个主题的Java 11规范:https://docs.oracle.com/javase/specs/jls/se11/html/jls-6.html#jls-6.7 例6.7 - 2。例6.7-2。分别讨论了完全限定名称和完全限定名称v.规范名称

有趣的是，当类名格式错误时，getCanonicalName()和getSimpleName()会引发InternalError。这种情况发生在一些非java JVM语言上，例如Scala。

考虑以下(Java 8上的Scala 2.11):

scala> case class C()
defined class C

scala> val c = C()
c: C = C()

scala> c.getClass.getSimpleName
java.lang.InternalError: Malformed class name
  at java.lang.Class.getSimpleName(Class.java:1330)
  ... 32 elided

scala> c.getClass.getCanonicalName
java.lang.InternalError: Malformed class name
  at java.lang.Class.getSimpleName(Class.java:1330)
  at java.lang.Class.getCanonicalName(Class.java:1399)
  ... 32 elided

scala> c.getClass.getName
res2: String = C

对于混合语言环境或动态加载字节码的环境，例如应用程序服务器和其他平台软件，这可能是一个问题。

除了Nick Holt的观察之外，我还运行了一些Array数据类型的案例:

//primitive Array
int demo[] = new int[5];
Class<? extends int[]> clzz = demo.getClass();
System.out.println(clzz.getName());
System.out.println(clzz.getCanonicalName());
System.out.println(clzz.getSimpleName());       

System.out.println();


//Object Array
Integer demo[] = new Integer[5]; 
Class<? extends Integer[]> clzz = demo.getClass();
System.out.println(clzz.getName());
System.out.println(clzz.getCanonicalName());
System.out.println(clzz.getSimpleName());

上面的代码片段打印:

[I
int[]
int[]

[Ljava.lang.Integer;
java.lang.Integer[]
Integer[]

这是我找到的描述getName()， getSimpleName()， getCanonicalName()的最好的文档

https://javahowtodoit.wordpress.com/2014/09/09/java-lang-class-what-is-the-difference-between-class-getname-class-getcanonicalname-and-class-getsimplename/

// Primitive type
int.class.getName();          // -> int
int.class.getCanonicalName(); // -> int
int.class.getSimpleName();    // -> int

// Standard class
Integer.class.getName();          // -> java.lang.Integer
Integer.class.getCanonicalName(); // -> java.lang.Integer
Integer.class.getSimpleName();    // -> Integer

// Inner class
Map.Entry.class.getName();          // -> java.util.Map$Entry
Map.Entry.class.getCanonicalName(); // -> java.util.Map.Entry
Map.Entry.class.getSimpleName();    // -> Entry     

// Anonymous inner class
Class<?> anonymousInnerClass = new Cloneable() {}.getClass();
anonymousInnerClass.getName();          // -> somepackage.SomeClass$1
anonymousInnerClass.getCanonicalName(); // -> null
anonymousInnerClass.getSimpleName();    // -> // An empty string

// Array of primitives
Class<?> primitiveArrayClass = new int[0].getClass();
primitiveArrayClass.getName();          // -> [I
primitiveArrayClass.getCanonicalName(); // -> int[]
primitiveArrayClass.getSimpleName();    // -> int[]

// Array of objects
Class<?> objectArrayClass = new Integer[0].getClass();
objectArrayClass.getName();          // -> [Ljava.lang.Integer;
objectArrayClass.getCanonicalName(); // -> java.lang.Integer[]
objectArrayClass.getSimpleName();    // -> Integer[]