JAVA reflection mechanism for obtaining class information

The reflection mechanism in Java allows us to obtain the constructors, member variables, and member functions in the bytecode file of a Java class at runtime.

1. Three ways to obtain a Class object:

1. Class.forname (” Class name string “) (Note: Class name string must be full, package name + Class name)

        Class baseInfo = Class.forName("top.sguotao.ReflectionJava");
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2. The name of the class. The class

        Class object = Object.class;
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3. Instance object.getClass ()

        Class date = (new Date()).getClass();
        Class testclass = this.getClass();
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2. Obtain class Constructor ().

1. The parameter list is parameterTypes, and the access control is a public constructor

        public Constructor getConstructor(Class[] parameterTypes)
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2. Constructor that gets all access controls that are public

        public Constructor[] getConstructors()
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3. The parameter list is parameterTypes and is a constructor declared by the class itself. The access control includes public, protected, and private functions.

	public Constructor getDeclaredConstructor(Class[] parameterTypes)
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4. Gets all constructors declared by the class itself. The access control includes public, protected, and private functions.

	public Constructor[] getDeclaredConstructors()
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5. Return the constructor of the class if it is declared in another class’s constructor, or null if it is not

	public Constructor getEnclosingConstructor()
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3. Get the member variables of the class

1. Getname (” name is name “); getname (” name is name “); getname (” name is name “);

	public Field getField(String name)
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2. Get all public member variables (including all public member variables inherited from the base class and implemented from the interface)

	public Field[] getFields()
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3. Gets “name is name” and is a member variable declared by the class itself, including public, protected, and private member variables.

	public Field getDeclaredField(String name)
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4. Gets all member variables declared by the class itself, including public, protected, and private.

	public Field[] getDeclaredFields()
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4. Get the member functions of the class

1. Get a function whose name is name and whose parameters are public of parameterTypes (including all public functions inherited from the base class and implemented from the interface)

	public Method getMethod(String name, Class[] parameterTypes)
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2. Get all public functions (including all public functions inherited from the base class and implemented from the interface)

	public Method[] getMethods()
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3. Get the name of the function that takes parameterTypes and is declared by the class itself, including public, protected, and private methods.

	public Method getDeclaredMethod(String name, Class[] parameterTypes)
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4. Gets all functions declared by the class itself, including public, protected, and private methods.

	public Method[] getDeclaredMethods()
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5. If the class is an inner class of a method in another class, calling getEnclosingMethod() is the class’s method; If not, return NULL.

	public Method getEnclosingMethod()
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