Java：反射中Class.forName和classloader的区别。

旧城等待， 2022-03-06 02:20 291阅读 0赞

*  Java中Class.forName和classloader都可以用来对类进行加载。
 *  Class.forName除了将类的.class文件加载到jvm中之外，还会对类进行解释，执行类中的static块。
 *  而classloader只干一件事情，就是将.class文件加载到jvm中，不会执行static中的内容，只有在newInstance才会去执行static块。
 *  Class.forName(name,initialize,loader)带参数也可控制是否加载static块。并且只有调用了newInstance()方法采用调用构造函数，创建类的对象。

# 代码 #

package com.mangosoft.java.reflect;
    
    /**
     * Created by zhangshengjian on 2017/3/1.
     */
    public class Line {
        static {
            System.out.println("static code executing: loading line...");
        }
    }
    
    package com.mangosoft.java.reflect;
    
    /**
     * Created by zhangshengjian on 2017/3/1.
     */
    public class Point {
        static {
            System.out.println("static code executing: loading point...");
        }
    }
    
    package com.mangosoft.java.reflect;
    
    /**
     * classloader和Class.forName的区别
     *
     * Created by zhangshengjian on 2017/3/1.
     */
    public class ClassLoaderAndForNameTest {
    
        public static void main(String[] args) {
            String wholeNameLine = "com.mangosoft.java.reflect.Line";
            String wholeNamePoint = "com.mangosoft.java.reflect.Point";
    
            System.out.println("classloader testing...");
            testClassLoader(wholeNameLine, wholeNamePoint);
            System.out.println("---------------------------------------");
            System.out.println("Class.forName testing...");
            testForName(wholeNameLine, wholeNamePoint);
        }
    
        //classloader
        public static void testClassLoader(String wholeNameLine, String wholeNamePoint) {
            ClassLoader loader = ClassLoader.getSystemClassLoader();
            Class<?> line;
            Class<?> point;
            try {
                line = loader.loadClass(wholeNameLine);
                point = loader.loadClass(wholeNamePoint);
                System.out.println("line " + line.getName());
                System.out.println("point " + point.getName());
            } catch (ClassNotFoundException e){
                e.printStackTrace();
            }
        }
    
        //Class.forName
        public static void testForName(String wholeNameLine, String wholeNamePoint) {
            try {
                Class line = Class.forName(wholeNameLine);
                Class point = Class.forName(wholeNamePoint);
                System.out.println("line " + line.getName());
                System.out.println("point " + point.getName());
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    }

# 运行结果 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2VuX2pva2Vy_size_16_color_FFFFFF_t_70][]

转载：[http://www.cnblogs.com/mangosoft/p/6485790.html][http_www.cnblogs.com_mangosoft_p_6485790.html]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2VuX2pva2Vy_size_16_color_FFFFFF_t_70]: /images/20220303/50914b9aa007410787d43ff67fbddf6a.png
[http_www.cnblogs.com_mangosoft_p_6485790.html]: http://www.cnblogs.com/mangosoft/p/6485790.html