率先加载当前应用的class的ClassLoader,web应用也是如此

古城微笑少年丶 2022-03-28 11:39 91阅读 0赞

/*
    *  Copyright (c) 2005-2012, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
    *
    *  WSO2 Inc. licenses this file to you under the Apache License,
    *  Version 2.0 (the "License"); you may not use this file except
    *  in compliance with the License.
    *  You may obtain a copy of the License at
    *
    *    http://www.apache.org/licenses/LICENSE-2.0
    *
    * Unless required by applicable law or agreed to in writing,
    * software distributed under the License is distributed on an
    * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    * KIND, either express or implied.  See the License for the
    * specific language governing permissions and limitations
    * under the License.
    */
    package org.wso2.carbon.server;
    
    import java.net.URL;
    import java.net.URLClassLoader;
    import java.net.URLStreamHandlerFactory;
    import java.security.AllPermission;
    import java.security.CodeSource;
    import java.security.Permission;
    import java.security.PermissionCollection;
    import java.util.Enumeration;
    import java.util.NoSuchElementException;
    
    public class ChildFirstURLClassLoader extends URLClassLoader {
    
    
        public ChildFirstURLClassLoader(URL[] urls) {
            super(urls);
        }
    
        public ChildFirstURLClassLoader(URL[] urls, ClassLoader parent) {
            super(urls, parent);
        }
    
        public ChildFirstURLClassLoader(URL[] urls, ClassLoader parent,
                                        URLStreamHandlerFactory factory) {
            super(urls, parent, factory);
        }
    
        public URL getResource(String name) {
            URL resource = findResource(name);
            if (resource == null) {
                ClassLoader parent = getParent();
                if (parent != null) {
                    resource = parent.getResource(name);
                }
            }
            return resource;
        }
    
        protected synchronized Class loadClass(String name, boolean resolve)
                throws ClassNotFoundException {
            Class clazz = findLoadedClass(name);
            if (clazz == null) {
                try {
                    clazz = findClass(name);
                } catch (ClassNotFoundException e) {
                    ClassLoader parent = getParent();
                    if (parent != null) {
                        clazz = parent.loadClass(name);
                    } else {
                        clazz = getSystemClassLoader().loadClass(name);
                    }
                }
            }
    
            if (resolve) {
                resolveClass(clazz);
            }
    
            return clazz;
        }
    
        // we want to ensure that the framework has AllPermissions
        protected PermissionCollection getPermissions(CodeSource codesource) {
            return allPermissions;
        }
    
    
        static final PermissionCollection allPermissions = new PermissionCollection() {
            private static final long serialVersionUID = 482874725021998286L;
            // The AllPermission permission
            Permission allPermission = new AllPermission();
    
            // A simple PermissionCollection that only has AllPermission
            public void add(Permission permission) {
                // do nothing
            }
    
            public boolean implies(Permission permission) {
                return true;
            }
    
            public Enumeration<Permission> elements() {
                return new Enumeration<Permission>() {
                    int cur = 0;
    
                    public boolean hasMoreElements() {
                        return cur < 1;
                    }
    
                    public Permission nextElement() {
                        if (cur == 0) {
                            cur = 1;
                            return allPermission;
                        }
                        throw new NoSuchElementException();
                    }
                };
            }
        };
    }