JRE 8 rt.jar is the JAR file for JRE 8 RT (Runtime) libraries. JRE (Java Runtime) 8 is the runtime environment included in JDK 8. JRE 8 rt.jar libraries are divided into 6 packages:

com.* - Internal Oracle and Sun Microsystems libraries
java.* - Standard Java API libraries.
javax.* - Extended Java API libraries.
jdk.* -  JDK supporting libraries.
org.* - Third party libraries.
sun.* - Old libraries developed by Sun Microsystems.

JAR File Information:

Directory of C:\fyicenter\jdk-1.8.0_191\jre\lib
      63,596,151 rt.jar

Here is the list of Java classes of the java.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ java/rmi/RMISecurityManager.java

/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.rmi;

import java.security.*;

/**
 * {@code RMISecurityManager} implements a policy identical to the policy
 * implemented by {@link SecurityManager}. RMI applications
 * should use the {@code SecurityManager} class or another appropriate
 * {@code SecurityManager} implementation instead of this class. RMI's class
 * loader will download classes from remote locations only if a security
 * manager has been set.
 *
 * @implNote
 * <p>Applets typically run in a container that already has a security
 * manager, so there is generally no need for applets to set a security
 * manager. If you have a standalone application, you might need to set a
 * {@code SecurityManager} in order to enable class downloading. This can be
 * done by adding the following to your code. (It needs to be executed before
 * RMI can download code from remote hosts, so it most likely needs to appear
 * in the {@code main} method of your application.)
 *
 * <pre>{@code
 *    if (System.getSecurityManager() == null) {
 *        System.setSecurityManager(new SecurityManager());
 *    }
 * }</pre>
 *
 * @author  Roger Riggs
 * @author  Peter Jones
 * @since JDK1.1
 * @deprecated Use {@link SecurityManager} instead.
 */
@Deprecated
public class RMISecurityManager extends SecurityManager {

    /**
     * Constructs a new {@code RMISecurityManager}.
     * @since JDK1.1
     */
    public RMISecurityManager() {
    }
}

⏎ java/rmi/RMISecurityManager.java

Or download all of them as a single archive file:

File name: jre-rt-java-1.8.0_191-src.zip
File size: 6664831 bytes
Release date: 2018-10-28
Download 

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