java.lang.ClassCastException: com.sun.net.ssl.internal.www.protocol.https.HttpsURLConnectionOldImpl cannot be cast to javax.net.ssl.HttpsURLConnection

Question

I tried this code in my Netbeans 7.4 and it works without problem

import java.io.IOException;
import java.net.URL;
import javax.net.ssl.HttpsURLConnection;

public class JavaApplication148 {
    public static void main(String[] args) throws IOException {
        URL url = new URL("https://redmine.ackee.cz/time_entries.xml");
        HttpsURLConnection httpCon = (HttpsURLConnection) url.openConnection();
    }
}

However then I used it in eclipse in my maven-driven project and it throws following exception :

java.lang.ClassCastException: com.sun.net.ssl.internal.www.protocol.https.HttpsURLConnectionOldImpl 
cannot be cast to javax.net.ssl.HttpsURLConnection

This is following class in my maven project that throws an error

package cz.ackee.redmine.commands;

import java.io.IOException;
import java.net.URL;
import javax.net.ssl.HttpsURLConnection;

public abstract class RedmineCommand {      
    public void write(String xmlAddress, String text, String requestMethod) throws IOException{         
         URL url = new URL("https://redmine.xxx.cz/time_entries.xml");
         HttpsURLConnection httpCon = (HttpsURLConnection) url.openConnection(); //this line throws exception
    }       
}

This is my pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>cz.ackee</groupId>
    <artifactId>pan-unicorn-bot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Pan Unicorn Bot</name>
    <description>Pan unicorn IRC Bot</description>

  <repositories>
  <repository>
    <id>apache-snapshots</id>
    <url>http://repository.apache.org/snapshots/</url>
  </repository>
  </repositories>

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.30</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>4.3.5.Final</version>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-cli</artifactId>
            <version>1.3-SNAPSHOT</version>
        </dependency>

        <dependency>
            <groupId>com.taskadapter</groupId>
            <artifactId>redmine-java-api</artifactId>
            <version>1.23</version>
        </dependency>
    </dependencies>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
  </properties>

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <groupId>org.apache.maven.plugins</groupId>
                <version>2.3</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>true</downloadJavadocs>
                </configuration>
            </plugin>

            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>2.2.1</version>
                <configuration>
                    <descriptors>
                        <descriptor>/src/main/assembly/binary.xml</descriptor>
                    </descriptors>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <archive>
                        <index>true</index>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <mainClass>cz.ackee.unicorn.PanUnicornMain</mainClass>
                        </manifest>
                        <manifestEntries>
                            <mode>development</mode>
                            <url>${project.url}</url>
                            <key>value</key>
                        </manifestEntries>
                    </archive>
                </configuration>

            </plugin>
        </plugins>
    </build>

</project>

Any idea, why it does compile and run without problem on netbeans and why it does not go well on maven-eclipse project?

(I compile through command line using mvn package, I run it through eclipse)

Answer 1

The solution is to change this line

URL url = new URL("https://redmine.xxx.cz/time_entries.xml");

into this line

URL url = new URL(null, "https://redmine.xxx.cz/time_entries.xml", new sun.net.www.protocol.https.Handler());

Answer 2

If you are using simply HTTP protocol (not HTTPS), instead of:

HttpsURLConnection httpCon = (HttpsURLConnection) url.openConnection();

Use this:

HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();

Just drop the "s" in "HttpsURLConnection"

Answer 3

To avoid this kind of error you can use HttpUrlConnection (java.net.HttpUrlConnection) for both http and https url

HttpsUrlConnection only add extra methods that "can be used" for https connection but you probably won't use these methods.

Both HttpsUrlConnection and HttpUrlConnection derives from UrlConnection which contains methods that permit to read the response like getInputStream(). HttpsUrlConnection derives from HttpUrlConnection which derived from UrlConnection.

java.net.HttpUrlConnection just add methods relative to http protocol (these methods apply to https)

https://docs.oracle.com/javase/8/docs/api/java/net/HttpURLConnection.html https://docs.oracle.com/javase/8/docs/api/javax/net/ssl/HttpsURLConnection.html

Thus you can do this :

URL url = new URL(urlString);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("GET");
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));

As well you can do this and obtain the same result, the connection will be the same :

URL url = new URL(urlString);
HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
con.setRequestMethod("GET");
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));

Answer 4

It called if url starts with "https"

    if(url.startswith("https"){ HttpsURLConnection httpCon = (HttpsURLConnection) url.openConnection(); }

use netty-3.9.2 > .jar to solve this issue When you use this netty.jar. the process of post call changed.

http://dl.bintray.com/netty/downloads/netty-3.9.12.Final.tar.bz2