#26 Allow to download schema from http(s)

pom.xml

@@ -70,6 +70,11 @@
       <artifactId>json-schema-validator</artifactId>
       <version>${json-schema-validator-version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.apache.httpcomponents</groupId>
+      <artifactId>httpclient</artifactId>
+      <version>4.5.13</version>
+    </dependency>
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter-api</artifactId>

src/it/multiple-validation-sets/pom.xml

@@ -38,6 +38,12 @@
                     <include>src/main/resources/malformed.yml</include>
                   </includes>
                 </validationSet>
+                <validationSet>
+                  <jsonSchema>https://swagger.io/v2/schema.json</jsonSchema>
+                  <includes>
+                    <include>src/main/resources/swagger-editor-example.yml</include>
+                  </includes>
+                </validationSet>
               </validationSets>
             </configuration>
           </execution>

src/main/java/com/github/sylvainlaurent/maven/yamljsonvalidator/ValidateMojo.java

@@ -1,15 +1,18 @@
 package com.github.sylvainlaurent.maven.yamljsonvalidator;
 
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClients;
 import org.apache.maven.plugin.AbstractMojo;
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugins.annotations.LifecyclePhase;
 import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
 
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.InputStream;
+import java.io.*;
+import java.net.URI;
+import java.net.URISyntaxException;
 
 /**
  * This mojo validates YAML and JSON files for well-formedness. If JSON schema is provided, it also
@@ -111,23 +114,39 @@ public void execute() throws MojoExecutionException {
 
     InputStream openJsonSchema(String jsonSchemaFile) throws MojoExecutionException {
         if (jsonSchemaFile != null && jsonSchemaFile.length() > 0) {
-            File file = new File(jsonSchemaFile);
-            if (file.isFile()) {
-                try {
-                    return new FileInputStream(file);
-                } catch (FileNotFoundException e) {
-                    throw new MojoExecutionException("Could not load schema file ["+ jsonSchemaFile + "]", e);
-                }
-            } else {
-                try {
-                    InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(jsonSchemaFile);
-                    if (inputStream != null) {
-                        return inputStream;
+            try {
+                URI uri = new URI(jsonSchemaFile);
+                if(uri.getScheme() == null) {
+                    File file = new File(jsonSchemaFile);
+                    if (file.isFile()) {
+                        try {
+                            return new FileInputStream(file);
+                        } catch (FileNotFoundException e) {
+                            throw new MojoExecutionException("Could not load schema file ["+ jsonSchemaFile + "]", e);
+                        }
+                    } else {
+                        try {
+                            InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(jsonSchemaFile);
+                            if (inputStream != null) {
+                                return inputStream;
+                            }
+                            throw new MojoExecutionException("Could not load schema neither from filesystem nor classpath ["+ jsonSchemaFile + "]");
+                        } catch (Exception e){
+                            throw new MojoExecutionException("Could not load schema file from classpath ["+ jsonSchemaFile + "]", e);
+                        }
+                    }
+                } else {
+                    try (final CloseableHttpClient httpclient = HttpClients.custom().useSystemProperties().build()) {
+                        HttpGet get = new HttpGet();
+                        get.setURI(uri);
+                        try (CloseableHttpResponse response = httpclient.execute(get)) {
+                            return response.getEntity().getContent();
+                        }
                     }
-                    throw new MojoExecutionException("Could not load schema neither from filesystem nor classpath ["+ jsonSchemaFile + "]");
-                } catch (Exception e){
-                    throw new MojoExecutionException("Could not load schema file from classpath ["+ jsonSchemaFile + "]", e);
                 }
+            } catch (URISyntaxException | IOException use) {
+                getLog().warn("An error occurs while reading schema from URI " + jsonSchemaFile);
+                getLog().debug(use);
             }
         }
         return null;

src/test/java/com/github/sylvainlaurent/maven/yamljsonvalidator/ValidateMojoTest.java

@@ -23,6 +23,12 @@ public void accept_schema_from_filepath() throws MojoExecutionException {
         assertNotNull(validateMojo.openJsonSchema("src/test/resources/schema-with-ref.json"));
     }
 
+    @Test
+    public void accept_schema_from_http() throws MojoExecutionException {
+        ValidateMojo validateMojo = new ValidateMojo();
+        assertNotNull(validateMojo.openJsonSchema("https://json.schemastore.org/geojson.json"));
+    }
+
 
     @Test
     public void accept_schema_from_classpath() throws MojoExecutionException {