instantiation

integrity checks

.editorconfig

@@ -0,0 +1,11 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+charset = utf-8
+indent_style = space
+indent_size = 4
+tab_width = 4
+trim_trailing_whitespace = true
+max_line_length = 120

pom.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <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">
+    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>de.joshavg</groupId>
@@ -23,10 +23,28 @@
     </build>
 
     <dependencies>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>1.7.21</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>1.7.21</version>
+        </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-core</artifactId>
+            <version>1.3</version>
+            <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>com.google.collections</groupId>
@@ -36,4 +54,4 @@
     </dependencies>
 
 
-</project>
+</project>

src/main/java/de/joshavg/simpledic/Instantiator.java

@@ -0,0 +1,31 @@
+package de.joshavg.simpledic;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+
+class Instantiator<T> {
+
+    private final Class<T> clz;
+
+    Instantiator(Class<T> clz) {
+        this.clz = clz;
+    }
+
+    T createInstance()
+        throws IllegalAccessException, InvocationTargetException, InstantiationException {
+        @SuppressWarnings("unchecked")
+        Constructor<T> constructor = (Constructor<T>) clz.getDeclaredConstructors()[0];
+
+        Class<?>[] parameterTypes = constructor.getParameterTypes();
+        Object[] parameters = new Object[parameterTypes.length];
+
+        for (int i = 0; i < parameterTypes.length; ++i) {
+            @SuppressWarnings("unchecked")
+            Class<Object> paramClz = (Class<Object>) parameterTypes[i];
+            parameters[i] = new Instantiator<>(paramClz).createInstance();
+        }
+
+        return constructor.newInstance(parameters);
+    }
+
+}

src/main/java/de/joshavg/simpledic/IntegrityCheck.java

@@ -0,0 +1,142 @@
+package de.joshavg.simpledic;
+
+import com.google.common.annotations.VisibleForTesting;
+import de.joshavg.simpledic.exception.ClassNotRegistered;
+import de.joshavg.simpledic.exception.integrity.DependencyCycleDetected;
+import de.joshavg.simpledic.exception.integrity.DependencyNotSatisfied;
+import de.joshavg.simpledic.exception.integrity.DuplicatedServiceClassesFound;
+import de.joshavg.simpledic.exception.integrity.MoreThanOneConstructor;
+import de.joshavg.simpledic.exception.integrity.SdicClassNotFound;
+import java.lang.reflect.Constructor;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.Properties;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+class IntegrityCheck {
+
+    private static final Logger LOG = LoggerFactory.getLogger(IntegrityCheck.class);
+
+    private final Properties props;
+    private final List<ServiceDefinition> definitions;
+
+    IntegrityCheck(Properties props) {
+        this.props = props;
+        this.definitions = new ArrayList<>();
+    }
+
+    void check() {
+        List<Class<?>> services = fetchAllServices();
+        checkConstructorDependencies(services);
+        checkDuplicateServices(services);
+        checkCycles();
+    }
+
+    private void checkDuplicateServices(List<Class<?>> services) {
+        int size = services.size();
+        int distinctSize = services.stream().distinct().collect(Collectors.toList()).size();
+        if (size != distinctSize) {
+            throw new DuplicatedServiceClassesFound();
+        }
+    }
+
+    private List<Class<?>> fetchAllServices() {
+        return props.entrySet().stream()
+            .filter(e -> isServiceName(e.getKey().toString()))
+            .map(entry -> {
+                String key = entry.getKey().toString();
+                String value = entry.getValue().toString();
+
+                LOG.info("found service class for name {}: {}", key, value);
+                try {
+                    Class<?> clz = Class.forName(value);
+                    definitions.add(new ServiceDefinition().setClz(clz).setName(value));
+                    return clz;
+                } catch (ClassNotFoundException e) {
+                    throw new SdicClassNotFound(e);
+                }
+            }).collect(Collectors.toList());
+    }
+
+    private void checkConstructorDependencies(List<Class<?>> services) {
+        services.stream()
+            // get the first and only constructor
+            .map(Class::getDeclaredConstructors)
+            .collect(ArrayList::new,
+                this::collectConstructors,
+                List::addAll)
+            // get all parameter types
+            .stream()
+            .map(Constructor::getParameterTypes)
+            .collect((Supplier<ArrayList<Class<?>>>) ArrayList::new,
+                (l, arr) -> {
+                    List<Class<?>> types = Arrays.asList(arr);
+                    l.addAll(types);
+                },
+                List::addAll)
+            // search for services with needed types
+            .stream()
+            .distinct()
+            .forEach((Class<?> t) -> {
+                LOG.info("found service dependency: {}", t);
+                if (!services.contains(t)) {
+                    throw new DependencyNotSatisfied(t);
+                }
+            });
+    }
+
+    private void collectConstructors(ArrayList<Constructor> l, Constructor<?>[] arr) {
+        Class<?> clz = arr[0].getDeclaringClass();
+        if (arr.length > 1) {
+            throw new MoreThanOneConstructor(clz);
+        }
+        l.add(arr[0]);
+        findDefinition(clz).setConstructor(arr[0]);
+    }
+
+    private ServiceDefinition findDefinition(Class<?> clz) {
+        Optional<ServiceDefinition> first = definitions.stream()
+            .filter(d -> d.getClz() == clz).findFirst();
+
+        if (!first.isPresent()) {
+            throw new ClassNotRegistered(clz);
+        }
+
+        return first.get();
+    }
+
+    private void checkCycles() {
+        definitions.forEach(def -> {
+            checkConstructorParameter(null, def.getClz());
+        });
+    }
+
+    private void checkConstructorParameter(Class<?> rootClz, Class<?> paramClz) {
+        if (rootClz == paramClz) {
+            throw new DependencyCycleDetected(rootClz);
+        }
+
+        Class<?>[] parameterTypes = findDefinition(paramClz).getConstructor().getParameterTypes();
+        for (Class<?> innerParamClz : parameterTypes) {
+            if (rootClz == null) {
+                checkConstructorParameter(paramClz, innerParamClz);
+            } else {
+                checkConstructorParameter(rootClz, innerParamClz);
+            }
+        }
+    }
+
+    @VisibleForTesting
+    static boolean isServiceName(String name) {
+        return !"service.".equals(name) && name.startsWith("service.");
+    }
+
+    List<ServiceDefinition> getDefinitions() {
+        return definitions;
+    }
+}

src/main/java/de/joshavg/simpledic/SdiContainer.java

@@ -1,27 +1,27 @@
 package de.joshavg.simpledic;
 
-import com.google.common.annotations.VisibleForTesting;
+import de.joshavg.simpledic.exception.ClassNotRegistered;
 import de.joshavg.simpledic.exception.ContainerInitException;
-import de.joshavg.simpledic.exception.DependencyNotSatisfiedException;
-import de.joshavg.simpledic.exception.SdicClassNotFoundException;
-
+import de.joshavg.simpledic.exception.SdicInstantiationException;
 import java.io.IOException;
 import java.io.InputStream;
-import java.lang.reflect.Constructor;
-import java.util.ArrayList;
-import java.util.Arrays;
+import java.lang.reflect.InvocationTargetException;
 import java.util.List;
 import java.util.Properties;
-import java.util.function.Function;
 import java.util.stream.Collectors;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class SdiContainer {
 
+    private static final Logger LOG = LoggerFactory.getLogger(SdiContainer.class);
+
     private final Properties props;
+    private final List<ServiceDefinition> definitions;
 
-    @VisibleForTesting
-    SdiContainer(Properties props) {
+    private SdiContainer(Properties props, List<ServiceDefinition> definitions) {
         this.props = props;
+        this.definitions = definitions;
     }
 
     public static SdiContainer load() {
@@ -32,74 +32,40 @@ public class SdiContainer {
         Properties props = new Properties();
 
         InputStream inputStream = SdiContainer.class.getClassLoader().getResourceAsStream(filename);
+        if (inputStream == null) {
+            throw new ContainerInitException("config file " + filename + " not found", null);
+        }
+
         try {
             props.load(inputStream);
         } catch (IOException e) {
             throw new ContainerInitException("failed loading properties", e);
         }
 
-        SdiContainer container = new SdiContainer(props);
-        container.integrityCheck();
-        return container;
+        IntegrityCheck integrityCheck = new IntegrityCheck(props);
+        integrityCheck.check();
+        return new SdiContainer(props, integrityCheck.getDefinitions());
     }
 
-    private void integrityCheck() {
-        List<Class<?>> services = fetchAllServices();
-        checkConstructorDependencies(services);
+    private List<Class<?>> serviceClasses() {
+        return definitions.stream().map(ServiceDefinition::getClz).collect(Collectors.toList());
     }
 
-    private List<Class<?>> fetchAllServices() {
-        return props.entrySet().stream()
-                    .filter(e -> isServiceName(e.getKey().toString()))
-                    .map(e -> e.getValue().toString())
-                    .map(n -> {
-                        try {
-                            return Class.forName(n);
-                        } catch (ClassNotFoundException e) {
-                            throw new SdicClassNotFoundException(e);
-                        }
-                    }).collect(Collectors.toList());
-    }
+    public <T> T createInstance(Class<T> clz) {
+        if (clz == null) {
+            throw new NullPointerException();
+        }
 
-    private void checkConstructorDependencies(List<Class<?>> services) {
-        for(Class<?> c : services) {
-            Constructor<?>[] constructors = c.getDeclaredConstructors();
-            for(Constructor constructor : constructors) {
-                Class[] parameterTypes = constructor.getParameterTypes();
-                System.out.println(Arrays.toString(parameterTypes));
-                System.out.println(Arrays.asList(parameterTypes));
-            }
+        LOG.trace("instance ordered: ", clz);
+        if (!serviceClasses().contains(clz)) {
+            throw new ClassNotRegistered(clz);
         }
-      /*  services.stream()
-                // get all constructors
-                .map(Class::getDeclaredConstructors)
-                .reduce(new ArrayList<Constructor>(),
-                        (l, arr) -> {
-                            l.addAll(Arrays.asList(arr));
-                            return l;
-                        },
-                        (l1, l2) -> l1)
-                // get all parameter types
-                .stream()
-                .map(Constructor::getParameterTypes)
-                .reduce(new ArrayList<Class<?>>(),
-                        (l, arr) -> {
-                            l.addAll(Arrays.asList(arr));
-                            return l;
-                        },
-                        (l1, l2) -> l1)
-                // search for services with needed types
-                .stream()
-                .distinct()
-                .forEach(t -> {
-                    if (!services.contains(t)) {
-                        throw new DependencyNotSatisfiedException(t);
-                    }
-                });*/
-    }
 
-    @VisibleForTesting
-    static boolean isServiceName(String name) {
-        return name.startsWith("service.");
+        try {
+            return new Instantiator<>(clz).createInstance();
+        } catch (IllegalAccessException | InvocationTargetException | InstantiationException e) {
+            throw new SdicInstantiationException(e);
+        }
     }
+
 }

src/main/java/de/joshavg/simpledic/ServiceDefinition.java

@@ -0,0 +1,37 @@
+package de.joshavg.simpledic;
+
+import java.lang.reflect.Constructor;
+
+class ServiceDefinition {
+
+    private Class<?> clz;
+    private String name;
+    private Constructor<?> constructor;
+
+    public Class<?> getClz() {
+        return clz;
+    }
+
+    public ServiceDefinition setClz(Class<?> clz) {
+        this.clz = clz;
+        return this;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public ServiceDefinition setName(String name) {
+        this.name = name;
+        return this;
+    }
+
+    public Constructor<?> getConstructor() {
+        return constructor;
+    }
+
+    public ServiceDefinition setConstructor(Constructor<?> constructor) {
+        this.constructor = constructor;
+        return this;
+    }
+}

src/main/java/de/joshavg/simpledic/exception/ClassNotRegistered.java

@@ -0,0 +1,8 @@
+package de.joshavg.simpledic.exception;
+
+public class ClassNotRegistered extends RuntimeException {
+
+    public ClassNotRegistered(Class<?> clz) {
+        super(String.format("class not registered in container: %s", clz));
+    }
+}

src/main/java/de/joshavg/simpledic/exception/DependencyNotSatisfiedException.java

@@ -1,7 +0,0 @@
-package de.joshavg.simpledic.exception;
-
-public class DependencyNotSatisfiedException extends RuntimeException {
-    public DependencyNotSatisfiedException(Class<?> dependency) {
-        super(String.format("Dependency %s not satisfied", dependency.getName()));
-    }
-}

src/main/java/de/joshavg/simpledic/exception/NoDefaultConstructorException.java

@@ -1,7 +0,0 @@
-package de.joshavg.simpledic.exception;
-
-public class NoDefaultConstructorException extends RuntimeException {
-    public NoDefaultConstructorException(Throwable cause) {
-        super(cause);
-    }
-}

src/main/java/de/joshavg/simpledic/exception/SdicClassNotFoundException.java

@@ -1,7 +0,0 @@
-package de.joshavg.simpledic.exception;
-
-public class SdicClassNotFoundException extends RuntimeException {
-    public SdicClassNotFoundException(Throwable cause) {
-        super(cause);
-    }
-}

src/main/java/de/joshavg/simpledic/exception/SdicInstantiationException.java

@@ -0,0 +1,7 @@
+package de.joshavg.simpledic.exception;
+
+public class SdicInstantiationException extends RuntimeException {
+    public SdicInstantiationException(Throwable cause) {
+        super(cause);
+    }
+}

src/main/java/de/joshavg/simpledic/exception/integrity/DependencyCycleDetected.java

@@ -0,0 +1,8 @@
+package de.joshavg.simpledic.exception.integrity;
+
+public class DependencyCycleDetected extends RuntimeException {
+
+    public DependencyCycleDetected(Class<?> clz) {
+        super(String.format("%s has a dependency cycle", clz));
+    }
+}

src/main/java/de/joshavg/simpledic/exception/integrity/DependencyNotSatisfied.java

@@ -0,0 +1,7 @@
+package de.joshavg.simpledic.exception.integrity;
+
+public class DependencyNotSatisfied extends RuntimeException {
+    public DependencyNotSatisfied(Class<?> dependency) {
+        super(String.format("Dependency %s not satisfied", dependency.getName()));
+    }
+}

src/main/java/de/joshavg/simpledic/exception/integrity/DuplicatedServiceClassesFound.java

@@ -0,0 +1,5 @@
+package de.joshavg.simpledic.exception.integrity;
+
+public class DuplicatedServiceClassesFound extends RuntimeException {
+
+}

src/main/java/de/joshavg/simpledic/exception/integrity/MoreThanOneConstructor.java

@@ -0,0 +1,8 @@
+package de.joshavg.simpledic.exception.integrity;
+
+public class MoreThanOneConstructor extends RuntimeException {
+
+    public MoreThanOneConstructor(Class<?> clz) {
+        super(String.format("class %s has more than one constructor", clz));
+    }
+}

src/main/java/de/joshavg/simpledic/exception/integrity/SdicClassNotFound.java

@@ -0,0 +1,7 @@
+package de.joshavg.simpledic.exception.integrity;
+
+public class SdicClassNotFound extends RuntimeException {
+    public SdicClassNotFound(Throwable cause) {
+        super(cause);
+    }
+}

src/test/java/de/joshavg/simpledic/ErrorTests.java

@@ -0,0 +1,50 @@
+package de.joshavg.simpledic;
+
+import de.joshavg.simpledic.exception.ClassNotRegistered;
+import de.joshavg.simpledic.exception.ContainerInitException;
+import de.joshavg.simpledic.exception.SdicInstantiationException;
+import de.joshavg.simpledic.exception.integrity.DependencyCycleDetected;
+import de.joshavg.simpledic.exception.integrity.DependencyNotSatisfied;
+import de.joshavg.simpledic.exception.integrity.DuplicatedServiceClassesFound;
+import de.joshavg.simpledic.services.Depends1;
+import de.joshavg.simpledic.services.PrivateConstructor;
+import java.util.Map;
+import org.junit.Test;
+
+public class ErrorTests {
+
+    @Test(expected = DuplicatedServiceClassesFound.class)
+    public void testDuplicationDetection() {
+        SdiContainer.load("duplicated.properties");
+    }
+
+    @Test(expected = DependencyCycleDetected.class)
+    public void testCycleDetection() {
+        SdiContainer.load("cycle.properties").createInstance(Depends1.class);
+    }
+
+    @Test(expected = ClassNotRegistered.class)
+    public void requestUnknownClass() {
+        SdiContainer.load("almostsane.properties").createInstance(Map.class);
+    }
+
+    @Test(expected = DependencyNotSatisfied.class)
+    public void requestServiceWithUnregisteredDependency() {
+        SdiContainer.load("unknowndep.properties").createInstance(Depends1.class);
+    }
+
+    @Test(expected = SdicInstantiationException.class)
+    public void privateConstructor() {
+        SdiContainer.load("almostsane.properties").createInstance(PrivateConstructor.class);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void requestNull() {
+        SdiContainer.load("almostsane.properties").createInstance(null);
+    }
+
+    @Test(expected = ContainerInitException.class)
+    public void loadUnknownFile() {
+        SdiContainer.load("unknown.properties");
+    }
+}

src/test/java/de/joshavg/simpledic/IntegrityCheckTest.java

@@ -0,0 +1,18 @@
+package de.joshavg.simpledic;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.Test;
+
+public class IntegrityCheckTest {
+
+    @Test
+    public void servicesStartWithServiceDot() {
+        assertThat(IntegrityCheck.isServiceName("dingens"), is(false));
+        assertThat(IntegrityCheck.isServiceName("service"), is(false));
+        assertThat(IntegrityCheck.isServiceName("service."), is(false));
+        assertThat(IntegrityCheck.isServiceName("service.a"), is(true));
+    }
+
+}

src/test/java/de/joshavg/simpledic/NoDependencies.java

@@ -1,4 +0,0 @@
-package de.joshavg.simpledic;
-
-public class NoDependencies {
-}

src/test/java/de/joshavg/simpledic/ServiceOne.java

@@ -1,6 +0,0 @@
-package de.joshavg.simpledic;
-
-public class ServiceOne {
-    public ServiceOne(NoDependencies b) {
-    }
-}

src/test/java/de/joshavg/simpledic/SimpleDependenciesTest.java

@@ -0,0 +1,20 @@
+package de.joshavg.simpledic;
+
+import de.joshavg.simpledic.services.DependsOnNoDependencies;
+import org.junit.Test;
+
+public class SimpleDependenciesTest {
+
+    private static final String FILENAME = "almostsane.properties";
+
+    @Test
+    public void testIntegrityCheck() {
+        SdiContainer.load(FILENAME);
+    }
+
+    @Test
+    public void createOneDependencyService() {
+        SdiContainer container = SdiContainer.load(FILENAME);
+        container.createInstance(DependsOnNoDependencies.class);
+    }
+}

src/test/java/de/joshavg/simpledic/TestProperties.java

@@ -1,11 +0,0 @@
-package de.joshavg.simpledic;
-
-import org.junit.Test;
-
-public class TestProperties {
-
-    @Test
-    public void testIntegrityCheck() {
-        SdiContainer.load("test.properties");
-    }
-}

src/test/java/de/joshavg/simpledic/services/Depends1.java

@@ -0,0 +1,7 @@
+package de.joshavg.simpledic.services;
+
+public class Depends1 {
+
+    public Depends1(Depends2 d) {
+    }
+}

src/test/java/de/joshavg/simpledic/services/Depends2.java

@@ -0,0 +1,7 @@
+package de.joshavg.simpledic.services;
+
+public class Depends2 {
+
+    public Depends2(Depends3 d) {
+    }
+}

src/test/java/de/joshavg/simpledic/services/Depends3.java

@@ -0,0 +1,7 @@
+package de.joshavg.simpledic.services;
+
+public class Depends3 {
+
+    public Depends3(Depends1 d) {
+    }
+}

src/test/java/de/joshavg/simpledic/services/DependsOnNoDependencies.java

@@ -0,0 +1,6 @@
+package de.joshavg.simpledic.services;
+
+public class DependsOnNoDependencies {
+    public DependsOnNoDependencies(NoDependencies b) {
+    }
+}

src/test/java/de/joshavg/simpledic/services/NoDependencies.java

@@ -0,0 +1,4 @@
+package de.joshavg.simpledic.services;
+
+public class NoDependencies {
+}

src/test/java/de/joshavg/simpledic/services/PrivateConstructor.java

@@ -0,0 +1,8 @@
+package de.joshavg.simpledic.services;
+
+public class PrivateConstructor {
+
+    private PrivateConstructor() {
+    }
+
+}

src/test/resources/almostsane.properties

@@ -0,0 +1,3 @@
+service.one: de.joshavg.simpledic.services.DependsOnNoDependencies
+service.nodeps: de.joshavg.simpledic.services.NoDependencies
+service.private: de.joshavg.simpledic.services.PrivateConstructor

src/test/resources/cycle.properties

@@ -0,0 +1,3 @@
+service.dep1:de.joshavg.simpledic.services.Depends1
+service.dep2:de.joshavg.simpledic.services.Depends2
+service.dep3:de.joshavg.simpledic.services.Depends3

src/test/resources/duplicated.properties

@@ -0,0 +1,3 @@
+service.one:de.joshavg.simpledic.services.DependsOnNoDependencies
+service.nodeps:de.joshavg.simpledic.services.NoDependencies
+service.nodeps2:de.joshavg.simpledic.services.NoDependencies

src/test/resources/test.properties

@@ -1,2 +0,0 @@
-service.one: de.joshavg.simpledic.ServiceOne
-service.nodeps: de.joshavg.simpledic.NoDependencies

src/test/resources/unknowndep.properties

@@ -0,0 +1 @@
+service.dep1: de.joshavg.simpledic.services.Depends1