FEAT simple Optional based PropertyProvider class

src/main/java/de/nclazz/commons/env/PropertyProvider.java

@@ -0,0 +1,67 @@
+package de.nclazz.commons.env;
+
+import lombok.SneakyThrows;
+
+import java.io.InputStream;
+import java.io.Writer;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Properties;
+
+public class PropertyProvider {
+
+    private final Properties properties;
+
+    public PropertyProvider(Properties defaults) {
+        this.properties = new Properties(defaults);
+    }
+    public PropertyProvider() {
+        this.properties = new Properties();
+    }
+
+    public Optional<String> getProperty(String key) {
+        return Optional.ofNullable(this.properties.getProperty(key));
+    }
+
+    public Optional<String> putProperty(String key, Object value) {
+
+        String last = this.properties.getProperty(key);
+        if(value == null) {
+            this.properties.remove(key);
+        }else {
+            this.properties.setProperty(key, value.toString());
+        }
+
+        return Optional.ofNullable(last);
+    }
+
+    public void clear() {
+        this.properties.clear();
+    }
+
+    @SneakyThrows
+    public void write(Writer writer) {
+        for(Map.Entry<Object, Object> entry : this.properties.entrySet()) {
+            String key = entry.getKey().toString();
+            Object value = entry.getValue();
+            String valueStr = value != null ? value.toString() : "";
+            writer.append(key)
+                    .append(" = ")
+                    .append(valueStr)
+                    .append(System.lineSeparator());
+        }
+    }
+
+    /**
+     * Loads the properties from given {@code stream}.
+     * The stream remains open after loading.
+     * @param stream
+     */
+    @SneakyThrows
+    public void load(InputStream stream) {
+        this.properties.load(stream);
+    }
+
+
+
+}

src/test/java/de/nclazz/commons/env/PropertyProviderTests.java

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+package de.nclazz.commons.env;
+
+import de.nclazz.commons.io.FileUtils;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class PropertyProviderTests {
+
+    @Test
+    void testPropertyProviderBasic() throws Exception {
+        PropertyProvider provider = new PropertyProvider();
+
+        try(InputStream stream = PropertyProviderTests.class.getResourceAsStream("/test-files/env.properties")) {
+            provider.load(stream);
+
+            assertEquals("Hello World", provider.getProperty("property.string").orElse(""));
+            assertEquals(12, (int)provider.getProperty("property.int")
+                                                        .map(Integer::parseInt)
+                                                        .orElse(0));
+            assertEquals(12.2f, (float)provider.getProperty("property.float")
+                    .map(Float::parseFloat)
+                    .orElse(0f));
+        }catch(Exception e) {
+            throw e;
+        }
+    }
+
+    @Test
+    void testIORoundTrip() throws Exception {
+        PropertyProvider provider = new PropertyProvider();
+
+        InputStream stream = PropertyProviderTests.class.getResourceAsStream("/test-files/env.properties");
+        provider.load(stream);
+        stream.close();
+
+        FileUtils.withTempFile("test", ".properties", file -> {
+            FileUtils.writeFile(file, provider::write);
+            provider.clear();
+
+            try(InputStream fstream = new FileInputStream(file)) {
+                provider.load(fstream);
+            }catch(Exception e) {
+                throw new RuntimeException(e);
+            }
+
+        });
+
+        assertEquals("Hello World", provider.getProperty("property.string").orElse(""));
+        assertEquals(12, (int)provider.getProperty("property.int")
+                .map(Integer::parseInt)
+                .orElse(0));
+        assertEquals(12.2f, (float)provider.getProperty("property.float")
+                .map(Float::parseFloat)
+                .orElse(0f));
+
+
+
+
+
+
+    }
+
+}

src/test/resources/test-files/env.properties

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+property.string = Hello World
+property.int = 12
+property.float = 12.2