#499 Add JsonHelper class

Author: Igor Polevoy

javalite-common/pom.xml

@@ -85,5 +85,18 @@
                 </exclusion>
             </exclusions>
         </dependency>
+
+        <dependency>
+            <groupId>org.codehaus.jackson</groupId>
+            <artifactId>jackson-core-asl</artifactId>
+            <version>1.9.13</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.codehaus.jackson</groupId>
+            <artifactId>jackson-mapper-asl</artifactId>
+            <version>1.9.13</version>
+        </dependency>
+
     </dependencies>
 </project>

javalite-common/src/main/java/org/javalite/common/JsonHelper.java

@@ -0,0 +1,78 @@
+package org.javalite.common;
+
+import org.codehaus.jackson.map.ObjectMapper;
+import org.codehaus.jackson.map.SerializationConfig;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Convenience class to convert JSON strings to and from objects.
+ *
+ * @author Igor Polevoy on 5/26/16.
+ */
+
+public class JsonHelper {
+    private static final ObjectMapper mapper = new ObjectMapper();
+    static {
+        mapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESTAMPS, false);
+    }
+
+
+    /**
+     * Convert a JSON map to a Java Map
+     *
+     * @param json JSON map
+     * @return Java Map.
+     */
+    public static Map toMap(String json) {
+        try {
+            return mapper.readValue(json, Map.class);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Convert JSON Array to Java array of maps.
+     *
+     * @param json JSON array
+     * @return Java array.
+     */
+    public static Map[] toMaps(String json) {
+        try {
+            return mapper.readValue(json, Map[].class);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Convert Java object to a JSON string.
+     *
+     * @param val Java object
+     * @return JSON string.
+     */
+    public static String toJsonString(Object val) {
+        try {
+            return mapper.writeValueAsString(val);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Convert JSON array tp Java List
+     *
+     * @param json JSON array string.
+     * @return Java List instance.
+     */
+    public static List toList(String json) {
+        try {
+            return mapper.readValue(json, List.class);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}

javalite-common/src/test/java/org/javalite/common/JsonHelperSpec.java

@@ -0,0 +1,69 @@
+package org.javalite.common;
+
+import org.junit.Test;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.javalite.test.jspec.JSpec.$;
+import static org.javalite.test.jspec.JSpec.a;
+
+/**
+ * @author Igor Polevoy on 5/26/16.
+ */
+public class JsonHelperSpec {
+
+    @Test
+    public void shouldConvertObject2JSON(){
+        class Person {
+            String firstName, lastName;
+            public Person(String firstName, String lastName) {
+                this.firstName = firstName;
+                this.lastName = lastName;
+            }
+
+            public String getFirstName() {
+                return firstName;
+            }
+
+            public String getLastName() {
+                return lastName;
+            }
+
+            public void setFirstName(String firstName) {
+                this.firstName = firstName;
+            }
+
+            public void setLastName(String lastName) {
+                this.lastName = lastName;
+            }
+        }
+        a(JsonHelper.toJsonString(new Person("John", "Smith"))).shouldBeEqual("{\"firstName\":\"John\",\"lastName\":\"Smith\"}");
+    }
+
+    @Test
+    public void shouldConvertArray2List(){
+        List l = JsonHelper.toList("[1, 2]");
+        $(l.size()).shouldBeEqual(2);
+        $(l.get(0)).shouldBeEqual(1);
+        $(l.get(1)).shouldBeEqual(2);
+    }
+
+    @Test
+    public void shouldConvertMap2Map(){
+        Map m = JsonHelper.toMap("{ \"name\" : \"John\", \"age\": 22 }");
+        $(m.size()).shouldBeEqual(2);
+        $(m.get("name")).shouldBeEqual("John");
+        $(m.get("age")).shouldBeEqual(22);
+    }
+
+    @Test
+    public void shouldConvertMaps2Maps(){
+        Map[] maps = JsonHelper.toMaps("[{ \"name\" : \"John\", \"age\": 22 },{ \"name\" : \"Samantha\", \"age\": 21 }]");
+        $(maps.length).shouldBeEqual(2);
+        $(maps[0].get("name")).shouldBeEqual("John");
+        $(maps[0].get("age")).shouldBeEqual(22);
+        $(maps[1].get("name")).shouldBeEqual("Samantha");
+        $(maps[1].get("age")).shouldBeEqual(21);
+    }
+}