Sample showing how to map custom exceptions to HTTP Response codes

Author: Bhakti Mehta

exception-mapper/Readme.md

@@ -0,0 +1,28 @@
+This is a very basic sample which shows exception mapper and JAX-RS
+
+Download Glassfish 4.0
+
+Start Glassfish
+cd glassfish4/glassfish/bin
+./asadmin start-domain
+
+Build the sample by running
+mvn clean install
+cd target
+deploy exception-mapper.war
+./asadmin deploy <folder of sample>/target/exception-mapper.war
+
+
+curl http://localhost:8080/exception-mapper/v1/coffees/orders/1/
+You will see response like this {"name":"Mocha","order":1,"size":"Small","type":"Brewed"}
+
+curl http://localhost:8080/exception-mapper/v1/coffees/orders/100
+Powered-By: Servlet/3.1 JSP/2.3 (GlassFish Server Open Source Edition  4.0  Java/Oracle Corporation/1.7)
+Server: GlassFish Server Open Source Edition  4.0 
+Content-Type: application/json
+Date: Tue, 12 Aug 2014 00:08:18 GMT
+Content-Length: 54
+
+{"code":404,"message":"No coffee found for order 100"}
+
+

exception-mapper/pom.xml

@@ -0,0 +1,59 @@
+<?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">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>exception-mapper</groupId>
+    <artifactId>exception-mapper</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <packaging>war</packaging>
+    <description>Basic "exception-mapper" sample</description>
+    <dependencies>
+        <dependency>
+            <groupId>javax.ws.rs</groupId>
+            <artifactId>javax.ws.rs-api</artifactId>
+            <version>2.0-rc2</version>
+            <scope>provided</scope>
+        </dependency>
+
+
+        <dependency>
+            <groupId>javax</groupId>
+            <artifactId>javaee-web-api</artifactId>
+            <version>7.0</version>
+            <scope>provided</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>javax.validation</groupId>
+            <artifactId>validation-api</artifactId>
+            <version>1.1.0.Beta2</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.glassfish.jersey.ext</groupId>
+            <artifactId>jersey-bean-validation</artifactId>
+            <version>2.1</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-war-plugin</artifactId>
+                <version>2.1-beta-1</version>
+                <configuration>
+                    <failOnMissingWebXml>false</failOnMissingWebXml>
+                </configuration>
+            </plugin>
+
+        </plugins>
+        <finalName>exception-mapper</finalName>
+    </build>
+
+</project>
+

exception-mapper/src/main/java/org/coffeeshop/Coffee.java

@@ -0,0 +1,83 @@
+package org.coffeeshop;
+
+import javax.validation.constraints.NotNull;
+import javax.ws.rs.DefaultValue;
+import javax.xml.bind.annotation.XmlRootElement;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * A plain Coffee resource
+ * @author  Bhakti Mehta
+ */
+@XmlRootElement
+public class Coffee {
+
+
+    private String type;
+
+    private String size;
+
+    @NotNull
+    private String name;
+
+    private double price;
+
+
+    private int order;
+
+    public Coffee(String type, String size,String name, double price) {
+        this.type = type;
+        this.size = size;
+        this.name = name;
+        this.price = price;
+        this.order = getOrder();
+
+    }
+
+    public void setOrder(int order) {
+        this.order = order;
+    }
+
+    public int getOrder() {
+        return CoffeeService.getCounter();
+    }
+
+
+
+    public Coffee(){
+
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    public String getSize() {
+        return size;
+    }
+
+    public void setSize(String size) {
+        this.size = size;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public double getPrice() {
+        return price;
+    }
+
+    public void setPrice(double price) {
+        this.price = price;
+    }
+
+}

exception-mapper/src/main/java/org/coffeeshop/CoffeeApplication.java

@@ -0,0 +1,35 @@
+package org.coffeeshop;
+
+/**
+ * This is an application which will register the JAX-RS resources
+ * @author Bhakti Mehta
+ */
+
+import org.glassfish.jersey.server.ServerProperties;
+import org.glassfish.jersey.server.validation.ValidationFeature;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+import javax.ws.rs.ApplicationPath;
+import javax.ws.rs.core.Application;
+
+@ApplicationPath("/")
+public class CoffeeApplication extends Application {
+
+    @Override
+    public Set<Class<?>> getClasses() {
+        Set<Class<?>> classes = new HashSet<Class<?>>();
+        classes.add(CoffeesResource.class);
+        classes.add(MyExceptionMapper.class);
+        return classes;
+    }
+
+
+
+
+
+}
+

exception-mapper/src/main/java/org/coffeeshop/CoffeeNotFoundException.java

@@ -0,0 +1,14 @@
+package org.coffeeshop;
+
+/**
+ * This is a custom exception thrown
+ * in case the resource method does not find
+ * any coffee orders
+ * @author Bhakti Mehta
+ */
+public class CoffeeNotFoundException extends RuntimeException {
+
+    public CoffeeNotFoundException(String message) {
+        super(message);
+    }
+}

exception-mapper/src/main/java/org/coffeeshop/CoffeeService.java

@@ -0,0 +1,45 @@
+package org.coffeeshop;
+
+import javax.ejb.Singleton;
+import java.util.HashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * A basic collection of coffee orders for simplicity
+ * @author Bhakti Mehta
+ */
+@Singleton
+public class CoffeeService {
+    private static final HashMap<Integer, Coffee> coffees = new HashMap<Integer, Coffee>();
+    private static AtomicInteger orderCounter = new AtomicInteger(0);
+
+    public static int incrementOrderCounter() {
+        return orderCounter.incrementAndGet();
+    }
+
+
+    public static int addCoffee(Coffee coffee) {
+        int counter = incrementOrderCounter();
+        coffees.put(counter, coffee);
+        return counter;
+    }
+
+    public static int getSize() {
+        return  coffees.size();
+    }
+
+    public static Coffee getCoffee(int order) {
+        return coffees.get(order);
+    }
+
+    public CoffeeService() {
+        // initial content
+        addCoffee(new Coffee("Brewed", "Small", "Mocha", 3.50));
+
+    }
+
+    public static int getCounter() {
+
+        return orderCounter.get();
+    }
+}

exception-mapper/src/main/java/org/coffeeshop/CoffeesResource.java

@@ -0,0 +1,35 @@
+package org.coffeeshop;
+
+import org.glassfish.jersey.server.ChunkedOutput;
+
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.core.StreamingOutput;
+import java.io.*;
+
+/**
+ *
+ * A simple JAX-RS resource which demonstrates custom exception handling
+ * @author Bhakti Mehta
+ *
+ */
+@Path("v1/coffees")
+public class CoffeesResource {
+
+
+    @GET
+    @Produces(MediaType.APPLICATION_JSON)
+    @Path("/orders/{id}")
+    public Response getCoffee(@PathParam("id") int id) {
+        Coffee coffee =  CoffeeService.getCoffee(id);
+        if (coffee == null)
+            throw new CoffeeNotFoundException("No coffee found for order " + id);
+        return Response.ok(coffee).type(MediaType.APPLICATION_JSON_TYPE).build();
+    }
+
+
+
+
+
+}

exception-mapper/src/main/java/org/coffeeshop/MyExceptionMapper.java

@@ -0,0 +1,31 @@
+package org.coffeeshop;
+
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.ExceptionMapper;
+import javax.ws.rs.ext.Provider;
+
+/**
+ * This is an implementation of the ExceptionMapper class
+ * to convert a user defined Exception to a JAX-RS response
+ * @author Bhakti Mehta
+ */
+@Provider
+public class MyExceptionMapper implements ExceptionMapper<Exception> {
+
+    public Response toResponse(Exception e) {
+        ResourceError resourceError = new ResourceError();
+
+        String error = "Service encountered an internal error";
+        if (e instanceof CoffeeNotFoundException) {
+            resourceError.setCode(Response.Status.NOT_FOUND.getStatusCode());
+            resourceError.setMessage(e.getMessage());
+
+            return Response.status(Response.Status.NOT_FOUND).entity(resourceError)
+                    .type(MediaType.APPLICATION_JSON_TYPE)
+                    .build();
+        }
+        return Response.status(503).entity(resourceError).type(MediaType.APPLICATION_JSON_TYPE)
+                .build();
+    }
+}

exception-mapper/src/main/java/org/coffeeshop/Preference.java

@@ -0,0 +1,9 @@
+package org.coffeeshop;
+
+/**
+ * A basic class to indicate preference for coffee
+ * @author Bhakti Mehta
+ */
+public enum Preference {
+    NonFat, Regular, Lowfat;
+}

exception-mapper/src/main/java/org/coffeeshop/ResourceError.java

@@ -0,0 +1,36 @@
+package org.coffeeshop;
+
+import javax.xml.bind.annotation.XmlRootElement;
+
+/**
+ * This is a user defined class which will contain
+ * the status code and response message when an error occurs
+ * @author Bhakti Mehta
+ */
+@XmlRootElement
+public class ResourceError {
+
+    private int code;
+
+    private String message;
+
+    public int getCode() {
+        return code;
+    }
+
+    public void setCode(int code) {
+        this.code = code;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public ResourceError(){
+
+    }
+}