JAX-RS - @Context Examples

import com.logicbig.example.Item;
import com.logicbig.example.DataService;

import javax.ws.rs.*;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriInfo;
import java.util.List;

@Path("items")
public class ItemRestService {

    @Context
    private UriInfo uriInfo;

    private DataService dataService = DataService.getInstance();

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public List<Item> getItems() {
        return dataService.getItemList();
    }


    @Path("{sku}")
    @PUT
    @Consumes(MediaType.APPLICATION_JSON)
    public Response createItem(Item item,
                          @PathParam("sku") String sku) {

        System.out.println(item);
        if (dataService.itemExists(sku)) {
            //status code 204
            System.out.println("no content");
            return Response.noContent()
                      .build();
        } else {
            dataService.createItem(item, sku);
            //status code 201
            //sends back new URI in header key = 'LOCATION'
            System.out.println("good");
            return Response.created(uriInfo.getAbsolutePath())
                      .build();
        }
    }

    @GET
    @Path("{sku}")
    @Produces(MediaType.APPLICATION_JSON)
    public Response getCustomer(@PathParam("sku") String sku) {
        Item item = dataService.getItemBySku(sku);
        if (item == null) {
            return Response.status(Response.Status.NOT_FOUND)
                      .build();
        } else {
            return Response.ok()
                      .entity(item)
                      .build();
        }
    }
}

    @GET
    @Path("test11")
    public String clientTest(@Context HttpHeaders headers) {
        MultivaluedMap<String, String> rh = headers.getRequestHeaders();
        String str = rh.entrySet()
                       .stream()
                       .map(e -> e.getKey() + " = " + e.getValue())
                       .collect(Collectors.joining("\n"));

        return str;
    }

    @GET
    @Path("test2")
    public String readAllCookies(@Context HttpHeaders headers) {
        Map<String, Cookie> cookies = headers.getCookies();
        String str = cookies.entrySet()
                            .stream()
                            .map(e -> e.getKey() + " = " + e.getValue().getValue())
                            .collect(Collectors.joining("<br/>"));
        return str;
    }

    @GET
    @Path("{path}")
    public String create(@PathParam("path") String path,
                         @Context Providers providers) {
        ContextResolver<MyContext> cr = providers
                .getContextResolver(MyContext.class, MediaType.WILDCARD_TYPE);
        MyContext<String> c = cr.getContext(String.class);
        String r = c.get(path);
        return "response:  " + r;
    }

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.UriInfo;
import java.net.URI;

@Path("/users")
public class UserResource {
    @Context
    UriInfo uriInfo;

    public UserResource() {
        printUriInfo("In constructor");
    }

    @GET
    public String getUsers() {
        printUriInfo("In getUsers() method");
        return "returning dummy user list";
    }

    @GET
    @Path("{id}")
    public String getUserById(@PathParam("id") String id) {
        printUriInfo("In getUserById() method");
        return "returning dummy user by id " + id;
    }

    private void printUriInfo(String msg) {
        System.out.println("---------------");
        System.out.println(msg);
        System.out.println("-- UriInfo --");
        if (uriInfo == null) {
            System.out.println("UriInfo: " + uriInfo);
            return;
        }
        System.out.println("absolutePath: " + uriInfo.getAbsolutePath());
        System.out.println("baseUri: " + uriInfo.getBaseUri());
        System.out.println("matchedResource: " + uriInfo.getMatchedResources());
        System.out.println("matchedUri: " + uriInfo.getMatchedURIs());
        System.out.println("path: " + uriInfo.getPath());
        System.out.println("pathParameters: " + uriInfo.getPathParameters());
        System.out.println("pathSegments: " + uriInfo.getPathSegments());
        System.out.println("queryParameters: " + uriInfo.getQueryParameters());
        System.out.println("requestUri: " + uriInfo.getRequestUri());
        System.out.println("relativize test: " + uriInfo.relativize(URI.create("test")));
        System.out.println("resolve test: " + uriInfo.resolve(URI.create("test")));
    }
}

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MultivaluedMap;
import java.util.List;
import java.util.Map;

@Path("/users")
public class UserResource {
    @Context
    private HttpHeaders httpHeaders;

    @GET
    public String getUsers() {
        System.out.println("In getUsers() method");
        printHeaderInfo();
        return "returning dummy user list";
    }

    private void printHeaderInfo() {
        System.out.println("---------------");
        MultivaluedMap<String, String> requestHeaders = httpHeaders.getRequestHeaders();
        for (Map.Entry<String, List<String>> entry : requestHeaders.entrySet()) {
            System.out.println(entry.getKey() + "=" + entry.getValue());
        }
    }
}

package com.logicbig.example;

import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.container.ResourceContext;
import javax.ws.rs.core.Context;

@Path("/")
public class OrderResource {

    @Context
    private ResourceContext resourceContext;

    @Path("/orders/{id}")
    public OrderDetails getOrderById(@PathParam("id") int orderId) {
        return resourceContext.initResource(new OrderDetails(orderId));
    }
}

package com.logicbig.example;

import javax.ws.rs.GET;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.HttpHeaders;

public class OrderDetails {

    private final int id;
    @Context
    private HttpHeaders headers;

    public OrderDetails(int id) {
        System.out.println("--- init --");
        this.id = id;
    }

    @GET
    public String getOrderDetails() {
        return String.format("response from getOrderDetails(), headers: %s%n",
                headers.getRequestHeaders());
    }
}

package com.logicbig.example;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.core.Configuration;
import javax.ws.rs.core.Context;
import java.util.Map;

@Path("/")
public class ExampleResource {
    @Context
    private Configuration configuration;

    @GET
    @Path("/test1")
    public String getResponse() {
        Map<String, Object> properties = configuration.getProperties();
        properties.forEach((k, v) -> System.out.println(k + " = " + v));
        return "test response";
    }
}

@Provider
@Produces("text/csv")
public class CsvWriter<T> implements MessageBodyWriter<List<T>> {
    @Context
    Providers providers;

    @Override
    public void writeTo(List<T> ts, Class<?> type, Type genericType, Annotation[] annotations,
                        MediaType mediaType, MultivaluedMap<String, Object> httpHeaders,
                        OutputStream entityStream) throws IOException, WebApplicationException {
        String response = "";
        for (T t : ts) {
            try {
                Class<?> c = t.getClass();
                //using Java Bean API to access property values
                BeanInfo beanInfo = Introspector.getBeanInfo(c);
                String temp = "";
                for (PropertyDescriptor pd : beanInfo.getPropertyDescriptors()) {
                    if (pd.getName().equals("class")) {//skip getClass()
                        continue;
                    }
                    Object o = pd.getReadMethod().invoke(t);
                    temp += "," + o;
                }
                if (temp.length() > 0) {
                    temp = temp.substring(1);
                    response += temp + "\n";
                }
            } catch (Exception e) {
                throw new WebApplicationException(e);
            }
        }
        //using Providers instance
        MessageBodyWriter<String> plainTextWriter = providers.getMessageBodyWriter(String.class,
                genericType, annotations, MediaType.TEXT_PLAIN_TYPE);
        plainTextWriter.writeTo(response, String.class, genericType, annotations, mediaType,
                httpHeaders, entityStream);
    }

    @Override
    public boolean isWriteable(Class<?> type, Type genericType,
                               Annotation[] annotations, MediaType mediaType) {
        return true;
    }

    @Override
    public long getSize(List<T> ts, Class<?> type, Type genericType,
                        Annotation[] annotations, MediaType mediaType) {
        return -1;
    }
}

package com.logicbig.example;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.core.Context;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;

@Path("/")
public class ExampleResource {
    @Context
    private ServletConfig servletConfig;
    @Context
    private ServletContext servletContext;
    @Context
    private HttpServletRequest httpServletRequest;
    @Context
    private HttpServletResponse httpServletResponse;

    @GET
    @Path("/test")
    public void handleRequest() throws IOException {
        System.out.println("-- in resource method --");
        printServletConfigInfo();
        printServletContextInfo();
        printServletRequestInfo();
        //committing response using HttpServletResponse
        httpServletResponse.getWriter().write("Test response");
        httpServletResponse.getWriter().flush();
    }

    private void printServletRequestInfo() {
        System.out.println("-- Servlet Request --");
        System.out.println("Request URI: " + httpServletRequest.getRequestURI());
        Enumeration<String> headerNames = httpServletRequest.getHeaderNames();
        ArrayList<String> list = Collections.list(headerNames);
        System.out.println("Request headers: " + list.size());
        list.forEach(h -> System.out.println(h + " = " + httpServletRequest.getHeader(h)));
    }

    private void printServletContextInfo() {
        System.out.println("-- Servlet Context --");
        System.out.println("Context path: " + servletContext.getContextPath());
        System.out.println("Server info: " + servletContext.getServerInfo());
        Enumeration<String> attributeNames = servletContext.getAttributeNames();
        ArrayList<String> list = Collections.list(attributeNames);
        System.out.println("Context attributes: " + list.size());
        System.out.println("Session Tracking modes: " + servletContext.getDefaultSessionTrackingModes());
    }

    private void printServletConfigInfo() {
        System.out.println("-- Servlet Config Params --");
        Enumeration<String> initParameterNames = servletConfig.getInitParameterNames();
        ArrayList<String> list = Collections.list(initParameterNames);
        System.out.println("Init params: " + list.size());
        list.forEach(n -> System.out.println(n + " = " + servletConfig.getInitParameter(n)));
        System.out.println("Servlet name: " + servletConfig.getServletName());
    }
}