Gotowe przykłady RestKlient - jeszcze bez modelu

PC28-RestKlient/src/main/java/rest_klient/Klient01_URL.java

+package rest_klient;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+
+public class Klient01_URL {
+
+    public static void main(String[] args) {
+        // Najprostszy sposób w Javie, aby pobrać dane z adresu URL, to użyć klasy URL.
+        try {
+            URL url = new URL("http://localhost:8080/PC35-RestSerwer/products.json");
+            System.out.println("Odczytuję dane...");
+            try (InputStream input = url.openStream()) {
+                // teraz z inputa możemy czytać ciąg bajtów
+                // ja przerzucę bajty czytane z sieci bezpośrednio do System.out
+                // (w przypadku obcego serwisu może być to niebezpieczne)
+                input.transferTo(System.out);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC28-RestKlient/src/main/java/rest_klient/Klient02_URL_JSON.java

+package rest_klient;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+
+import jakarta.json.Json;
+import jakarta.json.JsonArray;
+import jakarta.json.JsonReader;
+import jakarta.json.JsonValue;
+
+public class Klient02_URL_JSON {
+
+    public static void main(String[] args) {
+        try {
+            URL url = new URL(Ustawienia.ADRES_USLUGI + "/products.json");
+            try(InputStream inputStream = url.openStream();
+                JsonReader reader = Json.createReader(inputStream)) {
+                JsonArray array = reader.readArray();
+                // System.out.println(array);
+                for(JsonValue jsonValue : array) {
+                    //System.out.println(jsonValue);
+                    System.out.println(jsonValue.asJsonObject().getString("productName"));
+                    System.out.println("    opis: " + jsonValue.asJsonObject().getString("description", ""));
+                    System.out.println("    cena: " + jsonValue.asJsonObject().getJsonNumber("price").bigDecimalValue());
+                }
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC28-RestKlient/src/main/java/rest_klient/Klient03_HttpClient.java

+package rest_klient;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public class Klient03_HttpClient {
+    /* W Java 11 pojawiło się rozwiązanie "HttpClient", które umożliwia komunikację HTTP z dużą kontrolą nad szczegółami.
+     * Wysyłając zapytanie, od razu trzeba podać odpowiedni "BodyHandler",
+     * który pozwoli nam odczytać treść odpowiedzi we właściwy dla nas sposób.
+     * 
+     * W tej wersji wynik jest zapisywany do pliku.
+     */
+
+    public static void main(String[] args) {
+        HttpClient httpClient = HttpClient.newHttpClient();
+        try {
+            URI uri = new URI(Ustawienia.ADRES_USLUGI + "/products.json");
+            HttpRequest request = HttpRequest.newBuilder(uri).build();
+            HttpResponse<Path> response = httpClient.send(request, BodyHandlers.ofFile(Paths.get("wynik03.json")));
+            System.out.println("response " + response);
+            System.out.println("status: " + response.statusCode());
+            System.out.println("Content-Type: " + response.headers().firstValue("Content-Type").orElse("BRAK"));
+            System.out.println("OK, zapisany plik: " + response.body());
+        } catch (URISyntaxException | IOException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC28-RestKlient/src/main/java/rest_klient/Klient04_HttpClient_String.java

+package rest_klient;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+
+public class Klient04_HttpClient_String {
+
+    public static void main(String[] args) {
+        HttpClient httpClient = HttpClient.newHttpClient();
+        try {
+            URI uri = new URI(Ustawienia.ADRES_USLUGI + "/products.json");
+            HttpRequest request = HttpRequest.newBuilder(uri).build();
+            // Body z odpowiedzi pobierzemy jako obiekt String z całą treścią
+            HttpResponse<String> response = httpClient.send(request, BodyHandlers.ofString());
+            System.out.println("response " + response);
+            System.out.println("status: " + response.statusCode());
+            System.out.println("Content-Type: " + response.headers().firstValue("Content-Type").orElse("BRAK"));
+            System.out.println("Treść odpowiedzi:\n" + response.body()); // tutaj
+        } catch (URISyntaxException | IOException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC28-RestKlient/src/main/java/rest_klient/Klient05_HttpClient_Accept.java

+package rest_klient;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+
+public class Klient05_HttpClient_Accept {
+
+    public static void main(String[] args) {
+        HttpClient httpClient = HttpClient.newHttpClient();
+        try {
+            URI uri = new URI(Ustawienia.ADRES_USLUGI + "/products");
+            // W tej wersji do zapytania dodajemy nagłówek Accept
+            HttpRequest request = HttpRequest.newBuilder(uri)
+                    .header("Accept", "text/plain")
+                    .build();
+            HttpResponse<String> response = httpClient.send(request, BodyHandlers.ofString());
+            System.out.println("response " + response);
+            System.out.println("status: " + response.statusCode());
+            System.out.println("Content-Type: " + response.headers().firstValue("Content-Type").orElse("BRAK"));
+            System.out.println("Treść odpowiedzi:\n" + response.body());
+        } catch (URISyntaxException | IOException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC28-RestKlient/src/main/java/rest_klient/Klient06_HttpClient_JSON.java

+package rest_klient;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.math.BigDecimal;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+
+import jakarta.json.Json;
+import jakarta.json.JsonObject;
+import jakarta.json.JsonReader;
+
+public class Klient06_HttpClient_JSON {
+    /* W tej wersji używamy technologii Jakarta JSON P.
+     * 
+     * Widzimy drzewo danych jsonowych i jego elementytakie jak JsonObject, JsonArray, ...
+     * Mamy dostęp do poszczególnych pól.
+     */
+
+    public static void main(String[] args) {
+        HttpClient httpClient = HttpClient.newHttpClient();
+        try {
+            URI uri = new URI(Ustawienia.ADRES_USLUGI + "/products/1");
+            HttpRequest request = HttpRequest.newBuilder(uri)
+                    .header("Accept", "application/json")
+                    .build();
+            HttpResponse<InputStream> response = httpClient.send(request, BodyHandlers.ofInputStream());
+            System.out.println("response " + response);
+            System.out.println("status: " + response.statusCode());
+            System.out.println("Content-Type: " + response.headers().firstValue("Content-Type").orElse("BRAK"));
+            
+            JsonReader reader = Json.createReader(response.body());
+            JsonObject product = reader.readObject();
+            System.out.println("Pobrany obiekt jsonowy: " + product);
+            String nazwa = product.getString("productName");
+            String opis = product.getString("description", "BRAK OPISU");
+            BigDecimal cena = product.getJsonNumber("price").bigDecimalValue();
+            System.out.println(nazwa + " za cenę " + cena + " , opis: " + opis);
+            reader.close();
+        } catch (URISyntaxException | IOException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC28-RestKlient/src/main/java/rest_klient/Klient07_HttpClient_JSON_Lista.java

+package rest_klient;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+
+import jakarta.json.Json;
+import jakarta.json.JsonArray;
+import jakarta.json.JsonObject;
+import jakarta.json.JsonReader;
+import jakarta.json.JsonValue;
+
+public class Klient07_HttpClient_JSON_Lista {
+
+    public static void main(String[] args) {
+        try {
+            JsonArray array = pobierzJsona(Ustawienia.ADRES_USLUGI + "/products.json");
+            for(JsonValue jsonValue : array) {
+                JsonObject jsonObject = jsonValue.asJsonObject();
+                System.out.println(jsonObject.getString("productName"));
+                if(jsonObject.containsKey("description")) {
+                    System.out.println("    opis: " + jsonObject.getString("description", ""));
+                }
+                System.out.println("    cena: " + jsonObject.getJsonNumber("price").bigDecimalValue());
+            }
+        } catch (IOException | InterruptedException | URISyntaxException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private static JsonArray pobierzJsona(String adres) throws IOException, InterruptedException, URISyntaxException {
+        HttpClient httpClient = HttpClient.newHttpClient();
+        URI uri = new URI(adres);
+        HttpRequest request = HttpRequest.newBuilder(uri).build();
+        HttpResponse<InputStream> response = httpClient.send(request, BodyHandlers.ofInputStream());
+        System.out.println("response " + response);
+        System.out.println("status: " + response.statusCode());
+        System.out.println("Content-Type: " + response.headers().firstValue("Content-Type").orElse("BRAK"));
+        return wczytajJsona(response.body());
+    }
+
+    private static JsonArray wczytajJsona(InputStream input) {
+        try(JsonReader reader = Json.createReader(input)) {
+            return reader.readArray();
+        }
+    }
+
+}

PC28-RestKlient/src/main/java/rest_klient/Ustawienia.java

+package rest_klient;
+
+public class Ustawienia {
+    public static final String ADRES_USLUGI = "http://localhost:8080/PC27-RestSerwer";
+}