Przykłady HttpClient

PC27-RestKlient/src/main/java/pobieranie/Pobieranie1_URL.java

+package pobieranie;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+
+public class Pobieranie1_URL {
+
+    public static void main(String[] args) {
+        final String adres = "http://api.nbp.pl/api/exchangerates/tables/A/?format=json";
+
+        try {
+            URL url = new URL(adres);
+            // Od Java 21 bardziej zalecane jest:
+            // URI uri = new URI(adres);
+            // URL url = uri.toURL();
+            try(InputStream input = url.openStream()) {
+                // z input stream dane można czytać porcjami jako ciągi bajtów
+                // byte[] tablica_bajtow = new byte[1024];
+                // int ile = input.read(tablica_bajtow);
+                // System.out.println(new String(tablica_bajtow, 0, ile));
+                // ale tutaj całość pobrnaych danych zapiszemy do pliku
+                Files.copy(input, Path.of("waluty.json"), StandardCopyOption.REPLACE_EXISTING);
+                System.out.println("Gotowe");
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC27-RestKlient/src/main/java/pobieranie/Pobieranie2_HttpClient_DoPliku.java

+package pobieranie;
+
+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 java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+
+public class Pobieranie2_HttpClient_DoPliku {
+
+    public static void main(String[] args) {
+        final String adres = "http://api.nbp.pl/api/exchangerates/tables/A/?format=json";
+
+        try {
+            URI uri = new URI(adres);
+            HttpClient client = HttpClient.newHttpClient();
+            HttpRequest request = HttpRequest.newBuilder(uri).build();
+            HttpResponse<InputStream> response = client.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("--"));
+            if(response.statusCode() != 200) {
+                return;
+            }
+            // body jest takiego typu, jaki wynika z użytego BodyHandler
+            try(InputStream input = response.body()) {
+                Files.copy(input, Path.of("waluty.json"), StandardCopyOption.REPLACE_EXISTING);
+                System.out.println("Gotowe");
+            }
+        } catch (IOException | URISyntaxException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC27-RestKlient/src/main/java/pobieranie/Pobieranie3_HttpClient_String.java

+package pobieranie;
+
+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 Pobieranie3_HttpClient_String {
+
+    public static void main(String[] args) {
+        final String adres = "http://api.nbp.pl/api/exchangerates/tables/A/?format=json"; // spróbuj xml
+
+        try {
+            URI uri = new URI(adres);
+            HttpClient client = HttpClient.newHttpClient();
+            HttpRequest request = HttpRequest.newBuilder(uri).build();
+            HttpResponse<String> response = client.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("--"));
+//			if(response.statusCode() != 200) {
+//				return;
+//			}
+            // body jest takiego typu, jaki wynika z użytego BodyHandler
+            String body = response.body();
+            System.out.println("Długość stringa: " + body.length());
+            System.out.println(body);
+        } catch (IOException | URISyntaxException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC27-RestKlient/src/main/java/pobieranie/Pobieranie4_JSON.java

+package pobieranie;
+
+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.JsonArray;
+import jakarta.json.JsonObject;
+import jakarta.json.JsonReader;
+import jakarta.json.JsonValue;
+
+public class Pobieranie4_JSON {
+
+    public static void main(String[] args) {
+        final String adres = "http://api.nbp.pl/api/exchangerates/tables/A/?format=json";
+
+        try {
+            URI uri = new URI(adres);
+            HttpClient client = HttpClient.newHttpClient();
+            HttpRequest request = HttpRequest.newBuilder(uri).build();
+            HttpResponse<InputStream> response = client.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("--"));
+            if(response.statusCode() != 200) {
+                return;
+            }
+            // parsowanie JSONa z pomocą biblioteki Jakarta JSON (utworzone w Java EE 7 i dalej rozwijane)
+            // alternatywy: GSON, org.json, Jackson
+            
+            JsonArray json;
+            try(JsonReader reader = Json.createReader(response.body())) {
+                json = reader.readArray();				
+            } // tutaj już zamykamy połączenie
+            // zerowym (i jedynym) elementem tablicy jest {obiekt JSONowy} odpowiadający tabeli walut
+            JsonObject tabela = json.getJsonObject(0);
+            // bezpośrednio w tym obiekcie są takie pola, jak numer i data
+            System.out.println("Numer tabeli: " + tabela.getString("no"));
+            System.out.println("Data: " + tabela.getString("effectiveDate"));
+            // w polu rates znajduje się tablica zawierająca dane poszczególnych walut
+            JsonArray rates = tabela.getJsonArray("rates");
+            System.out.println("Liczba walut: " + rates.size());
+            System.out.println();
+            for(JsonValue rate : rates) {
+                // System.out.println(rate);
+                JsonObject rateObj = rate.asJsonObject();
+                String nazwa = rateObj.getString("currency");
+                String kod = rateObj.getString("code");
+                BigDecimal kurs = rateObj.getJsonNumber("mid").bigDecimalValue();
+                System.out.println(kod + " " + nazwa + ": " + kurs);
+            }
+        } catch (IOException | URISyntaxException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC27-RestKlient/src/main/java/sklep/klient/Klient02_URL_JSON.java

@@ -5,6 +5,7 @@ import java.io.InputStream;
 import java.net.URL;
 
 import jakarta.json.*;
+import jakarta.json.JsonValue.ValueType;
 
 public class Klient02_URL_JSON {
     /* W tej wersji pobieramy dane JSON podstawowym sposobem URL, ale pobrane dane parsujemy za pomocą narzędzi
@@ -19,6 +20,7 @@ public class Klient02_URL_JSON {
                 JsonArray array = reader.readArray();
                 // System.out.println(array);
                 for(JsonValue jsonValue : array) {
+                    // if(jsonValue.getValueType() == ValueType.OBJECT)
                     //System.out.println(jsonValue);
                     JsonObject jsonObject = jsonValue.asJsonObject();
                     System.out.println(jsonObject.getString("productName"));

PC27-RestKlient/src/main/java/sklep/klient/Klient03_HttpClient.java

+package sklep.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) {
+        try(HttpClient httpClient = HttpClient.newHttpClient()) {
+            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();
+        }
+    }
+
+}

PC27-RestKlient/src/main/java/sklep/klient/Klient04_HttpClient_String.java

+package sklep.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) {
+        try(HttpClient httpClient = HttpClient.newHttpClient()) {
+            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"));
+            String body = response.body();
+            System.out.println("Treść odpowiedzi:\n" + body);
+        } catch (URISyntaxException | IOException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

PC27-RestKlient/src/main/java/sklep/klient/Klient05_HttpClient_Accept.java

+package sklep.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) {
+        try(HttpClient httpClient = HttpClient.newHttpClient()) {
+            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") // albo application/xml, application/json, text/html
+                    .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();
+        }
+    }
+
+}

PC27-RestKlient/src/main/java/sklep/klient/Klient06_HttpClient_JSON.java

+package sklep.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) {
+        try(HttpClient httpClient = HttpClient.newHttpClient()) {
+            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();
+        }
+    }
+
+}

PC27-RestKlient/src/main/java/sklep/klient/Klient07_HttpClient_JSON_Lista.java

+package sklep.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 {
+        try(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();
+        }
+    }
+
+}