Java REST API kliens - HttpURLConnection

Szerző: Sallai András
Copyright © 2024, Sallai András
Szerkesztve: 2024
Licenc: CC BY-SA 4.0
Web: https://szit.hu

Használatra példa

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
 
public class Client {
  public static void connect() throws IOException {
    URL url = new URL("https://jsonplaceholder.typicode.com/users/");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("GET");
    conn.connect();
 
    InputStream is = conn.getInputStream();
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr);
 
    StringBuffer sb = new StringBuffer();
    String line = br.readLine();
    while (line != null) {
      sb.append(line);
      sb.append(System.lineSeparator());
      line = br.readLine();
    }    
    conn.disconnect();
    System.out.println(sb.toString());
 
  }
}

App.java

public class App {
    public static void main(String[] args) throws Exception {
        Client.connect();
    }
}

CRUD műveletek

Client.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
 
public class Client {
  public static void get() throws IOException {
    URL url = new URL("https://jsonplaceholder.typicode.com/users/");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("GET");
    conn.connect();
 
    InputStream is = conn.getInputStream();
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr);
 
    StringBuffer sb = new StringBuffer();
    String line = br.readLine();
    while (line != null) {
      sb.append(line);
      sb.append(System.lineSeparator());
      line = br.readLine();
    }    
    conn.disconnect();
    System.out.println(sb.toString());
 
  }
 
  public static void post() throws IOException {
    URL url = new URL("https://jsonplaceholder.typicode.com/users/");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("POST");
    conn.setRequestProperty("Content-type", "application/json");
    conn.setDoOutput(true);
 
    String jsonInputString = "{\"name\":\"morpheus\",\"job\":\"leader\"}";
    conn.getOutputStream().write(jsonInputString.getBytes());
    conn.getOutputStream().flush();
    conn.getOutputStream().close();
    conn.connect();
 
    InputStream is = conn.getInputStream();
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr);
 
    StringBuffer sb = new StringBuffer();
    String line = br.readLine();
    while (line != null) {
      sb.append(line);
      sb.append(System.lineSeparator());
      line = br.readLine();
    }    
    conn.disconnect();
    System.out.println(sb.toString());
 
  }
 
  public static void put() throws IOException {
    URL url = new URL("https://jsonplaceholder.typicode.com/users/1");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("PUT");
    conn.setRequestProperty("Content-type", "application/json");
    conn.setDoOutput(true);
 
    String jsonInputString = "{\"name\":\"morpheus\",\"job\":\"zion resident\"}";
    conn.getOutputStream().write(jsonInputString.getBytes());
    conn.getOutputStream().flush();
    conn.getOutputStream().close();
    conn.connect();
 
    InputStream is = conn.getInputStream();
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr);
 
    StringBuffer sb = new StringBuffer();
    String line = br.readLine();
    while (line != null) {
      sb.append(line);
      sb.append(System.lineSeparator());
      line = br.readLine();
    }    
    conn.disconnect();
    System.out.println(sb.toString());
 
  }
 
  public static void delete() throws IOException {
    URL url = new URL("https://jsonplaceholder.typicode.com/users/1");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("DELETE");
    conn.connect();
 
    InputStream is = conn.getInputStream();
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr);
 
    StringBuffer sb = new StringBuffer();
    String line = br.readLine();
    while (line != null) {
      sb.append(line);
      sb.append(System.lineSeparator());
      line = br.readLine();
    }    
    conn.disconnect();
    System.out.println(sb.toString());
  }
 
}