JSONObjectJSONWriter和JSONTokener类的一些用法组织.json

Posted 2021-02-23

This snippet of code, illustrates how to put, remove or accumulate values in a JSONObject object, use of JSONWriter for putting key/value pairs in "quick and convenient way" as stated by official documentation, and more practical uses for org.json beginners

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StringWriter;
import java.net.URI;
import java.net.URISyntaxException;
import org.json.*;
 
 
/**
 * @author prgrmmr.aben [at] gmail (dot) com
 * http://fivesnippets.blogspot.com/2014/09/jsonobject-jsonwriter-and-jsontokener.html
 * please give back a small donation if you find
 * this little educational snippet of code useful 
 */
public class test {
 
 int intValue=0;
 public int getIntValue() {
  return intValue;
 }
 
 public void setIntValue(int intValue) {
  this.intValue = intValue;
 }
 
 public String getStringValue() {
  return stringValue;
 }
 
 public void setStringValue(String stringValue) {
  this.stringValue = stringValue;
 }
 
 public Double getDoubleValue() {
  return doubleValue;
 }
 
 public void setDoubleValue(Double doubleValue) {
  this.doubleValue = doubleValue;
 }
 
 String stringValue="azerty0123";
 Double doubleValue = new Double(100.01);
 static URI uri =null;
 static { //is there a way to create an object which constructor can throw
    //an exception without using static block?, please answer me in comments
  try {
  uri = new URI("https://raw.githubusercontent.com/originals974/symfony/master/composer.json");
 } catch (URISyntaxException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }
 }
 
 public static void main(String[] args) throws IOException, URISyntaxException  {
  // TODO Auto-generated method stub
  /*
   *  creation of an URI object consisted of parsing a Json file in this address
   *  creation of two Json objects one by default construct,
   *  the other with a bean as an argument, a bean is an object 
   *  with public getters and setters
  */
  JSONObject jsonObj = new JSONObject();
  JSONObject jsonObj2 = new JSONObject(new test());
  //put key/value pairs and experimenting the toString() method
  //on Json objects
  jsonObj.put("value1", "qwerty");
  jsonObj.accumulate("value1", "azerty");
  System.out.println(jsonObj.toString());
  System.out.println(jsonObj2.toString());
  //we can put objects of type JSONObject, like we did with beans,
  //we do with JSONObject objects
  jsonObj.put("innerJson", jsonObj2);
  System.out.println(jsonObj.toString());
  jsonObj.remove("innerJson");
  System.out.println(jsonObj.toString());
  //JSONObject.doubleToString() returns null
  //when NaN (not finite number) value is passed as its argument
  System.out.println(JSONObject.doubleToString(new Double(0.0/0.0)));
  System.out.println(JSONObject.doubleToString(new Double(0.0/2)));
  //getting Names (keys) of jsonObj2
  for (String string : JSONObject.getNames(jsonObj2)) {
   System.out.print(string+", ");
  }
  System.out.println();
  //you need to activate assertions, pass -ea as an argument to the JVM
  assert !jsonObj.isNull("[email protected]") : "key not found";
  /*
   *  making a JSONWriter object to put key/value pairs in "quick and convenient way"
   *  as stated in the documentation of JSONWriter
  */
  StringWriter writer = new StringWriter();
  JSONWriter JsonWriter = new JSONWriter(writer);
  JsonWriter.object().key("key1").value(new String("value1")).key("key2").value("value2").key("key3").value("value3").endObject();
  System.out.println(writer.toString());
  /*
   *  experiencing parsing methods in JSONTokener objects
   *  we pass an inputStream after opening a connection to an URL 
  */
  InputStream jsonStreamExample = uri.toURL().openStream();
  BufferedReader reader = new BufferedReader(new InputStreamReader(jsonStreamExample));
  StringBuilder builder = new StringBuilder();
  String aux = "";
  while ((aux = reader.readLine()) != null) {
      builder.append(aux);
  }
  String text = builder.toString();
  System.out.println(text);
 
  jsonStreamExample = uri.toURL().openStream();
  JSONTokener tokener = new JSONTokener(jsonStreamExample);
  System.out.println("1-->"+tokener.next()+"<-- is a bracket");
  System.out.println("2-->"+tokener.next()+"<-- is a back-space");
  System.out.println("3-->"+tokener.next()+"<-- is a space");
  System.out.println("4-->"+tokener.next()+"<-- is a space");
  System.out.println("5-->"+tokener.next()+"<-- is a space");
  System.out.println("6-->"+tokener.next()+"<-- is a space");
  System.out.println("7-->"+tokener.next()+"<-- is a quote");
  System.out.println("8-->"+tokener.next()+"<-- is first character of "name"  ");
  System.out.println("9-->"+tokener.nextValue()+"<-- is the value that comes next");
  System.out.print(tokener.next()+","+tokener.next());
  System.out.println("
this is the value that comes next to the space after ':' --> "+tokener.nextValue());
 
}
}