The following are samples that show how to parse JSON strings.
public class JSONParserUtil { @future(callout=true) public static void parseJSONResponse() { Http httpProtocol = new Http(); // Create HTTP request to send. HttpRequest request = new HttpRequest(); // Set the endpoint URL. String endpoint = 'https://docsample.herokuapp.com/jsonSample'; request.setEndPoint(endpoint); // Set the HTTP verb to GET. request.setMethod('GET'); // Send the HTTP request and get the response. // The response is in JSON format. HttpResponse response = httpProtocol.send(request); System.debug(response.getBody()); /* The JSON response returned is the following: String s = '{"invoiceList":[' + '{"totalPrice":5.5,"statementDate":"2011-10-04T16:58:54.858Z","lineItems":[' + '{"UnitPrice":1.0,"Quantity":5.0,"ProductName":"Pencil"},' + '{"UnitPrice":0.5,"Quantity":1.0,"ProductName":"Eraser"}],' + '"invoiceNumber":1},' + '{"totalPrice":11.5,"statementDate":"2011-10-04T16:58:54.858Z","lineItems":[' + '{"UnitPrice":6.0,"Quantity":1.0,"ProductName":"Notebook"},' + '{"UnitPrice":2.5,"Quantity":1.0,"ProductName":"Ruler"},' + '{"UnitPrice":1.5,"Quantity":2.0,"ProductName":"Pen"}],"invoiceNumber":2}' + ']}'; */ // Parse JSON response to get all the totalPrice field values. JSONParser parser = JSON.createParser(response.getBody()); Double grandTotal = 0.0; while (parser.nextToken() != null) { if ((parser.getCurrentToken() == JSONToken.FIELD_NAME) && (parser.getText() == 'totalPrice')) { // Get the value. parser.nextToken(); // Compute the grand total price for all invoices. grandTotal += parser.getDoubleValue(); } } system.debug('Grand total=' + grandTotal); } }
public static void parseJSONString() { String jsonStr = '{"invoiceList":[' + '{"totalPrice":5.5,"statementDate":"2011-10-04T16:58:54.858Z","lineItems":[' + '{"UnitPrice":1.0,"Quantity":5.0,"ProductName":"Pencil"},' + '{"UnitPrice":0.5,"Quantity":1.0,"ProductName":"Eraser"}],' + '"invoiceNumber":1},' + '{"totalPrice":11.5,"statementDate":"2011-10-04T16:58:54.858Z","lineItems":[' + '{"UnitPrice":6.0,"Quantity":1.0,"ProductName":"Notebook"},' + '{"UnitPrice":2.5,"Quantity":1.0,"ProductName":"Ruler"},' + '{"UnitPrice":1.5,"Quantity":2.0,"ProductName":"Pen"}],"invoiceNumber":2}' + ']}'; // Parse entire JSON response. JSONParser parser = JSON.createParser(jsonStr); while (parser.nextToken() != null) { // Start at the array of invoices. if (parser.getCurrentToken() == JSONToken.START_ARRAY) { while (parser.nextToken() != null) { // Advance to the start object marker to // find next invoice statement object. if (parser.getCurrentToken() == JSONToken.START_OBJECT) { // Read entire invoice object, including its array of line items. Invoice inv = (Invoice)parser.readValueAs(Invoice.class); system.debug('Invoice number: ' + inv.invoiceNumber); system.debug('Size of list items: ' + inv.lineItems.size()); // For debugging purposes, serialize again to verify what was parsed. String s = JSON.serialize(inv); system.debug('Serialized invoice: ' + s); // Skip the child start array and start object markers. parser.skipChildren(); } } } } } // Inner classes used for serialization by readValuesAs(). public class Invoice { public Double totalPrice; public DateTime statementDate; public Long invoiceNumber; List<LineItem> lineItems; public Invoice(Double price, DateTime dt, Long invNumber, List<LineItem> liList) { totalPrice = price; statementDate = dt; invoiceNumber = invNumber; lineItems = liList.clone(); } } public class LineItem { public Double unitPrice; public Double quantity; public String productName; }