在 apex 中解析 json

Question

您好，我创建了一个 RESTful Web 服务，它以以下格式返回响应：

[
{"empId":1,"empName":"A"},
{"empId":2,"empName":"B"},
{"empId":3,"empName":"C"},
{"empId":4,"empName":"D"},
{"empId":5,"empName":"E"}
]

我已经编写了简单的 visualforce 页面来在按钮单击操作上调用名为“lookup”的方法。我的 Apex 课程如下所示。

public class REST {
  public PageReference lookup()
  {
    string resp;

    // Note this version of the API is only for the US
    string endpoint ='http://localhost:8080/RESTfulExample/rest/json/metallica/get';

    HttpRequest req = new HttpRequest();
    HttpResponse res = new HttpResponse();
    Http http = new Http();
    req.setMethod('GET');
    req.setEndpoint(endpoint);

    try {
      res = http.send(req);
    } catch (Exception e) {
      system.debug(LoggingLevel.Error, 'Error HTTP response code = '+res.getStatusCode()+'; calling '+endpoint );
      return null;
    }

    resp = res.getBody();
    JSONParser parser = JSON.createParser(resp);

    // Parsing The JSON & set the list of values to the variables 'empid' & 'empname'

    return null;
  }
}

谁能帮助我如何使用 JSON 解析器来解析 JSON 并将值存储到变量中。

谢谢你！！！

Answer 1

如果您想使用 JSONParser，这里是 Salesforce 文档中关于 JSONParser(https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_json_jsonparser.htm) 的示例：

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);
    }   
}

尽管从您在问题中所说的内容来看，我认为进行 JSON 反序列化会更简单。

下面是一个例子：

包装类

public class EmployeeWrapper {
    public Integer empId {get;set;}
    public String empName {get;set;}
}

JSON 反序列化

String jsonContent = '[{"empId": 1,"empName": "A"}, {"empId": 2,"empName": "B"}, {"empId": 3,"empName": "C"}, {"empId": 4,"empName": "D"}, {"empId": 5,"empName": "E"}]';
List<EmployeeWrapper> employeeWrapperList = (List<EmployeeWrapper>)JSON.deserialize(jsonContent, List<EmployeeWrapper>.class);
System.debug(employeeWrapperList);
//Do actions to WrapperList