Question

我从代码中得到以下输出： {＆＃34;列表＆＃34;：[{＆＃34; X＆＃34;：＆＃34; Y＆＃34;}，{＆＃34;＆＃34;：＆＃34; B＆＃34;} ]}

相反，我希望得到输出 [{＆＃34; X＆＃34;：＆＃34; Y＆＃34;}，{＆＃34;＆＃34;：＆＃34; B＆＃34;}]

代码如下。

public class Test {
List<Map> list = new ArrayList();
public static void main(String [] args){
    Test t = new Test();

    Map m1 = new HashMap();
    m1.put("x","y");
    t.list.add(m1);

    Map m2 = new HashMap();
    m2.put("a","b");
    t.list.add(m2);

    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.setSerializationInclusion(Include.NON_EMPTY);
    objectMapper.setVisibility(PropertyAccessor.FIELD, Visibility.NON_PRIVATE);
    Writer writer = new StringWriter();
    try {
        objectMapper.writeValue(writer, t);
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
    System.out.println("The json is:\n"+writer.toString());
  }
 }

更新此问题 - 使其更上一层楼给我：

{＆＃34;列表＆＃34;：[{＆＃34;映射＆＃34; {＆＃34; X＆＃34;：＆＃34; Y＆＃34;＆＃34; X 1＆＃34 ;：＆＃34; Y 1＆＃34;}}，{＆＃34;映射＆＃34; {＆＃34; A1＆＃34;：＆＃34; B1＆＃34;＆＃34;＆＃34; ：＆＃34; b＆＃34;}}]}

我想要{{＆＃34; x＆＃34;：＆＃34; y＆＃34;，＆＃34; x1＆＃34;：＆＃34; y1＆＃34;}，{＆＃ 34; A1＆＃34;：＆＃34; B1＆＃34;＆＃34;＆＃34;：＆＃34; b＆＃34;}]

 public class Test {
public class Car{
    Map map = new HashMap();
}
List<Car> list = new ArrayList();
public static void main(String [] args){
    Test t = new Test();

    Test.Car car = t.new Car();
    Map m1 = new HashMap();
    m1.put("x","y");
    m1.put("x1","y1");
    car.map = m1;
    t.list.add(car);

    car = t.new Car();
    Map m2 = new HashMap();
    m2.put("a","b");
    m2.put("a1","b1");
    car.map = m2;
    t.list.add(car);

    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.setSerializationInclusion(Include.NON_EMPTY);
    objectMapper.setVisibility(PropertyAccessor.FIELD, Visibility.NON_PRIVATE);
    Writer writer = new StringWriter();
    try {
        objectMapper.writeValue(writer, t);
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
    System.out.println("The json is:\n"+writer.toString());
}
 }

Answer 1

您可能希望使用@JsonValue注释，其文档说明：

类似于XmlValue的标记注释，表示带注释的“getter”方法的结果（这意味着签名必须是getter的结果;非void返回类型，没有args）将被用作序列化的单个值。实例。通常，value将是一个简单的标量类型（String或Number），但它可以是任何可序列化的类型（Collection，Map或Bean）。

这是一个有效的例子：

public class Test {
    public static class Car {
        Map map = new HashMap();

        @JsonValue
        public Map getMap() {
            return map;
        }
    }

    List<Car> list = new ArrayList();

    @JsonValue
    public List<Car> getList() {
        return list;
    }

    public static void main(String[] args) throws IOException {
        Test t = new Test();

        Car car = new Car();
        Map m1 = new HashMap();
        m1.put("x", "y");
        m1.put("x1", "y1");
        car.map = m1;
        t.list.add(car);

        car = new Car();
        Map m2 = new HashMap();
        m2.put("a", "b");
        m2.put("a1", "b1");
        car.map = m2;
        t.list.add(car);

        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
        Writer writer = new StringWriter();

        objectMapper.writeValue(writer, t);
        System.out.println("The json is:\n" + writer.toString());
    }
}

Answer 2

我实现了import com.fasterxml.jackson.databind.JsonSerializable;在Car class上做了以下几点。

  private void downloadImage(String urlStr) {
        progressDialog = ProgressDialog.show(this, "", "Downloading CSV file from " + urlStr);
        final String url = urlStr;
        Intent intent = new Intent(getApplicationContext(), ChartScreen.class);
        final ArrayList resultList = new ArrayList();
       Thread downloadImage = new Thread() {
            public void run() {
                InputStream in = null;
                Message msg = Message.obtain();
                msg.what = 1;
                try {
                    in = openHttpConnection(url);
                    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                    try {
                        String csvLine;
                        while ((csvLine = reader.readLine()) != null) {
                            String[] row = csvLine.split(",");
                            resultList.add(row);
                        }
                    }catch (IOException ex) {
                        throw new RuntimeException("Error in reading CSV file: "+ex);
                    }finally {
                            in.close();
                   }
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
        }.start();
      downloadImage.join();
   **//**Start activity with a new task flag or you will get error****
        Bundle b = new Bundle();
        b.putParcelableArrayList("Data", resultList);
        intent.putExtras(b);
        progressDialog.dismiss();
        startActivity(intent);
    }





     Bundle b = new Bundle();
        b.putParcelableArrayList("Data", resultList);
        intent.putExtras(b);
        progressDialog.dismiss();
        startActivity(intent);

这删除了map关键字。我不能像上面的代码库一样使用JsonValue我不允许在Map上使用getter而JsonValue不适用于非公共字段。（或者我无法使它工作）

如何忽略变量名但序列化值 - jackson fasterxml

2 个答案: