如何在java中获取类的字段名

大家好抱歉我的语言不好

这是我的代码：

MyCustomClass temp = new MyCustomClass();
for (int i = 0; i < jsonarray.length(); i++) {
    JSONObject obj = jsonarray.getJSONObject(i);
    temp.ID = obj.getInt("ID");
    temp.PicName = obj.getString("PicName");
    temp.PicURL = obj.getString("PicURL");
    Items.add(temp);
}

MyCustomClass temp=新的MyCustomClass（）；
for（int i=0；i

我想采取这种动态

像这样的

MyCustomClass temp = new MyCustomClass();
Field[] myFields= MyCustomClass.class.getFields();
for (int i = 0; i < jsonarray.length(); i++) {
    JSONObject obj = jsonarray.getJSONObject(i);
    for(int j=0;j<myFields.lenghth();j++)
    {
        myFields[j]=obj.getString(myFields[j].toString());
        Items.add(temp);
    }
}

MyCustomClass temp=新的MyCustomClass（）；
字段[]myFields=MyCustomClass.class.getFields（）；
for（int i=0；i对于（int j=0；j您可以使用此结构获得所有类字段：

Class class = ...//obtain class object
Field[] methods = class.getFields();

在你的课堂上：

MyCustomClass temp = new MyCustomClass();
Field[] methods = temp.getFields();

使用jackson库，您可以直接使用json注释设置POJO，并且可以将json字符串直接转换为java对象

解析的一般方法可以是这样的：

public static <T> T deserialize(T t, Class<T> clazz, String json) throws JsonParseException, JsonMappingException, IOException{
        ObjectMapper mapper = new ObjectMapper();
        return mapper.readValue(json, clazz);
    }

MyCustomClass myCustomClass= new MyCustomClass();
myCustomClass= JsonUtil.deserialize(myCustomClass, MyCustomClass.class, json);

@JsonIgnoreProperties // ignores properties from json String which are not in your Pojo
public class MyCustomClass {

    @JsonProperty("anotherNameIfFieldNameIsNotEqual")
    private String picName;
    private String picURL;

    public String getPicName() {
        return picName;
    }
    public void setPicName(String picName) {
        this.picName = picName;
    }
    public String getPicURL() {
        return picURL;
    }
    public void setPicURL(String picURL) {
        this.picURL= picURL;
    }
}

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.6.3</version>
</dependency>

您的Pojo可以如下所示：

public static <T> T deserialize(T t, Class<T> clazz, String json) throws JsonParseException, JsonMappingException, IOException{
        ObjectMapper mapper = new ObjectMapper();
        return mapper.readValue(json, clazz);
    }

MyCustomClass myCustomClass= new MyCustomClass();
myCustomClass= JsonUtil.deserialize(myCustomClass, MyCustomClass.class, json);

@JsonIgnoreProperties // ignores properties from json String which are not in your Pojo
public class MyCustomClass {

    @JsonProperty("anotherNameIfFieldNameIsNotEqual")
    private String picName;
    private String picURL;

    public String getPicName() {
        return picName;
    }
    public void setPicName(String picName) {
        this.picName = picName;
    }
    public String getPicURL() {
        return picURL;
    }
    public void setPicURL(String picURL) {
        this.picURL= picURL;
    }
}

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.6.3</version>
</dependency>

这就是您需要的maven依赖关系：

public static <T> T deserialize(T t, Class<T> clazz, String json) throws JsonParseException, JsonMappingException, IOException{
        ObjectMapper mapper = new ObjectMapper();
        return mapper.readValue(json, clazz);
    }

MyCustomClass myCustomClass= new MyCustomClass();
myCustomClass= JsonUtil.deserialize(myCustomClass, MyCustomClass.class, json);

@JsonIgnoreProperties // ignores properties from json String which are not in your Pojo
public class MyCustomClass {

    @JsonProperty("anotherNameIfFieldNameIsNotEqual")
    private String picName;
    private String picURL;

    public String getPicName() {
        return picName;
    }
    public void setPicName(String picName) {
        this.picName = picName;
    }
    public String getPicURL() {
        return picURL;
    }
    public void setPicURL(String picURL) {
        this.picURL= picURL;
    }
}

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.6.3</version>
</dependency>


com.fasterxml.jackson.core
和
并将为您完成所有这些

static class TestClass {
    public int id;
    public String name;
}

@Test
public void gson() {
    Gson gson = new Gson();
    TestClass[] item = gson.fromJson("[{'id': 1, 'name': 'testclass'}]", TestClass[].class);
    assertThat(item[0].id, is(1));
    assertThat(item[0].name, is("testclass"));
    assertThat(item.length, is(1));
}

@Test
public void jackson() throws IOException {
    ObjectMapper jacksonObjectMapepr = new ObjectMapper();
    TestClass[] item = jacksonObjectMapepr.readValue("[{\"id\": 1, \"name\": \"testclass\"}]", TestClass[].class);
    assertThat(item[0].id, is(1));
    assertThat(item[0].name, is("testclass"));
    assertThat(item.length, is(1));
}

然而，为了回答您的问题，您可以查找每个字段的内容，但是您必须做大量的工作来处理所有类型映射

@Test
public void sillyWayIDontRecommend() throws NoSuchFieldException, IllegalAccessException {
    TestClass[] item = new TestClass[1];

    JsonArray array = new JsonParser().parse("[{\"id\": 1, \"name\": \"testclass\"}]").getAsJsonArray();
    for(int i = 0; i<array.size(); i++) {
        item[i] = new TestClass();

        JsonObject object = array.get(i).getAsJsonObject();
        for(Map.Entry<String, JsonElement> entry : object.entrySet()) {
            Field field = TestClass.class.getDeclaredField(entry.getKey());
            if(field.getType().equals(int.class)) {
                field.setInt(item[i], entry.getValue().getAsInt());
            } else {
                field.set(item[i], entry.getValue().getAsString());
            }
        }
    }

    assertThat(item[0].id, is(1));
    assertThat(item[0].name, is("testclass"));
    assertThat(item.length, is(1));
}

@测试
public void sillyWayIDontRecommend（）不会引发此字段异常、非法访问异常{
TestClass[]项=新的TestClass[1]；
JsonArray数组=新的JsonParser（）.parse（“[{\'id\'：1，\'name\'：\'testclass\'}]”）。getAsJsonArray（）；
对于（int i=0；i您可以使用
Gson
库而不是
json simple
Gson
可以将json字符串转换为Java对象，另一种方法是使用类似
jackson
的json库吗？有了jackson，您可以用注释设置
MyCustomClass
Pojo，以及应该解析哪些字段。您是否需要这些答案对你有帮助吗？