从Java类生成JSON示例 [英] Generate JSON sample from Java class
本文介绍了从Java类生成JSON示例的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
如何使用Java类定义中的伪数据生成JSON示例? (注意:我并不是在问如何从POJO生成JSON.这是在stackoverflow上问过的.)
How can you generate a JSON sample with dummy data from a Java class definition? (Note: I am not asking about generating JSON from a POJO. This is something that has been asked before on stackoverflow).
我想要的是直接从Java类生成一些示例虚拟数据.例如，您有一个像这样的班级:
What I want is to generate some sample dummy data from a Java class directly. For example you have a class like this one:
public class Reservation {
@ApiModelProperty(value = "")
private Traveller leadTraveller = null;
@ApiModelProperty(example = "2", value = "")
private Integer sourceSystemID = null;
@ApiModelProperty(value = "")
private String recordLocation = null;
@ApiModelProperty(example = "2010", value = "")
private Integer recordLocatorYear = null;
}
然后您有一个函数，该函数无需创建POJO即可生成具有伪值的JSON字符串，例如:
And then you have a function which generates without creating a POJO a JSON string with dummy values like:
{
"leadTraveller": {
"firstNames": "firstNames",
"lastName": "lastName",
"email": "email",
"travellerGUID": "travellerGUID",
"travellerRefs": [{
"customerReportingRank": 37,
"value": "value",
"description": "description"
}]
},
"sourceSystemID": 38,
"recordLocation": "recordLocation",
"recordLocatorYear": 9
}
默认情况下是否存在可以执行此操作的库?
Is there a library which can do this by default?
我尝试使用具有以下Maven依赖项的Java代码解决此问题:
I have tried to solve this problem using Java code with these Maven dependencies:
<dependency>
<groupId>fctg-ngrp</groupId>
<artifactId>model-core</artifactId>
<version>1.0.4-SNAPSHOT-MODEL-CORE</version>
</dependency>
<dependency>
<groupId>io.vavr</groupId>
<artifactId>vavr</artifactId>
<version>0.9.2</version>
<scope>test</scope>
</dependency>
Jackson主要用于验证和格式化输出JSON.
Jackson is mainly used for verifying and formatting the output JSON.
下面是我使用的Java代码:
Below is the Java code I used:
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.io.Files;
import io.vavr.API;
import io.vavr.collection.Array;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.math.BigDecimal;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.OffsetDateTime;
import java.time.format.DateTimeFormatter;
import java.util.*;
import java.util.stream.Collectors;
/**
* Sample utility for generating dummy JSON sample code from a JAva class directly.
*/
public class GenerateJSONFromClasses {
private static final Random R = new Random();
/**
* Used to avoid infinite loops.
*/
private static final Map<Class<?>, Integer> visited = new HashMap<>();
private static final ObjectMapper mapper = new ObjectMapper();
public static void main(String[] args) throws IOException {
Class<Reservation> clazz = Reservation.class;
generateDummyJSON(clazz, args);
}
public static void generateDummyJSON(Class<Reservation> clazz, String... paths) throws IOException {
StringWriter out = new StringWriter();
try (PrintWriter writer = new PrintWriter(out)) {
writer.println(printObj(clazz));
JsonNode jsonNode = mapper.readTree(out.toString());
String prettyJson = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(jsonNode);
if (paths == null || paths.length == 0) {
System.out.println(prettyJson);
} else {
Array.of(paths).map(sPath -> Paths.get(sPath))
.map(Path::toFile)
.map(API.unchecked(file -> {
Files.write(prettyJson, file, StandardCharsets.UTF_8);
return file;
}));
}
}
}
private static String printObj(Class<?> clazz) {
if (!visited.containsKey(clazz) || visited.get(clazz) <= 1) {
visited.merge(clazz, 1, (integer, integer2) -> integer + integer2);
Field[] declaredFields = clazz.getDeclaredFields();
return "{" +
Array.of(declaredFields).map(field -> String.format(" \"%s\" : %s%n", field.getName(), printFieldValue(field)))
.collect(Collectors.joining(String.format(",%n"))) +
"}";
}
return "";
}
private static Object printFieldValue(Field field) {
Class<?> fieldType = field.getType();
if (String.class.equals(fieldType)) {
return String.format("\"%s\"", field.getName());
} else if (Integer.class.equals(fieldType)) {
return R.nextInt(99) + 1;
} else if (LocalDate.class.equals(fieldType)) {
return String.format("\"%s\"", LocalDate.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
} else if (LocalDateTime.class.equals(fieldType)) {
return String.format("\"%s\"", LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss")));
} else if (OffsetDateTime.class.equals(fieldType)) {
return String.format("\"%s\"", LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss")));
} else if (Date.class.equals(fieldType)) {
return System.currentTimeMillis();
} else if (List.class.equals(fieldType)) {
ParameterizedType parameterizedType = (ParameterizedType) field.getGenericType();
Class<?> clazz = (Class<?>) parameterizedType.getActualTypeArguments()[0];
return String.format("[%s]", printObj(clazz));
} else if (fieldType.isAssignableFrom(Number.class)) {
return R.nextDouble() * 10.0;
} else if (BigDecimal.class.equals(fieldType)) {
return new BigDecimal(R.nextDouble() * 10.0);
} else if (Boolean.class.equals(fieldType)) {
return R.nextBoolean();
} else {
return printObj(fieldType);
}
}
}
推荐答案
感谢@ gil.fernandes， 我已经对您的代码进行了少量修改.
thanks @gil.fernandes, I have used your code with small modifications.
1)多次允许相同类型，但将访问数保持为100，以防止无限循环.我以为您的用例不一样.
1) allow the same type multiple times but keep visited count to 100 to prevent infinite loops. I supposed your use case was different.
2)添加了java.util.Date和Enum.
2) added java.util.Date and Enum.
3)打印伪值作为类的简单名称.对于枚举，请打印出字符串of"及其值列表.
3) print dummy values as the simple name of the class. In the case of enum print out "String of " and a list of its values.
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.io.Files;
import com.jnj.na.webmethods.core.dto.MaterialWsDTO;
import io.vavr.API;
import io.vavr.collection.Array;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.math.BigDecimal;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.OffsetDateTime;
import java.util.*;
import java.util.stream.Collectors;
/**
* Sample utility for generating dummy JSON sample code from a JAva class directly.
*/
public class GenerateJSONFromClasses {
/**
* Used to avoid infinite loops.
*/
private static final Map<Class<?>, Integer> visited = new HashMap<>();
private static final ObjectMapper mapper = new ObjectMapper();
public static void main(String[] args) throws IOException {
Class<MaterialWsDTO> clazz = MaterialWsDTO.class;
generateDummyJSON(clazz, args);
}
public static void generateDummyJSON(Class<MaterialWsDTO> clazz, String... paths) throws IOException {
StringWriter out = new StringWriter();
try (PrintWriter writer = new PrintWriter(out)) {
writer.println(printObj(clazz));
JsonNode jsonNode = mapper.readTree(out.toString());
String prettyJson = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(jsonNode);
if (paths == null || paths.length == 0) {
System.out.println(prettyJson);
} else {
Array.of(paths).map(sPath -> Paths.get(sPath))
.map(Path::toFile)
.map(API.unchecked(file -> {
Files.write(prettyJson, file, StandardCharsets.UTF_8);
return file;
}));
}
}
}
private static String printObj(Class<?> clazz) {
if (!visited.containsKey(clazz) || visited.get(clazz) <= 100) {
visited.merge(clazz, 1, (integer, integer2) -> integer + integer2);
Field[] declaredFields = clazz.getDeclaredFields();
return "{" +
Array.of(declaredFields)
.filterNot(e->Modifier.isStatic(e.getModifiers()))
.map(field -> String.format(" \"%s\" : %s%n", field.getName(), printFieldValue(field)))
.collect(Collectors.joining(String.format(",%n"))) +
"}";
}
return "";
}
private static Object printFieldValue(Field field) {
Class<?> fieldType = field.getType();
if (String.class.equals(fieldType)) {
return name(fieldType);
} else if (Integer.class.equals(fieldType)) {
return name(fieldType);
} else if (Enum.class.isAssignableFrom(fieldType)) {
return printEnum(fieldType);
} else if (Double.class.equals(fieldType)) {
return name(fieldType);
} else if (LocalDate.class.equals(fieldType)) {
return name(fieldType);
} else if (LocalDateTime.class.equals(fieldType)) {
return name(fieldType);
} else if (OffsetDateTime.class.equals(fieldType)) {
return name(fieldType);
} else if (Date.class.equals(fieldType)) {
return name(fieldType);
} else if (List.class.equals(fieldType)) {
ParameterizedType parameterizedType = (ParameterizedType) field.getGenericType();
Class<?> clazz = (Class<?>) parameterizedType.getActualTypeArguments()[0];
return String.format("[%s]", printObj(clazz));
} else if (fieldType.isAssignableFrom(Number.class)) {
return name(fieldType);
} else if (BigDecimal.class.equals(fieldType)) {
return name(fieldType);
} else if (Boolean.class.equals(fieldType)) {
return name(fieldType);
} else {
return printObj(fieldType);
}
}
private static String printEnum(Class<?> fieldType) {
Field[] declaredFields = fieldType.getDeclaredFields();
return "\"String of " + Arrays.stream(declaredFields)
.filter(field -> field.getType()==fieldType)
.map(Field::getName)
.collect(Collectors.joining(",")) +
"\"";
}
private static Object name(Class<?> fieldType) {
return "\""+fieldType.getSimpleName()+"\"";
}
}
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