Java 如何将POJO转换为JSON,反之亦然?
我想知道是否有Java API可用于将POJO对象转换为JSON对象,反之亦然 [已编辑] 假设您有这样一个简单的Java类:Java 如何将POJO转换为JSON,反之亦然?,java,json,pojo,Java,Json,Pojo,我想知道是否有Java API可用于将POJO对象转换为JSON对象,反之亦然 [已编辑] 假设您有这样一个简单的Java类: public class Person { private String name; private Integer age; public String getName() { return this.name; } public void setName( String name ) { this.name = name; }
public class Person {
private String name;
private Integer age;
public String getName() { return this.name; }
public void setName( String name ) { this.name = name; }
public Integer getAge() { return this.age; }
public void setAge( Integer age ) { this.age = age; }
}
因此,将其转换为JSon对象非常简单。像这样:
import org.json.JSONObject;
public class JsonTest {
public static void main( String[] args ) {
Person person = new Person();
person.setName( "Person Name" );
person.setAge( 333 );
JSONObject jsonObj = new JSONObject( person );
System.out.println( jsonObj );
}
}
希望能有帮助
[已编辑]
这里还有另一个例子,在本例中使用Jackson:
马文:
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.6.1</version>
</dependency>
com.fasterxml.jackson.core
我们还可以在pom文件中使用下面给定的依赖项和插件-我使用maven。通过使用这些,您可以根据JSON模式生成POJO,然后使用下面给出的代码通过指定为gson.toJson(object src)参数的src对象填充请求JSON对象,反之亦然。请看下面的代码:
Gson gson = new GsonBuilder().create();
String payloadStr = gson.toJson(data.getMerchant().getStakeholder_list());
Gson gson2 = new Gson();
Error expectederr = gson2.fromJson(payloadStr, Error.class);
以及Maven设置:
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>1.7.1</version>
</dependency>
<plugin>
<groupId>com.googlecode.jsonschema2pojo</groupId>
<artifactId>jsonschema2pojo-maven-plugin</artifactId>
<version>0.3.7</version>
<configuration>
<sourceDirectory>${basedir}/src/main/resources/schema</sourceDirectory>
<targetPackage>com.example.types</targetPackage>
</configuration>
<executions>
<execution>
<phase>generate-sources</phase>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
</plugin>
com.google.code.gson
格森
1.7.1
com.googlecode.jsonschema2pojo
jsonschema2pojo maven插件
0.3.7
${basedir}/src/main/resources/schema
com.example.types
生成源
生成
如果您了解《杰克逊2》,在上有一个关于如何将Java对象转换为JSON以及如何将Java对象转换为JSON的精彩教程。以下代码片段取自该教程
将Java对象转换为JSON,writeValue(…)
:
ObjectMapper mapper = new ObjectMapper();
Staff obj = new Staff();
//Object to JSON in file
mapper.writeValue(new File("c:\\file.json"), obj);
//Object to JSON in String
String jsonInString = mapper.writeValueAsString(obj);
ObjectMapper mapper = new ObjectMapper();
String jsonInString = "{'name' : 'mkyong'}";
//JSON from file to Object
Staff obj = mapper.readValue(new File("c:\\file.json"), Staff.class);
//JSON from URL to Object
Staff obj = mapper.readValue(new URL("http://mkyong.com/api/staff.json"), Staff.class);
//JSON from String to Object
Staff obj = mapper.readValue(jsonInString, Staff.class);
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.6.3</version>
</dependency>
将JSON转换为Java对象,readValue(…)
:
ObjectMapper mapper = new ObjectMapper();
Staff obj = new Staff();
//Object to JSON in file
mapper.writeValue(new File("c:\\file.json"), obj);
//Object to JSON in String
String jsonInString = mapper.writeValueAsString(obj);
ObjectMapper mapper = new ObjectMapper();
String jsonInString = "{'name' : 'mkyong'}";
//JSON from file to Object
Staff obj = mapper.readValue(new File("c:\\file.json"), Staff.class);
//JSON from URL to Object
Staff obj = mapper.readValue(new URL("http://mkyong.com/api/staff.json"), Staff.class);
//JSON from String to Object
Staff obj = mapper.readValue(jsonInString, Staff.class);
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.6.3</version>
</dependency>
Jackson 2依赖项:
ObjectMapper mapper = new ObjectMapper();
Staff obj = new Staff();
//Object to JSON in file
mapper.writeValue(new File("c:\\file.json"), obj);
//Object to JSON in String
String jsonInString = mapper.writeValueAsString(obj);
ObjectMapper mapper = new ObjectMapper();
String jsonInString = "{'name' : 'mkyong'}";
//JSON from file to Object
Staff obj = mapper.readValue(new File("c:\\file.json"), Staff.class);
//JSON from URL to Object
Staff obj = mapper.readValue(new URL("http://mkyong.com/api/staff.json"), Staff.class);
//JSON from String to Object
Staff obj = mapper.readValue(jsonInString, Staff.class);
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.6.3</version>
</dependency>
com.fasterxml.jackson.core
杰克逊数据绑定
2.6.3
有关完整教程,请转到上面给出的链接。使用GSON将POJO转换为JSONObject
要将JSONObject转换为POJO,只需在POJO中调用setter方法,并直接从JSONObject分配值。您可以使用jackson api进行转换
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.4</version>
</dependency>
稍后,我们需要将POJO类添加到映射器中
String json = mapper.writeValueAsString(pojo);
使用下面的引用将JSON转换为POJO,反之亦然
假设您的JSON模式如下所示:
{
"type":"object",
"properties": {
"dataOne": {
"type": "string"
},
"dataTwo": {
"type": "integer"
},
"dataThree": {
"type": "boolean"
}
}
}
然后,要转换为POJO,您需要按照下面的风格解释一些类:
==================================
package ;
public class DataOne
{
private String type;
public void setType(String type){
this.type = type;
}
public String getType(){
return this.type;
}
}
==================================
package ;
public class DataTwo
{
private String type;
public void setType(String type){
this.type = type;
}
public String getType(){
return this.type;
}
}
==================================
package ;
public class DataThree
{
private String type;
public void setType(String type){
this.type = type;
}
public String getType(){
return this.type;
}
}
==================================
package ;
public class Properties
{
private DataOne dataOne;
private DataTwo dataTwo;
private DataThree dataThree;
public void setDataOne(DataOne dataOne){
this.dataOne = dataOne;
}
public DataOne getDataOne(){
return this.dataOne;
}
public void setDataTwo(DataTwo dataTwo){
this.dataTwo = dataTwo;
}
public DataTwo getDataTwo(){
return this.dataTwo;
}
public void setDataThree(DataThree dataThree){
this.dataThree = dataThree;
}
public DataThree getDataThree(){
return this.dataThree;
}
}
==================================
package ;
public class Root
{
private String type;
private Properties properties;
public void setType(String type){
this.type = type;
}
public String getType(){
return this.type;
}
public void setProperties(Properties properties){
this.properties = properties;
}
public Properties getProperties(){
return this.properties;
}
}
Thnx但是。。。我想知道,如果我得到一个Pojo,我可以传递Pojo对象,这样库就可以构造JSON对象。。。格森能做到吗?你能给我举个例子吗?thnx alot@Bruno我们如何使用这个JSONObject获取List或Set的值。我喜欢这种方法——不幸的是,它对我不起作用。我收到错误消息:“构造函数JSONObject(Person)未定义”。。知道为什么吗?我用一些Android代码调用它。。它是纯Java。Thanks@gnB:即使我也会遇到同样的错误,我想如果你在安卓系统中尝试,那么它指的是。所以试着创建一个