这可能是一个重复的问题..请参阅此
link.
我能够将一个json对象映射到POJO.But如何使用相同的jackson框架将json对象的数组转换为pojo.
我能够将一个json对象映射到POJO.But如何使用相同的jackson框架将json对象的数组转换为pojo.
private void jsonToPojo(){
ObjectMapper mapper=new ObjectMapper();
try {
User1 user1=mapper.readValue(readFromFile(),User1.class);
User1[] user2=mapper.readValue(readFromFile(),User1[].class);
System.out.println(user1);
Toast.makeText(getApplicationContext(),"inside try",0).show();
} catch (JsonParseException e) {
// TODO Auto-generated catch block
Log.i("Exception","jsonparseexception");
e.printStackTrace();
} catch (JsonMappingException e) {
// TODO Auto-generated catch block
Log.i("Exception","jsonmapping exception");
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
Log.i("Exception","ioexception");
e.printStackTrace();
}
}
这是类用户对象.
public class User {
private int age = 23;
private String name = "amal";
private List<String> messages = new ArrayList<String>() {
{
add("hi");
add("how");
add("are u.");
}
};
//getter and setter methods
@Override
public String toString() {
return "User [age=" + age + ",name=" + name + "," +
"messages=" + messages + "]";
}
这是我试图做的：(readFromFile()从文件中获取json)
User1[] user2=mapper.readValue(readFromFile(),User1[].class);
jsonToPojo()仅适用于一个对象.但是,如果我尝试上面的代码行,它不会采取以下json：
[
{
"age":"23","messages":["hi","how","are u."],"name":"amal"
},{
"age":"98","messages":["Reply","my","question"],"name":"You"
}
]
解决方法
尝试这样的事情：
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
User a = new User(23,"amal");
ArrayList<String> message = new ArrayList<String>();
message.add("m1");
message.add("m2");
a.setMessages(message);
User b = new User(58,"pete");
User[] ab = new User[] {a,b};
ObjectMapper mapper = new ObjectMapper();
try {
String s1 = getJson1(a);
System.out.println(s1);
User user1 = mapper.readValue(s1,User.class);
System.out.println(user1);
System.out.println("----------------");
String s2 = getJson2(ab);
System.out.println(s2);
User[] user2 = mapper.readValue(s2,User[].class);
for (User u : user2)
System.out.println(u);
} catch (Exception e) {
e.printStackTrace();
}
}
private static String getJson1(User user) throws JsonProcessingException {
ObjectMapper mapper = new ObjectMapper();
return mapper.writeValueAsString(user);
}
private static String getJson2(User[] ab) throws JsonProcessingException {
ObjectMapper mapper = new ObjectMapper();
return mapper.writeValueAsString(ab);
}
}
public class User {
private int age;
private String name;
private ArrayList<String> messages;
public User() {
super();
}
public User(int age,String name) {
this();
this.age = age;
this.name = name;
}
// ****************
// Getter & Setter ....
// ****************
}
你会得到这个输出：
{"age":23,"name":"amal","messages":["m1","m2"]}
User [age=23,name=amal,messages=[m1,m2]]
----------------
[{"age":23,"m2"]},{"age":58,"name":"pete","messages":null}]
User [age=23,m2]]
User [age=58,name=pete,messages=null]
