用Jackson進行Java JSON解析

Question

我正在嘗試通過此處的玩具示例來了解Jackson的知識，以進行JSON解析： http : //wiki.fasterxml.com/JacksonInFiveMinutes

JSON：

{
  "name" : { "first" : "Joe", "last" : "Sixpack" },
  "gender" : "MALE",
  "verified" : false,
  "userImage" : "Rm9vYmFyIQ=="
}

我在使用“原始”數據綁定片段時遇到了麻煩：

1 ObjectMapper mapper = new ObjectMapper(); // can reuse, share globally
2 Map<String,Object> userData = mapper.readValue(new File("user.json"), Map.class);

“名稱”上的值為{first = Joe，last = Sixpack}。 當然，原始數據綁定可以處理嵌套的JSON對象，但是我不知道如何訪問first和last的值。 我究竟做錯了什么？

Answer 1

我知道已經晚了，但是這就是我的方法。 請看下面。

MainClass.java =

import java.io.IOException;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

 public class MainClass {

public static void main(String[] args) throws JsonParseException, JsonMappingException, IOException {

    String jsonStr = "{\r\n" + "  \"name\" : { \"first\" : \"Joe\", \"last\" : \"Sixpack\" },\r\n"
            + "  \"gender\" : \"MALE\",\r\n" + "  \"verified\" : false,\r\n"
            + "  \"userImage\" : \"Rm9vYmFyIQ==\"\r\n" + "}";

    ObjectMapper mapper = new ObjectMapper();

    EntityClass jsonObj = mapper.readValue(jsonStr, EntityClass.class);

    System.out.println(jsonObj.getName().getFirst());
    System.out.println(jsonObj.getName().getLast());
    System.out.println(jsonObj.getGender());
    System.out.println(jsonObj.getVerified());
    System.out.println(jsonObj.getUserImage() + "\n");

}

}

EntityClass.java =

  public class EntityClass
  {
          private String verified;

private Name name;

private String userImage;

private String gender;

public String getVerified ()
{
    return verified;
}

public void setVerified (String verified)
{
    this.verified = verified;
}

public Name getName ()
{
    return name;
}

public void setName (Name name)
{
    this.name = name;
}

public String getUserImage ()
{
    return userImage;
}

public void setUserImage (String userImage)
{
    this.userImage = userImage;
}

public String getGender ()
{
    return gender;
}

public void setGender (String gender)
{
    this.gender = gender;
}

@Override
public String toString()
{
    return "ClassPojo [verified = "+verified+", name = "+name+", userImage = "+userImage+", gender = "+gender+"]";
}

}

Name.java =

  public class Name {
private String last;

private String first;

public String getLast() {
    return last;
}

public void setLast(String last) {
    this.last = last;
}

@Override
public String toString() {
    return "Name [last=" + last + ", first=" + first + "]";
}

public String getFirst() {
    return first;
}

public void setFirst(String first) {
    this.first = first;
} }

結果：-Joe Sixpack男假Rm9vYmFyIQ ==