用Jackson进行Java JSON解析 [英] Java JSON parsing with Jackson

问题描述

我正在尝试通过这里的玩具示例来了解Jackson的知识，以进行JSON解析: http://wiki.fasterxml.com/JacksonInFiveMinutes

I'm trying to get the hang of Jackson for JSON parsing by going through the toy examples here: http://wiki.fasterxml.com/JacksonInFiveMinutes

JSON:

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

我在使用原始"数据绑定片段时遇到了麻烦:

I'm having trouble with the "Raw" Data Binding snippets:

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

名称"处的值为{first = Joe，last = Sixpack}.当然，原始数据绑定可以处理嵌套的JSON对象，但是我不知道如何访问first和last的值.我在做什么错了?

The value at "name" is {first=Joe, last=Sixpack}. Surely the raw data binding can handle nested JSON objects, but I can't figure out how to access the value of first and last. What am I doing wrong?

推荐答案

我知道已经很晚了，但这就是我的方法.请参见下面.

I know it's late but This is how I did it. Please see below.

MainClass.java =

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 =

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 =

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;
} }

结果:- 乔 Sixpack 男性 错误的 Rm9vYmFyIQ ==

RESULT:- Joe Sixpack MALE false Rm9vYmFyIQ==

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