gson使用教程-翻譯5

原文地址:http://www.studytrails.com/java/json/java-google-json-serialize-inner-classes.jsp
Gson可以解析內部類和靜態內部類.下面的demo中給我們展示了以下的內容:
- 序列化包含靜態內部類的類
- 序列化包含內部類的類
- 反序列化json爲一個包含靜態內部類和內部類的類
- 序列化靜態內部類(不是封閉類型)
- 序列化非靜態內部類(不是封閉類型)
- 反序列化json爲一個靜態內部類(不是封閉類型)
- 反序列化json爲一個非靜態內部類((不是封閉類型))

Demo:

package com.studytrails.json.gson;

import java.lang.reflect.Modifier;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.studytrails.json.gson.AlbumsWithInnerClass.Dataset;
import com.studytrails.json.gson.AlbumsWithInnerClass.Dataset2;

public class SerializeInnerClassExample4 {
    public static void main(String[] args) {
        // 添加數據
        AlbumsWithInnerClass albums = new AlbumsWithInnerClass();
        albums.setName("SerializeInnerClass");
        albums.setYear("1988");

        Dataset dataset = albums.new Dataset();
        dataset.setAlbum_id("1");
        dataset.setAlbum_name("albums1");
        albums.setDatasetsInner(new Dataset[] { dataset });

        Dataset2 dataset2 = new Dataset2();
        dataset2.setAlbum_id("2");
        dataset2.setAlbum_name("albums2");
        albums.setDatasetsStatic(new Dataset2[] { dataset2 });

        // create the GsonBuilder把對象轉換成對應的json
        GsonBuilder builder = new GsonBuilder();
        // we ignore Private fields 忽略掉private修飾的字段
        builder.excludeFieldsWithModifiers(Modifier.PRIVATE);
        Gson gson = builder.create();
        // serialize the albums object
        String json = gson.toJson(albums);
        System.out.println(json);
        // 打印的結果：
        // {"name":"SerializeInnerClass","datasetsInner":[{"album_name":"SerializeInnerClass_albums1","album_id":"1"}],
        // "datasetsStatic":[{"album_name":"albums2","album_id":"2"}]}

        // We read the json string now and recreate the AlbumsWithInnerClass
        // class反序列化上面生成的json
        Gson gson3 = new Gson();
        AlbumsWithInnerClass parsedAlbums = gson3.fromJson(json,
                AlbumsWithInnerClass.class);
        System.out.println(parsedAlbums.datasetsInner[0].album_name);
        // 打印的結果：SerializeInnerClass_albums1
        System.out.println(parsedAlbums.datasetsStatic[0].album_name);
        // 打印的結果：albums2

        // now lets try and serialize only the object of inner class 僅僅序列化內部類
        Gson gson2 = new Gson();
        String json2 = gson2.toJson(dataset);
        System.out.println(json2);
        // 打印的結果： {"album_name":"SerializeInnerClass_albums1","album_id":"1"}

        // serialize nested static class序列化靜態內部類
        String json3 = gson2.toJson(dataset2);
        System.out.println(json3);
        // 打印的結果： {"album_name":"albums2","album_id":"2"}

        // let us now create the inner class from the json string反序列化內部類
        Gson gson4 = new Gson();
        Dataset parsedDataset = gson4.fromJson(json2, Dataset.class);
        System.out.println(parsedDataset.getClass());
        // 打印的結果： class com.studytrails.json.gson.AlbumsWithInnerClass$Dataset
        System.out.println(parsedDataset.album_name);
        // 打印的結果：SerializeInnerClass_albums1

        // create nested static class from the json string反序列化靜態內部類
        Dataset2 parsedStaticNestedClass = gson4
                .fromJson(json3, Dataset2.class);
        System.out.println(parsedStaticNestedClass.getClass());
        // 打印的結果： class com.studytrails.json.gson.AlbumsWithInnerClass$Dataset2
        System.out.println(parsedStaticNestedClass.album_name);
        // 打印的結果： albums2
     }
}

AlbumsWithInnerClass類的代碼

package com.studytrails.json.gson;
public class AlbumsWithInnerClass {
    public String name;
    private String year;
    public Dataset[] datasetsInner;
    public Dataset2[] datasetsStatic;

    public void setDatasetsInner(Dataset[] datasetsInner) {
        this.datasetsInner = datasetsInner;
    }

    public void setDatasetsStatic(Dataset2[] datasetsStatic) {
        this.datasetsStatic = datasetsStatic;
    }

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

    public void setYear(String year) {
        this.year = year;
    }

    class Dataset {
        public String album_name;
        public String album_id;

        public void setAlbum_id(String album_id) {
            this.album_id = album_id;
        }

        public void setAlbum_name(String album_name) {
            this.album_name = name + "_" + album_name;
        }
    }

    static class Dataset2 {
        public String album_name;
        public String album_id;

        public void setAlbum_id(String album_id) {
            this.album_id = album_id;
        }

        public void setAlbum_name(String album_name) {
            this.album_name = album_name;
        }
    }
}