Android-Gson使用

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在日常的Android开发当中，我们肯定少不了要使用Gson框架解析JSON字符串。这篇博客分享一下我了解到Gson框架的知识，希望对看文章的小伙伴有所帮助。
Gson的依赖
implementation 'com.google.code.gson:gson:2.9.0'
这里需要注意的是：
Gson2.9.0最低适配Java7，如果想要是用Java6及其以下的版本要使用Gson2.8.9。

使用Gson开发的时候，我推荐一个工具类：

package com.blankj.utilcode.util;

import android.text.TextUtils;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;

import java.io.Reader;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import androidx.annotation.NonNull;


/**
 * 
 *     author: Blankj
 *     blog  : http://blankj.com
 *     time  : 2018/04/05
 *     desc  : utils about gson
 * 
 */

public final class GsonUtils {
    private static final String KEY_DEFAULT   = "defaultGson";

    private static final String KEY_DELEGATE  = "delegateGson";

    private static final String KEY_LOG_UTILS = "logUtilsGson";
    private static final Map GSONS = new ConcurrentHashMap<>();
    private GsonUtils() {

        throw new UnsupportedOperationException("u can't instantiate me...");

    }
    /**

     * Set the delegate of {@link Gson}.

     *

     * @param delegate The delegate of {@link Gson}.

     */

    public static void setGsonDelegate(Gson delegate) {

        if (delegate == null) return;

        GSONS.put(KEY_DELEGATE, delegate);

    }
    /**

     * Set the {@link Gson} with key.

     *

     * @param key  The key.

     * @param gson The {@link Gson}.

     */

    public static void setGson(final String key, final Gson gson) {

        if (TextUtils.isEmpty(key) || gson == null) return;

        GSONS.put(key, gson);

    }
    /**

     * Return the {@link Gson} with key.

     *

     * @param key The key.

     * @return the {@link Gson} with key

     */

    public static Gson getGson(final String key) {

        return GSONS.get(key);

    }
    public static Gson getGson() {

        Gson gsonDelegate = GSONS.get(KEY_DELEGATE);

        if (gsonDelegate != null) {

            return gsonDelegate;

        }

        Gson gsonDefault = GSONS.get(KEY_DEFAULT);

        if (gsonDefault == null) {

            gsonDefault = createGson();

            GSONS.put(KEY_DEFAULT, gsonDefault);

        }

        return gsonDefault;

    }
    /**

     * Serializes an object into json.

     *

     * @param object The object to serialize.

     * @return object serialized into json.

     */

    public static String toJson(final Object object) {

        return toJson(getGson(), object);

    }
    /**

     * Serializes an object into json.

     *

     * @param src       The object to serialize.

     * @param typeOfSrc The specific genericized type of src.

     * @return object serialized into json.

     */

    public static String toJson(final Object src, @NonNull final Type typeOfSrc) {

        return toJson(getGson(), src, typeOfSrc);

    }
    /**

     * Serializes an object into json.

     *

     * @param gson   The gson.

     * @param object The object to serialize.

     * @return object serialized into json.

     */

    public static String toJson(@NonNull final Gson gson, final Object object) {

        return gson.toJson(object);

    }
    /**

     * Serializes an object into json.

     *

     * @param gson      The gson.

     * @param src       The object to serialize.

     * @param typeOfSrc The specific genericized type of src.

     * @return object serialized into json.

     */

    public static String toJson(@NonNull final Gson gson, final Object src, @NonNull final Type typeOfSrc) {

        return gson.toJson(src, typeOfSrc);

    }
    /**

     * Converts {@link String} to given type.

     *

     * @param json The json to convert.

     * @param type Type json will be converted to.

     * @return instance of type

     */

    public static  T fromJson(final String json, @NonNull final Class type) {

        return fromJson(getGson(), json, type);

    }
    /**

     * Converts {@link String} to given type.

     *

     * @param json the json to convert.

     * @param type type type json will be converted to.

     * @return instance of type

     */

    public static  T fromJson(final String json, @NonNull final Type type) {

        return fromJson(getGson(), json, type);

    }
    /**

     * Converts {@link Reader} to given type.

     *

     * @param reader the reader to convert.

     * @param type   type type json will be converted to.

     * @return instance of type

     */

    public static  T fromJson(@NonNull final Reader reader, @NonNull final Class type) {

        return fromJson(getGson(), reader, type);

    }
    /**

     * Converts {@link Reader} to given type.

     *

     * @param reader the reader to convert.

     * @param type   type type json will be converted to.

     * @return instance of type

     */

    public static  T fromJson(@NonNull final Reader reader, @NonNull final Type type) {

        return fromJson(getGson(), reader, type);

    }
    /**

     * Converts {@link String} to given type.

     *

     * @param gson The gson.

     * @param json The json to convert.

     * @param type Type json will be converted to.

     * @return instance of type

     */

    public static  T fromJson(@NonNull final Gson gson, final String json, @NonNull final Class type) {

        return gson.fromJson(json, type);

    }
    /**

     * Converts {@link String} to given type.

     *

     * @param gson The gson.

     * @param json the json to convert.

     * @param type type type json will be converted to.

     * @return instance of type

     */

    public static  T fromJson(@NonNull final Gson gson, final String json, @NonNull final Type type) {

        return gson.fromJson(json, type);

    }
    /**

     * Converts {@link Reader} to given type.

     *

     * @param gson   The gson.

     * @param reader the reader to convert.

     * @param type   type type json will be converted to.

     * @return instance of type

     */

    public static  T fromJson(@NonNull final Gson gson, final Reader reader, @NonNull final Class type) {

        return gson.fromJson(reader, type);

    }
    /**

     * Converts {@link Reader} to given type.

     *

     * @param gson   The gson.

     * @param reader the reader to convert.

     * @param type   type type json will be converted to.

     * @return instance of type

     */

    public static  T fromJson(@NonNull final Gson gson, final Reader reader, @NonNull final Type type) {

        return gson.fromJson(reader, type);

    }
    /**

     * Return the type of {@link List} with the {@code type}.

     *

     * @param type The type.

     * @return the type of {@link List} with the {@code type}

     */

    public static Type getListType(@NonNull final Type type) {

        return TypeToken.getParameterized(List.class, type).getType();

    }
    /**

     * Return the type of {@link Set} with the {@code type}.

     *

     * @param type The type.

     * @return the type of {@link Set} with the {@code type}

     */

    public static Type getSetType(@NonNull final Type type) {

        return TypeToken.getParameterized(Set.class, type).getType();

    }
    /**

     * Return the type of map with the {@code keyType} and {@code valueType}.

     *

     * @param keyType   The type of key.

     * @param valueType The type of value.

     * @return the type of map with the {@code keyType} and {@code valueType}

     */

    public static Type getMapType(@NonNull final Type keyType, @NonNull final Type valueType) {

        return TypeToken.getParameterized(Map.class, keyType, valueType).getType();

    }
    /**

     * Return the type of array with the {@code type}.

     *

     * @param type The type.

     * @return the type of map with the {@code type}

     */

    public static Type getArrayType(@NonNull final Type type) {

        return TypeToken.getArray(type).getType();

    }
    /**

     * Return the type of {@code rawType} with the {@code typeArguments}.

     *

     * @param rawType       The raw type.

     * @param typeArguments The type of arguments.

     * @return the type of map with the {@code type}

     */

    public static Type getType(@NonNull final Type rawType, @NonNull final Type... typeArguments) {

        return TypeToken.getParameterized(rawType, typeArguments).getType();

    }
    static Gson getGson4LogUtils() {

        Gson gson4LogUtils = GSONS.get(KEY_LOG_UTILS);

        if (gson4LogUtils == null) {

            gson4LogUtils = new GsonBuilder().setPrettyPrinting().serializeNulls().create();

            GSONS.put(KEY_LOG_UTILS, gson4LogUtils);

        }

        return gson4LogUtils;

    }
    private static Gson createGson() {

        return new GsonBuilder().serializeNulls().disableHtmlEscaping().create();

    }

}


这个Gson工具类来源于AndroidUtilCode工具类开源库，主要实现了一下几种功能呢：

设置代理对象：setGsonDelegate();
设置Gson对象：setGson();
获取Gson对象：getGson();
对账转Json字符串：toJson()，这个方法常用于服务器请求使用Json传递参数；
Json转对象：fromJson();
获取链表类型：getListType();
获取集合类型：getSetType();
获取字典类型：getMapType();
获取数组类型：getArrayType();
获取类型：getType()。