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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;
/**
* <pre>
* author: Blankj
* blog : http://blankj.com
* time : 2018/04/05
* desc : utils about gson
* </pre>
*/
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<String, Gson> 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> T fromJson(final String json, @NonNull final Class<T> 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> 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> T fromJson(@NonNull final Reader reader, @NonNull final Class<T> 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> 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> T fromJson(@NonNull final Gson gson, final String json, @NonNull final Class<T> 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> 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> T fromJson(@NonNull final Gson gson, final Reader reader, @NonNull final Class<T> 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> 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()。
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