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Java Gson-fromJson反序列化泛型

java json generics

Java Gson-fromJson反序列化泛型,java,json,generics,gson,deserialization,Java,Json,Generics,Gson,Deserialization,在Android应用程序上工作时，我遇到了一个问题，当时我想创建一个最终的通用方法来发送HTTP请求（使用loopj）并反序列化它们（使用Gson） 您可能知道，在使用gson.fromJson时，您不能这样做： gson.fromJson(responseBody, new TypeToken<T>() {}.getType()); gson.fromJson（responseBody，newTypeToken（）{}.getType（））； 或 gson.fromJson（r

在Android应用程序上工作时，我遇到了一个问题，当时我想创建一个最终的通用方法来发送HTTP请求（使用loopj）并反序列化它们（使用Gson）

您可能知道，在使用gson.fromJson时，您不能这样做：

gson.fromJson(responseBody, new TypeToken<T>() {}.getType());

gson.fromJson（responseBody，newTypeToken（）{}.getType（））；
或

gson.fromJson（responseBody，新类型令牌




将JSON对象反序列化为泛型java对象


public <T> void getObject(String url, HashMap<String, String> paramsMap, final GetObjectCallback<T> callback) {
    RequestParams params = convertParams(paramsMap);
    client.get(url, params, new TextHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseBody) {
            try {
                Class cl = getTypeClassOfInterfaceObject(callback);
                T object = gson.fromJson(responseBody, new Element<T>(cl));
                if (object != null) {
                    callback.onSuccess(object);
                } else {
                    callback.onFailure();
                }
            } catch (Exception e) {
                e.printStackTrace();
                callback.onFailure();
            }
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseBody, Throwable error) {
            error.printStackTrace();
            callback.onFailure();
        }
    });
}

private RequestParams convertParams(HashMap<String, String> paramsMap) {
    RequestParams params = new RequestParams();
    if (paramsMap != null) {
        for (String key : paramsMap.keySet()) {
            params.put(key, paramsMap.get(key));
        }
    }
    return params;
}

public interface GetObjectCallback<T> {
    void onSuccess(T item);
    void onFailure();
}



public <T> void getList(String url, HashMap<String, String> paramsMap, final GetListCallback<T> callback) {
    RequestParams params = convertParams(paramsMap);
    client.get(url, params, new TextHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseBody) {
            try {
                Class cl = getTypeClassOfInterfaceObject(callback);
                List<T> list  = gson.fromJson(responseBody, new ListWithElements<T>(cl));
                if (list != null) {
                    callback.onSuccess(list);
                } else {
                    callback.onFailure();
                }
            } catch (Exception e) {
                e.printStackTrace();
                callback.onFailure();
            }
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseBody, Throwable error) {
            error.printStackTrace();
            callback.onFailure();
        }
    });
}

public interface GetListCallback<T> {
    void onSuccess(List<T> list);
    void onFailure();
}



api.getObject(URL, paramsMap, new GetObjectCallback<NewsItem>() {
    @Override
    public void onSuccess(NewsItem item) {
        // do something
    }

    @Override
    public void onFailure() {
        // do something
    }
});



api.getList(URL, paramsMap, new GetListCallback<Comment>() {
    @Override
    public void onSuccess(List<Comment> list) {
        // do something
    }

    @Override
    public void onFailure() {
        // do something
    }
});


首先，我们需要得到泛型类型
T
的实际类

我们可以通过传递类本身（
class cl
）或通过从泛型类型的对象（
SomeObject-someObjectWithGenericType
）获取类来实现

然后我们需要创建一个class
Element
的特殊对象，它将告诉Gson使用哪个类进行反序列化


public <T> T getObject(String json, SomeObject<T> someObjectWithGenericType) {
    Class cl = getTypeClassOfObject(someObjWithGenericType);
    T object = gson.fromJson(json, new Element<T>(cl));
    return object;
}

private Class getTypeClassOfObject(Object obj) {
    return (Class) ((ParameterizedType) obj.getClass().getGenericSuperclass()).getActualTypeArguments()[0];
}

private class Element<T> implements ParameterizedType {

    private Class<T> cl;

    public Element(Class<T> cl) {
        this.cl = cl;
    }

    public Type[] getActualTypeArguments() {
        return new Type[] {cl};
    }

    public Type getRawType() {
        return cl;
    }

    public Type getOwnerType() {
        return null;
    }
}



将JSON数组反序列化为泛型java对象列表

同样的想法，但我们有一个不同的特殊类来帮助Gson进行反序列化：


public <T> List<T> getList(String json, SomeObject<T> someObjectWithGenericType) {
    Class cl = getTypeClassOfObject(someObjWithGenericType);
    List<T> list = gson.fromJson(json, new ListWithElements<T>(cl));
    return list;
}

private class ListWithElements<T> implements ParameterizedType {

    private Class<T> elementsClass;

    public ListWithElements(Class<T> elementsClass) {
        this.elementsClass = elementsClass;
    }

    public Type[] getActualTypeArguments() {
        return new Type[] {elementsClass};
    }

    public Type getRawType() {
        return List.class;
    }

    public Type getOwnerType() {
        return null;
    }
}


loopj+Gson与泛型：列表


public <T> void getObject(String url, HashMap<String, String> paramsMap, final GetObjectCallback<T> callback) {
    RequestParams params = convertParams(paramsMap);
    client.get(url, params, new TextHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseBody) {
            try {
                Class cl = getTypeClassOfInterfaceObject(callback);
                T object = gson.fromJson(responseBody, new Element<T>(cl));
                if (object != null) {
                    callback.onSuccess(object);
                } else {
                    callback.onFailure();
                }
            } catch (Exception e) {
                e.printStackTrace();
                callback.onFailure();
            }
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseBody, Throwable error) {
            error.printStackTrace();
            callback.onFailure();
        }
    });
}

private RequestParams convertParams(HashMap<String, String> paramsMap) {
    RequestParams params = new RequestParams();
    if (paramsMap != null) {
        for (String key : paramsMap.keySet()) {
            params.put(key, paramsMap.get(key));
        }
    }
    return params;
}

public interface GetObjectCallback<T> {
    void onSuccess(T item);
    void onFailure();
}



public <T> void getList(String url, HashMap<String, String> paramsMap, final GetListCallback<T> callback) {
    RequestParams params = convertParams(paramsMap);
    client.get(url, params, new TextHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseBody) {
            try {
                Class cl = getTypeClassOfInterfaceObject(callback);
                List<T> list  = gson.fromJson(responseBody, new ListWithElements<T>(cl));
                if (list != null) {
                    callback.onSuccess(list);
                } else {
                    callback.onFailure();
                }
            } catch (Exception e) {
                e.printStackTrace();
                callback.onFailure();
            }
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseBody, Throwable error) {
            error.printStackTrace();
            callback.onFailure();
        }
    });
}

public interface GetListCallback<T> {
    void onSuccess(List<T> list);
    void onFailure();
}



api.getObject(URL, paramsMap, new GetObjectCallback<NewsItem>() {
    @Override
    public void onSuccess(NewsItem item) {
        // do something
    }

    @Override
    public void onFailure() {
        // do something
    }
});



api.getList(URL, paramsMap, new GetListCallback<Comment>() {
    @Override
    public void onSuccess(List<Comment> list) {
        // do something
    }

    @Override
    public void onFailure() {
        // do something
    }
});



public void getList（字符串url、HashMap参数映射、最终GetListCallback回调）{
RequestParams-params=convertParams（paramsMap）；
get（url、参数、新文本HttpResponseHandler（）{
@凌驾
成功时公共void（int statusCode，Header[]headers，String responseBody）{
试一试{
类cl=getTypeClassOfInterfaceObject（回调）；
List List=gson.fromJson（responseBody，newlistwithelements（cl））；
如果（列表！=null）{
callback.onSuccess（列表）；
}否则{
callback.onFailure（）；
}
}捕获（例外e）{
e、 printStackTrace（）；
callback.onFailure（）；
}
}
@凌驾
public void onFailure（int statusCode，Header[]headers，String responseBody，Throwable error）{
错误。printStackTrace（）；
callback.onFailure（）；
}
});
}
公共接口GetListCallback{
成功时作废（列表）；
失效时无效（）；
}


用法：对象


public <T> void getObject(String url, HashMap<String, String> paramsMap, final GetObjectCallback<T> callback) {
    RequestParams params = convertParams(paramsMap);
    client.get(url, params, new TextHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseBody) {
            try {
                Class cl = getTypeClassOfInterfaceObject(callback);
                T object = gson.fromJson(responseBody, new Element<T>(cl));
                if (object != null) {
                    callback.onSuccess(object);
                } else {
                    callback.onFailure();
                }
            } catch (Exception e) {
                e.printStackTrace();
                callback.onFailure();
            }
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseBody, Throwable error) {
            error.printStackTrace();
            callback.onFailure();
        }
    });
}

private RequestParams convertParams(HashMap<String, String> paramsMap) {
    RequestParams params = new RequestParams();
    if (paramsMap != null) {
        for (String key : paramsMap.keySet()) {
            params.put(key, paramsMap.get(key));
        }
    }
    return params;
}

public interface GetObjectCallback<T> {
    void onSuccess(T item);
    void onFailure();
}



public <T> void getList(String url, HashMap<String, String> paramsMap, final GetListCallback<T> callback) {
    RequestParams params = convertParams(paramsMap);
    client.get(url, params, new TextHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseBody) {
            try {
                Class cl = getTypeClassOfInterfaceObject(callback);
                List<T> list  = gson.fromJson(responseBody, new ListWithElements<T>(cl));
                if (list != null) {
                    callback.onSuccess(list);
                } else {
                    callback.onFailure();
                }
            } catch (Exception e) {
                e.printStackTrace();
                callback.onFailure();
            }
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseBody, Throwable error) {
            error.printStackTrace();
            callback.onFailure();
        }
    });
}

public interface GetListCallback<T> {
    void onSuccess(List<T> list);
    void onFailure();
}



api.getObject(URL, paramsMap, new GetObjectCallback<NewsItem>() {
    @Override
    public void onSuccess(NewsItem item) {
        // do something
    }

    @Override
    public void onFailure() {
        // do something
    }
});



api.getList(URL, paramsMap, new GetListCallback<Comment>() {
    @Override
    public void onSuccess(List<Comment> list) {
        // do something
    }

    @Override
    public void onFailure() {
        // do something
    }
});



api.getObject（URL、paramsMap、新的GetObjectCallback（）{
@凌驾
成功时公共无效（新闻项）{
//做点什么
}
@凌驾
公共失效（）{
//做点什么
}
});


用法：列表


public <T> void getObject(String url, HashMap<String, String> paramsMap, final GetObjectCallback<T> callback) {
    RequestParams params = convertParams(paramsMap);
    client.get(url, params, new TextHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseBody) {
            try {
                Class cl = getTypeClassOfInterfaceObject(callback);
                T object = gson.fromJson(responseBody, new Element<T>(cl));
                if (object != null) {
                    callback.onSuccess(object);
                } else {
                    callback.onFailure();
                }
            } catch (Exception e) {
                e.printStackTrace();
                callback.onFailure();
            }
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseBody, Throwable error) {
            error.printStackTrace();
            callback.onFailure();
        }
    });
}

private RequestParams convertParams(HashMap<String, String> paramsMap) {
    RequestParams params = new RequestParams();
    if (paramsMap != null) {
        for (String key : paramsMap.keySet()) {
            params.put(key, paramsMap.get(key));
        }
    }
    return params;
}

public interface GetObjectCallback<T> {
    void onSuccess(T item);
    void onFailure();
}



public <T> void getList(String url, HashMap<String, String> paramsMap, final GetListCallback<T> callback) {
    RequestParams params = convertParams(paramsMap);
    client.get(url, params, new TextHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseBody) {
            try {
                Class cl = getTypeClassOfInterfaceObject(callback);
                List<T> list  = gson.fromJson(responseBody, new ListWithElements<T>(cl));
                if (list != null) {
                    callback.onSuccess(list);
                } else {
                    callback.onFailure();
                }
            } catch (Exception e) {
                e.printStackTrace();
                callback.onFailure();
            }
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseBody, Throwable error) {
            error.printStackTrace();
            callback.onFailure();
        }
    });
}

public interface GetListCallback<T> {
    void onSuccess(List<T> list);
    void onFailure();
}



api.getObject(URL, paramsMap, new GetObjectCallback<NewsItem>() {
    @Override
    public void onSuccess(NewsItem item) {
        // do something
    }

    @Override
    public void onFailure() {
        // do something
    }
});



api.getList(URL, paramsMap, new GetListCallback<Comment>() {
    @Override
    public void onSuccess(List<Comment> list) {
        // do something
    }

    @Override
    public void onFailure() {
        // do something
    }
});



api.getList（URL、paramsMap、new GetListCallback（）{
@凌驾
成功时公开作废（列表）{
//做点什么
}
@凌驾
公共失效（）{
//做点什么
}
});


欢迎任何改进