在Retrofit网络请求数据，使用泛型解析json时，出现了com.google.gson.internal.LinkedTreeMap cannot be cast to com.xylife.community.bean.Exercise的异常，折腾了好久总算解决了。
先看下异常log：

java.lang.ClassCastException: com.google.gson.internal.LinkedTreeMap cannot be cast to com.xylife.community.bean.Exercise
at com.xylife.community.adapter.ExerciseListAdapter.onBindViewHolder(ExerciseListAdapter.java:36)
at jp.wasabeef.recyclerview.adapters.AnimationAdapter.onBindViewHolder(AnimationAdapter.java:54)
at com.cundong.recyclerview.HeaderAndFooterRecyclerViewAdapter.onBindViewHolder(HeaderAndFooterRecyclerViewAdapter.java:258)
at android.support.v7.widget.RecyclerView Adapter.onBindViewHolder(RecyclerView.java:5471)atandroid.support.v7.widget.RecyclerView <script type="math/tex" id="MathJax-Element-1">Adapter.onBindViewHolder(RecyclerView.java:5471) at android.support.v7.widget.RecyclerView</script>Adapter.bindViewHolder(RecyclerView.java:5504)
at android.support.v7.widget.RecyclerView Recycler.getViewForPosition(RecyclerView.java:4741)atandroid.support.v7.widget.RecyclerView <script type="math/tex" id="MathJax-Element-2">Recycler.getViewForPosition(RecyclerView.java:4741) at android.support.v7.widget.RecyclerView</script>Recycler.getViewForPosition(RecyclerView.java:4617)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1994)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1390)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1353)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:574)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3028)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2906)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3283)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1077)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1695)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15718)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15718)
at android.view.ViewG

下面我们分析下。

先看json数据。

{
    "state": "1001",
    "resut": {
        "data": {
            "total": "9",
            "list": [
                {
                    "name": "微博",
                    "desc": "本地相机即拍即传，随时随地分享身边新鲜事",
                    "size": "36.58M",
                    "icon": "http://p18.qhimg.com/t0194819784f6b3224b.png",
                    "url": "http://shouji.360tpcdn.com/150723/de6fd89a346e304f66535b6d97907563/com.sina.weibo_2057.apk"
                },
                {
                    "name": "开心消消乐",
                    "desc": "宇宙超人气三消休闲游戏“开心消消乐”",
                    "size": "55.49M",
                    "icon": "http://p17.qhimg.com/t01f9c104ccb2614350.png",
                    "url": "http://shouji.360tpcdn.com/150707/2ef5e16e0b8b3135aa714ad9b56b9a3d/com.happyelements.AndroidAnimal_25.apk"
                }
            ]
        }
    }
}

这里要感谢有心课堂的stay4it给我写的测试接口（虽然我们不熟），如果你幸运，还能打开链接：http://api.stay4it.com/test/jdsjlzx.php

这里不再讲解Retrofit和RxJava的知识，有需要请看扔物线大神的讲解：http://gank.io/post/560e15be2dca930e00da1083

Retrofit快速入门：http://blog.csdn.net/jdsjlzx/article/details/51354778

先看个简单的根据json数据来创建一个Response数据对象：

public class Response<T> {

    public boolean isSuccess() {
        return state == 1001;
    }


    public int total;
    public int state;
    public String reason;
    public T result;
}

根据http://api.stay4it.com/test/jdsjlzx.php接口返回的json数据，我们写出如下数据对象：

public class ListResponse<T> extends HttpResponse {

    public ListEntity resut;

    public class ListEntity{
        public Data data;
    }

    public class Data<T>{
        public int total;
        public List<T> list;
    }

}

HttpResponse代码

public class HttpResponse{

    public boolean isSuccess() {
        return state == 1001;
    }

    public int state;
}

调试中就毫不留情的抛出了异常。

查找资料，找各种办法。

---

问题没有解决之前，还找到了篇好文章：
Java泛型让声明方法返回子类型

---

不经意的那么一瞬间，有个念头闪过脑海，赶紧试了下，没有想到解决了问题。

快来看看吧。

public class ListResponse<T> extends HttpResponse {

    public ListEntity<T> resut;

    public class ListEntity<T>{
        public Data<T> data;
    }

    public class Data<T>{
        public int total;
        public List<T> list;
    }

}

写到这里已经是深夜23：52了，当解决问题的那一刻顿时有种如释重负的感觉。。。。

分享知识，希望这个思路能够帮助其他人！

至于泛型为什么非要那么写才能解决问题，我还没有理解到位，如果有高人知道请指教！

如果你是Java编程，上面的思路如果不行，请参考：http://www.ways2u.com/?post=535