fragment-实例创建跟使用

今天接触到了fragment，在网上看到了它的使用方法。现在把它的创建跟使用记录下，方便以后查询。

1.创建一个自己的fragment，继承自fragment

package com.android.calculator2;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ListView;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;

public class HistoryFragment extends Fragment {
    private View mView;
    private ListView mListView;
    private Button mClearHistoryBtn;
    private Button mBackCalculatorBtn;
    private HistoryAdapter mHistoryAdapter;
    private Animation myAnimationIn;
    private Animation myAnimationOut;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        mView = inflater.inflate(R.layout.history_display, container, false);
        myAnimationIn = AnimationUtils.loadAnimation(getActivity(), R.anim.history_fragment_in_anim);
        myAnimationOut = AnimationUtils.loadAnimation(getActivity(),R.anim.history_fragment_out_anim);
        myAnimationIn.setFillAfter(true);
        myAnimationOut.setFillAfter(true);
        if (mView != null) {
            mView.startAnimation(myAnimationIn);
            mClearHistoryBtn = (Button) mView.findViewById(R.id.history_clear);
            mBackCalculatorBtn = (Button) mView.findViewById(R.id.history_back);
            mListView = (ListView) mView.findViewById(R.id.history_list);
            if (getActivity() instanceof HistoryClickListener) {
                mHistoryAdapter = ((HistoryClickListener) getActivity()).getHistoryAdapter();
            }
            mListView.setAdapter(mHistoryAdapter);
            mBackCalculatorBtn.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View arg0) {
                    if (getActivity() instanceof HistoryClickListener) {
                        ((HistoryClickListener) getActivity()).historyClickHide();
                    }   

             }
            });
            mClearHistoryBtn.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View arg0) {
                        // TODO Auto-generated method stub
                    if (getActivity() instanceof HistoryClickListener) {
                        ((HistoryClickListener) getActivity()).historyClickClear();
                    }

                }
            });

            return mView;
        } else {
            return super.onCreateView(inflater, container, savedInstanceState);
        }

    }

    public interface HistoryClickListener {
            void historyClickHide();
            void historyClickClear();
            HistoryAdapter getHistoryAdapter();
    }
    @Override
    public void onDestroyView() {
        if (mView != null) {
            mView.startAnimation(myAnimationOut);
        }
        super.onDestroyView();
    }
}

然后在代码中使用

                FragmentManager mHistoryFm = getFragmentManager();
                FragmentTransaction mHistoryTx = mHistoryFm.beginTransaction();
                mHistoryTx.replace(R.id.frame_layout, mHistoryFragment, "history");
                mHistoryTx.addToBackStack(null);
                mHistoryTx.commit();

它的使用也很简单。只需要创建，然后在activity中加载到一个布局里面就行了。

有以下几点需要注意

1.你必须在activity的xml中分配一个布局容器给你的fragment，就是方法里面的

mHistoryTx.replace(R.id.frame_layout, mHistoryFragment, "history");

R.id.frame_layout

2.如果你想移除一个fragment，你必须拥有这个fragment的实例，也就是

mHistoryTx.replace(R.id.frame_layout, mHistoryFragment, "history");
mHistoryTx.remove( mHistoryFragment);

上面的两个mHistoryFragment是同一个实例

3.尽量让fragment中事件的处理，交给activity来处理。常用的方法就是

在fragment想要实现的操作，定义为一个接口，然后在activity中实现这个接口

定义接口

    public interface HistoryClickListener {
            void historyClickHide();
            void historyClickClear();
            HistoryAdapter getHistoryAdapter();
    }

实现接口

public class Calculator extends Activity implements Logic.Listener, HistoryClickListener{

    @Override
    public void historyClickHide() {
        android.util.Log.e("zhangshuli", "mmmm");
        FragmentManager mHistoryFm = getFragmentManager();
        FragmentTransaction mHistoryTx = mHistoryFm.beginTransaction();
        mHistoryTx.remove(mHistoryFragment);
        mHistoryTx.commit();
    }

    @Override
    public void historyClickClear() {
        android.util.Log.e("zhangshuli", "nnnn");
        mHistory.clear();
        mLogic.onClear();
    }

    @Override
    public HistoryAdapter getHistoryAdapter() {
        return mAdapter;
    }

}

在fragment中回调activity中的方法

if (getActivity() instanceof HistoryClickListener) {
       ((HistoryClickListener) getActivity()).historyClickClear();
}