继承SwipeRefreshLayout实现上拉刷新

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对了，我就通过这篇文章写出这个上拉刷新的，非常感谢他，但是我还是要吐槽一下，因为他里面有个问题并没有提及怎么解决，addFooterView()在setAdapter()后调用无法显示的问题，后面我自己也有写错一个，出现问题，文末我会提示注意事项，下面请看我如何写。

基本逻辑就是：

触摸滚动时，滚动到最后一条数据时，显示底部加载条，并加载数据，数据加载完成隐藏底部加载条

一开始当然是要获取自定义布局所嵌套的子控件，即嵌套的listView嘛，因为要需要addFooterView()嘛

1
if (listView==null) {//这里listview是一个全局变量
2
      if (getChildCount()>0) {
3
        for (int i = 0; i < getChildCount(); i++) {
4
          if (getChildAt(i) instanceof ListView) {
5
            listView=(ListView) getChildAt(i);
6
            Log.i(CustomSwipeRefreshLayout, "找到了LIstView");
7
            initLoadLayout();//初始化加载控件
8
            setListViewOnScroll();//滚动监听
9
            break;
10
          }else {
11
            Log.i(CustomSwipeRefreshLayout, "不是LIstView的实例");
12
          }
13
        }
14
        Log.i(CustomSwipeRefreshLayout, "LIstView是否为空："+(listView==null));
15
      }
16
    }

底部刷新的View，我是自己用java写，这样有个好处，下次要用直接一个类拷走，代码看起来好像有点多，其实很简单

1
  /**
2
   * 初始化底部加载视图
3
   */
4
  private void initLoadLayout() {
5
    //布局，由于父控件是ListView，所以 LayoutParams 是AbsListView的LayoutParams
6
    AbsListView.LayoutParams listLayoutParams =new AbsListView.LayoutParams(listView.getLayoutParams());
7
    listLayoutParams.width=LayoutParams.MATCH_PARENT;
8
    listLayoutParams.height=100;
9
    loadLayout=new LinearLayout(context);//这里是一个全局变量哦，初始化这个，其他地方就可以用了
10
    loadLayout.setOrientation(LinearLayout.HORIZONTAL);
11
    loadLayout.setLayoutParams(listLayoutParams);
12
    loadLayout.setGravity(Gravity.CENTER_HORIZONTAL);
13
    //dialog
14
    android.view.ViewGroup.LayoutParams layoutParams =new android.view.ViewGroup.LayoutParams(android.view.ViewGroup.LayoutParams.WRAP_CONTENT, android.view.ViewGroup.LayoutParams.MATCH_PARENT);
15
    ProgressBar progressBar=new ProgressBar(context,null,android.R.attr.progressBarStyleInverse);
16
    progressBar.setLayoutParams(layoutParams);
17
    //textview
18
    android.view.ViewGroup.LayoutParams layoutParams2 =new android.view.ViewGroup.LayoutParams(android.view.ViewGroup.LayoutParams.WRAP_CONTENT, android.view.ViewGroup.LayoutParams.MATCH_PARENT);
19
    TextView textView=new TextView(context);
20
    textView.setText("正在加载.....");
21
    textView.setTextSize(15);
22
    textView.setLayoutParams(layoutParams2);
23
    textView.setGravity(Gravity.CENTER_VERTICAL);
24
    //设置子控件
25
    loadLayout.addView(progressBar);
26
    loadLayout.addView(textView);
27
  }

基本上靠这段代码来判断是否加载的

1
/**
2
   * 设置滚动监听
3
   */
4
  private void setListViewOnScroll() {
5
    if (listView!=null) {
6
      listView.setOnScrollListener(new OnScrollListener() {
7
        //正在移动
8
        @Override
9
        public void onScrollStateChanged(AbsListView view, int scrollState) {
10
          Log.i(CustomSwipeRefreshLayout, ""+listView.getLastVisiblePosition());
11
          if (canLoadMore()) {//判断加载条件是否成立
12
            loadData();//加载数据
13
          }else {
14
            Log.i(CustomSwipeRefreshLayout, "不可以加载新数据");
15
          }
16
        }
17

18
        @Override
19
        public void onScroll(AbsListView view, int firstVisibleItem,
20
            int visibleItemCount, int totalItemCount) {
21
          // TODO Auto-generated method stub
22

23
        }
24
      });
25
    }
26
  }

我们需要先把所有条件成立，即什么时候可以加载数据的条件：

1、是否已经正在加载数据了，正在加载，我们不允许再次加载的，因为一般都执行线程，所以执行太多会卡的

2、是否滑动到最后一个item，所以使用listview.getLastVisblePosition()==(listview.getCount()-1)

3、触摸滑动的距离是否符合我们的标准的

获取触摸，用来判断是否符合滑动距离

1
  //获取startY和endY
2
  @Override
3
  public boolean dispatchTouchEvent(MotionEvent ev) {
4
    //按下时
5
    if (ev.getAction()==MotionEvent.ACTION_DOWN) {
6
      startY=ev.getY();
7
    }
8
    //手指离开时
9
    else if(ev.getAction()==MotionEvent.ACTION_UP){
10
      endY=ev.getY();
11
    }
12
    return super.dispatchTouchEvent(ev);
13
  }

这个就是加载条件的代码

1
/**
2
   * 三个条件可以加载数据
3
   * 1、滑动距离合适的时候
4
   * 2、最后一个条目
5
   * 3、没有正在加载数据
6
   * @return
7
   */
8
  protected boolean canLoadMore() {
9
    //判断没有在加载
10
    boolean condition1=false;
11
    if (!isLoading){
12
      condition1=true;
13
    }
14
    //判断是最后item并且已显示
15
    boolean condition2=false;
16
    if (listView.getLastVisiblePosition()==(listView.getCount()-1)) {
17
      condition2=true;
18
    }
19
    //判断滑动距离是否合适，touchInstance这个设置个差不多就行
20
    boolean condition3=false;
21
    if ((startY-endY)>touchInstance) {
22
      condition3=true;
23
    }
24
    Log.i(CustomSwipeRefreshLayout, "是否正在加载"+condition1+"是否是最后一个并且已经显示出来"+condition2+"触摸距离是否合适"+condition3);
25
    return condition1&&condition2&&condition3;
26
  }

所有条件成立之后我们就可以加载数据了

1
/**
2
   * 接口回调实现自定义加载数据
3
   */
4
  protected void loadData() {
5

6
    if (onLoadListener!=null) {
7
      if (loadLayout!=null) {
8
        addLoadLayout();//添加footerView
9
      }
10
      onLoadListener.onLoad();
11
    }
12

13
  }
14
  //调用这个我们自定义刷新控件
15
    public void setOnLoadListener(OnLoadListener onLoadListener) {
16
    this.onLoadListener = onLoadListener;
17
  }

那什么时候remove加载条呢

1
//外部调用，即用户重写onLoadListener在onload方法中调用即可
2
  public void setOnload(boolean isLoad){
3
    isLoading=isLoad;
4
    if (!isLoad) {
5
      removeLoadLayout();
6
    }
7
  }

以下使用方法

XML写法

1
<com.tc.customswiperefreshview.CustomSwipeRefreshLayout
2
    android:id="@+id/customSwipeRefreshLayout "
3
    xmlns:android="http://schemas.android.com/apk/res/android"
4
    xmlns:tools="http://schemas.android.com/tools"
5
    android:layout_width="match_parent"
6
    android:layout_height="match_parent"
7
    tools:context="com.tc.customswiperefreshview.MainActivity" >
8
  <ListView
9
      android:id="@+id/listView"
10
      android:layout_width="match_parent"
11
      android:layout_height="match_parent"
12
      >
13
  </ListView>
14
</com.tc.customswiperefreshview.CustomSwipeRefreshLayout>

activity调用

1
customSwipeRefreshLayout.setOnLoadListener(new CustomSwipeRefreshLayout.OnLoadListener() {
2

3
      @Override
4
      public void onLoad() {
5
        new Handler().postDelayed(new Runnable() {
6

7
          @Override
8
          public void run() {
9
            if (test) {
10
              for (int i = 15; i <20; i++) {
11
                data.add("我是天才"+i);
12
                test=false;
13
              }
14
            }else {
15
              Toast.makeText(MainActivity.this, "没有数据啦", Toast.LENGTH_SHORT).show();
16
            }
17
            customSwipeRefreshLayout.setOnload(false);
18
            adapter.notifyDataSetChanged();
19
          }
20
        }, 1000);
21
      }
22
    });

接下来是两点注意问题：

1、addFooterView()需要在setAdapter之前调用怎么解决呢，其实我的这个解决也是不怎么好，对，就是重新获取adapter重新适配

1
private void addLoadLayout() {
2
    listView.addFooterView(loadLayout);
3
    if ( listView.getAdapter() instanceof BaseAdapter) {
4
      BaseAdapter adapter=(BaseAdapter) listView.getAdapter() ;
5
      listView.setAdapter(adapter);
6
      Log.i(CustomSwipeRefreshLayout, "是baseAdapter");
7
    }else{
8
      Log.i(CustomSwipeRefreshLayout, "不是baseAdapter");
9
    }
10
  }

2、之前一直报这个错误

Caused by: java.lang.NoSuchMethodException: [class android.content.Context, interface android.util.AttributeSet]

出错原因

1）

1
public CustomSwipeRefreshLayout(Context context) {
2
    super(context);
3
  }
4
  public CustomSwipeRefreshLayout(Context context, AttributeSet attrs) {//没有生成这个构造方法，所以报错
5
    super(context, attrs);
6
    this.context=context;
7
  }

2）

1
  private CustomSwipeRefreshLayout(Context context, AttributeSet attrs) {
2
    super(context, attrs);
3
    this.context=context;
4
  }

不知道有没有发现什么不一样的，就访问权限，private，说起来也是奇葩，eclipse快捷键自动生成的，居然是private

接下来贴出全部代码

1
package com.tc.customswiperefreshview;
2

3
import android.content.Context;
4
import android.support.v4.widget.SwipeRefreshLayout;
5
import android.util.AttributeSet;
6
import android.util.Log;
7
import android.view.Gravity;
8
import android.view.MotionEvent;
9
import android.view.View;
10
import android.widget.AbsListView;
11
import android.widget.AbsListView.OnScrollListener;
12
import android.widget.LinearLayout.LayoutParams;
13
import android.widget.BaseAdapter;
14
import android.widget.LinearLayout;
15
import android.widget.ListAdapter;
16
import android.widget.ListView;
17
import android.widget.ProgressBar;
18
import android.widget.RelativeLayout;
19
import android.widget.TextView;
20
import android.widget.Toast;
21

22
public class CustomSwipeRefreshLayout extends SwipeRefreshLayout {
23
  private static final String CustomSwipeRefreshLayout = "CustomSwipeRefreshLayout";
24
  public OnLoadListener onLoadListener;
25
  Context context;
26
  ListView listView;
27
  float startY=0;
28
  float endY=0;
29
  private static  float touchInstance=150;
30
  boolean isLoading=false;
31
  LinearLayout loadLayout;
32
  public CustomSwipeRefreshLayout(Context context) {
33
    super(context);
34
  }
35
  public CustomSwipeRefreshLayout(Context context, AttributeSet attrs) {
36
    super(context, attrs);
37
    this.context=context;
38
  }
39
  @Override
40
  protected void onLayout(boolean changed, int left, int top, int right,
41
      int bottom) {
42
    if (listView==null) {
43
      if (getChildCount()>0) {
44
        for (int i = 0; i < getChildCount(); i++) {
45
          if (getChildAt(i) instanceof ListView) {
46
            listView=(ListView) getChildAt(i);
47
            Log.i(CustomSwipeRefreshLayout, "找到了LIstView");
48
            initLoadLayout();//初始化加载控件
49
            setListViewOnScroll();//滚动监听
50
            break;
51
          }else {
52
            Log.i(CustomSwipeRefreshLayout, "不是LIstView的实例");
53
          }
54
        }
55
        Log.i(CustomSwipeRefreshLayout, "LIstView是否为空："+(listView==null));
56
      }
57
    }
58
    super.onLayout(changed, left, top, right, bottom);
59
  }
60

61

62

63
  public OnLoadListener getOnLoadListener() {
64
    return onLoadListener;
65
  }
66

67
  public void setOnLoadListener(OnLoadListener onLoadListener) {
68
    this.onLoadListener = onLoadListener;
69
  }
70

71
  /**
72
   * 设置滚动监听
73
   */
74
  private void setListViewOnScroll() {
75
    if (listView!=null) {
76
      listView.setOnScrollListener(new OnScrollListener() {
77
        //正在移动
78
        @Override
79
        public void onScrollStateChanged(AbsListView view, int scrollState) {
80
          Log.i(CustomSwipeRefreshLayout, ""+listView.getLastVisiblePosition());
81
          if (canLoadMore()) {
82
            loadData();
83
          }else {
84
            Log.i(CustomSwipeRefreshLayout, "不可以加载新数据");
85
          }
86
        }
87

88
        @Override
89
        public void onScroll(AbsListView view, int firstVisibleItem,
90
            int visibleItemCount, int totalItemCount) {
91
          // TODO Auto-generated method stub
92

93
        }
94
      });
95
    }
96
  }
97
  /**
98
   * 三个条件可以加载数据
99
   * 1、滑动距离合适的时候
100
   * 2、最后一个条目
101
   * 3、没有正在加载数据
102
   * @return
103
   */
104
  protected boolean canLoadMore() {
105
    boolean condition1=false;
106
    if (!isLoading){
107
      condition1=true;
108
    }
109
    boolean condition2=false;
110
    if (listView.getLastVisiblePosition()==(listView.getCount()-1)) {
111
      condition2=true;
112
    }
113
    boolean condition3=false;
114
    if ((startY-endY)>touchInstance) {
115
      condition3=true;
116
    }
117
    Log.i(CustomSwipeRefreshLayout, "是否正在加载"+condition1+"是否是最后一个并且已经显示出来"+condition2+"触摸距离是否合适"+condition3);
118
    return condition1&&condition2&&condition3;
119
  }
120
  /**
121
   * 接口回调实现自定义加载数据
122
   */
123
  protected void loadData() {
124

125
    if (onLoadListener!=null) {
126
      if (loadLayout!=null) {
127
        addLoadLayout();//添加footerView
128
      }
129
      onLoadListener.onLoad();
130
    }
131

132
  }
133
  private void addLoadLayout() {
134
    listView.addFooterView(loadLayout);
135
    if ( listView.getAdapter() instanceof BaseAdapter) {
136
      BaseAdapter adapter=(BaseAdapter) listView.getAdapter() ;
137
      listView.setAdapter(adapter);
138
      Log.i(CustomSwipeRefreshLayout, "是baseAdapter");
139
    }else{
140
      Log.i(CustomSwipeRefreshLayout, "不是baseAdapter");
141
    }
142
  }
143
  private void removeLoadLayout() {
144
    listView.removeFooterView(loadLayout);
145
  }
146

147
  public void setOnload(boolean isLoad){
148
    isLoading=isLoad;
149
    if (!isLoad) {
150
      removeLoadLayout();
151
    }
152
  }
153

154

155
  @Override
156
  public boolean dispatchTouchEvent(MotionEvent ev) {
157
    //按下时
158
    if (ev.getAction()==MotionEvent.ACTION_DOWN) {
159
      startY=ev.getY();
160
    }
161
    //离开时
162
    else if(ev.getAction()==MotionEvent.ACTION_UP){
163
      endY=ev.getY();
164
    }
165
    return super.dispatchTouchEvent(ev);
166
  }
167

168
  /**
169
   * 初始化底部加载视图
170
   */
171
  private void initLoadLayout() {
172
    //布局，由于父控件是ListView，所以 LayoutParams 是AbsListView的LayoutParams
173
    AbsListView.LayoutParams listLayoutParams =new AbsListView.LayoutParams(listView.getLayoutParams());
174
    listLayoutParams.width=LayoutParams.MATCH_PARENT;
175
    listLayoutParams.height=100;
176
    loadLayout=new LinearLayout(context);
177
    loadLayout.setOrientation(LinearLayout.HORIZONTAL);
178
    loadLayout.setLayoutParams(listLayoutParams);
179
    loadLayout.setGravity(Gravity.CENTER_HORIZONTAL);
180
    //dialog
181
    android.view.ViewGroup.LayoutParams layoutParams =new android.view.ViewGroup.LayoutParams(android.view.ViewGroup.LayoutParams.WRAP_CONTENT, android.view.ViewGroup.LayoutParams.MATCH_PARENT);
182
    ProgressBar progressBar=new ProgressBar(context,null,android.R.attr.progressBarStyleInverse);
183
    progressBar.setLayoutParams(layoutParams);
184
    //textview
185
    android.view.ViewGroup.LayoutParams layoutParams2 =new android.view.ViewGroup.LayoutParams(android.view.ViewGroup.LayoutParams.WRAP_CONTENT, android.view.ViewGroup.LayoutParams.MATCH_PARENT);
186
    TextView textView=new TextView(context);
187
    textView.setText("正在加载.....");
188
    textView.setTextSize(15);
189
    textView.setLayoutParams(layoutParams2);
190
    textView.setGravity(Gravity.CENTER_VERTICAL);
191
    //设置子控件
192
    loadLayout.addView(progressBar);
193
    loadLayout.addView(textView);
194
  }
195
   interface OnLoadListener{
196
    public void onLoad();
197
  }
198

199
}