自动加载下一页
社会化APP（比如凤凰FM）在列表类页面中，当用户滑动到当前页面的最后一条数据后，会自动下载下一页数据。今天在这里做一个Demo探究一下。
理论讲解
- 定义一个加载更多的接口
package com.example.androidtest;
/** */
public interface LoadListDataInterface {
/** * * @param position getView */
public void loadMoreData();
}
- 在Activity中实现该接口
package com.example.androidtest;
public class MainActivity extends Activity implements LoadListDataInterface {
@Override
public void loadMoreData() {
//TODO
}
}
- 将该接口放入Adapter中，借用Adapter.getView判断用户是否滑动到了最后一条数据
public LoadNextAdapter(Context context, LoadListDataInterface dataInferface) {
this.mContext = context;
mLoadDataInferface = dataInferface;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (mLoadDataInferface != null && position == getCount() - 1) {
mLoadDataInferface.loadMoreData();
} public void appendData(List<AnchorBean> anchorList) {
if (mData == null) {
mData = new ArrayList<AnchorBean>();
}
if (anchorList != null && anchorList.size() > 0) {
mData.addAll(anchorList);
// be careful,notifyDataSetChanged must be called when there is more
// data
// or there will be a loop request
notifyDataSetChanged();
}
}这里要注意以下，获取下一页数据的时候，只有“真”的获取到了数据在调用notifyDataSetChanged()，否则会陷入死循环。
到这里就结束了。
2.张贴详细代码
由于网络访问/网络数据的解析等较为繁琐，这里使用了Volley+Gson完成。
- Model
package com.example.androidtest.model;
import com.google.gson.JsonObject;
import com.google.gson.annotations.SerializedName;
/** * 用于解析从服务器返回的数据 * * @author Chuanhang.Gu * */
public class ResponseBean {
@SerializedName("ErrorCode")
private String errorCode;
@SerializedName("ErrorString")
private String errorString;
/** * 当返回的数据合法时，才有意义 */
@SerializedName("ResponseObject")
private JsonObject responseObject;
@Override
public String toString() {
return "ErrorCode:" + errorCode + " ErrorString:" + errorString
+ " ResponseObject" + responseObject;
}
public String getErrorCode() {
return errorCode;
}
public void setErrorCode(String errorCode) {
this.errorCode = errorCode;
}
public String getErrorString() {
return errorString;
}
public void setErrorString(String errorString) {
this.errorString = errorString;
}
public JsonObject getResponseObject() {
return responseObject;
}
public void setResponseObject(JsonObject responseObject) {
this.responseObject = responseObject;
}
}
package com.example.androidtest.model;
import java.io.Serializable;
/** * @author Chuanhang.Gu * */
public class AnchorBean implements Serializable{
public static final String tableName = "UserTable";
private static final long serialVersionUID = 1L;
private String UserName;
public String getUserName() {
return UserName;
}
public void setUserName(String userName) {
UserName = userName;
}
}
- LoadNextAdapter.java
-
用到的布局文件item.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/usernameTextView" android:layout_width="match_parent" android:layout_height="100dp" android:gravity="center" android:textColor="@color/black" android:textStyle="bold" />
package com.example.androidtest;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import com.example.androidtest.model.AnchorBean;
public class LoadNextAdapter extends BaseAdapter {
private LoadListDataInterface mLoadDataInferface;
private List<AnchorBean> mData;
private Context mContext;
private LayoutInflater inflater;
public LoadNextAdapter(Context context, LoadListDataInterface dataInferface) {
this.mContext = context;
mLoadDataInferface = dataInferface;
inflater = (LayoutInflater) mContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public List<AnchorBean> getData() {
return mData;
}
public void setData(List<AnchorBean> anchorList) {
mData = anchorList;
notifyDataSetChanged();
}
public void appendData(List<AnchorBean> anchorList) {
if (mData == null) {
mData = new ArrayList<AnchorBean>();
}
if (anchorList != null && anchorList.size() > 0) {
mData.addAll(anchorList);
// be careful,notifyDataSetChanged must be called when there is more
// data
// or there will be a loop request
notifyDataSetChanged();
}
}
@Override
public AnchorBean getItem(int position) {
return mData == null ? null : mData.get(position);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (mLoadDataInferface != null && position == getCount() - 1) {
mLoadDataInferface.loadMoreData();
}
View v = convertView;
ViewHolder viewHolder;
if (v == null) {
v = inflater.inflate(R.layout.item, parent, false);
viewHolder = new ViewHolder();
viewHolder.userNameTextView = (TextView) v
.findViewById(R.id.usernameTextView);
v.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) v.getTag();
}
AnchorBean anchorBean = getItem(position);
viewHolder.userNameTextView.setText(anchorBean.getUserName());
return v;
}
@Override
public int getCount() {
return mData == null ? 0 : mData.size();
}
static class ViewHolder {
TextView userNameTextView;
}
@Override
public long getItemId(int position) {
return 0;
}
}- MainActivity
package com.example.androidtest;
import java.util.List;
import android.app.Activity;
import android.net.Uri;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.Toast;
import com.android.volley.RequestQueue;
import com.android.volley.Response.ErrorListener;
import com.android.volley.Response.Listener;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.Volley;
import com.example.androidtest.model.AnchorBean;
import com.example.androidtest.model.ResponseBean;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;
public class MainActivity extends Activity implements LoadListDataInterface {
public static final String BASE_URL = "http://www.dingdongfm.com/DingDongFM/servlet/MobileServlet";
public static final String TAG = MainActivity.class.getSimpleName();
protected LoadNextAdapter mAdapter;
private ListView mListView;
public static final int ITEM_PAGE = 7;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mListView = new ListView(this);
setContentView(mListView);
mAdapter = new LoadNextAdapter(this, this);
mListView.setAdapter(mAdapter);
loadMoreData();
}
@Override
public void loadMoreData() {
Uri.Builder uriBuilder = Uri
.parse(BASE_URL)
.buildUpon()
.appendQueryParameter("ObjectName", "UserTable")
.appendQueryParameter("Style", "Total")
.appendQueryParameter("StartRow", "" + mAdapter.getCount())
.appendQueryParameter("EndRow",
"" + (mAdapter.getCount() + ITEM_PAGE))
.appendQueryParameter("model", "" + 28);
GsonRequest<ResponseBean> gsonRequest = new GsonRequest<ResponseBean>(
uriBuilder.build().toString(), ResponseBean.class, null,
mSuccessListener, errorListener);
gsonRequest.setShouldCache(false);
RequestQueue mQueue = Volley.newRequestQueue(MainActivity.this);
mQueue.add(gsonRequest);
}
ErrorListener errorListener = new ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
// TODO Auto-generated method stub
}
};
Listener<ResponseBean> mSuccessListener = new Listener<ResponseBean>() {
@Override
public void onResponse(ResponseBean responseBean) {
GsonBuilder gsonBuilder = new GsonBuilder();
Gson gson = gsonBuilder.create();
List<AnchorBean> anchorList = null;
try {
anchorList = gson.fromJson(responseBean.getResponseObject()
.getAsJsonArray("UserTable"),
new TypeToken<List<AnchorBean>>() {
}.getType());
if (mAdapter.getCount() == 0) {
mAdapter.setData(anchorList);
} else if (mAdapter.getCount() > 0) {
mAdapter.appendData(anchorList);
} else if (anchorList.size() == 0) {
Toast.makeText(MainActivity.this, " no more data ~",
Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
e.printStackTrace();
}
}
};
}
Demo下载：
http://download.csdn.net/detail/guchuanhang/9507965