ListView中展示SD卡、数据库、网络图片
ListView中显示SD卡、数据库、网络图片
实现下图，图片来自SD卡、数据库、网络图片
定义一个ListView的xml（res/layout/list_view.xml）
<?xml version="1.0" encoding="utf-8"?> <ListView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/h_list_view" android:layout_width="fill_parent" android:layout_height="fill_parent" />
Activity代码
public class MessageListActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home);
setViews();
}
private void setViews() {
ListView lv = (ListView)findViewById(R.id.h_list_view);
SimpleAdapter adapter = new ImageSimpleAdapter(this, getDatas() ,R.layout.message_list
, new String[]{"icon","title","shortContent"}, new int[]{R.id.ml_icon,R.id.ml_title,R.id.ml_short_content});
lv.setAdapter(adapter);
lv.setOnItemClickListener(new OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> av, View v, int position, long id) {
//处理列表项的点击事件
}
});
}
private List<Map<String,Object>> getDatas() {
List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
for (int i=1; i<=12; i++) {
Map<String,Object> map = new HashMap<String,Object>();
String imagePath = "/sdcard/image_0"+i+".jpg";
if (i >= 10) imagePath = "/sdcard/image_"+i+".jpg";
map.put("icon", BitmapFactory.decodeFile(imagePath));
map.put("title", "My Title "+i);
map.put("shortContent", "my short content "+i);
list.add(map);
}
return list;
}
}
SimpleAdapter中能放置drawable中的图片，如果想放置其它来源的图片（如：SD卡、数据库、网络图片），那么需要重写它的bindView方法，这是个private方法，因此还需要重写所以调用它的方法。
package com.example.adapter;
import java.util.List;
import java.util.Map;
import android.content.Context;
import android.graphics.Bitmap;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Checkable;
import android.widget.ImageView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class ImageSimpleAdapter extends SimpleAdapter {
private int[] mTo;
private String[] mFrom;
private ViewBinder mViewBinder;
private List<? extends Map<String, ?>> mData;
private int mResource;
private int mDropDownResource;
private LayoutInflater mInflater;
public ImageSimpleAdapter(Context context, List<? extends Map<String, ?>> data, int resource, String[] from, int[] to) {
super(context, data, resource, from, to);
mTo = to;
mFrom = from;
mData = data;
mResource = mDropDownResource = resource;
mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public View getView(int position, View convertView, ViewGroup parent) {
return createViewFromResource(position, convertView, parent, mResource);
}
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
return createViewFromResource(position, convertView, parent, mDropDownResource);
}
private View createViewFromResource(int position, View convertView,
ViewGroup parent, int resource) {
View v;
if (convertView == null) {
v = mInflater.inflate(resource, parent, false);
} else {
v = convertView;
}
bindView(position, v);
return v;
}
private void bindView(int position, View view) {
final Map dataSet = mData.get(position);
if (dataSet == null) {
return;
}
final ViewBinder binder = mViewBinder;
final String[] from = mFrom;
final int[] to = mTo;
final int count = to.length;
for (int i = 0; i < count; i++) {
final View v = view.findViewById(to[i]);
if (v != null) {
final Object data = dataSet.get(from[i]);
String text = data == null ? "" : data.toString();
if (text == null) {
text = "";
}
boolean bound = false;
if (binder != null) {
bound = binder.setViewValue(v, data, text);
}
if (!bound) {
if (v instanceof Checkable) {
if (data instanceof Boolean) {
((Checkable) v).setChecked((Boolean) data);
} else if (v instanceof TextView) {
// Note: keep the instanceof TextView check at the bottom of these
// ifs since a lot of views are TextViews (e.g. CheckBoxes).
setViewText((TextView) v, text);
} else {
throw new IllegalStateException(v.getClass().getName() +
" should be bound to a Boolean, not a " +
(data == null ? "<unknown type>" : data.getClass()));
}
} else if (v instanceof TextView) {
// Note: keep the instanceof TextView check at the bottom of these
// ifs since a lot of views are TextViews (e.g. CheckBoxes).
setViewText((TextView) v, text);
} else if (v instanceof ImageView) {
if (data instanceof Integer) {
setViewImage((ImageView) v, (Integer) data);
} else if (data instanceof Bitmap) {//仅仅添加这一步
setViewImage((ImageView) v, (Bitmap)data);
} else {
setViewImage((ImageView) v, text);
}
} else {
throw new IllegalStateException(v.getClass().getName()
+ " is not a view that can be bounds by this SimpleAdapter");
}
}
}
}
}
/**
* 添加这个方法来处理Bitmap类型参数
* @param v
* @param bitmap
*/
public void setViewImage(ImageView v, Bitmap bitmap) {
v.setImageBitmap(bitmap);
}
}
使用这个类替代SimpleAdapter就可以放SD卡、数据库、网络图片了（先将图片转换成Bitmap）
适配器布局（res/layout/message_list.xml）
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageView android:id="@+id/ml_icon" android:layout_width="50dp" android:layout_height="58dp" android:src="@drawable/ml_default_image" /> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="58dp" android:layout_weight="1"> <TextView android:id="@+id/ml_title" android:layout_width="fill_parent" android:layout_height="25dp" android:textStyle="bold" android:textSize="20dp" /> <TextView android:id="@+id/ml_short_content" android:layout_width="fill_parent" android:layout_height="35dp" /> </LinearLayout> <TextView android:layout_width="30dp" android:layout_height="58dp" android:text=">" android:textSize="26dp" android:layout_gravity="right" android:gravity="center" /> </LinearLayout>