Android ListView 的优化使用

第一种写法：BaseAdapter的使用

   1.布局中添加listview

       main_layout.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

    <ListView
android:id="@+id/list"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
    </ListView>

</LinearLayout>

2.定义listview条目布局

item.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"
android:orientation="vertical">
    <TextView
android:id="@+id/tv1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="我是标题"/>
    <TextView
android:id="@+id/tv2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="我是文章"/>

</LinearLayout>

3.主activity中获取控件，添加适配器

ListViewlistView;

listView = (ListView) findViewById(R.id.list);

listView.setAdapter(new MyAdapter());

4.写适配类继承于BaseAdapter

(1).第一种常规写法

class MyAdapter extends BaseAdapter {
    View vv;

//listview长度
@Override
public int getCount() {
return result.size();
}

//当前的listview
@Override
public Object getItem(int i) {
return result.get(i);
}

//listview的id
@Override
public long getItemId(int i) {
return i;
}

//listview 的条目
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder holder;
        if (view == null) {
vv = View.inflate(getApplicationContext(), R.layout.item_fre, null);
holder = new ViewHolder();
holder.textView = (TextView) vv.findViewById(R.id.tv1);
holder.textView2 = (TextView) vv.findViewById(R.id.tv2);
vv.setTag(holder);
} else {
vv = view;
holder = (ViewHolder) vv.getTag();
}
        String title = (String) result.get(i).get("title");
String title2 = (String) result.get(i).get("url");
holder.textView.setText(title);
holder.textView2.setText(title2);
        return vv;
}

//承载控件的viewholder
class ViewHolder {
        TextView textView;
TextView textView2;
}
}

(2).第二种优化写法,把臃肿的getView的代码移动到holdview中

class MyAdapter extends BaseAdapter {
//listview长度
@Override
public int getCount() {
return result.size();
}

//当前的listview
@Override
public Object getItem(int i) {
return result.get(i);
}

//listview的id
@Override
public long getItemId(int i) {
return i;
}

//listview 的条目
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder holder;
        if (view == null) {
            holder = new ViewHolder();
} else {
            holder = (ViewHolder) view.getTag();
}
        String title = (String) result.get(i).get("title");
String title2 = (String) result.get(i).get("url");
holder.textView.setText(title);
holder.textView2.setText(title2);
        return holder.getVv();
}

//承载控件的viewholder
class ViewHolder {
        View vv;
TextView textView;
TextView textView2;
        public ViewHolder() {
              initView();
}
private void initView() {
vv = View.inflate(getApplicationContext(), R.layout.item_fre, null);
            this.textView = (TextView) vv.findViewById(R.id.tv1);
            this.textView2 = (TextView) vv.findViewById(R.id.tv2);
vv.setTag(this);
}
public View getVv() {
return vv;
}
    }
}

(3),第三种代码提取，减少代码的复用，此多用于项目需要写多个listview的

  --建立BaseHolder用于提取许多viewHolder中相似或者重复的代码

package googlestory.siqiyan.com.csdntest;

import android.view.View;
/**
 * 泛型T代表list里面的数据类型
* Created by threes on 2016/2/6.
 */
public abstract class BaseHolder<T> {
protected View vv;
      protected T  data;
    public BaseHolder() {
vv = initView();
vv.setTag(this);//在此位置设置标签
}
/**
     * 为listveiw设置数据
* @param data 条目数据
*/
public void setData(T data) {
this.data=data;
refreshView(data);
}
/**
     * 当Holder中的view对象显示到界面上的时候调用
* @return
*/
public View getVview() {
return vv;
}
/**
     * 初始化View对象 及其控件
* @return
*/
public abstract View  initView();
/**
     * 当setData调用的时候 会调用该方法  根据数据 显示界面
*/
public abstract void  refreshView(T data);
}

  --建立DefaultAdapter用于提取许多BaseAdapter中相似或者重复的代码

package googlestory.siqiyan.com.csdntest;

import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import java.util.List;
/**
 * 泛型T代表list里面的数据类型
* Created by threes on 2016/2/6.
 */
public abstract class DefaultAdapter<T> extends BaseAdapter {
    List<T> datas;
//创建构造函数初始化的时候给数据赋值
public DefaultAdapter(List<T> datas) {
this.datas = datas;
}
@Override
public int getCount() {
return datas.size();
}
@Override
public Object getItem(int i) {
return datas.get(i);
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
        BaseHolder<T> holder;
        if (view == null) {
            holder = getHolder();
} else {
            holder = (BaseHolder<T>) view.getTag();
}
T string = datas.get(i);//获取listview条目的数据
holder.setData(string);
        return holder.getVview();
}
protected abstract BaseHolder<T> getHolder();
}

此时mainActivity的代码如下

package googlestory.siqiyan.com.csdntest;

import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.appindexing.Action;
import com.google.android.gms.appindexing.AppIndex;
import com.google.android.gms.common.api.GoogleApiClient;
import com.lidroid.xutils.HttpUtils;
import com.lidroid.xutils.exception.HttpException;
import com.lidroid.xutils.http.ResponseInfo;
import com.lidroid.xutils.http.callback.RequestCallBack;
import com.lidroid.xutils.http.client.HttpRequest;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MainActivity extends AppCompatActivity {
    List<Map<String, Object>> datas ;
ListView listView;
String path = "http://www.youkuaiyun.com/";
    private GoogleApiClient client;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
datas = new ArrayList<>();
getIntepubntnet();
listView = (ListView) findViewById(R.id.list);
listView.setAdapter(new MyAdapter(datas));
client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}

@Override
public void onStart() {
super.onStart();
client.connect();
Action viewAction = Action.newAction(
                Action.TYPE_VIEW, // TODO: choose an action type.
"Main Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
                // Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://googlestory.siqiyan.com.csdntest/http/host/path")
        );
AppIndex.AppIndexApi.start(client, viewAction);
}
@Override
public void onStop() {
super.onStop();

// ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
Action viewAction = Action.newAction(
                Action.TYPE_VIEW, // TODO: choose an action type.
"Main Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
                // Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://googlestory.siqiyan.com.csdntest/http/host/path")
        );
AppIndex.AppIndexApi.end(client, viewAction);
client.disconnect();
}

class MyAdapter extends DefaultAdapter<Map<String, Object>> {
public MyAdapter(List<Map<String, Object>> datas) {
super(datas);
}
@Override
protected BaseHolder<Map<String, Object>> getHolder() {
return new ViewHolder();
}
    }
//承载控件的viewholder
class ViewHolder  extends BaseHolder<Map<String, Object>>{
        TextView textView;
TextView textView2;
        public View initView() {
vv = View.inflate(getApplicationContext(), R.layout.item_fre, null);
            this.textView = (TextView) vv.findViewById(R.id.tv1);
            this.textView2 = (TextView) vv.findViewById(R.id.tv2);
            return vv;
}
@Override
public void refreshView(Map<String, Object> datas) {
            String title = (String) datas.get("title");
String title2 = (String) datas.get("url");
System.out.println(title);
textView.setText(title);
textView2.setText(title2);
}
    }
private void getIntepubntnet() {
        HttpUtils utils = new HttpUtils();
utils.send(HttpRequest.HttpMethod.GET, path, new RequestCallBack<String>() {
@Override
public void onFailure(HttpException arg0, String arg1) {
                Toast.makeText(getApplicationContext(), "加载失败",
Toast.LENGTH_SHORT).show();
}
@Override
public void onSuccess(ResponseInfo<String> res) {
                Toast.makeText(getApplicationContext(), "加载成功",
Toast.LENGTH_SHORT).show();
String ss = res.result;
getCsdnNetDate(ss);
}
        });
}
private void getCsdnNetDate(String da) {
        String csdnString = da;
String pp = " href=\"(.*?)\" data-original.*? alt=\"(.*?)\"";
String p2 = "title=\"(.*?)\" href=\"(.*?)\".*?363";
Pattern p = Pattern.compile(p2);
Matcher m = p.matcher(csdnString);
        while (m.find()) {
            MatchResult mr = m.toMatchResult();
Map<String, Object> map = new HashMap<String, Object>();
map.put("title", mr.group(1));
map.put("url", mr.group(2));
datas.add(map);
}
    }
}

修改代码前版本：

package googlestory.siqiyan.com.csdntest;

import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.appindexing.Action;
import com.google.android.gms.appindexing.AppIndex;
import com.google.android.gms.common.api.GoogleApiClient;
import com.lidroid.xutils.HttpUtils;
import com.lidroid.xutils.exception.HttpException;
import com.lidroid.xutils.http.ResponseInfo;
import com.lidroid.xutils.http.callback.RequestCallBack;
import com.lidroid.xutils.http.client.HttpRequest;

import java.text.Format;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MainActivity extends AppCompatActivity {
    List<String> ff = new ArrayList<>();
List<Map<String, Object>> result = new ArrayList<Map<String, Object>>();

ListView listView;
String path = "http://www.youkuaiyun.com/";
/**
     * ATTENTION: This was auto-generated to implement the App Indexing API.
     * See https://g.co/AppIndexing/AndroidStudio for more information.
     */
private GoogleApiClient client;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.list);
getIntepubntnet();
listView.setAdapter(new MyAdapter());
client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}

@Override
public void onStart() {
super.onStart();

// ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
client.connect();
Action viewAction = Action.newAction(
                Action.TYPE_VIEW, // TODO: choose an action type.
"Main Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
                // Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://googlestory.siqiyan.com.csdntest/http/host/path")
        );
AppIndex.AppIndexApi.start(client, viewAction);
}
@Override
public void onStop() {
super.onStop();

// ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
Action viewAction = Action.newAction(
                Action.TYPE_VIEW, // TODO: choose an action type.
"Main Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
                // Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://googlestory.siqiyan.com.csdntest/http/host/path")
        );
AppIndex.AppIndexApi.end(client, viewAction);
client.disconnect();
}

class MyAdapter extends BaseAdapter {
//listview长度
@Override
public int getCount() {
return result.size();
}

//当前的listview
@Override
public Object getItem(int i) {
return result.get(i);
}

//listview的id
@Override
public long getItemId(int i) {
return i;
}

//listview 的条目
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
            ViewHolder holder;
            if (view == null) {
                holder = new ViewHolder();
} else {
                holder = (ViewHolder) view.getTag();
}
            String title = (String) result.get(i).get("title");
String title2 = (String) result.get(i).get("url");
holder.textView.setText(title);
holder.textView2.setText(title2);
            return holder.getVv();
}

//承载控件的viewholder
class ViewHolder {
            View vv;
TextView textView;
TextView textView2;
            public ViewHolder() {
                  initView();
}
private void initView() {
vv = View.inflate(getApplicationContext(), R.layout.item_fre, null);
                this.textView = (TextView) vv.findViewById(R.id.tv1);
                this.textView2 = (TextView) vv.findViewById(R.id.tv2);
vv.setTag(this);
}
public View getVv() {
return vv;
}
        }
    }


private void getIntepubntnet() {
        HttpUtils utils = new HttpUtils();
utils.send(HttpRequest.HttpMethod.GET, path, new RequestCallBack<String>() {
@Override
public void onFailure(HttpException arg0, String arg1) {
                Toast.makeText(getApplicationContext(), "加载失败",
Toast.LENGTH_SHORT).show();
}
@Override
public void onSuccess(ResponseInfo<String> res) {
                Toast.makeText(getApplicationContext(), "加载成功",
Toast.LENGTH_SHORT).show();
String ss = res.result;
getCsdnNetDate(ss);
}
        });

}

private void getCsdnNetDate(String datas) {
        String csdnString = datas;
String pp = " href=\"(.*?)\" data-original.*? alt=\"(.*?)\"";
String p2 = "title=\"(.*?)\" href=\"(.*?)\".*?363";
Pattern p = Pattern.compile(p2);
Matcher m = p.matcher(csdnString);
        while (m.find()) {
            MatchResult mr = m.toMatchResult();
Map<String, Object> map = new HashMap<String, Object>();
map.put("title", mr.group(1));
map.put("url", mr.group(2));
result.add(map);
}
    }
}

第二种写法：ArrayAdapter的使用 

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = (ListView) findViewById(R.id.list2);

        String[] ff= new String[]{"小名","小挂钩","小高","王热","李四","话哈"};
        ArrayAdapter<String > adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_checked,ff);
        listView.setAdapter(adapter);
    }
}

listview 指定的外观:

android.R.layout.simple_list_item_1   每个列表项都是一个普通的文本

android.R.layout.simple_list_item_2   每个列表都是一个普通的文本（字体略大）

android.R.layout.simple_list_item_checked  每个列表都有一个已勾选的列表

android.R.layout.simple_list_item_multiple_choice   每个列表项都是带多选框的文本

android.R.layout.simple_list_item_single_choice    每个列表项都是带单选按钮的文本